Monday, January 28, 2008

Winter weather outlook for the next two weeks

For snowlovers, in a word: Yuck!

It's not a particularly warm pattern, but all the storms projected by models are "cutters" -- they drive northeastward toward the Great Lakes, passing to our west. There is almost no way to get winter weather in the Carolinas when storms pass to our west.

Anyway, this pattern rinses and repeats a number of times in the next 2 weeks.

There are SOME indications we move back to a more favorable pattern around Feb. 10 or so, but we'll have to see about that.

Bottom line: It won't be balmy by any stretch (highs generally in the 50s) and there will be some cold-air damming events that lead to chilly rains. But as far as snow goes, we're at least two weeks away from a realistic shot.


Sunday, January 20, 2008

Looking ahead to next week

Not sure what the hype is regarding potential storms next week -- models are not impressive.

There is some indication some light freezing rain might break out Tuesday morning before quickly changing to rain, but now the models aren't even forecasting much precip with that system.

Same with Thursday.

It will be a chilly week -- somewhat below normal (tonight, well below normal with lows in the teens to near 10), but doesn't look as storm as it did a few days ago.

Then, we warm up slightly the following week.

That will put us past the midway point of climatological winter, but February is a strong months for us in terms of winter potential, so don't give up the ship.

I'll be on a business trip next week, so updates will be less frequent unless I see something very compelling and have time to post.

Saturday, January 19, 2008

All over but the shouting

Radar upstream of us is thinning out -- it will get below freezing shortly, so whatever falls will stick, but I don't see much falling -- maybe a dusting.

Thanks for sticking it out all you observation posters -- I haven't looked closely at down the road, but the pattern remains decent so we'll have some more shots -- we'll get us a good one here soon, hopefully.

Sorry this one didn't pan out -- I sure wish it had.

1:45 p.m.: Snow showing up -- is it too late

Concerned that the radar back over N. Ga. is thinning out -- hoping our precip doesn't poop out before the VERY tardy cold air arrives in force. We'll be wondering how we lacked cold air tomorrow and tommorow night when it's bone-chilling cold, esp. at night with lows in the teens.

We can start posting comments in this post because the other had gotten so long.

It's really fun to share observations, but if you are trolling I will start deleting your posts.

11:00 a.m -- tracking the storm

OK, want to make a nice clean thread for observations -- use the comment tool to post conditions where you are.

Most of N. Georgia now changing to snow -- cold air racing down the mountains.

Will it beat the precip???????

10:30 a.m. update: Still hope

Frankly, my love for snow is being overcome with my fascination in this system.

First, temps and dewpoints are CRASHING to our north and west.

Go this link and then hover over "dew," which is dewpoints. You can see the arctic air pouring in from the northwest. As precip falls through this drier air it will cool the surface temperature.

Dewpoints in the mid 20s have made it as far as Henderson County.

Now, check out this radar loop.

Clearly, we are going to see precipitation.

Now, the fascinating part -- will the cold air beat or meet the precip?

This is why this is such an unusual system and why the professional forecasters have been pulling their hair out over it.

Good news: There has been a changover to snow in some places in N. Ga.

More good news: NAM puts us back in to about .4-.5 inches of precip.

Bad news: Clearly the models overestimated the speed at which cold air would arrive.

Verdict: There aren't many times you can be 2-4 hours away from an event and STILL not know what's going to happen.

I think we will see snow today -- whether it's a quick burst at the end of a long rain or accumulating snows remains to be seen.

Watch that radar and local observations for the verdict.

IMPORTANT: Rutherford County posters -- please share your conditions as well as Cleveland County folks on the west side of the county -- when you turn sharply colder, the rest of us will be soon to follow. Also, it will be interesting to know the intensity of the precip band that's moving in, so Gaffney folks and others on the southwest, let us know how hard it rains at the start.

Let's not give up hope!

6:50 am. update: Hopes are high

Overnight, the National Weathe Service saw something they liked in the radar trends. Check out this snippet from their area forecast discussion:


The "FA" is their forecast area and "warning criteria" snows would be 4 inches or more.

Radar trends look OK to me -- I don't see where we're a mortal lock for big precip, but the shield is definitely north of where models said it would be.

It's warm -- low 40s -- but don't let that fool you -- the arctic air is racing in from the east -- it's snow in places like Tuscaloosa and other points in Alabama and Ga. have winter precip. As mentioned before, we'll start out as a short period of rain before changing over -- if we do, in fact, see precip.

I'm going to look at some more data but it's primarily radar-watching time.

Fingers crossed!

Friday, January 18, 2008

0z GFS: Guess what?

It trended west -- not a lot, but by golly, by the looks of the maps it checks in back up to about .3-.4 inches of liquid.

Where does that leave us?

Apparently, only the snowman knows.

You saw my call earlier today (felt like I needed to put a prediction out there before, you know, the event actually begins, which it will in about 12 hours).

It showed the highest probability being 1-2 inches
Next highest 1 inch or less
And next highest 2-4 inches.

I'll stick with that while confessing I really have no idea what is going to happen tomorrow -- those are nothing more than educated guesses.

Off to bed -- I'm going to try and get up early for an early morning update -- by then we should know how the event will unfold.

Thanks for all your support!

0z NAM: A painful betrayal

The NAM has been our friend in the leadup this storm. It's the one that first latched on to the storm and it's the model that has kept the highest precip totals over the past few days.

Tonight, after all that flirting, it dumped us.

The 0z NAM lurched south taking most of its precip with it. Instead of a 4-6 inch snow, it leaves us with a paltry .25 inches of precip -- barely enough for an inch, maybe 2 of snow. This puts it squarely in the GFS camp and means the chances of a big snow -- as I have feared all day -- have greatly diminished.

Here is the 0z NAM precip map for the storm.
Here's the same map, but from the 18z NAM.

