Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
143 AM EST Thu Dec 12 2019
Valid Dec 12/0000 UTC thru Dec 15/1200 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
00 UTC Model Evaluation with Preferences and Forecast Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...Southern Stream/Southeast to Mid Atlantic and Northeast surface
low Fri-Sun...
Preference: 00 UTC GFS/ECMWF/UKMET/Canadian Blend
Confidence: Average
Details with upper support/impulses seem small scale and noisy,
with larger guidance variance more evident with surface based
system progressions/QPF into the weekend. The 00 UTC NAM and to a
lesser extent the 00 UTC GFS are faster to lift northward the main
East Coast coastal plain low than yesterdays 12 UTC and todays 00
UTC ECMWF/UKMET and Canadian. The 18/00 UTC GEFS and 12 UTC ECMWF
ensemble low clusters offer better support for the slower
solutions.
...Northern Stream shortwaves across the Northern Plains to the
Upper MS Valley and Upper Great Lakes...
Preference: General 00 UTC Model Blend
Confidence: Average
Prefer a general model blend with reasonably well clustered model
and ensemble solutions despite fast flow with numerous embedded
smaller scale impusles and some weekend stream interactions. A
composite seems reasonable and offers decent continuity given
complexity.
...West/Rockies/Plains...
Preference: 00 UTC GFS/Canadian/UKMET/ECMWF Composite
Confidence: Slightly below average
A strong Day 1 surge of Pacifc energy into the Northwest seems
pretty well defined in satellite and guidance, with blended
precipitable water loops showing a long fetch moisture connection
into the tropical Pacific. The inland progression of subsequent
Pacific system energy farther south into CA and the Southwest over
the weekend leads to differences with the 00 UTC ECMWF and 12 UTC
ECMWF ensembles uncharacteristically showing faster progression
than most other guidance. The 00 UTC GFS/Canadian/UKMET trend for
increased amplitude and slower progression may be reasonable given
upstream mid-upper level ridge amplitude, but suggest holding onto
some blend input from the 00 UTC ECMWF considering forecast
spread/uncertainty.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Schichtel