Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
247 AM EDT Fri Oct 19 2018

Valid Oct 19/0000 UTC thru Oct 22/1200 UTC

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

00Z model evaluation...with final preferences and confidence
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...Overall Pattern Across the CONUS...
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Preference: Blend of the 00Z GFS/ECMWF/UKMET
Confidence: Slightly above average

...07Z update...

The 00Z ECMWF/UKMET/CMC converged with the timing of the western
trough axis/closed low late Sunday into Monday and are also more
similar to one another with mid-level energy over Texas on
Saturday. The 00Z NAM continues to stand out the greatest from the
latest deterministic guidance across the West and the southern
Plains, while the 00Z CMC differs with its placement of a frontal
boundary/trough axis in the western Gulf through Sunday
night...lying east of the remaining consensus. Therefore, a 00Z
GFS/ECMWF/UKMET blend is preferred for the lower 48.

...previous discussion below...

The current synoptic setup featured a weakening shortwave trough
over Colorado with a stronger and amplifying shortwave over
south-central Canada. Shortwave ridging was located east of these
features over the Ohio Valley and Great lakes while strong ridging
was located over the Pacific Northwest coast with a developing
upper low off of the central California coast. A strong
sub-tropical ridge remains in place over the northern Gulf of
Mexico. Over the next 2-3 days, the pattern will evolve into mean
troughing over the northeastern quadrant of the U.S. with a few
shortwaves tracking through carrying reinforcing shorts of colder
air. Out West, a quasi-rex block will dominate the region with
only minor changes through Monday morning.

Differences are small regarding the synoptic scale features with
only minor timing/amplitude differences noted. However, the 00Z
NAM was noted to be stronger with mid-level vorticity coming out
of Mexico into western Texas on Saturday while the 12Z UKMET/CMC
were weaker. Thus, the middle ground 00Z GFS/12Z ECMWF are favored
here.

Out West, the ensemble means showed fairly good agreement with the
timing of a closed low expected to slowly nudge east Sunday into
Monday, with the 00Z NAM and 12Z CMC stronger or faster with the
12Z ECMWF/UKMET slightly slower. The 00Z GFS was similar in
magnitude and timing to the latest ensemble means.

Overall, a 00Z GFS/12Z ECMWF blend is preferred for the lower 48
from east to west.

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

Otto