While from afar the differences may seem subtle, if you zoom in, you see that the dark blue area of precip (.5 or higher) that brushed the southeast corner of Cleveland County has retreated 80 miles to the southeast (we were hoping for an 80 mile move THE OTHER WAY).

Now, there is model agreement that this is a very minor event for us. Worse yet, any type of further move east could result in just a dusting of snow or no snow at all.

Is there hope?
A glimmer or two. First, temps are great. There may be a quick initial period of rain, but it will quickly and permanently be cold enough for snow. Second, radar trends from the Gulf Coast still aren't matching up with the models' short term forecasts. It could be simply a complex system that the models are not and will not correctly forecast -- it has happened before. But that's hoping, not forecasting.

I would now place heavy emphasis on a marginal to minor event from a dusting to 1 inch, possibly 2.

Maybe the 0z GFS will do the same flip flop the other way, but this one is looking like a very near and very frustrating miss.

3:30 p.m. update: Some good signs

A few good signs.

1) The 18z NAM inched west. It now gives us .5 inches of precip again -- probably a 2-4 inch snow. 18z GFS out later this afternoon -- it will REALLY tell the tale.
2) Radar trends are good. None of the models projected precipitation making it north of the La./Ark. border, which has obviously happened -- for us it's all about north trends with precip. You can follow this all night
3) The EURO -- which had not been our friend for this entire storm -- made a late jump north this afternoon. The very short term is hardly this model's specialty, but we'll take any trend we can get.
4) WBTV -- a weather operation which I greatly respect -- is calling for 4-6 inches in our area. Frankly, I can't believe they did that and I don't think that will verify, but it shows that some pros have confidence in the upper end of the forecast.

The new weather service forecast is, I said earlier, for 1-3 inches. I think that's prudent and probably where I would fall if you pinned me down.

Precip will likely start as a rain snow mix before quickly changing to all snow -- heaviest precip should be late morning/early afternoon.

Here's the latest breakdown:

No precip: 2 percent
All rain: less than 1 percent
Marginal event (1 inch or less of snow): 27 percent
Minor event (1-2 inches): 34 percent
Moderate event (2-4 inches) 24 percent
Major event (4-6 inches) 8 percent
Big dog event (6 inches or higher) 5 percent

As you can see, I'm giving us a 58 percent chance of an inch of snow or more. Of course, the half empty way to look at it is 30 percent chance of a dusting to nothing.

We'll see!

2:30 p.m.update: Advance word on NWS forecast

It appears that our Winter Storm Watch will become a Winter Weather Advisory for the new forecast package.

Expect snow accumulation forecasts somewhere between 1 and 3 inches.

Frankly, if we got 3 inches out of this I'd be thrilled.

Also, I keep forgetting to mention how cold it will be Sunday and particularly Sunday night -- if we have snow cover, lows could very well make it down into the single digits Monday morning.

Finally, there are positive indications from radars down in the Gulf Coast where precipitation is being reported north of where models said it would fall. This is the kind of trend we're looking for.

11:30 a.m. update: Bust potential high -- either way

This storm is a mess. I wouldn't want to be a NWS forecaster right now. Take Atlanta -- the 12z NAM says: 8-12 inches. The 12z GFS says: 1 inch. What do you do?

Here, the differences aren't that sever, but are marked.

The NAM held steady with a nice 2-4 inch snow for us with just under .5 of liquid. The NAM actually twitched back the west a little bit.

The GFS, however, nosed further to the east with OUR precip-- I can't get to numeric guidance yet, but we look to be at about .2 inches of liquid, which would be a dusting to 1 inch snow, maybe 2 inches tops. Yet, the area of .5-.75 precip and higher (4-5 inch snow) is in Union County, N.C. -- just 60 miles away! And the .75-1.0 inch sector (6-8 inches of snow) is only about another 75 miles ESE of that.

Meanwhile, another short range model called the MM5 gives us about .6, even more than the NAM.

Still waiting on the Canadian and UK models (which have been the farthest east).

Bottom line: I have extremely low confidence in this forecast. With a 70 mile error further east we could see a big fat nothing. With a 70-mile error further west we could see a half a foot of snow.

Then there is the differences BETWEEN the models -- the NAM gives us more than TWICE the precip as the GFS.

And we're less than 24 hours from the start of the event (still some time tomorrow morning or early afternoon).

My best guess right now is that we'll see an inch or so out of this, but that could change dramatically based on current radar observation in the Gulf or anything else for that matter.


7 a.m. update: Trend is not our friend

The model shift overnight continued to ease east -- that move is ushering in plenty of cold air, but taking precip with it.

Instead of looking at models with .5 to .8 of liquid falling - a 4-6 inch snow storm -- we are now down to the .2-.5 range -- more like 1-3 inches.

Still not a bad consolation prize, of course. And to wit, the National Weather Service has issued a Winter Storm Watch for Cleveland County and other counties to our east.

You'll notice, though, that we are the western most county in the watch area -- never like being "on the edge."

The 12z models will be crucial -- if the east trend is arrested and current model projections are close, we won't walk away empty handed.

But if the models continue to trend east, we will end up with little to nothing in the way of snow.

Also, this is a rare time when KM and Grover stand to do better than Casar in this storm -- the farther south and especially east you are the better.

Full update after the 12z model run late this morning.

Thursday, January 17, 2008

11 p.m. update: This one's going down to the wire

Have you ever watched a basketball game and even though it's early in the second half, you can see that both teams are evenly matched and that the game will be decided in the final moments?

That's the feeling I'm getting from the Saturday event.

The 0z NAM stubbornly hangs on to a snowy solution for us (and many other areas -- from Northern Miss. through Alabama, especially northern Ga. where Atlanta would get hammered).
Taken literally, the NAM spits out about .7 inches of liquid - at least a 4-6 inch snow.

The 0z GFS, on the other hand, eased a little farther east and took some moisture with it. Whereas it showed a nice moderate event at 18z, now it has scaled back to .3-.4 of an inch liquid, a 1-3 inch snow.

