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Pattern Dazzling December

ILMRoss said:
the storm the gave nashville 8 inches of snow last year or something like that was high clouds in the models like 4 days out. i think about that basically every time there's a shortwave hanging around in the 3/5 day range
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When I was a kid I remember John Cessarich at WYFF4 made a late call on a low coming out of the gulf 24-48 hours before it happened. We got several inches. Different times I know.
 
ILMRoss said:
the storm the gave nashville 8 inches of snow last year or something like that was high clouds in the models like 4 days out. i think about that basically every time there's a shortwave hanging around in the 3/5 day range
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I can remember plenty of southern sliders over the years that my area was forecasted to be dry 3-4 days out but ended up getting a decent snowfall. February 2010 was probably the best example as it was forecasted a slight chance of flurries 24 hours prior and ended up with 5” of snow
 
griteater said:
This is the second iteration of this graph

From the 00z runs last night, here is the percentage of members with a winter storm (snow or ice) in the blue area on the map (2nd image).

I changed it to express the numbers as a percentage since each ensemble has a different number of members (10 of 30 hits on GEFS is 33% hit rate / 10 of 50 hits on EPS is 20% hit rate). It doesn't effect the % for the total (black line) because it just so happens that we have 100 total ensemble members

qjm7MlO.png


vAyeaGN.png


Reminders:
1. I didn't count upslope snow in the mountains
2. I didn't count rain storms that ended as some snow
3. I didn't count weak storms with skiffs of snow
4. I didn't count the operational or control runs in the total
5. If a storm spanned multiple days or time periods, I only counted it once
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. What was the Black line yesterday when you 1st introduced this to us? Did it increase or decrease for the dates 12/20-12/25. Thats a great metric to observe. Thank you for sharing
 
Big high pressure sliding down the Rockies. This is the tablesetter if you’re holding out hope for a Christmas storm. I don’t know how much more any of us can ask for. This gives everyone in America a fighting chance at a white Christmas.
 
Hypsometric said:
Pretty obvious where this is going now.

View attachment 126050
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Just can't seem to get this into the southeast though. The overall trend is obvious but still wrestling with how far into the southeast this can penetrate into meaningful cold for true winter weather. That seems to be the wobble from my untrained eye
 
Just curious, does anyone have access to the upper level archives to Christmas eve 1983? I wonder how this would compare....83" was supposed to be the coldest Christmas on record for the continental US.
 
WEATHERBOYROY said:
Just curious, does anyone have access to the upper level archives to Christmas eve 1983? I wonder how this would compare....83" was supposed to be the coldest Christmas on record for the continental US.
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Here was the pattern surrounding Christmas '83 when compared to the LR EPS. Some noticeable similarities between the strong -NAO and +PNA. However, this pattern has a -NAO, but less of a SE Canada Vortex.
compday.fOzkRndWef.gifecmwf-ensemble-avg-nhemi-z500_anom_7day-2185600.png
 
Need the trough to pull back west some and that would've been the Christmas of all Christmas gifts. Artic air flying in behind it over a snow airmass? it would be there for a week and we would likely get single digit and subzero temps for lows.
 
griteater said:
If we were going in a bad direction, you would think the ensemble mean would be either going in a worse direction or holding the line....but it's improving here on Dec 20th. I especially like the slight improvement with the -NAO placement. This is the GEFS Mean, last 5 runs

8WKsm5C.gif
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Notice the faster the cutoff ridge occurs on the trend/faster it disconnects from the higher heights in the GOA, the quicker the TPV moves out. That’s key since the cutoff ridge has flow sped up underneath, then the pac trough does it’s job pumping heights out west
 
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