Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1140 AM EST Thu Nov 14 2019
Valid Nov 14/1200 UTC thru Nov 18/0000 UTC
..See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
12Z Model Evaluation with Preferences and Confidence
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...Closed low development over the Southeast...
...Cyclogenesis off the Southeast Coast...
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Preference: Non-ECMWF blend
Confidence: Average
A shortwave will begin to separate out from the westerlies and dig
down across the lower MS and TN Valleys on today, and as this
energy drops southeast across the Gulf Coast states tonight, it
should interact with and capture energy associated with an
ejecting southern stream closed low crossing through south Texas
and the western Gulf of Mexico. The result of this interaction
will be a closed low over the Southeast by Friday, with coastal
cyclogenesis taking place just southeast of the Carolinas.
The 00Z ECMWF gradually becomes slower than the remaining suite of
guidance with the surface and mid-level low centers with this
system, with the remaining guidance clustered on a somewhat more
progressive solution off to the northeast relative to the
Southeast coastline. The 12Z GFS and 00Z UKMET are a tad faster
than the global model consensus, but are within the ensemble model
spread and are not considered outliers to the extent that the
ECMWF is. The 06Z GEFS mean and 00Z ECENS mean are more supportive
of the non-ECMWF guidance, so a non-ECMWF blend will be preferred
at this time.
...Strong northern stream trough brushing the Northeast by Fri...
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Preference: General model blend
Confidence: Above average
The models drive a strong northern stream closed low through
southeast Canada through Friday and Saturday, with the southern
portion of the trough brushing the Northeast. The guidance is in
sufficiently good enough agreement for a general model blend to be
preferred.
...Mid-level shortwaves impacting the Intermountain West...
...Trough amplification across the Plains this weekend...
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Preference: Blend of the 12Z GFS/00Z CMC and 00Z UKMET
Confidence: Slightly above average
A relatively weak mid-level shortwave arrives across the West
Coast today while a second shortwave farther north aims toward
Vancouver Island and southern British Columbia by early Friday.
The initial shortwave should dampen out over the Intermountain
region on Friday, but the second shortwave farther north is
expected to drop southeast down across the Intermountain region
and begin to amplify through Saturday. The 12Z NAM overall appears
to be a bit too weak with the amplification compared to the global
models. Among the global models, the 00Z ECMWF becomes a bit of a
slower outlier solution, with the 12Z GFS, 00Z CMC and 00Z UKMET
showing better model clustering as the energy ejects east out
across the Plains by Sunday. Will prefer a compromise of the GFS,
CMC and UKMET solutions at this time.
...Closed low development offshore southern California on Fri...
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Preference: Blend of the 12Z GFS and 00Z UKMET
Confidence: Above average
Additional shortwave energy approaching California later today
will break away and dig southeast to offshore southern California
on Friday, with the guidance supporting a weak closed low
evolution that drops down to west of the Baja Peninsula this
weekend. The guidance is in good agreement with the height fall
evolution through 60 hours, however, beyond this time frame the
00Z ECMWF focuses the closed low closer to the Baja Peninsula,
with the 12Z NAM and 00Z CMC much farther west and to the left of
the model consensus. The model consensus is best approximated by
the 12Z GFS and 00Z UKMET by the end of the period, which is also
well supported by the 00Z ECENS mean. So, a general model blend
will be preferred through about 60 hours, followed by a GFS/UKMET
blend thereafter.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Orrison