Here's the difference between the 18z and 0z runs -- for Saturday early afternoon.


You can see that we're solidly in the dark green on the first map, but barely in it on the second. It's subtle shift of less than 100 miles, but that's the kind of shift that is going to be very disappointing for someone in the southeast.

Could be us, but barring a real model consensus developing, we probably won't know until the event is right on top of us.

Now, I need to correct a point I think I made earlier. The NAM actually did better with the precip on last night's event. We had almost 1 inch of liquid. The problem is, so much of it was as sleet (a real precip eater -- 1 inch of rain equals 12 inches of snow, but 1 inch of rain equals just 2 inches of sleet) and then freezing rain.

Coming later tonight, the UK, Candian and Euro, but that will be past my bedtime (esp. after last night!).

I'll update first thing in the morning.

7:35 update: Saturday could be "all or nothing"

The 18z runs of the NAM and GFS look similar -- both gives us a moderate to heavy snow on Saturday.

Here is the NAM at dawn. Precip just moving in.
Then just after lunch. A nice snow.

Total accumulation for this model run is about ...

Now, here is the GFS at dawn. Looks pretty similar, huh?
And early afternoon. The field of precip looks different, but the amount is about the same.

Both atmospheric profiles show all snow, perhaps starting as rain for an hour or so.

Total snowfall for the NAM would be 5-8 and for the GFS would be 3-6.

I'd take either of those, wouldn't you?

The Euro, though, gives us just a dusting. The UK model nothing.

So, very much up in the air, but two of the most reliable models say we get a significant event starting Saturday.

Here's my first percentage breakdown on the storm:

No precip: 30 percent
All rain: Less than 1 percent
Marginal event (1 inch or less of snow): 5 percent
Minor event (1-2 inches): 10 percent
Moderate event (2-4 inches): 15 percent
Major event (4-6 inches): 25 percent
BIG DOG event (6 inches or more): 15 percent

Now, this might look odd, but there is rhyme to the reason. The gradient for this storm is going to be sharp. So, you'll have a broad area with major snows a broad area with nothing and then a small area with totals in between. So, it's kind of an all-or-nothing setup which means we have a 40 percent change of a major or big dog event and a similarly high percentage of nothing at all.

I would call this a particularly low confidence forecast, given the major model disagreement this close to the event.

2:30 p.m. update: Big, bad model shift

Boy, what looked so promising a couple hours a go took a big hit this afternon. One after one, new models runs shifted the track of Saturday's system south and east -- the Euro, UK and Canadian models all moved east of even the GFS this afternoon, giving us zippo in terms of precip.

Now, you've got the GFS hanging onto a minor 2 inch-type even for us and the NAM a major westward outlier model.

We're VERY close to this event meteorologically, so what I would expect is the outlier to "blink" and move toward the other models, but we'll have to see about that.

Right now, my expectations are very low -- would be happy with another minor event like the GFS depicts.

12z GFS -- Good ... but close to great

The 12z GFS reminds me so much of the maps in the days leading up to our big Feb. 2006 storm.

As you can see, it shows us getting just under .5 inches of precip -- a 2-4 inch snow which would be fine with me.

But if you slide that precip field just 60 miles west -- that total doubles or triples and looks like the NAM.

The issue here is called "phasing" and it has to do with interactions between disturbances in the different jet streams. I don't really understand it, but when there is phasing (as the NAM is showing moreso than the GFS) storms tend to be bigger and are drawn together, which often means a more northerly component to the track.

Anyway, if the GFS moves as far west on its next run as it does on this one, we'll be in the jackpot. Btw, temps look good on this run -- close, but good.

OK, need to get some real work done -- I'll update again late this afternoon or tonight.

Sat. storm update: NAM gives us a foot

I'm not saying it's right, I'm only saying -- this is what the 12z run of the NAM shows starting Saturday morning. Check out these maps and tell me if you've ever seen anything snowier.

Dawn on Saturday. Precip moves in with temps below freezing
Early Saturday afternoon. That's more than .75 liquid in a 6-hour period -- apparently all as snow. If accurate, that's 1-inch per hour snow for 6 hours. You do the math.
Saturday evening. Storm winding down, but not before another 2-3 inches falls.

Only thing about this run is temps look a little iffier, so we'll have to look at 12z GFS very closely. Still, the amazing thing about this event is that it is so CLOSE -- onset us just 48 hours away!

More to come......

7:50 a.m. update: This event is over; next one looms

Well, after my last post at 1:45 a.m. I took one last walk outside and darned if it didn't change to sleet just as I headed back inside. So, I wasn't surprised to see basically the same picture out my window when I woke up as when I went to bed.

The event looks to be over. Temps are at or above freezing, as best I can tell, in and around Cleveland County.

Looks like snow amounts ranged from 1-2 inches in Cleveland County. Rutherford County reported 3 inches with 4-6 in some mountain locations. I haven't gotten outside to check on the ice coating, but looking out my window, I don't see any trees dramatically bent over or branches on the ground.

The 1-2 was squarely in the middle of my "minor event" range in which I had the largest percentage chance of happening.

Now, on to Saturday. Unlike the relative model consistency we had with this storm, there is wide divergance just 54 hours on Storm No. 2. The meteogram attached to this post is from the 6z NAM.

Check out the second area of precip (on the right). As you can see 850 temps are solidly below freezing and we are AT freezing at the surface -- ALL SNOW. If taken literally, we're talking 6-8 inches.

Now, remember, the NAM overestimated the precip on our current system.

The GFS, on the other hand, misses us almost completely to the east. It is just as "wet" as the NAM, but that moisture is not over us. As a result, we get just a dusting of snow.

BUT, our old friend the EURO is solidly in the Saturday storm camp, spitting out a 2-8 storm across the region. There is also support from the Canadian and UK models.

