Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
258 PM EDT Tue Jul 07 2020
Valid Jul 07/1200 UTC thru Jul 11/0000 UTC
...See NOUS42 KWNO (ADMSDM) for the status of the upper air
ingest...
12Z Final 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: 12Z ECMWF/NAM/CMC with some 12Z GFS
Confidence: Average
A slightly negatively tilted trough axis over the Pacific
Northwest swings northeast over the northern Rockies rest of
today, closing over Alberta tonight. This low then shifts east
across the Canadian Prairies through Thursday before opening and
lifting northeast over northern Ontario on Friday. The associated
cold front shifts onto the Montana Plains this evening and crosses
the Dakotas through Wednesday night before crossing the central
Great Lakes through Friday. The 12Z ECMWF became more progressive
and in terms of progression of the leading trough/cold front from
the northern Plains to the Great Lakes is quite similar to the 12Z
NAM and 12Z CMC. The 12Z GFS 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. The
12Z UKMET is notably flatter than consensus which makes it an
outlier.
Next trough moving into the Pacific Northwest Thursday
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Preference: General Model Blend
Confidence: Slightly above average
The 12Z global suite is in good agreement with the depth and
progression of this feature into the Pacific Northwest late
Thursday. The 12Z CMC came much more in line with the rest of the
guidance, with a less positively tilted and therefore more
progressive trough.
Low pressure moving northeast along Eastern Seaboard into this
weekend
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Preference: 12Z NAM/ECMWF/CMC
Confidence: Average
A fairly weak cyclone is expected to move drift east-northeast
across the Carolinas through Wednesday before turning northeast up
the Eastern Seaboard Thursday/Friday as a mid-level ridge builds
to the north across the northern Appalachians and New England. The
presence of this ridge continues to suggest a slower solution. The
12Z GFS remains the most progressive guidance with the turn north
on Thursday. The 12Z UKMET is a little less deep with the cyclone
than the 00Z, but is even slower now and a notable outlier. the
12Z NAM and 12Z ECMWF/CMC were steady with their 00Z runs and have
similar depth and timing and remain preferred at this time.
Shortwave trough moving across New England Wednesday
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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
Jackson