Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1142 AM EST Tue Mar 05 2019
Valid Mar 05/1200 UTC thru Mar 09/0000 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
12Z Model Evaluation Including Preference and Confidence
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...Deep trough over the Great Lakes/Northeast...
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Preference: General model blend
Confidence: Above average
Above average confidence and model agreement continues for the
deep trough over the Great Lakes and Northeast US. The main trough
axis will pivot through the region into Wednesday. A secondary
shortwave trough will round the base quickly Wednesday night into
Thursday. While there are some very subtle timing differences,
placement in the mass fields are above average, with good
agreement in the QPF fields. As such, a general model blend looks
appropriate at this time.
...Deep closed low center near 32N 143W...
...Arriving across CA by Wed...
...Shearing downstream across the central Plains on Thurs...
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Preference: General model blend...through 48 hours (7.12z)
00z ECMWF/UKMET/GFS blend after
Confidence: Slightly above average
Closed low currently centered near 35N, 133W will move
northeastward toward the central California coast into Wednesday.
In the big picture, model agreement is fairly good but looking at
the details shows some timing and placement differences still. The
GFS is a faster solution, bringing the open low onshore a few
hours ahead of the NAM/ECMWF/UKMET. All of the guidance at least
has similar placement. That wave then moves into the central
Rockies where the model agreement actually improves and a general
model blend is preferred.
After 48 hours, another strong shortwave trough will approach the
California coast. Here, model differences are more significant.
The NAM is much stronger, closing off at 500 mb, while the ECMWF
is more compact (but open) while the GFS is more open and faster
compared to the rest of the guidance. Finally, the UKMET is on the
slower side of the guidance, keeping the wave well offshore
through 08.00z. For now, will suggest a general model blend early
in the period (first 48 hours) then lean on a ECMWF/UKMET/GFS
blend after.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Taylor