Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1249 PM EDT Tue Jul 14 2020
Valid Jul 14/1200 UTC thru Jul 18/0000 UTC
...See NOUS42 KWNO (ADMSDM) for the status of the upper air
ingest...
12Z Model Evaluation with Preliminary Preferences/Confidence
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...Mid-level shortwave troughing over the northeastern quarter of
the U.S. Monday to Wednesday...
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Preference: General model blend
Confidence: Average
The models show similarly with this system. Any differences, which
correspond to a departing offshore surface low located east of
Nova Scotia, appear once this system's impacts have left the
Northeast. Therefore, a general model blend can still be used.
...Longwave trough axis moving through the north-central U.S.
through Wednesday with accompanying surface cold front...
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Preference: 12Z GFS...14/00Z ECMWF/UKMET blend
Confidence: Average
As a large closed low and associated longwave trough axis track
eastward across southern Canada through the rest of the week, a
corresponding cold front will move into the Great Lakes and Great
Plains. With the 14/12Z GFS mass fields aloft maintaining a high
degree of continuity, differences related to a shortwave tracking
through the base of the trough on Wednesday remain--the GFS being
on the faster side of the guidance. Still think that 14/12Z GFS,
14/00Z ECMWF/UKMET are in good enough agreement to each other to
prefer a blend of them.
...Cut off low west of California by Thursday morning and
progressive trough crossing the Pacific Northwest...
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Preference: non 14/00Z UKMET blend
Confidence: Average
The latest models continue to show good agreement with a 700-500
mb low closing off by mid-week over the western U.S. and
retrograding offshore of California by late in the day Wednesday.
There is also good agreement, albeit minor amplitude differences,
with a progressive mid-level trough axis into the Northwest on
Thursday. A general model blend represents both systems along the
West Coast well.
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:
www.weather.gov/media/notification/pdf2/scn20-58pmdhmd_termination.
pdf
Otto