The first official month of the Winter 2024-25 season brought a notable change in the prevailing unseasonably warm fall weather. For the most part; the month of December contained equal amounts of below normal temperatures and above until the end; when a quick mild spell boosted the monthly average to above normal at 33.3/+2.0. All in all; December was a fairly "snowless" month with below average snowfall at 3.6" /normal 8.9"/ through the 31st but with above normal precipitation with 3.27". Thus far; only half our normal amount of snow has fallen this winter with 5.4" /Norm -10.8"/
The outlook for January 2025 keeps the declining temperature trend in vogue for now with a predominantly colder than normal January in store for the early - mid month period. Latest indications are a gradual stratospheric warming trend (not official SSW) far aloft over Siberia toward the North Pole will help elongate the Polar Vortex (and some of the brutal cold at the surface) and push it south (blue/purple) into the mid latitudes, including North America with some moderation. Coldest air at the surface would concentrate over the eastern two-thirds of the nation and deep into the south!
Projected 500 MB upper air pattern for all of January shows the elongated trough over eastern Canada into the eastern U.S.
With the ridging/upper high pressure building over the eastern Pacific and western U.S at times and blocking in Greenland, this will enable the delivery of Polar/Arctic air south into the U.S.
Low pressure will move along the Polar front early in the new week but at this time it appears much of the snow will stay south in the Ohio Valley. Models have had a terrible time with this system varying from a snowstorm for the southern Great Lakes to nothing, keeping it south. The dynamics and upper air pattern won't be sampled better until Friday. Any significant changes will be blogged.
Making weather fun while we all
learn,
Bill Deedler
- SEMI_WeatherHistorian
