Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1235 AM EDT Mon Oct 08 2018

Valid Oct 08/0000 UTC thru Oct 11/1200 UTC

...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...

00Z Model Evaluation...with latest preferences and confidence
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...Overall Pattern Across the CONUS...
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Preference: Blend of the 00Z GFS/12Z UKMET AND 12Z ECMWF
Confidence: Slightly above average
 
A highly amplified pattern across the CONUS will continue through
Tuesday as a deep longwave trough evolves over the Western U.S.
and a strong subtropical ridge remains intact across the Eastern
U.S. By Wednesday, the ridge across the Eastern U.S. will begin to
retreat eastward and allowing the height falls to eject well out
across the Plains and Midwest. The guidance though agrees in
reinforcing a broad trough over the West through Thursday as
additional shortwave energy drops southward down from Southwest
Canada and into the Intermountain region.

Regarding the details, the models agree very well with the deep
trough evolving over the Four Corners region through Monday and
Tuesday, although there remains some differences with the
placement of the front across the Plains and Midwest, as the 00Z
NAM is still displacing its front a tad farther south and east
versus the global model consensus. The global models are well
clustered with the portion of the front over the southern High
Plains, but farther north there remains spread as the 00Z GFS
still focuses its boundary a tad northwest of the non-NCEP
guidance along an axis from eastern CO northeast up across the
upper Midwest. The 12Z ECMWF still overall has stronger support
for a solution essentially in between the NAM and GFS, which is
favored by the 12Z CMC/UKMET solutions and the 12Z ECENS mean.

However, by Tuesday night and Wednesday, the models all agree in
shifting the longwave trough east across the Plains and toward the
Midwest which will allow the front to advance east toward the MS
Valley and with low pressure lifting up across the upper Midwest.
By Thursday, a trailing front will advance well east across the
OH/TN Valleys, as low pressure deepens up across the upper Great
Lakes region. Gradually, the CMC and to an extent the NAM become
deeper outliers with the height falls that pivot up across the
upper Midwest. The GFS, UKMET and ECMWF are better clustered
although the GFS is a tad slower than the model consensus with the
trailing cold front sweeping east across the MS/OH/TN Valleys.

Elsewhere across the CONUS, the guidance reloads the troughing
across the West by Wednesday as additional energy drops south from
British Columbia. The 00Z NAM is a tad stronger than the global
models with the additional energy. The 00Z GFS and 00Z ECMWF are
better clustered with the reloading trough over the West through
Thursday.

Based on the latest model spread and clustering of solutions
across the CONUS for this period, a blend of the 00Z GFS/12Z UKMET
and 12Z ECMWF will be preferred.


...Tropical Storm Michael...
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Preference: See the latest NHC forecast advisory

The guidance all agrees in taking Tropical Storm Michael northward
across the eastern Gulf of Mexico over the next 48 to 72 hours
with the system likely making a landfall on Wednesday in vicinity
of the FL panhandle. The 12Z CMC by far is the fastest and
farthest west solution with Michael and will be dismissed.
Meanwhile, the 00Z NAM and 12Z ECMWF are slow outliers with
Michael and track the system west of the model consensus. The 00Z
GFS and 12Z UKMET are farther east, with the UKMET overall the
farthest east. The latest NHC forecast track is generally a
compromise of the GFS and UKMET solutions and is a bit to the
right of the overall global model consensus. Please consult the
latest NHC forecast advisory for more details on Tropical Storm
Michael.


Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml

Orrison