Thursday, January 17, 2008

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.

18 comments:

Anonymous said...

Skip, thanks for being so dedicated to this blog! I really learn a lot from it.

Anonymous said...

Some fresh hot Krispy Kremes and a hot cup of coffee would be good right about now....I've got the coffee, but Shelby has no donut shop....might be why there is so much turnover at Shelby PD. There's you a real news story Skip....ain't no blizzard coming here, nothing on the nws.noaa.gov website to show it either....

Anonymous said...

I apologize deeply Skip, yes Shelby needs donuts! However, I just checked the local forecast discussion on the nws.noaa.gov website and they are sounding even more hopeful than you!

As long as it is all snow, let it pour baby, no ice on the power lines, we don't need that.

Anonymous said...

Youmust live somewhere else. The NWS says chance of rain, Mountain snow. How is that even a possibility. Its good to hope but don't read something that isn't there.

Anonymous said...

Bring on the snow. I was disappointed with today,just the usual slushy mess.

Anonymous said...

Can someone tell me what our big February 2006 total was? I've asked several people and they don't remember anything big. Our definition of big is 6" +.

Skip Foster said...

Feb. 2006 -- well, shows you how old I am getting.

It was actually Feb. 2004!

Here is a summary:

http://www.erh.noaa.gov/gsp/localdat/cases/26-27Feb2004Snow/Feb_26_27.htm

8-10 for Cleveland County even though were were projected to get 1-3 up until about 2 days before the storm hit.

Sorry some aren't happy with our 1-2 overnight -- still a nice little snow for our neck of the woods.

Anonymous said...

Can you explain the jargon? (as the NAM is showing moreso than the GFS) What are those things?

Skip Foster said...

NAM and GFS are both computer models. Both American models -- NAM is a shorter range model while GFS cranks out maps out to 15 days or something.

Generally, inside 48 hours is considered the NAM's wheelhouse -- but it was overdone with precip somewhat on last night's event.

Anonymous said...

I have loved Skips love for tracking weather over the years. I'm a huge weather buff and check his blogs every hour.
***I'm curious in how correct NAM and GFS has been over the years. I get so excited with the Nam outlook, but then if it is wrong 50% of the time, what good it is, same for GFS? Also Weather channel has snow/rain for Fri. 25th! What's with that?

Anonymous said...

Ah, Feb. 2004. Remember that well. Thats where the upper level developed and we got slammed. Would like to see another one of those.

Skip Foster said...

On NAM vs. GFS, there are statistical comparisons which I'll try to look up.

Here are some general rules:

NAM is generally good on temps -- esp. in CAD events -- this was proven out by last night's event -- in fact, even NAM wasn't cold enough until right before event started.

GFS has a bias toward suppression -- so, it's a good thing when it shows you getting missed to the south and east.

NAM becomes quite unreliable at the end of its range -- 72-84 hours.

The NAM isn't having a particularly good winter thus far -- missing out on a NE storm last week pretty badly.

That probably causes more confusion than anything, but it's about all I know.

Anonymous said...

I remember the 2004 storm well. It caused me to go and buy a 4x4 vehicle afterward because I couldnt get in to work that morning. A fat lot of good that did me, as we didnt have any snow after that until last night. I sold the 4x4 in April 06. hehe

I, too, love Skip's love for the weather analysis. I find it very interesting. Last night's precip fall was kinda fun to watch, but just a mess this morning. I'm hoping for something more of a REAL THING for Saturday! Glad you're watching things for us, Skip.

Anonymous said...

Is it possible we could end up with a snowstorm Saturday like the one in 2004???

Anonymous said...

A question, Skip, re: the timing of the various models, NAM, GFS, etc. When it's referred to as the "12z GFS", does that mean that it's the GFS model published at 12:00 noon GMT, which I guess would be 7:00 am EST? Am always a tad puzzled by the terminology.

Skip Foster said...

Yes 12z is basically 7 a.m. -- zulu time is 5 hours earlier than our time.

Is 2004 possible? Yes, if the NAM verifies. But other models runs this afternoon are actually east of the GFS -- that means nada for us. We'll have to see -- the Euro moved east, but it's not really a short range model.

GFS is in the middle -- looks like at 18z it might choose its partner, so to speak.

Mr. M said...

Yes! I love it! I work for a local elementary school and requested that our students do a snow dance yesterday at school to boost the chances of snow! Thank for your dedication and passion. Principal's love days off too!
DM

Anonymous said...

So Skip do you think schools we be on a delay tomorrow?