Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
321 AM EDT Wed Jul 29 2020
Valid Jul 29/0000 UTC thru Aug 01/1200 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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07Z update: No significant changes in the rest of the 00Z guidance
...Mid-upper level troughing over the Great Lakes and Northeast...
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Preference: General model blend
Confidence: Average
The troughing expected to develop over the Great Lakes and
Northeast shows very good model agreement through 60 hours with
very little spread in the various deterministic guidance. From 60
to 84 hours, some timing issues develop with the ECMWF on the
slower side of the model spread while the NAM and GFS to some
degree are faster. Despite these differences, a general model
blend is still preferred through the period.
...Energy advancing across the Plains through Thursday...
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Preference: non 12Z UKMET blend
Confidence: Average
Mid-level energy coming out of the Rockies into the Central Plains
slowly sags southeastward toward the Ozarks by 48 hours and
elongates with the broader, larger scale troughing along the MS
River through the Great Lakes region. In general, model guidance
looks fairly reasonable with some minor timing issues where the
NAM/GFS are slightly ahead of the ECMWF/CMC. The UKMET continues
to show the biggest differences, particularly at the surface with
its low track across the mid-MS Valley Thursday night into Friday,
with its further south placement. For now will continue to
advertise a non-UKMET blend for the period.
...Upper low/trough approaching the Pacific Northwest...
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Preference: General model blend
Confidence: Average
There is reasonably good agreement with the closed low advancing
east toward the Pacific Northwest Thursday and Friday. There are
some minor timing differences seen in the GFS/NAM versus the other
models, but the deterministic models are in good enough agreement
at this point to go with a general model blend through the
forecast period.
...Potential Tropical Cyclone Nine Approaching Southern Florida
Day 3...
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Preference: Official NHC Advisory
Best Model Proxy: CMC/ECMWF/UKMET blend
Potential Tropical Cyclone Nine will track from near the US Virgin
Islands westward toward Cuba and southern Florida by the end of
day 3. Model spread varies considerably with this feature with a
somewhat western/southwestern trend in the last couple of model
cycles. The best model proxy to the official NHC forecast is a
blend of the ECMWF/CMC/UKMET, where the NAM and GFS are to the
right of the current path. For the latest information of PTC Nine,
see the updated NHC advisory.
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