Weather Headlines
Friday December 21, 2001
Legitimate cold air poised to move into the U.S. the last week of the year.
Some models also hint at significant winter storminess next week as well.
The next system should start cranking up over SE Colorado today and track
towards the Great Lakes this weekend. This will still be more of a rain
than snow event, but finally is the catalyst to really show the pattern
change. As the storm exits in the East, a strong ridge builds on the West
coast up into Canada which forces polar air South. High latitude blocking
then keeps the polar air in place. The Midwest is the first recipient of
this and it then spreads East into next week. We are rapidly losing the
positive temperature departures. They should be gone all together East of
the Rockies by Christmas. Of course they will be growing under the ridge
West of the Rockies. Negative departures should become more prominent next
week under this polar vortex. They will show up more in daytime highs
rather than night time lows. I don't expect heavy precipitation in the
short term from this, but persistent cloudiness and wind will add to the
chill.
The 6-10 day period shows the polar vortex locked into place over the Great
Lakes. It is also possible that Southern jet stream energy will undercut
this polar air spinning up a winter storm in the South that could head up
the East Coast. This storm is clearly in the speculative stages and should
be watched. But, the cold is not speculative, it is real. I am very
confident in the evolution of this at long last. It appears to be a fairly
long lasting event, the question now is how long and how severe. One
extreme example of how strong this potential may be down the road was a
report earlier this week that record high barometric pressure readings were
approached in Mongolia. The center of this Siberian high had a pressure of
around 32.00" of mercury. The temperature at the time of the reading was 41
below zero. Most of the models on a hemispheric scale are now lining up the
surface highs from the U.S. Northwest to the Pole. The Canadian model in
particular shows some very frigid air in the NW territories on its Day 10
depiction. If this trend continues, it could be extremely cold early in
2002.
Note: This is my final weather commentary until January 2'nd of 2002. Best
wishes for a happy holiday season.
For the period Friday December 21 through Tuesday December 25, expect the
following temperature trends:
Average 1 to 3-degrees below normal: Intermountain West, Desert SW, Central
and Southern Plains?
Average 1 to 3-degrees above normal: Pacific NW, California, Rockies, Ohio
and Mississippi Valleys, Northern Plains, Great Lakes, Gulf Coast ?
Average 4 to 6-degrees above normal: Southeast, Northeast, Mid-Atlantic ?
Andy Weingarten, Meteorologist APB Energy / True Quote