dendrite

Looks like it was the coldest day on record for Bozeman airport. All-time record low max of -24, 3rd coldest min on record of -45, and coldest mean on record of -34.5. Departure of -54

The squall line with the fropa isn't going to be snow

They have similar maps on their briefing page https://www.weather.gov/box/emhome

Maybe a little for the west slopes, but keep in mind that isn't all instantaneous. That's thickness paired with 6hr averaged precip. So a lot of that precip is outta here before the column cools to support snow.

Do you recall what Feb 2010 was offhand? I was pretty inverted in that, but obviously CON/MHT-SE roared. Quite a different sfc low position in that one.

It did a couple weeks later.

3k NAM has some 75kt gusts to the sfc in W VT. 100kt at H85 over Lake Champlain

That's not bad for them.

There's a new all-time December record low temp for Casper....they hit -42F before midnight local time. Ironically their only other -40s in December were 12/21 as well in 1990. They'll beat today's record with another -41 or -42 in the books. So it'll go into the records with 2 days with -40s when their previous record history, going back to 1939, had only 1 day total. Bozeman is down to -44F. That's their 2nd coldest Dec temp on record. edit...looks like the CPR reading is an all-time record low...not just for Dec.

I thought it could precipitate, the models always fool me

huge standardized anomalies up there

I noticed that up there. The western slope downslope favored areas are going to roar.

DEN 42 to 18 in 7 mins

Greeley CO just went from 48° to 18° in 9 minutes.

Well here's the d7-11 and d12-16 5d avg GEFS.

Yeah that's BUF. They're still going wild. .LONG TERM /FRIDAY THROUGH TUESDAY/... ...Once in a Generation Winter Storm to Slam the Region Heading into and THROUGH the Christmas Weekend... Old Man Winter will unleash the full fury of winter upon our region during this period...as an extremely amplified longwave pattern will spawn one of the most intense storm systems in decades to impact the Mid West and Great Lakes region. This system will likely end up setting low pressure records once it passes north of the border and will have the potential to generate at LEAST storm force winds over the Lower Great lakes. As if the very real threat for damaging winds of 60-70 mph were not enough...there will also be the risk for a prolonged...paralyzing heavy lake effect snow event. The very strong to damaging winds, blowing and drifting snow with localized blizzard conditions preceded by a rapid flash freeze all coming right before the Christmas holiday weekend resulted in a *long duration* winter storm watch being issued for western NY. A Winter Storm Watch has also now been issued for Jefferson and Lewis county from midday Friday through Monday. While heavy lake effect snows have already occurred this winter season...this will be the first event with multiple impacts from such intense winds. Winter storm watches are already in effect for parts of western New York with the high component wrapped into the same product. An extremely amplified longwave pattern during this period will spawn one of the most intense storm systems in decades to impact the Mid West and Great Lakes region. This system will likely end up setting low pressure records once it passes north of the border and will have the potential to generate storm force winds over the Lower Great lakes. Explosive cyclogenesis will take place over the mid western states into southern Ontario on Friday...as an anomalously strong 150kt H25 jet will pass through the base of a very deep longwave trough. This will support rapid deepening of a corresponding sfc low that will track southern Ontario by late Friday. The `bombing` low will deepen from roughly 990mb in the vcnty of Lake Erie/Lower Michigan late Thursday night...to 982mb over southernmost Ontario Friday morning to about 968mb near the Ontario-Quebec border by Friday evening... easily meeting the definition of bombogenesis (24mb/24hrs). Such deepening is relatively rare in the LOWER Great lakes...but more common across the UPPER Great Lakes and certainly with Nor`easters along the coast. Some of the parameters of this intense storm are climatologically `off the charts`...such as MSLP and strength of both the low level and upper level jets. One could certainly describe this storm system as a once in a generation type of event. Subtle differences remain...but there remains general model agreement in the overall large scale scenario...which adds confidence. The rapidly intensifying low is forecast to pass just to our west on Friday. Winds will ramp up in the cold air advection and during when max pressure rise/fall couplet crosses. This is about as good as it gets in terms of maximizing winds/gusts to the sfc. Several guidance packages are now advertising wind gusts over the IAG Frontier to near 60 mph late in the day as another intense 70kt LLJ enters the region. This is NOT when the strongest winds are expected though. That is yet to come. In regards to pcpn on Friday...the strong winds will open the door for MUCH colder air to pour across our forecast area. This will result in a RAPID change over of the rain to snow with deep frontogenetic forcing leading to a burst of moderately heavy snow that will yield accumulations of several inches expected by late afternoon. Temperatures that will start the day in the low to mid 40s in most areas will PLUMMET into the single digits across the Srn Tier by the end of the day...while readings will range from the teens across the remainder of wrn NY to the lower 30s east of Lake Ontario. This dramatic plunge in temperatures will likely result in a flash freeze of the snow/water/slush. As the extremely deep storm system further deepens in place over the Ontario-Quebec border Friday night...a strong secondary cold front/sfc trough will plow across our forecast area. This will be accompanied by the second 70kt low level jet that...being found in the cold sector...should largely mix to the sfc at times. The threat for high winds at the sfc will be greatest in the typical corridor from Lake Erie and the IAG Frontier to Rochester and then to the Thousand Island region. Increased winds some in these corridors. Power outages will be a concern as will be blowing snow and drifting snow. The widespread synoptic snow during the first half of Friday night should then taper off as the deepest forcing exits and limited drying arrives in the mid levels. Meanwhile...a 230-240 flow of -20c H85 air will promote an area of lake snow to become established Buffalo northward...across IAG and the Northtowns. The snow... whether it be synoptic or lake induced in nature...will be blown around by +50 mph winds so significant blowing and drifting can be anticipated along with near zero visibility and at least localized blizzard conditions. As is typically the case...the very strong southwest flow will also shove a great deal of water up to the Buffalo end of Lk Erie...so lakeshore flooding will be a possibility. More specifics on that in the lakeshore flooding discussion. A very tight sfc pressure gradient will remain in place across our forecast area on the day before Christmas...so while the winds should diminish as bit by way of a weaker LLJ especially later in the day, they will still be strong enough to possibly cause issues and certainly to support continued blowing snow. Models have trended a bit quicker with veering of winds, to more of 240-250 flow so that more of the Buffalo Metro would be impacted by lake snows Saturday into Saturday night with the visibility remaining near zero at times within the band. It will be quite cold with Saturdays highs ranging from the single digits over the Srn Tier to the teens and low 20s elsewhere resulting wind chills falling to as low as 10 to 20 degrees below zero. Christmas Day promises to remain cold with highs only in the teens to low 20s and winds to 30 mph generating wind chills of 10 below to just a few degrees abv zero. Meanwhile...a 240-250 flow will keep the lake snow machine in full gear for sites near and just south of the Buffalo and Watertown areas. No big change to forecast thinking. While the very cold weather will persist into Monday...sfc based ridging should help to at least lessen the potential for additional significant lake snows later Monday into Tuesday. Possible that conditions moderate more significantly by middle of next week, but not surprisingly, not a clear signal yet.

Peak gust O/U for mby is 25mph

What if they cross?

lol

Idk but not this year

"artic"