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Pattern Dazzling December

John1122 said:
If worried about a warm up after this cold shot, read the CPC long range forecast discussion from earlier today. It notes the GFS is basically not very usable currently because it's improperly handling storms in relation to the -NAO/blocking pattern. That is causing it to have wildly varying results from run to run as it gets further into the extended. CPC said they aren't even using it in their longer range forecasts right now and instead are using the Euro/EPS.
Click to expand...
Thanks John. Just read thru it. A lot of times they don't add those types of interesting tidbits like they did in the old days....maybe this "Scott H" forecaster is one of the better ones to follow

Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EST Fri December 09 2022

8-14 DAY OUTLOOK FOR DEC 17 - 23 2022

During the week-2 period, models are in good agreement in persisting a 500-hPa
ridge across Alaska, but differ as to the strength and orientation. Farther to
the east, as the GEFS significantly weakens the ridge predicted over eastern
Canada relative to today's ECMWF and Canadian Ensemble Means. The increased
model uncertainty across the higher latitudes of North America results in high
forecast spread in the predicted strength of the AO, which in turn, increases
uncertainty in the overall pattern farther to the south over the CONUS. The
ECMWF ensemble mean solution maintains the strongest ridge over Alaska, thus,
reflects a correspondingly strong trough farther to the south near California.
Meanwhile, the Canadian ensemble maintains a strong trough across the eastern
CONUS, consistent with anomalous ridging forecast near Greenland. The GEFS
depicts near normal heights over most of the CONUS, with significant below
normal heights confined to the southwestern CONUS. Today’s week-2 manual height
blend favors the 00z ECMWF Ensemble Mean solution, based on considerations of
recent skill.

The official 8-14 day 500-hPa height blend consists of: 20% of Today's 6z GFS
Ensemble Mean centered on Day 11, 55% of Today's 0z European Ensemble Mean
centered on Day 11, and 25% of Today's 0z Canadian Ensemble Mean centered on
Day 11

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: About Average, 3 out of 5, due to
good agreement among models on an amplified pattern early in the period offset
by significantly increased model uncertainty by the end of week-2.

FORECASTER: Scott H


DfTBZZo.png
 
John1122 said:
If worried about a warm up after this cold shot, read the CPC long range forecast discussion from earlier today. It notes the GFS is basically not very usable currently because it's improperly handling storms in relation to the -NAO/blocking pattern. That is causing it to have wildly varying results from run to run as it gets further into the extended. CPC said they aren't even using it in their longer range forecasts right now and instead are using the Euro/EPS.
Click to expand...

Just look at the GFS here for 3 days before Christmas. It goes from average to really cold in 3 runs(!)... I mean... How can anyone take it seriously in the Christmas timeframe?

Watch the ensembles and the larger signals
 
griteater said:
Thanks John. Just read thru it. A lot of times they don't add those types of interesting tidbits like they did in the old days....maybe this "Scott H" forecaster is one of the better ones to follow

Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EST Fri December 09 2022

8-14 DAY OUTLOOK FOR DEC 17 - 23 2022

During the week-2 period, models are in good agreement in persisting a 500-hPa
ridge across Alaska, but differ as to the strength and orientation. Farther to
the east, as the GEFS significantly weakens the ridge predicted over eastern
Canada relative to today's ECMWF and Canadian Ensemble Means. The increased
model uncertainty across the higher latitudes of North America results in high
forecast spread in the predicted strength of the AO, which in turn, increases
uncertainty in the overall pattern farther to the south over the CONUS. The
ECMWF ensemble mean solution maintains the strongest ridge over Alaska, thus,
reflects a correspondingly strong trough farther to the south near California.
Meanwhile, the Canadian ensemble maintains a strong trough across the eastern
CONUS, consistent with anomalous ridging forecast near Greenland. The GEFS
depicts near normal heights over most of the CONUS, with significant below
normal heights confined to the southwestern CONUS. Today’s week-2 manual height
blend favors the 00z ECMWF Ensemble Mean solution, based on considerations of
recent skill.

The official 8-14 day 500-hPa height blend consists of: 20% of Today's 6z GFS
Ensemble Mean centered on Day 11, 55% of Today's 0z European Ensemble Mean
centered on Day 11, and 25% of Today's 0z Canadian Ensemble Mean centered on
Day 11

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: About Average, 3 out of 5, due to
good agreement among models on an amplified pattern early in the period offset
by significantly increased model uncertainty by the end of week-2.

FORECASTER: Scott H
Click to expand...
Give this one a try as well. It's the one that speaks about the GFS having issues and expects the cold air to continue into week 3, and that week 3 will be so BN that the week 4 will average out to BN even if there's warming in parts of the country as they expect the return of the -PNA. They note the -NAO is likely to continue, along with the -AO through the 4 week period.

Climate Prediction Center - Week 3-4 Outlook

www.cpc.ncep.noaa.gov www.cpc.ncep.noaa.gov
 
John1122 said:
Give this one a try as well. It's the one that speaks about the GFS having issues and expects the cold air to continue into week 3, and that week 3 will be so BN that the week 4 will average out to BN even if there's warming in parts of the country as they expect the return of the -PNA. They note the -NAO is likely to continue, along with the -AO through the 4 week period.

Climate Prediction Center - Week 3-4 Outlook

www.cpc.ncep.noaa.gov www.cpc.ncep.noaa.gov
Click to expand...
Thanks, good nuggets in there and well written
 
The GFS is struggling mainly with the second piece of energy coming into the US along with our first piece.

0424BF83-BE3E-41B3-AFAF-A095644179AE.jpeg

A few things I think are in play here. Mainly, the GFS is holding back our first piece JUST a bit more than the EURO. Obviously this allows for more interaction between the two. Here is the Euro.9C109144-EDFF-4EB3-84DD-8A25FA833401.png
The GFS has started to build separation back between the waves at 6z. (Does it stick?)

B91B0B0F-0E56-43FA-99E1-2BAE6F102D3F.gif

This doesn't matter a ton for this initial storm other than NW flow threat. BUT it has everything to do witch our second system and the pattern after. I guess the point I'm making is it's not surprising the GFS is all over the place given one of the elements is over the Pacific and closer to Russia at this point.
F61BBEA5-6161-438F-8F76-F38403DCFE40.jpeg
 
I gotta say the Euro and CMC keeps the cold in place and has been consistent showing that. I’m not trusting the GFS at this moment with how much flip flopping it’s doing. Look at the last 3 Euro runs compared to last 3 GFS runs for 200-240 hours out. Euro is clearly more consistent.
 
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