The Friday afternoon edition of the ABC 33/40 Weather Xtreme video is available in the player below, and on iTunes:
A reader in Texas sent me a copy of the forecast discussion from our friends at the NWS in Norman, OK this morning… an interesting quote:
“THIS LONGWAVE PATTERN IS VERY FAMILIAR – A CLASSIC PATTERN B OR ARCTIC HEAVY SNOW PATTERN FOR OK. THIS ONE IS NOTORIOUS FOR PRODUCING SNEAK SNOW EVENTS DUE TO THE DOMINANCE OF THE LARGE-SCALE PATTERN AND THE RELATIVELY BENIGN OR EVEN NON-DETECTABLE SMALLER-SCALE FEATURES. SNOW EVENTS TYPICALLY OCCUR WITHIN ABOUT 12-24 HR AFTER COLD FRONT PASSAGE – OF WHICH THERE WILL BE SEVERAL – AND MAY BE TIED TO MESOSCALE WARM ADVECTION… SPEED MAX DYNAMICS… OR FRONTOGENETIC FORCING. 06Z GFS MAY WELL BE OVERDONE ON RUN-TOTAL SNOWFALL… BUT FACT THAT MUCH OF THE CWA IS UNDER 6-14 INCHES BY NEXT FRIDAY IS WORTH NOTING. ANALOG CASE THAT COMES TO MIND IS JAN-FEB 1985… DURING WHICH SEVERAL SNOW EVENTS PILED UP TO MORE THAN A FOOT ACROSS EVEN S-SE OK.”
This is very well written, and the analogy to 1985 is a good one. Much of the nation east of the Rockies is in store for a period of very cold weather, and winter storms will form and roll along the southern edge of the Arctic air, bringing the threat of snow and ice from time to time to the southern part of the country. As the snow pack increases, of course, the cold air shots in the cross-Polar flow will become more severe.
By the way, Birmingham dropped to six degrees below zero in the winter of 1985. I doubt if we get that cold this year, but if by chance we get a good snow cover going I guess never say never…
THE WEEKEND: No real change in our weekend forecast idea. Light rain at times tomorrow night, maybe mixing with a few snow flakes or ice pellets after midnight north of Birmingham. Surface temperatures during this remain above freezing, and no icy travel at this moment is expected. Very cold air rolls in here on Sunday; the NAM MOS is now showing a high of only 36 on Sunday. We stay in the 30s all day, and a few morning snow flurries are not out of the question. The wind chill index on Sunday will be below freezing most of the day.
We note the NAM is now showing 19 degrees for Birmingham early Monday morning; this looks good to me. Colder valleys could be closer to 15. Welcome to winter.
NEXT WEEK: Model madness, to say the least. Arctic air over much of the nation, and wild model variations due to the anomalous pattern. We cannot ignore the idea of the lead wave producing snow and rain around here Tuesday night into Wednesday. I am not comfortable with this solution, but we will go ahead and insert that chance into the public forecast over on our seven day forecast page. Critical thickness values Tuesday night and Wednesday are hovering around I-20, as often is the case. QPF looks fairly light at this point, but models are not handling the cold air very well, and that might be our first shot at some travel issues over parts of North Alabama.
One issue discussed in this office is the possibility of the cold air being so shallow that we might have to look at some risk of freezing rain late Tuesday night and Wednesday morning along the I-20 corridor, with some light snow to the north, especially north of U.S. 278, where some accumulation is surely possible. I will make some posts over the weekend here in an effort to be much more specific.
The GFS really dampens the second wave at the end of the week, but the Canadian GEMS shows a significant winter storm threat for parts of the Deep South on Thursday. Like the guy in Norman writes, the mesoscale will play a big role in events next week, and that is very difficult to determine so far in advance. And, according to my way of doing things (handling one wave at a time), we need to get past the Tuesday night/Wednesday event before we look at the next one closely.
There will be move waves to deal with in the February 3-7 time frame, and with very cold air in place over so much of the nation we will have lots of winter weather mischief ahead.
BIG DEEP BREATH: Lovers of snow are very passionate, and I encourage everyone to relax and lets roll with the flow here in coming days. Remember, don’t look at every single model run. Live by the models, and die by them. I have lived and worked through many big, Arctic airmasses like this since 1978, when I first started doing weather on television. Winter storms on the southern periphery will come, most likely multiple times. While NWP is so much better now (numerical weather prediction), it still has big limitations during extremes. Readers here know we latched on to the idea of very cold and unsettled weather before the GFS had a clue. Now, we are all on the bandwagon, and unfortunately the models, and us humans, are just so limited in handling specific events days before they happen.
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STORM ALERT 2007: We kick off our annual weather tour across Alabama next Thursday night in Tuscaloosa… read more and see the entire schedule here.
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Brian Peters will have the Weather Xtreme videos here over the weekend… my next one will be up Monday morning around 7:00. Be sure and check in over the weekend for updates… these are interesting times!
