Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
257 PM EDT Mon Mar 11 2019
Valid Mar 11/1200 UTC thru Mar 15/0000 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
12Z Model Evaluation Including Preferences and Confidence
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...Upper trough departing from the Great Lakes/Northeast...
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Preference: General model blend
Confidence: Above average
Only minor differences remain with this system, with a general
model blend recommended to smooth out any smaller scale
discrepancies.
...Upper trough crossing the Pacific Northwest Tuesday...
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Preference: General model blend
Confidence: Above average
The models are in very good agreement in bringing a progressive
northern stream trough in across the Pacific Northwest on Tuesday
before then digging into the Intermountain West where it will
begin to interact with a large southern stream closed low ejecting
out of the Southwest. A general model blend will be preferred with
this system as it advances into the Intermountain West.
...Large closed low crossing the Southwest Monday/Tuesday...
...Phasing with digging northern stream trough...
...Associated deep surface low over the Plains/Midwest...
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Preference: 12Z NAM/GFS/ECMWF blend...thru 72 hrs
12Z GFS/ECMWF blend...after 72 hrs
Confidence: Slightly above average
A large deep layered closed low just offshore of southern CA will
move east across the Southwest through Tuesday and then eject
northeast out across the central Plains Wednesday where strong
lee-side cyclogenesis will take place. The guidance agrees in
showing strong phasing of this energy with the aforementioned
northern stream trough digging across the Intermountain West. This
will result in a very strong surface low moving from southeast CO
through western/central KS on Wednesday and then northeast across
IA by Thursday. The 12Z CMC and 12Z UKMET are still a little
weaker than the overall model consensus with the height falls, at
least through Wednesday which results in a modestly weaker surface
low. The 12Z NAM/GFS/ECMWF solutions along with a substantial
number of ensemble members favor a stronger/deeper evolution given
the degree of phasing over the High Plains. The latest ECMWF did
slow its low track down a bit and is a little farther south to put
it into better agreement with the NAM/GFS camp at least through 72
hours. After 72 hours, the NAM begins to lag the multi-model
consensus a bit with the timing of the wave, and UKMET begins to
shift its closed low a bit north and a little faster than the
model consensus. Will prefer a blend of the 12Z NAM/GFS/ECMWF
solutions through 72 hours, and then a 12Z GFS/ECMWF blend
thereafter.
...Upper trough approaching CA by Thursday...
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Preference: 12Z GFS/12Z GEFS mean/00Z ECENS mean blend
Confidence: Slightly above average
The models bring another shortwave trough toward CA on Thursday.
The 12Z UKMET/ECMWF solutions are the slowest, with the 12Z
GFS/CMC solutions the most progressive. The 12Z NAM is overall
just a little faster than the UKMET and ECMWF. The latest 12Z GEFS
mean and 00Z ECENS mean both favor a solution a little more
progressive, and so will lean in this direction with a blend of
the GFS and the GEFS/ECENS means.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Orrison