Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
244 AM EDT Fri Sep 20 2019

Valid Sep 20/0000 UTC thru Sep 23/1200 UTC

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

00Z Model Evaluation with Preferences and Forecast Confidence
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...Overall Pattern across the CONUS...
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Preference: Blend of the 00Z GFS/UKMET/ECMWF
Confidence: Slightly above average

The synoptic pattern will feature a rather strong deep layer ridge
across a large portion of the eastern U.S. over the next couple of
days, as a pair of fairly robust northern stream troughs traverse
the western U.S. The first trough will advance east across the
central/northern Plains and upper Midwest Saturday and Sunday
along with an attendant cold front and a multiple waves of low
pressure. This energy will break down the ridge over the East by
later Sunday and will allow a cold front to arrive across the OH
Valley and lower Great Lakes region by Monday. Meanwhile, a second
upstream trough will cross the West Coast and move into the Great
Basin by Monday.

Differences with the first trough are rather small through most of
the weekend as the energy crosses the Intermountain West and
advances out into the Plains, but by late Sunday into Monday, the
00Z CMC is seen as broadening the trough just a tad more than the
remainder of the guidance. The 00Z UKMET has trended closer to the
00Z GFS/ECMWF solutions, and the 00Z NAM is perhaps just a tad
more progressive than the multi-model consensus.

Regarding the second trough, the model guidance is well clustered
and in good agreement with respect to timing and depth as the
system arrives on Monday in across the Intermountain West.

Based on the 00Z model clustering and latest ensemble means, a
blend of the NAM, GFS and UKMET will be preferred across the
CONUS, but the differences with respect to the CMC and even more
so the NAM are quite modest.


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

Orrison