So, VERY interesting and actually better POTENTIAL than this current storm, for which temperatures was always going to be an issue (and they still could be for the next storm, but there looks to be more leeway there).
Feel free to post your final observations and thoughts in this thread -- I'll update later today on the Saturday storm.

1:45 a.m. update: Packing it in -- but important parting thoughts

Couple things -- first off, when sleet and freezing rain begin to fall they will compact the snow that has fallen, so depending on when you crash and when that changover occurs, you might see less snow when you wake up then when you went to bed.

Secondly, however, some great looking bands getting ready to move through -- wouldn't surprise me one bit to wake up to 4-6 inches of snow.

Third, models are making a stunning move toward a SATURDAY snow storm (I've touched on this recently).

Now, pro mets who have early access to the Euro say it has come around and shows a snow here Saturday.

More on that in the AM.

Thanks for hanging with me folks -- I'll be up early to catch up.

12:45 a.m. update: Snow in Shelby

Finally (although actually right on schedule) it is snowing here in Shelby. Sounds like much of Cleveland County is getting snow. Next up -- when will snow start to accumulate and how much.

Keep those reports coming!

Wednesday, January 16, 2008

11:50 update: It's time

Just got a report of moderate to heavy snow in Gaffney -- I believe this is the band that will graduate us beyond flurries to some real snow -- temps are dropping across the county, evident that the column is being saturated and all the precip can start making it to the ground.

I expect (gulp) that by 1. a.m. at least the southern locations of Cleveland County will some decent snowfall.

Famous last words? We shall see.

Keep those reports coming! If you're going to make fun of us snow lovers, you're comments will have a short life.

11 p.m update: Does snow observe state lines?

It's almost like a wall at the N.C./S.C. state line -- have to keep reminding myself that this is just what the models forecasted -- onset of precip at around midnight, give or take. Still, it's tough to see the snow on radar just 30 or so miles away -- and hear reports from Gaffney and Spartanburg.

0Z GFS actually came in wetter -- giving us .8 inches of precip -- it's highest total so far. And upstream radar still filling in over Alabama, so still hours upon hours of precip to go.

But, if you're like me, you want the snow NOW, darnit, NOW!

I'll be very anxious to hear observations from Gaffney/Blacksburg/Boiling Springs/Mooresboro/Earl and other areas south and west.

On toward midnight!

10:20 update: A new radar look (time sensitive)

Here is the NWS radar out of GSP. See the darker bands getting ready to hit Greenville? I think that's what "breaks though" our brick wall of dry air and brings us snow -- probably an hour or 2 away, maybe less.

Also, here is the 0z NAM snowfall map somebody requested in a comment. Still a range of 5-7 inches (8 up in the South Mountains).

9:45 p.m. update: Great looking radar

If you check out this radar loop, you'll see the precip backfilling nicely in Alabama -- that's a long way for precip to go to clear our area. We just have to be patient and let the precip work through all that dry air. Could be after midnight before it really starts coming down -- generally speaking those in the southwest part of the county (B. Springs) should see heavier snow first, with Fallston and Toluca last, although there will be exceptions to this.

By the way, NAM makes a big jump later in the period and gives us another hit on Saturday, as you can see here.

Keep those reports coming -- I might pull an all-nighter. Who's with me??????

9:20 update: Very light flurries in Shelby

Light flurries falling at my house in Shelby right now.

8:30 p.m. update: Snowing in Spartanburg

Not much new to report -- our wetbulb continues to sit at around freezing, so once precipitation starts falling through our very dry air, the temperature will drop.

Remember, the earliest we were expecting snow was 10 p.m., so anything before then is just a bonus.

There is some concern upstream that the snow in N. Georgia switched to freezing rain sooner than expected. We'll have to keep an eye on that.

Still like the 2-4 inch EDIT: SNOW! with some sleet and/or freezing rain after that.

Anybody reading this in the Gaffney area, please post when snow begins to fall.

7 p.m. update: Snow reported in Clemson, Augusta

1 inch on the ground in Dawsonville, Ga. and areas around Atlanta.

Precip having a VERY hard time overcoming our dry atmosphere -- the low dewpoints help us when it comes to getting snow instead of rain, but we lose some accumulation because it takes awhile for the atmosphere to be moistened. Don't be surprised if you check out a radar and it shows precip right over your house, but you go outside and nothing's happening -- that precip is drying up before it hits the ground -- but as that is happening, your temperature will start to drop.

Right now we're at 40 with a dewpoint of 14.

Update: Now snowing in Atlanta, headed our way

Widespread reports of snow in Not-so-hotlanta.

The final verdict on the 18Z Nam is a historic snowstorm of 6-12 inches. The 18z GFS is colder and snowier, but with less than half the total precip -- so more like 2-6 inches.

I'd be happy with any of that, wouldn't you?

Right now, I'd bank on about 4 inches of snow followed by a layer of sleet and ending as a glaze of ice, but we could get double (or half) that snow amount and it wouldn't surprise me.

You'll find all sorts of links to coverage on our home page -- if you take pictures of the storm with your cell phone or camera, send them in. Also, you'll be able to share storm reports. Finally, we'll be sending out The Star car to cover the storm.

More updates through the night!

FLASH: 18Z NAM goes nuts!!

It's almost too late to look at models, mainly because they rarely change in this tight to the actual event.

Don't tell that to the NAM.

It just turned a moderate to major winter storm into a Big Dog storm. NAM precip jumps from .8 inches in Cleveland County to a whopping 1.25 inches.

If that is all frozen we will have a collosal winter storm.

If that's all snow -- 8-12 inches.

If it's half snow, half ice, 4-6 inches of snow with a cripping coating of .5 inches of ice on top.

If it's mostly ice -- let's not even go there.

Haven't been able to analyze the temps yet, but this run is incredible if even close to reality.

Weather update: From marginal, to minor, to moderate, to major?

