Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1235 AM EDT Sat Jul 25 2020
Valid Jul 25/0000 UTC thru Jul 28/1200 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 tracking from the Northwest into the
north-central U.S. through the weekend...
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Preference: General model blend
Confidence: Above average
Shortwave energy will skirt southwestern to southern Canada over
the next 36 hours before closing off and settling west of the
Hudson Bay toward the end of the forecast period. The retrograding
upper ridge over the southern US toward the southwest US and some
phasing with energy coming out of the Front Range will allow the
trough to encompass more of the Great Lakes region by
Tuesday/Wednesday. The latest deterministic guidance shows this
idea and evolution fairly well and agrees on the synoptic pattern
such that for mass field purposes a general model blend is
preferred.
...Tropical Storm Hanna...
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Preference: Official NHC track
Best Model Proxy: 00Z GFS, 12Z UKMET/ECMWF blend
Confidence: See latest NHC products
T.S. Hanna will make landfall along the South Texas coast on
Saturday and outside of the CMC, the rest of the model guidance
has clustered very tightly on a track with respect to location and
speed. The 12Z CMC is a bit north and too fast comapred to the
official track while the NAM is off to the south a touch. The best
model proxy is the 00Z GFS, 12Z UKMET/ECMWF. Strengthening of the
mid-level subtropical ridge north of Hanna should steer the system
more westward during the day Saturday and then west-southwestward
Saturday night as the system crosses through the lower Rio Grande
Valley. On Sunday, Hanna should be weakening over northeast
Mexico. For the latest information on Hanna, see the most recent
advisory statement from the National Hurricane Center.
...Upper low/trough over California...
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Preference: General model blend
Confidence: Above average
A broad upper trough and embedded closed low over CA will
generally remain in place through early next week, with some
tendency for the energy to begin lifting north by the end of the
period. Overall, the models are in good agreement through the
period with the handling of this energy, so a general model blend
will be preferred.
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