Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
100 PM EDT Tue Mar 24 2020
Valid Mar 24/1200 UTC thru Mar 28/0000 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
12Z Model Evaluation with Preliminary Preferences and Confidence
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Shortwave tracking from the Central Plains to the East Coast on
Wednesday
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Preference: Non-GFS/GEFS blend
Confidence: Near average
The southern stream trough exiting the Rockies and emerging over
the Central Plains is forecast to remain intact as it reaches the
eastern U.S on Wednesday. Surface cyclogenesis is in progress
across northern Texas and Oklahoma, and this low reaches the
central Appalachians and weakens by early Wednesday, with
secondary cyclogenesis is likely off the Mid-Atlantic coast by
Wednesday afternoon. The 12Z NCEP runs maintained decent run to
run continuity...so the 24/12Z GFS and the 24/06Z GEFS mean were
decidedly fast outliers. As a result, still preferred a
non-GFS/non-GEFS mean model compromise.
Longwave trough over the western U.S.
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Preference: Non-UKMET blend after 12Z Thursday
Confidence: Average
The amplified pattern over the eastern Pacific will end up
producing a positively tilted longwave trough axis which will
slowly progress down the West Coast, gradually move inland across
the Desert Southwest by Friday morning and be about ready to cross
the Southern Rockies by Friday evening. The 12Z NCEP guidance
largely maintained continuity with respect to the timing and
strength of the feature...leaving the UKMET a more amplified
outlier than other guidance beginning on Thursday. The 24/12Z GFS
was slower than the 24/00Z ECMWF, with the surface features
reflecting the processes aloft, but not enough of a difference to
be unusuable.
Storm system crossing northern tier of the U.S. midweek
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Preference: Non-NAM consensus
Confidence: Average
The 24/12Z run of the NAM got into much better agreement with
other models in handling this system. The resulting agreement
among the various global models was good...so a general compromise
should work fine. The GFS heights at 700 mb may be a bit lower
than other guidance by Wednesday afternoon over the Upper Midwest.
Otherwise, details from any of the deterministic models could be
used to reflect smaller scale details.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Bann