It seems very clear that this storm is going to be stronger than many expected. I will be shocked if the NWS does not upgrade us to a Winter Storm Warning.

The cold trend in the models from overnight and early today is now being verified (if not STILL underdone) in current conditions. Snow is breaking out over central Alabama and Georgia.

Winter weather advisories have been extended far to our south - as far south east as Orangeburg, S.C. and as far southwest as Augusta, Ga.

Also, after trending yesterday to a more icy event, there is now a move to a sleetier and especially snowier event.

Here's how the event should unfold, based on the observations of a number of mets who post on message boards and model trends -- we will experience a considerable amount of what is called "virga" late this afternoon and tonight. Virga is precipitation that can often be picked up on radar, but which dries before it reaches the ground.

This begins the process of cooling the lower levels of the atmosphere (see earlier post on evaporational cooling and wet bulb temps).

By around midnight, give or take 2 hours, precipitation will start reaching the ground. It's possible this will be as rain for just a few minutes before snow kicks in.

Right now, it looks like snow will fall for at least 4 hours and as long as 8 or possibly even 10 hours. After that time, whatever it is, we will see a transition to sleet, then perhaps freezing rain. It's possible the CAD will be so strong that we stay below freezing for the entire event.

Here is the final percentage breakdown:
No precip: 0 percent
All rain: less than 1 percent
Marginal event (less than 1 inch of snow; very light icing): 10 percent
Minor event (1-2 inches of snow; .1 inches of icing): 25 percent
Moderate event (2-4 inches of snow; .1-.25 inches of icing) 45 percent
Major event (4 or more inches of snow; .25 or more of icing) 20 percent

Look for more updates throughout the day and night and morning!

Good radar link

Here is a good link to follow precip moving our way.

And here's another good link to follow temperature/dew point/wet bulb temperatures.

Speaking of temps, I'm a little concerned by this bright sunshine which was beating down until about 30 minutes ago.

Temps up to 42, but dewpoint still just 12.

One "s" word I should have mentioned ....


I don't understand how to read the soundings and other date to determine the atmospheric profile that indicates freezing rain vs. sleet, but apparently, someone in the SE will receive a good amount of sleet from this storm. Remember that big sleetstorm we had a few years back? I don't remember the year, but I recall that it was in the 60s one day, then by that night we had an inch of sleet on the ground.

One thing to look for today....

We are in "nowcasting" mode -- that is, the models become less relevant compared to actual observered conditions.

With that in mind, one thing to look for today is our high temperature.

The NWS has us reaching 47 degrees as a high.

My guess is, that will be vastly overstated -- if some cloud cover moves in, we'll be lucky to break 40.

And if we don't get to 40, that could have huge implications for the storm.

Will this dream map come true?

6z NAM snowfall map for the Southeast.

You'll note that the upper part of the county is in the 5-inch swath with 4 inches for the rest of us.

These maps are significantly less reliable than some of the numeric data, but still fun to look at and wish for.

7 a.m. weather update: Ramping it up!

The late trend is for a stronger storm. This started with 0z model runs and was strengthened with the 6z runs.

The 6z NAM shows us getting 2-3 inches of snow followed by a significant ice glaze. The 6z GFS has the same kind of temperature profile, but has markedly less precip -- it shows us with around an inch of snow followed by .1 to .2 glaze of ice, which is in line with the current NWS forecast.

Right now, I'd probably split the difference and go for 1-2 inches of snow and a .2 glaze of ice -- this would be very close to enough snow/ice to do damage to trees so this even now bears close watching in that respect.

More updates through the day.

Tuesday, January 15, 2008

Weather update: 11 p.m. Tuesday

Very brief because I'm very tired -- 0z GFS come in a tad colder but is still way short on precip when compared to the NAM -- about half.

If you took GFS temps and NAM precip, you'd have a major winter storm -- vice-versa, not so much.

I'll update my percentage tomorrow morning -- might go for slightly stronger system based on tonight's model runs.

National Weather Service issues Winter Storm Watch

Cleveland County is under a Winter Storm Watch as of about 30 minutes ago.

The latest run of the NAM is a trend back toward a more significant event -- the run is not over so I can't check detailed data yet, but taken at face value it looks like perhaps an inch of snow and then more ice than model showed earlier today.

I'll update again tonight after the 0z GFS run.

Weather update: Time for a call

This appears to be a minor, perhaps even marginal, event -- of course, when you've gone two years without ANY event, even minor events are worth SOMETHING.

Here's how it looks:

Precip will begin sometime between midnight and 5 a.m. Thursday morning, probably as a brief burst of snow. It will mix with, then transition to sleet rather quickly. At best, the snow and sleet are enough to cover the ground, but there may not even be that much.

Then we transition to freezing rain. We'll see light icing -- on the order of .1 to .2 inches, then it will turn to rain with temps holding between 32 and 35 for the rest of the day.

This is very close to what the NWS forecast which comes out later today will show and falls in the "marginal event" which was tied for my highest percentage probability Monday afternoon.

What can go wrong: 1) The model trend toward warming continues and we end up with all or nearly all rain. 2) Precip is so light that evaporational cooling does not kick in fully and we end up with all rain

What can go right: 1) Models significantly underestimate the strength of the CAD and we see a longer period of snow, giving us 1-2 inches, before a changeover to ice. 2) The NAM is right, precip is heavy and "dynamical cooling" helps keep precip frozen.

We're still about 36 hours for onset -- that is enough time for changes.

Current percentages:
No precip: Less than 1 percent
All rain: 35 percent
Marginal event (dusting of snow/slight ice glaze) 40 percent
Minor event (1-2 inches of snow/minor ice coating) 20 percent
Moderate event (2-4 inches of snow/moderate ice coating) 5 percent
Major event (4 or more inches of snow/major ice coating) less than 1 percent

Also, an important note, the UK model shows ANOTHER system affecting us Friday night into Saturday. The Euro and GFS suppress the system to our south and east -- this would be either snow or nothing (no ice or rain --- too cold). Looks like a long shot, but worth keeping an eye on.

