griteater
Member
Even the GFS run is getting really blocked up over N America in time
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Pattern Dazzling December
- Thread starter Rain Cold
- Start date
griteater
Member
The speed of the flow has come to a screeching halt there later in the GFS run. Big block / big log jam. Cold air sagging south
Cary_Snow95
Member
and it doesn’t really look like there’s a big ridge in the west either just the flow getting backed forcing the cold air in Canada south and east
griteater
Member
That’s correct. It’s the best way to get cold air. You don’t even have to work hard
But later on, the western ridging pops
This is honestly the evolution we would really want, it was showing up on ensembles days ago, would love for it to come back 
Per GFS we have a parade of troughs diving down into the LR forecast which is GREAT to see but we just don’t have any real cold to work with and I’m not sure when we will. We’ll need it
True we don't have the PV on our side, but we can manage with late December climo if we can get enough blocking.
griteater
Member
Um, yes, that would work ha
I guess my concern, which isn’t much of one, is the thing we love and have going for us (blocking) may have to break down a bit in order to allow cold back on this side of the pole. Which puts us back at square one ?
griteater
Member
I'm one to be concerned with ample supply of cold air as much as anyone. But IMO, it's a bit of a misnomer to say that we need a huge chunk of the PV on our side of the pole. We really just need a piece of it, with cold air pushing south out of Canada. With Asia being massive in size, with such huge land area, most of the time, it is going to hog the vast majority of the tropospheric PV
In this model run, the blocked flow is the catalyst for getting the cold air in Canada (and entire height pattern) to filter slowly south. We hardly have any semblance of the tropospheric PV in N America in this case. It's not an Arctic plunge type of scenario....but those come with their own challenges of fast flow and in/out cold surges. This is much preferred IMO, but as always, it has to setup just right (thus, our low snowfall climo).
This setup which lacks the TPV presence in Canada produces impressive cold sagging south into the Bay of Campeche
This is happening as I type this on the gefs right now
A brief interjection of looking 10 days in the future, to look outside right now. Love this weather, 49 and full clouds
Webberweather53
Meteorologist
There's a pretty hilarious amount of coastal cyclone spam on today's 12z GFS beginning this coming week & continuing til nearly Christmas/end of the run. Setting us up nicely for the heart of the holiday season/last week of December ish into the beginning of January.
We often forget sometimes that what I call homegrown cold will be enough especially when we’re going into the lowest sun angles and longest nights of the year.I'm one to be concerned with ample supply of cold air as much as anyone. But IMO, it's a bit of a misnomer to say that we need a huge chunk of the PV on our side of the pole. We really just need a piece of it, with cold air pushing south out of Canada. With Asia being massive in size, with such huge land area, most of the time, it is going to hog the vast majority of the tropospheric PV
In this model run, the blocked flow is the catalyst for getting the cold air in Canada (and entire height pattern) to filter slowly south. We hardly have any semblance of the tropospheric PV in N America in this case. It's not an Arctic plunge type of scenario....but those come with their own challenges of fast flow and in/out cold surges. This is much preferred IMO, but as always, it has to setup just right (thus, our low snowfall climo).
This setup which lacks the TPV presence in Canada produces impressive cold sagging south into the Bay of Campeche
SimeonNC
Member
It's honestly better that it won't be super cold due to the fact that the coldest patterns tend to be dry.
If you want snow, you want it cold but not too cold.
Sent from my LM-Q730 using Tapatalk
If you want snow, you want it cold but not too cold.
Sent from my LM-Q730 using Tapatalk
NoSnowATL
Member
Temps 25-35 . 15-25 = dry as hell.
This is so true…December 2000 was a great example of that for a lot of us
Hypsometric
Member
It's also worth pointing out that the infamous 2010 Christmas storm featured surface temperatures in the lower 30s during the event and that one was just a few timing differences away from being one of the biggest interior snowstorms in NC history. It was also basically an all-snow event for most just due to upper levels being plenty cold.
RDU (as an example): https://products.climate.ncsu.edu/weather/winter/station/?e=510&t=h&stn=KRDU
Great point. Heck the biggest storm that I’ve personally gone through in February 2004 had a lowest temperature of 28 degrees and that was during the heaviest rates as the upper low passed over… most of that storm was about 30-31 degrees and I ended up with 19” IMBY