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Pattern January 2020 - Operation Thaw Alaska

superjames1992 said:
That would be interesting. I’ve never found the data, though. I recall reading one time that Portland, OR, for example, averages 3” of snow per year but has a median of 0”, for example (I may be wrong on that, though). RDU’s obviously isn’t 0”, but I wouldn’t be surprised if it’s something like 4-5” as opposed to the mean of 6-7” (or whatever it is these days).
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Depends on what range your pulling the range from. 100yrs? 50? 30?
 
Per Maxar, here is the average 11-15 day bias for the major US cities averaged out per forecasts made in the first half of Dec.:

GEFS -4.8
GFS(FV3) -3.2 (so not quite as bad as the GEFS)
EPS -1.2 (easily the best of these 3 but even it has been slightly too cold overall)
 
Snowmageddon warnings in North America come from tropics more than Arctic stratosphere.
A team led by the University of Reading conducted the first ever study to identify how the four main winter weather patterns in North America behave depending on the strength of the stratospheric polar vortex. They found widespread extreme cold is more common when an area of high pressure extends up to Alaska, and the polar vortex stretches down towards North America—pushing cold Arctic air southward in the lower atmosphere.

https://m.phys.org/news/2019-12-snowmageddon-north-america-tropics-arctic.html

 
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From Maxar based on forecasting major US cities in the 11-15 day for forecasts made throughout the first half of December, 2019, here are the mean absolute errors in degrees F: (this isn't bias)

GFS (FV3):
0Z 7.9
6Z 8.1
12Z 8.3
18Z 8.3

GEFS:
0Z 7.4
6Z 7.3
12Z 7.9
18Z 7.5

EPS:
0Z 5.8
12Z 5.7

- So, although not great by any means, the EPS by a rather wide margin did the best during the first half of Dec.
- The GEFS didn't do that much better than the GFS
 
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metwannabe said:
Of course the GOA ridge is still there but we're somewhat saved by some blocking starting to show up.... and don't @ me, it's a weather discussion board.

View attachment 29078
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This is exactly what we need if the GOA ridge continues to show up...we need blocking. We’ve been in such patterns that have produced. No blocking and we get a SER in response to the trough on the west coast.


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Once again, the cold on the end of the euro backs off, western US/pacific pattern looked liked crap aswell, only thing interesting was that ridging tryna go up towards AK, but there was a very very ugly -PNA 42E66EFC-9E08-4D70-A662-0272E4378D6B.gif
 
12z euro vs 00z euro pathetic
5481190c8d0faf5dc6fc9c2fe734a059.png
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GaWx said:
From Maxar based on forecasting major US cities in the 11-15 day for forecasts made throughout the first half of December, 2019, here are the mean absolute errors in degrees F: (this isn't bias)

GFS (FV3):
0Z 7.9
6Z 8.1
12Z 8.3
18Z 8.3

GEFS:
0Z 7.4
6Z 7.3
12Z 7.9
18Z 7.5

EPS:
0Z 5.8
12Z 5.7

- So, although not great by any means, the EPS by a rather wide margin did the best during the first half of Dec.
- The GEFS didn't do that much better than the GFS
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Do they have these for November? Seems like the Euro banged a warm drum that never really happened then, but I could be misremembering.
 
John1122 said:
Do they have these for November? Seems like the Euro banged a warm drum that never really happened then, but I could be misremembering.
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I think the EPS was too warm in early to mid November but don't have the numbers right now.
 
GaWx said:
Here's the change map for the entire 11-15 12Z GEFS averaged out vs the 0Z GEFS: this warming brings the 12Z GEFS 11-15 to N in the SE vs BN in most of the recent runs. #GEFSSucksButJBWillRideItTilTheEndOfTime

View attachment 29083
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The map above is the change map for the GEFS 11-15 when comparing the 12Z to the 0Z. The first map below is the same type of comparison but for the 12Z EPS vs 0Z EPS: it is the exact opposite as it is colder and reversed much of the warm changes of the 0Z EPS torch. So, whereas at 0Z the EPS 11-15 torch was way warmer than the GEFS 11-15 chill, the 12Z EPS 11-15 and 12Z GEFS 11-15 are now about the same with near normal since the GEFS was much warmer than its 0Z and the EPS was much colder than its 0Z with near normal the result for both at 12Z (2nd map below shows 12Z EPS 11-15):

12Z EPS 11-15 change vs 0Z: much colder
1577476329685.png



12Z EPS 11-15 anomalies: near normal SE vs torch on the 0Z
1577476367991.png
 
If we can get that -EPO to verify and move about 500 miles east and 500 north, we'd be in big business with the MJO being low in 7-8-cod. Models headfake a lot when ending patterns, hopefully the EPS starts a trend. Carvers Gap on AWF has noted several times this winter than EPS runs are cooler at 12z and warmer at 00z pretty often lately. No idea what causes it, but he thinks possibly MJO convection flaring during the day causes the 00z run to be warmer.
 
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