Weather update: Bad trend -- ice overtaking snow as early precip-type

Very slight, subtle warming in the latest model runs -- perhaps only raising our temps by 1 degree or so -- could be setting stage for a minor to moderate ice storm.

And if the trend continues, our winter storm might become nothing more than a bone-chilling, raw, cold rain.

The latest NAM -- which has been the model of choice for snow lovers, warmed up every so slightly on its 12z run.

Yet, the difference between 30.8 and 32.3 degrees is, obviously, enormous.

Is it over? Hardly. We could still see a burst of snow to start --- maybe even an inch or two.

But it's looking more like the transition to freezing rain will be quick -- then the question is: how long does THAT last. Hopefully, the change to a cold rain will come quickly -- I don't know anybody from around here rooting for an ice storm.

Adjusted percentages coming later today.

Monday, January 14, 2008

Weather update: See post below, but check out this map

I have a post below with my late Monday night thoughts, but check out this map of what the NAM is forecasting for snowfall.
Can you pick out Cleveland County? Incredibly, we are RIGHT on the line -- if this were to verify, Kings Mountain would get less than an inch while Casar got 5!

Weather update: Getting very interesting

The 0z run of the NAM is out and it's a major hit -- 1-3 inches of snow followed by a serious ice storm. Is it right? Could be. As you will see from the picture I'm posting, the temps are as close as you can get. Above is what is called a meteogram. In layman's terms, this shows precise temperature forecasts at a given weather station, in this case, Shelby's airport.

As you can see, the NAM shows 29.2 mm of precip fall during this event -- that's just under 1 inch.

The two lines that are key to observe are the 850mb temperature line and the 2m temperature line.

For there to be snow, very generally speaking, both of those lines need to below 0C. As you can see, that's the case for the first 6 hours of the event during which about 8 mm of precip falls -- that's about 1/4 of the total precip which would be a 1-3 inch snow.

Again, generally speaking, when 850 temps are above freezing and 2m temps are below, you have ice. So, this depicts icing for the last .75 inches of precip -- which would not be good.

Now, a couple of things: First, the temps here are very close -- normally to get a real killer ice storm, you need temperatures as low as 30 or even the upper 20s -- otherwise what is called "latent heat release" (subtle, slight warmth generated when water freezes) can cause the temperature to rise above freezing.

On the other hand, even in this short range, models struggle to pick up on the strength of CAD.

In any event, this bears very close watching -- the NAM keeps trending stronger with precip and the GFS is trending stronger with the high pressure (up to 1032 mb last run). If both of those are right ..... could get REAL interesting.
Not sure if I'll stay up for the 0z GFS, but if so, I'll make a quick post.

Weather update: It's a close call, but confidence grows

First, a friendly reminder -- I'm not a meteorologist and for the most part, don't know what the heck I'm talking about. But I follow it as a hobby and can aggregate for you what the REAL experts think.

So, here's the story:

Confidence grows that we will see SOME sort of winter weather, starting Thursday morning.

The key factors:

1) The track of low pressure in the Gulf of Mexico -- over the last 48 hours, models have been nudging that to the north which makes our temperature forecast razor thin when it comes to winter precip.

2) The strength of the low and of the high pressure to the north. On the former, it means more precip on the latter it means a stronger CAD. The latest run of the short-range model NAM spit out more than .8 inches of precip -- if that was all frozen, any combination of snow and ice would be serious. For example if 1/4 was snow, then the rest ice, we'd be talking 1-2 inches of snow then .3 to .4 inches of ice -- a killer ice storm. If 1/2 and 1/2, it would be 2-4 inches of snow, then .1-.2 inches of ice -- still very dangerous.

3) The TIMING of the low -- if it lollygags, we'll see less snow and a quicker changeover to ice then rain. If it scoots in here quickly, we'll see more snow on the front end.

Now, we need to talk about that "i" word I mentioned before: ice. There are indications that the changeover from snow could happen quickly and that it would be to mostly freezing rain. Still too early to pin this down, but something that must be monitored.

Also, I should note that the coldest sustained airmass of the season (as alluded to last week) will move in behind this system. We will see a number of days in a row with highs in the 30s and 40s and lows in the teens and 20s -- maybe even lower.

So, here's the latest breakdown:
No precipitation to speak of: <1 percent
All rain: 30 percent
Marginal winter event (a dusting to less than an inch of snow/slight ice coating) 30 percent
Minor winter event (1-2 inches of snow/minor ice coating) 24 percent
Moderate winter event (3-5 inches of snow/moderate icing) 14 percent
Major winter event (6 or inches of snow/major icing) 2 percent

Adding most of the new weight to marginal and minor event.

GFS just rolling in -- pretty much holding serve.

By tomorrow morning we'll be within 48 hours!

"According to a new study ...."

I've lamented before the misuse of so-called scientific studies and the questionalbe methodology of the studies themselves.

Here are some great examples of "science" that wasn't in 2007.

Sunday, January 13, 2008

Weather update: Still in the hunt

There is a thing call climatology, which basically says: what usually happens weather-wise is what will probably happen.

Lately, what usually happens is that whenever computer models show us getting winter weather, it manages to bust.

Usually this is manifested by a few tantalizing runs of computer models followed by dashed hopes.

In that respect, my confidence that we see winter weather is higher than it has been in 2 years -- the GFS model has been relentless in its depiction of an event. Now the storm is coming into range of the shorter range NAM model and it too shows an event. The only model not on board is the European, which shows our low driving north right over our head -- not a good track for snow.

This is a classic CAD (cold-air damming) event - one key will be the strength of the high pressure to our north that feeds in the cold air which will convert precip to snow. The latest run projected a 1029 mb high, up slightly from the previous run -- anything 1030 or higher is considered a strong high pressure system which can be relied upon for a nice feed of cold, dry air.

