Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1144 AM EST Mon Feb 04 2019

Valid Feb 04/1200 UTC thru Feb 08/0000 UTC

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

12Z Model Evaluation...with Preferences and Confidence
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...Overall pattern across the CONUS...
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Preference: General model blend (excluding the GFS in a couple
areas described below)
Confidence: Average

Amplified flow across the CONUS during the short range is handled
similarly by the latest model/ensemble solutions. Models show good
consensus on amplifying shortwave crossing California Tue and
moving into the Southwest by Wed. As this feature reaches the
central U.S. by Thu, relatively minor timing/amplitude differences
emerge. A leading shortwave ejecting out across the northern
plains on Tue ahead of the main upper trough shows some subtle
differences among the guidance that seem to impact their
precipitation fields. The GFS was stronger and more compact with
this wave relative to other guidance, with The NAM and ECMWF
showing the most similar solutions in this specific area. A
surface low expected to develop across the southern/central plains
Wed in response to the main upper trough should track northeast
along the surface front into the Great Lakes by Thu. By Thu the
12Z GFS was northwest of the consensus with the surface low, but
still on the northwest fringe of the range of possible solutions
based on the spread among ECENS/GEFS ensemble members.

Elsewhere, models show good consensus that a barotropic low
initially off the coast of North Carolina today should move
northeastward away from the coast tonight into Tue. An upper
shortwave and low pressure initially across the Great Lakes today
should also move northeast into Ontario/Quebec tonight into Tue
with a surface frontal boundary affecting the Northeast U.S. Model
solutions are quite nicely clustered with this system with
relatively low spread. Lastly, models show general agreement that
additional shortwave energy should approach the Pacific Northwest
by late Thu, with some differences as to the specific nature of
this energy (open wave vs. a more compact/closed system). Trends
among the latest guidance have been toward something more closed,
so a blend of the latest guidance should reflect this trend well.


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

Ryan