Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
250 AM EDT Wed Jul 08 2020
Valid Jul 08/0000 UTC thru Jul 11/1200 UTC
...See NOUS42 KWNO (ADMSDM) for the status of the upper air
ingest...
00Z Model Evaluation with Model Preferences/Confidence
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Closed low moving east across south-central Canada through Friday
Associated cold front crossing the northern Plains
Wednesday/Thursday and the Great Lakes Friday
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Preference: 00Z NAM/GFS/ECMWF
Confidence: Average
A slightly negatively tilted trough axis moving out of the
Northern Rockies and beginning to make its way over southern
Alberta early this morning will continue to shift east across the
Canadian Prairies through Thursday before opening and lifting
northeast over northern Ontario on Friday. The 00Z NCEP guidance
was a bit faster and the 00Z NAM ended up becoming deeper/slower
by Day 2 as the systems makes its way into the northern Plains.
The 00Z GFS still slightly outpaces both with trough progression
through the Great Lakes Friday/Day 3, but is not too far ahead to
be totally discounted, just limited in the blend.
Next trough moving into the Pacific Northwest Thursday
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Preference: General Model Blend...except non-ECMWF after 12Z Friday
Confidence: Slightly above average
The 00Z NCEP models remained in good agreement with other models
from the 12Z cycle with respect to the depth and progression of
this feature into the Pacific Northwest late Thursday. The 00Z
ECMWF made a change in that rather than dampening a shortwave as
it did over the Great Basin on Friday, it now wants to deepen it
as it moves across the Dakotas and dives it into the Upper Midwest
by the end of Day 3. Thinking is that there may indeed be some
shortwave energy which does that, suspect the ECMWF idea is too
strong. Otherwise, no change made to the model preference.
Low pressure moving northeast along Eastern Seaboard into this
weekend
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Preference: 00Z NAM/ECMWF/CMC
Confidence: Average
A fairly weak cyclone is expected to move drift east-northeast
across the Carolinas today before turning northeast up the Eastern
Seaboard on Thursday and Friday. At the same time, a mid-level
ridge builds to the north of the low across the northern
Appalachians and New England. The presence of this ridge continues
to suggest a slower solution. The 00Z GFS remained the most
progressive guidance with the turn north on Thursday...which was
the primary reason that the GFS was not included in the model
preference. The 00Z NAM/ECMWF/CMC remained consistent with their
previous runs and were favored.
Shortwave trough moving across New England Today
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Preference: General Model Blend
Confidence: Above average
Good agreement with this Day 1 shortwave trough crossing northern
New England Wednesday.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
This product will terminate August 15, 2020 with the 21Z issuance:
www.weather.gov/media/notification/pdf2/scn20-58pmdhmd_termination.
pdf
Bann