Carvers Gap

Record lows. Seems to be an outlier at 12z, but…it caught the Dec 29th front first. Teens below zero.

The 12z GEM would shatter some records. Crazy run. A few places would have all time records at risk.

The 12z CMC and GFS in a bit of a model battle for Jan 1. The 12z has snow and below zero temps. My money is on the Canadian.

After a super quick skimming of models. The 0z Euro and 0z GEM are cold beginning sometime around Dec 28-29. The GFS really does not like the idea of the Jan 2 cold front...but sends one a few days later. Some of the AIFS models agree w/ the GFS...but for now, I am riding with the coldest models. Why? We have seen a tendency for models to miss or under-do cold fronts. I may try to update 500 here in a sec. That update was pretty much surface focused. As for snow? I have to think one or more of these really cold fronts is going to produce winter precip. It is worth remembering that models often lose systems in the the day 5-7 range...only to find them again, and they restrengthen. We may have short lead times on fronts which bring snow with cold fronts.

Fun with maps...the 18z GFS. We should see these types of runs given the potential for HL blocking. There are gonna be WILD swings as exemplified by the r-2-r map below.

Shiver me timbers. Trough drops into the East and holds. Slider present. NW flow present.

Nice run of the 18z GFS.....

Here are the WxBell maps at 342 from 12z. -75.4 is the coldest I could find. I have the 2m map, and for kicks and giggles, the real feel. I know there has been some discussion of the WxBell algorithm being colder than other models.

Thanks, man. I am finishing up some Christmas shopping so feel free! I am looking at them right now…Large scale changes.

Just looking at the cold in the Canadian front range and prairies across modeling at 12z...it sure looks like "when" not "if" that comes roaring into the Lower US. Modeling appears be working out which front is going to carry it. I would think some snow along the incoming front(whichever turns out to be strongest) seems like an increasing possibility. I think the GFS had -75F at some point late in the run (Yukon). Likely that is feedback, but if it isn't...we may challenge the NA record at some point during January.

The 12z GFS and GEPS ensembles have finally broken towards the deterministic camp...bout time.

The 12z suite looks reasonably consistent w/ the exception of the 12z GFS which for whatever reason sometimes completely loses the NAO on random runs. The 12z AIGFS looks about right. So, we are just gonna sub out the 12z GFS and grab the sixth guy off the bench.

Two, back-2-back cold fronts appear possible between Dec 28 and Jan4. If recent model history trends hold...that second front might be colder than what is modeled(well, except for the GDPS which brought it). The Canadian is likely too cold, but it looks like it might be about to score the coup for the Dec 28th run - most models have trended colder and if memory serves me correctly...it caught that first cold front before any other model(maybe the Euro Weeklies as well). Will models back off the intensity of the cold like they did in early December? I keep asking myself that, and then I remember this is a late December and early January air mass which is BN over western Canada. It is possible that the fronts are under modeled outside of seven days. The Music City Bowl is trending colder....oof.

Some bitterly cold runs overnight for the end of the year and beginning of the New Year. We are gonna get June and January within about 48 hours of each other. LR ext (weeklies) modeling has started to pick up on an EPO ridge towards the end of January. The CFSv2, Euro Weeklies, and CFSv2 seasonals have it. My guess could be sometime around the last week of January. The current pattern appears to be classic "C-FYAO" pattern, otherwise knows as a chinook - then freeze your tail off.

I will re-respond. Mercy! Cold source. Check.