Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1149 PM EST Thu Feb 14 2019

Valid Feb 15/0000 UTC thru Feb 18/1200 UTC

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

00Z Model Evaluation...with Preferences and Confidences
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Overall Pattern Across the CONUS...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: Blend of 00z GFS, 12z ECMWF, 00z NAM
Confidence: Slightly below average

One shortwave trough currently moving across the Four Corners
region will continue to open up as it moves into the Rockies over
the next 12-24 hours. This wave will move into the south-central
US and eventually lower Ohio Valley by Saturday morning. A weak
surface low will develop in response and generally track through
the Deep South and into the southeast US. There remains some
spatial differences (north/south extent) with the shortwave and
low track, especially by the time it reaches the MS River and
lower Ohio Valley. The NAM is slower/south while the ECMWF is a
bit further to the north while the GFS is on the faster side with
the low track across MS/AL/GA late Friday night into Saturday
morning. The QPF differences lie on the north side of the low with
the deformation band, which has implications for any winter
precipitation across the lower Ohio Valley.

A stronger closed low currently off the Pacific Northwest will
move inland over the next 24 hours with a couple impulses moving
through. One piece of energy will shear off and track through the
central US and lower Great Lakes late in the weekend and reach the
Northeast US by early next week. The biggest differences with this
system are seen in the UKMET which is a clear outlier with the
orientation and speed of the shortwave trough (too slow). The
ECMWF is a bit flatter across New England while the GFS and NAM
are on the faster side. The CMC is also notably different, being
more amplified across the Upper Midwest instead of the more
sheared look seen in the GFS/ECMWF/NAM.

Additional energy will remain back across the West, eventually
carving out a deeper, longwave trough that will remain in place
through the end of the forecast period. There is actually fairly
good agreement in the large scale features and timing with the
trough development across southern California and southwest US by
the end of Day 3 such that a general model blend is sufficient.

Overall, given some of the differences seen in the central/eastern
US, the WPC preference will be for a blend of the 00z GFS, 00z
NAM, and 12z ECMWF.


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

Taylor