Part of our winter forecast was the mantra that this December would be much different than December of 2015 and that, compared to average, December might be the coldest month of the season (December-February). That idea is coming to fruition now and the next 10 days or so could be quite interesting! Let’s dive in!
ARCTIC ATTACK #1
For much of October and November, the true arctic air sat on the other side of the pole. It was amazingly cold in Siberia (even for their standards) while North America was a “blow torch”. That has changed recently, as the arctic air has finally made it into Canada and the western United States. Lots of cold on the map this morning:
After a petty nice day today, the leading edge of this arctic air mass will arrive here tomorrow. A blustery and cold Thursday with temperatures no higher than about freezing and wind chills in the 20s.
Lake-effect snow will get going in NW PA and SW NY Thursday but won’t really impact our area until late Thursday night and Friday as the wind shifts to more of a northwesterly direction. This will be a lake-effect bonanza from Erie to just south of Buffalo. Check out the NWS forecast through Friday: 2 feet or more in SW NY. Yikes.
Here in the Valley, I think the snow showers will fall more into the “nuisance” category Friday with some places north of I-80 getting a handful of inches of snow and just about no accumulation expected south of 224.
CONFIDENCE IN FRIDAY SNOW FORECAST: MEDIUM HIGH
That said, even in areas that won’t pick up much accumulation, watch for slick travel at times Friday into Friday night. Snow showers and squalls can reduce visibility quickly.
The wind will whip Friday with wind chills never making it above 20 or so.
SATURDAY: A BREAK (BUT COLD!)
The lake-effect snow machine will shut down Saturday and the wind will not be as problematic. Cold at Stambaugh Stadium Saturday afternoon with temperatures no higher than about 29-30.
SUNDAY’S SNOW THREAT
Confidence is growing that a “warm advection” snow event will occur Sunday. Basically that means warmer air will be gliding up over colder air, causing rising air and precipitation. This has the potential to be a 1-3″-ish type of snow.
CONFIDENCE IN SUNDAY SNOW: MEDIUM
SUNDAY NIGHT/MONDAY: “BONUS” SNOW??
A cold front will cross the region in the Sunday-night/Monday time frame. A big question right now is: will the front come through “clean” or will a wave of low pressure form along the front, slowing it down and producing another wave of snow?
The operational European model has been advertising this idea for a couple of days now. A handful of members of the European ensemble model show this as well:
Other models have no such wave and thus no “bonus” snow. For example, the GFS just has some “ho hum” snow flurries and snow showers Monday morning:
Will not dismiss the European idea because, well it’s a better model, but it’s on it’s own right now. So:
CONFIDENCE IN ADDITIONAL SNOW ACCUMULATION SUNDAY NIGHT/MONDAY: LOW
NEXT WEEK: RELEASE THE ARCTIC HOUNDS!
This week’s release of arctic air into the US looks like an appetizer compared to next week’s cold shot. Temperature animation of Monday-Saturday (GFS model)
Of course it will be much colder to our northwest, but still this has the potential to produce a couple of days of highs near 20 and single digit lows. Temperatures compared to average next Thursday:
CONFIDENCE IN HARSH COLD LATE NEXT WEEK: HIGH
WARM UP FOR CHRISTMAS?
After that second polar plunge, there are signals that it will turn milder as we get closer to Christmas. But I would not guarantee something like that this far out. European model shows the cold retreating by December 21:
The CFS climate model has a mild signal for much of the country right before the holiday:
CONFIDENCE IN WARMER PATTERN FOR CHRISTMAS: LOW-MEDIUM