Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1241 AM EDT Mon Jul 6 2020
Valid Jul 6/0000 UTC thru Jul 9/1200 UTC
...See NOUS42 KWNO (ADMSDM) for the status of the upper air
ingest...
00Z Model Evaluation Including Preferences and Forecast Confidence
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Trough building over the Northeast U.S. this weekend
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Preference: GFS/ECMWF/UKMET
Confidence: Slightly above average
Northwest flow shortwave trough energy will move across the
Northeast and New England Monday, and is quickly replaced by brief
ridging for Tuesday. By mid-week, a broad shortwave trough
crosses northern New England. Overall, model guidance is fairly
agreeable through the period with some minor model differences
noted, with the NAM faster and the CMC not as strong with the
mid-week trough. Blending the GFS/ECMWF/UKMET should serve as a
good starting point.
Trough/weakness over the Gulf Coast region
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Preference: Non-UKMET blend
Confidence: Average
Broad weakness in the larger scale upper ridge over the Southeast
and Deep South will remain in place over the next several days
with some suggestion in the latest guidance of more organized
shortwave energy near the Southeast coast by mid-week. Model
guidance has consolidated better over the last couple of cycles
and largely agree on the evolution through Wednesday night. The
main exception is the UKMET, which shows a faster progression of
the weakness/energy off the Southeast coast compared to the rest
of the deterministic guidance, and continues to indicate a
stronger ridge over the central U.S. Therefore, a non-UKMET blend
is still preferred.
Trough with multiple shortwaves across the Pacific Northwest and
Canada
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Preference: ECMWF/CMC/EC mean blend
Confidence: Slightly above average
Within the broad trough over the Pacific Northwest, a stronger
shortwave trough approaches the coast late Monday into Tuesday.
Aside from a slightly deeper NAM, model agreement is very good
with this system. Eventually the energy works across the northern
Rockies and is forecast to close off over the southern Canadian
Rockies. The GFS is initially quicker here, but becomes well
clustered with the other guidance by the end of the forecast
period. The NAM becomes slower with the closed low across
south-central Canada by mid-week. With the next system arriving
towards the end of the forecast period, the NAM and GFS are more
potent by developing a closed low by Wednesday night, whereas the
non-NCEP guidance suggests more of an open trough.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Hamrick