Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
239 AM EDT Thu Jul 2 2020
Valid Jul 2/0000 UTC thru Jul 5/1200 UTC
...See NOUS42 KWNO (ADMSDM) for the status of the upper air
ingest...
00Z Final Model Evaluation Including Preferences and Forecast
Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Eastern U.S. trough
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: General model blend through Friday, then NAM/GFS/ECMWF
Confidence: Moderate
The upper low that is currently over New England will gradually
evolve into an open trough by Friday night as it slowly moves
offshore, and the models are in good agreement on its evolution,
thus meriting a general model blend. By Friday night, as a ridge
tries to build northeast from the Plains, a trough builds back
across northern New England, while a secondary trough develops
beneath the ridge axis across the Gulf Coast region. The NAM is
stronger with this second trough building in across New England,
and the UKMET is much weaker with the trough across the Gulf Coast
states since it is much stronger with the building upper level
ridge across the Plains and Midwest. A blend of the NAM/GFS/ECMWF
depicts a more realistic pattern with better support from the
ensemble means.
Deep upper trough/closed low across the Pacific Northwest and
western Canada
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: General model blend through Friday, then 00Z
CMC/UKMET/ECMWF blend
Confidence: Moderate
An expansive closed low meandering across Alberta and British
Columbia and the Pacific Northwest will linger through Friday as
multiple shortwaves rotate around it. The guidance does feature
subtle differences in the intensity and position of the individual
vorticity centers, but the general mass field shows good agreement
through Friday, with the GFS becoming more amplified with the
trough reaching the Pacific Northwest coast Friday night. By
Saturday, the NAM also becomes stronger with the next impulse to
come across the Pacific Northwest.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Hamrick