Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1241 AM EDT Thu Aug 09 2018

Valid Aug 09/0000 UTC thru Aug 12/1200 UTC

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

00Z NAM/GFS evaluation and preliminary preferences
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...Overall Synoptic Pattern across the CONUS...
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Preference: 00Z GFS/12Z ECMWF blend
Confidence: Average

The large scale pattern over the U.S. currently shows a longwave
trough over the eastern Pacific and a broader longwave trough over
the northeastern two thirds of the U.S. with a mid-level ridge
centered over the Great Basin between the two troughs. Over the
next 1-3 days, the ridge over the West will advance eastward into
the northern Plains as shortwave troughing advances across the
Pacific Northwest. Out East, the development of a closed low over
the Ohio Valley is expected by Sunday morning with a second closed
low over the southern High Plains.

Across the Northwest, compared to yesterday, the models have
slowed with their timing of a compact closed low except the 12Z
UKMET which is quite a bit faster. Ensemble agreement supports a
non-12Z UKMET blend here.

Across the central and eastern U.S., the 00Z NAM is less favored
given it is a bit stronger with low pressure in the 850-700 mb
layer over West Texas compared to the remaining guidance and the
NAM is farthest north/east with a surface low in the northern
Mid-Atlantic region on Saturday. The ensemble means fit best
toward a blend of the 00Z GFS and 12Z ECMWF across the central and
eastern U.S. while the 12Z UKMET/CMC are weaker with mid-level
troughing over New Mexico/Texas by Sunday morning.

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

Otto