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Pattern The Great December Dump

The GFS (FV3) performed way too intense with CAD last Winter. I do not know what has been fixed, maybe @Webberweather53 would know about any major modeling changes. We may be seeing that problem surface with the recent large ice storm runs.

The Euro holds back in the Southwest, and that has seemed to stay consistent or even worse with the model's higher resolution changes.. so I'd suggest taking a blend of the GFS/Euro/ ensembles with how that evolves.

Not playing debbie downer here.. but these are things that need attention.
 
It would be cool if we see a separate peice of the SW rollin due east turns into a nice bowling ball building a nice cold core and timing right with that high as well. I dont like the low hanging in the gulf that long, if it's a gulf low then we need to see a nice speed
 
12z EPS is looking better. The S/W is more SW
06z
1575871200-yRQxcOCe2Gg.png

12z
1575871200-fjPKx7P1rtc.png
 
To go along with my post above, the best guys to pay attention to when it comes to model blending and picks is the WPC. They have been doing this a long time, and end up being more right than wrong. Watch how they speak about what modeling they have chosen to use in their forecasts and for what reasons. It will help out a lot on which models are performing the best in the current (and future) pattern.

I highlighted important parts to pay attention to dealing with the models below. (Sometimes you will see them outright throw a rogue solution out due to inconsistency and they will explain it.)

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
120 PM EST Sat Dec 07 2019

Valid 12Z Tue Dec 10 2019 - 12Z Sat Dec 14 2019

...Much below normal temperatures for the Northern
Plains/Midwest/Great Lakes...

18 UTC Update...

No major changes were made to the ongoing forecast in this update.
The GFS/ECMWF were heavily used in the forecast for days 3-5
(Tue-Thu). For days 6-7 (Fri-Sat), ECENS/GEFS ensemble means
comprised a majority of the forecast, with some continued use of
the deterministic ECMWF as well. Models continue to show support
for the development of a significant wave of low pressure along a
surface front in the Gulf of Mexico by late next week, potentially
tracking northeastward across the Southeast U.S. by early next
weekend. Spread is considerable with respect to the timing and the
eventual track of this feature, however, which supported a
solution close to the ensemble means. Updated winter weather
outlooks this morning showed an expanded region of 10-30 percent
probabilities for days 6-7 across portions of the Mid-Atlantic and
Northeast, associated with this system.


Previous Discussion (issued at 0721 UTC)...

...Pattern Overview and Guidance/Predictability Assessment...

A southern stream flow associated with an amplifying Southwest
upper trough early week still offers some uncertainty in terms of
magnitude and ejection timing for the U.S. southern tier Tuesday
into Thursday, but guidance clustering has improved to bolster
forecast confidence.

Overtop, a cold Hudson Bay upper vortex lingers next week. A
notable upper trough rounding underneath amplifies to the central
then eastern lower 48 states Tuesday/Wednesday, with less
amplified troughing/cyclonic flow for much of the rest of week. An
upstream ridge amplifies up the North American West Coast early
week before being weakening midweek by eastern Pacific shortwaves
that cut inland from the Northwest to the snowy Rockies. A favored
and reasonably well clustered GFS/ECMWF and GEFS/ECMWF ensemble
solution suggests this energy may subsequently act to amplify
central to southern/eastern U.S. upper troughing. This may lead to
organized cyclogenesis to focus moisture and lift to produce a
risk of heavy rainfall across the Southeast. Subsequent system
deepening, northward lifting, and interaction with receding lower
atmospheric cold air damming over the East heading into next
weekend may offer an emerging wintry snow/ice threat to the north
to monitor.


...Weather Highlights/Threats...

There remains a strong signal for a swath of moderate rainfall
ahead of a main cold front from the lower MS Valley to the
Appalachians/Mid-Atlantic and southern/eastern New England
Tuesday. Activity will shift offshore midweek. Frontal waves and a
dynamic upper trough/jet also supports some enhanced snows on the
cooled northwest periphery of the precipitation shield from
Appalachians to the Northeast. Lake effect snow should also
persist across the Great Lakes in the wake of the cold front which
is particularly cold. Polar plunges are expected behind the cold
front offer temperature anomalies of 15 to 30 degrees below normal
centered over the Upper Midwest with reinforcing shots of cold
air.

