Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1228 AM EDT Sun Jul 26 2020
Valid Jul 26/0000 UTC thru Jul 29/1200 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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...Mid-upper level troughing over the northern CONUS...
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Preference: General model blend
Confidence: Above average
Mid to upper level energy over southern Canada is expected to
close off before settling over Ontario later in the period, while
the larger scale trough deepens over the Great Lakes region. At
the surface, a pronounced cold front is forecast to march across
the northern tier into the Great Lakes while upstream ridging
builds over the Canadian Rockies. In the increasingly amplified
pattern, the models have converged on a similar idea and show very
good agreement through 84 hours with the synoptic pattern.
...Hurricane Hanna...
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Preference: Official NHC track
Best Model Proxy: 12Z ECMWF/CMC blend
Confidence: See latest NHC products
Following the landfall of Hurricane Hanna along the South Texas
Gulf Coast, gradual weakening over land will occur as the system
tracks westward then southwestward into the rugged terrain of
Mexico on Sunday and Sunday evening. The biggest spread in the
models occurs after the system moves into Mexico where the GFS is
on the southern side of the model spread while the UKMET is a
touch fast. A CMC/ECMWF blend is the best proxy to the official
forecast and for the latest information on Hanna, please consult
the latest NHC public advisory.
...New upper trough/low approaching California by Tuesday...
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Preference: General model blend through 60 hours;
Non-GFS blend 60-84 hours
Confidence: Average
Toward the end of day 2 and into day 3, another shortwave trough
approaches the Northwest Pacific and northern CA. The 00Z GFS is a
touch faster and ahead of the rest of the guidance but otherwise,
the models show fairly good agreement for the system so far. The
slower timing makes more sense given the upstream ridging in
place, so a non-GFS blend on day 3 is preferred, which is
supported by the ECENS/GEFS means as 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
Taylor