Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
219 PM EDT Thu Mar 19 2020
Valid Mar 19/1200 UTC thru Mar 23/0000 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
12z Model Evaluation with Latest Preferences and Confidence
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...Closed low over the West...
...Low pressure crossing the Central Plains into the Upper Great
Lakes...
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Preference: General model blend
Confidence: Slightly above average
The 12z NAM/GFS are close to the consensus spinning down the
closed mid level low over CA/NV through 21/00z. Short wave energy
ejected from the weakening mid low tracks across eastern CO,
spinning up surface low pressure there before 20/00z. Once the
surface low develops, there is generally good model agreement with
the track and strength of the surface low as it crosses the
central Plains and Upper Great Lakes before reaching Quebec around
20/12z. Given the good agreement with the track of the surface
low, a general model blend is preferred, with slightly above
average confidence.
...Mid level troughs affect the Northern Plains into the Upper
Great Lakes...
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Preference: 12z NAM/GFS/12z ECWMF blend
Confidence: Average
For the first short wave tracking out of central Manitoba, the 12z
NAM/GFS are close to the consensus as it reaches the Upper Great
lakes 22/00z. The 12z UKMET remains slower than the consensus with
this feature, though the trend for the UKMET has been faster with
this feature. The 12z CMC remains much deeper with the system, and
has been trending in that direction. For the first short wave, a
12z
GFS/NAM/ ECWMF blend is preferred.
For the second short wave tracking from Alberta into the Northern
Plains by the end of the period, the 12z GFS is faster than the
consensus, while the 12z UKMET/CMC remain slower with this
feature. For the second short wave, the 12z NAM/ECMWF seem to form
the best consensus, and are preferred with this feature.
...Mid level trough crossing Southwest Sat...
...Closed mid level low approaching Central/Southern CA Sun...
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Preference: 12z NAM/GFS/ECMWF blend
Confidence: Average
Short wave energy originating near 32N 133W at 20/12z tracks
toward the Southern CA coast, reaching far Southern CA/northern
Baja Peninsula at 21/12z. The 12z UKMET continues it trend of
being the slowest member of the guidance envelope. For this
feature, a blend of the 12z
GFS/NAM/12z ECMWF is preferred.
A closed mid level low near 34N 135W at 21/12z wobbles toward the
Central and Southern CA coast by the end of the period (23/00z).
With this feature, the 12z GFS begins to become faster than the
consensus, and remains so through 23/00z. The 12z UKMET/CMC sped
up their solutions with the closed low, making the 12z GFS seem
not as fast. As a result, the 12z GFS was included in the blend
for this feature.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Hayes