Let's compare the GFS to the NAM and see how close they are:

Here is the 0z GFS at in the wee hours of Thursday morning.
And here is the NAM in the same time frame.
Then here is the NAM by dawn Thursday.
You can see the NAM is about 6 hours slower, but depicts the same kind of set up -- low pressure of the La./Miss. Gulf coast with precip starting to ride over the CAD.
Here's the GFS by Thursday AM. Snow is falling with more precip on the way.

So, what can go wrong?

Well, if the low tracks even slightly more north and west, it could scour out our cold wedge of air more quickly and we could transition to rain sooner. Or, the low might divert south and give us lighter precip.

Also, the models have pulled back some on the total precip -- a couple days back more than 1 inch of precip was depicted (using 10-1 ratio, that would have meant 10 inches of snow). Now, we're in more of .4-.8 area of precip.

Still, that would be plenty if even half of that fell as snow.

So, here is the new breakdown:
No precipitation to speak of: 5 percent
All rain: 40 percent
Marginal winter event (dusting of snow/slight ice coating) 25 percent
Minor winter event (1-2 inches of snow/minor ice coating) 18 percent
Moderate winter event (3-5 inches of snow/moderate icing) 10 percent
Major winter event (6 or inches of snow/major icing) 2 percent

I actually dropped the "major" category, but the other "snow" categories go up. We're really getting in a window now where the changes in the modeling should be more subtle, so I feel pretty safe saying there will be SOME sort of system coming out of the Gulf late week.

Stay tuned!

Saturday, January 12, 2008

Weather update: The big one or big rain?

Well, the beginning of the new pattern we talked about earlier this week is just a few days away and it might kick off with a bang.

Most model runs show a major Gulf of Mexico low forming early next week and moving northeast by midweek.

Let's look at how the latest (18z) run of the GFS depicts this storm:

Here is the wee hours Thursday morning. This map depicts surface temps (usually, the maps I show you refer to upper air temps. As you can see, the 32 line is to our south as precip moves in. Notice the high pressure to our north east -- recently these areas of high pressure have been oriented in a west/east manner. This one is more north-south which is better for cold-air damming to set up. To wit, you can see the little wind barb (if you zoom in) over the Charlotte region is showing a north/northeast wind.

Now for Thursday after dawn. Still at or below freezing at the surface (and in upper levels) as a 2-4 inches of snow falls.

Here's early Thursday afternoon. This is the upper air map which shows us JUST above freezing -- also borderline at the surface. BUT, you can see the heavy precip that is falling. If this were all snow, it would be an additional 3-6 inches, maybe more. Or it could be a little more snow, then some freezing rain. Or it could change to all rain.

IF it were all snow ... IF ... we'd be talking about 6-10 inches. BIG IF!

By Thursday night, the storm has pulled away.

Couple of things -- before this storm moves in, it will encounter very dry air, which will lead to what is called evaporational cooling. Basically, this means that as precip falls through dry air, the air is cooled. The "wet bulb" temperature is essentially the temperature to which the atmosphere will fall if saturated. So, if you had a temperature of 40F but because the air was so dry, the dewpoint was 10F. The wet bulb would be around 30F -- that means that the temperature would drop 10F once it started precipitating. Here is a web bulb calculator.

Computer models tend to underplay two things -- CAD (cold-air damming) and evaporational cooling. So, this is one time the models may trend MORE in our favor on temps.

And that is the ingredient which will be key here -- there is strong model agreement that there will be a significant low pressure system -- the question on temps will be the close call. The last few runs of the GFS have set up a rain-snow line somewhere along I-85.

Bottom line: This is BY FAR the best looking system since 2006 or earlier. Plus, there continue to be more chances downstream in the 12-day range and beyond.

Here's a breakdown on the Thursday event by percentages:

No precipation to speak of: 10 percent
All rain: 50 percent
Marginal winter event (dusting of snow/slight ice coating) 18 percent
Minor winter event (1-2 inches of snow/minor ice coating) 12 percent
Moderate winter event (3-5 inches of snow/moderate icing) 7 percent
Major winter event (6 or inches of snow/major icing) 3 percent

So, that's a 22 out of 100 chance of accumulating snow, which is pretty darned high for 5 days out.

Of course 78 percent chance of nothing or close to nothing.

Still, half (or more) of the fun is in the tracking!

Stay tuned!

Friday, January 11, 2008

All hail the pattern change

Very good news for winter weather lovers in the medium and long range -- all signs point to a major pattern change with sustained cold and a much higher chance of storms.

Almost all models point to a major cold outbreak across most of the central and eastern U.S. starting late next week into next weekend.

It all gets started in the Wed. night/early Thursday timeframe. As cold air begins to seep southward from the arctic regions, low pressure forms in the Gulf of Mexico. Will cold air arrive in time to make this a winter event? Way too soon to tell. Here is the storm depicted on the just-finished 12z GFS run.

More cold is ushered in the wake of this system, then another low tries to crank up in the Gulf. By the following week, cold is entrenched over the U.S.

One reason is the emergence of what pro mets call "blocking" over the Greenland area. This blocking "locks in" a cold pattern. If you've noticed, we've had what is called a "progressive" pattern thus far this winter -- it gets cold and warm, but nothing lasts very long.

With blocking, which can be measured by the North Atlantic Oscillation, cold air is continuously funneled south for weeks at a time, meaning one part of the N.C. snow equation is basically set -- then, all we need is lower pressure for a nice snow.

Check out this long-range map from the 6z GFS run. It's plenty cold here for snow, but notice the bitter cold on our doorstep -- this is all "fresh" cold, not the old stale airmasses out of which we have been hoping to squeeze a snowstorm.

