Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1123 AM EST Wed Jan 30 2019

Valid Jan 30/1200 UTC thru Feb 03/0000 UTC

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

12Z Model Evaluation...with Preferences and Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Overall Pattern across the CONUS...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: General model blend through 01.00z, blend of GFS/ECMWF
after
Confidence: Average

The deep cyclonic flow and trough currently encompassing much of
the central/eastern US will continue through the next 24-36 hours.
By 01.00z it will flatten out some as the deep low moves northeast
into Canada. Overall, while there is excellent model agreement in
the large scale mass fields across the CONUS through this time,

For 01.00z and beyond, there will be a couple features of note.
First will be a quick moving shortwave clipper dropping through
the cyclonic flow across the lower Ohio Valley into the
Mid-Atlantic. The models all show this feature with reasonable
agreement, with just some magnitude differences. The 00z UKMET/CMC
were the most amplified and thus had higher QPF values, especially
east of the Appalachians. The NAM was a bit faster while the
GFS/ECMWF were in reasonable agreement but in general weaker.

Across the western US, a closed low will approach the central
California coast Thursday and then drop southeast toward Southern
California by Friday into Friday night. Here, model agreement is
average.

Finally, a stronger an atmospheric river event will bring
widespread precipitation to California and parts of the Pacific
Northwest late Friday into Saturday as another closed upper low
and surface low approach the northern California coast. The
biggest model differences are in timing, with the GFS/ECMWF faster
than the UKMET/CMC/NAM solutions.

Overall the WPC preference will be for a general model blend
through 01.00z then a blend of the GFS/ECWMF after given some of
the QPF and timing issues with the 00z UKMET/CMC.


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

Taylor