Over the West...a building West Coast upper ridge should keep most
of the West dry through early next week beyond some Rockies snows.
The pattern should become more wet and elevation snowy for
especially the Pacific Northwest, but also inland to the Rockies
as shortwave energies round the northern part of the ridge later
week.
Click to expand...

https://www.wpc.ncep.noaa.gov/html/discuss.shtml
 
RollTide18 said:
I’m just not seeing it for Alabama or Georgia outside of the mountains, maybe I’m missing something.
Click to expand...
Unfortunately, outside of the Carolina CAD areas, there simply isn't anything to track. Pattern, for now, is meh. But it's only Dec 7, so not worried.
 
12z NAVGEM is still showing the beginnings of low development underneath the high at 06z Wednesday. I do think the timing of the high will slow and not cut out in front of the low. I'm going with the high and low pushing east at the same time.
We'll see what happens, I'm liking the trends so far!
391cd0b083911b0c86579aa66c151a1b.jpg


Sent from my SM-A102U using Tapatalk
 
Here is the link to the WPC model diagnostic page: https://www.wpc.ncep.noaa.gov/discussions/hpcdiscussions.php?disc=pmdhmd

Here, they give a summary of how the models are performing and their choices also. (below they are going with the Euro and saying while the GFS is possible, it needs more global support)

Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
135 PM EST Sat Dec 07 2019

Valid Dec 07/1200 UTC thru Dec 11/0000 UTC

...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...

12Z Model Evaluation with Preferences and Forecast Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Overall Pattern Across the CONUS...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: 12Z ECMWF; 00Z ECMWF Ensemble Mean
Confidence: Average

---18Z UPDATE---
While the 12Z UKMET remained relatively consistent with its 00Z
run, there were important trends on the CMC and ECMWF. The 12Z
ECMWF slowed down to be more comparable with the GFS, while the
12Z CMC sped up considerably and is now a reasonably good match to
the ECMWF with the southern stream wave digging through the
Southwest and into the Southern Plains. The preference has been
shifted to include the slower 12Z ECMWF scenario, but still
blended with the 00Z ECMWF Ensemble Mean to incorporate the prior
consensus. It may take another model cycle or two to determine
whether the slower trend will continue or not.

---PREVIOUS DISCUSSION---
Models are showing some more substantial differences beyond 09.06Z
(Sunday Night), particularly with how they handle a southern
stream wave digging through the Southwest, and how that eventually
phases with a larger, amplifying trough over the Central U.S. This
is most notable in a relatively large spread in timing centered
around 10.00Z (Monday evening) over the Southwest. Over the past
few model cycles, the ECMWF and ECMWF Ensemble Mean have gradually
converged around their positions depicted on the 00Z runs. Other
models have been less consistent, with the UKMET trending faster
and less amplified, and the GFS trending slower.

The preference will be to lean toward the 00Z ECMWF and 00Z ECMWF
Ensemble Mean, given the multi-run consistency they have shown,
and the 00Z GFS given its relatively good alignment with the ECMWF
ensemble envelope. Conceptually, the ECMWF also makes sense as the
southern stream wave may have a tendency to deamplify and
accelerate as it is overwhelmed by larger height falls from the
longwave trough expanding over the central U.S. The 00Z CMC and
many 00Z NAEFS members hang the southern stream wave back more
over the Southwest, and the 12Z GFS has joined that cluster. This
can't be completely discounted, but there is a lack of support
from other global models.

Finally, a preference centered around the 00Z GFS and ECMWF will
provide consistency with the previous forecast, as that was the
preferred model blend overnight as well.


Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml

Lamers
Click to expand...
 
I cant pull up EPS mix precip members, anyone have them
 
Shawn said:
To go along with my post above, the best guys to pay attention to when it comes to model blending and picks is the WPC. They have been doing this a long time, and end up being more right than wrong. Watch how they speak about what modeling they have chosen to use in their forecasts and for what reasons. It will help out a lot on which models are performing the best in the current (and future) pattern.

I highlighted important parts to pay attention to dealing with the models below. (Sometimes you will see them outright throw a rogue solution out due to inconsistency and they will explain it.)



https://www.wpc.ncep.noaa.gov/html/discuss.shtml
Click to expand...
Agree. WPC is rarely wrong.
 
I love the back and forth dance the GFS and Euro have been doing with the potential storm next week. To that says there is a legit shot at a winter storm here. Maybe it might not work out, but the potential is definitely there.
 
Jessy89 said:
Well simply because the Euro is the most reliable. Therefore I believe we will see the GFS trend that way. Just guessing though


Sent from my iPhone using Tapatalk
Click to expand...
Yes, the Euro can be more reliable in some cases, but not always. I wouldn't go with just with one model. This is where the blending of other models come into play.

Sent from my SM-A102U using Tapatalk
 
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