Bottom line: GREAT pattern emerging -- first chance at a payoff is Wed. night/Thursday morning, with good shots every few days thereafter for the next couple of weeks.

BOLD PREDICTION: We will see accumulating snows in Cleveland County before the end of January!

Thursday, January 10, 2008

Thursday weather update: So close, but yet .....

Well, there just isn't enough cold air to give us snow, it would appear, from this system.

But, if you check out this map, you'll see how close we are.

JUST as it gets cold enough for snow, the precip is moving out.

Might be a nice hit for the mountains.

Good news -- there are indications that we get into a much better overall pattern by late January and into February.

The overall pattern right now stinks so we have to have perfect timing to get snow.

If anything changes, I'll let you know.

Wednesday, January 09, 2008

Wed. noon weather update: Ehhhhhh.....

I hoped to offer better than 1 in 10 odds of snow Sunday, but I can't. In fact, I'm downgrading to 1 in 12. Still, we're hardly out of the running for some winter weather.

Here's the deal:

The latest runs of the GFS have the storm missing us to the south and east. Instead of low pressure hugging the Gulf Coast, then crossing the Fla. panhandle into South Ga. and off the S.C./Ga. coast, the low forms more south, crosses the Fla. peninsula and then offshore.

Here are a series of maps from the 12z run (for a definition of 12z see comments from my last post).

Late Saturday night Note the low pressure in the central gulf
Wee hours Sun. AM
Sunday morning Low over Fla. peninsula
Sunday afternoon Low moving offshore
Late Sunday night Low missing us to the east

You'll notice that the GFS is good on temperatures.

Now the good news (with some bad news mixed in).

The Euro (maps from the Euro are crude and not easy to link to) has a much better track for the low, but temps are not as good -- it would not get cold enough for snow until the system is moving away. Also, the Euro does not intensify the low until it is almost past us to the northeast, which means less precip.

So, there are ingredients in place and it's too soon to bail out, but we're definitely still talking about a low chance (although lately a low chance is better than NO chance).

Also, as a friendly reminder, I did not say it was going to snow, only that we had a system to track.

More later today or tonight.

Tuesday, January 08, 2008

Tuesday afternoon update: Hopes are high

The 12Z GFS run now has the storm suppressed to our south and east which, for me, is GREAT news, because the models have been terribly biased in the OPPOSITE direction all season -- that is, storms that looked good for us trended north and west as the event drew near.

These system never seem to get colder. Remember the big February snow we had a couple years back -- about 5 days out, models showed us getting zip, but eventually they trended north and we hit the jackpot.

More good news: The Euro is back on board, showing a nice little snow and a Miller A system. Interesting, we only see a minor event because the Euro doesn't really bomb out the low until it gets directly to our east -- by then the precip is starting to shut down. But I'd take 1-2 inches over a cold rain any day.

Finally the National Weather Service has taken notice -- here the current forecast for Cleveland County:


So, it's fun to at least have something to track. Usually, the magic window is about 78 hours -- if you can get a storm still showing up on model at that time frame (so, in this case, Thursday morning), you've got a good shot at seeing snow.

Not changing my percentages now, but might bump them up tonight or tomorrow if model trends hold.

Sunday snow? Our best shot this winter

Had a family illness to tend to or I would have given more advance notice of our best shot at snow since 2005 (remember, 2006 was a rare, big, fat goose egg for the white stuff.)

This system is a classic looking "Miller A" storm -- which basically means it is a low pressure system which develops in the Gulf of Mexico and tracks across the Gulf coast into the southwest Atlantic, somewhere of the Ga/S.C. coasts. "Miller A" is named after meteorologist James Miller.

This is how we USED to get most of our storms and is a favorable track for snow.

Here is the latest run of the GFS:

In the wee hours of Sunday morning. Note the low forming in the north central gulf
Sunday at church time. Precip spreading our way. High pressure building in from the north.
Sunday afternoon. Low still getting its act together in Gulf as precip breaks out.
Wee hours Monday morning. Low in perfect spot off S.C. coast, temps dropping, snow falling.
Monday late morning. Low heading up coast, snow still falling

The recent (6z) GFS was the warmest of recent runs. For example, the previous (0z) run showed cold air moving in more quickly.

Compare this to the "Sunday at church time" 6z run above.

The European model lost the storm yesterday, but got it back overnight. Temps are still an issue.

Overall, there are some things going for this system we haven't had in a while -- mainly, that it's "Miller A."

What's NOT going for it is that the overall pattern is still not great for winter weather here -- we have to have great timing between features to get a snow rather than simply waiting for a good pattern to crank out a storm.

I have a feeling temperatures are going to be the main problem. The high pressure to our north during this storm will have to be at least as strong or maybe even stronger than what is being modeled for the snow to come through.

Right now, I'd give us a 2 out of 10 shot of measureable snow with 1 out of 10 of a major event (4 inches or more).

New models runs late this morning and early this afternoon, so watch for updates.

Friday, January 04, 2008

An unbelievable forecast

I promise, I'm not making this up. This is the forecast for an area near Reno, Nev. for today.

To save you the math, that's a range of 115 to 131 inches of snow -- possibly almost 11 FEET!!!!

I think they'd probably call off school in Cleveland County for a year if that happened!

Here's a web cam from Mammoth Lake.

And here is an incredible time lapse video of the snow piling up on a deck.

Wednesday, January 02, 2008

January weather outlook


Just in case you forgot what cold weather feels like, the next couple of days will be a cold slap in the face.

But, incredibly, not only will the cold be short-lived, but we will actually transition by next week to a very warm pattern, with temperatures by mid-week reaching the 60s and maybe even near or above 70 degrees!

Some medium range models continue the roller-coaster ride by mid-month, with a colder, stormier pattern taking hold. While highly unreliable during this time frame, the GFS model has persistently shown some sort of east coast storm system in the January 14-18 time frame.

So winter is here, winter will leave, but winter will come again!