Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
241 PM EDT Fri Jun 01 2018

Valid Jun 01/1200 UTC thru Jun 05/0000 UTC

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

12Z model evaluation final preferences

Model initialization errors do not appear to be sufficiently large
to impact their forecasts of large scale features.

...Upper trough crossing the Great Lakes/Ohio Valley today and
Mid-Atlantic Sat/possibly off the coast Sun...
...Coastal low off of the northern Mid-Atlantic coast through
Monday morning...

Preference: ECMWF/CMC blend
Confidence: Average

Models show good consensus with the shortwave as it crosses the
Great Lakes/Ohio Valley/Appalachians through Sat morning, and the
NAM/GFS handle the feature similarly to consensus. The upper wave
should prompt a surface low to develop along the Mid-Atlantic
coast on Sat, which is then expected to drift slowly east into Sun
before accelerating away from the coast on Monday. The NAM/GFS
handle the low similarly to the model consensus through Sunday.
Some differences emerge by Monday with the GFS and UKMET keeping
the surface low closer to the Northeast U.S. coast. At this time,
based on a look at ECENS/GEFS ensemble members, the 12Z ECMWF/CMC
appear closest to consensus, and blend of these two 12Z solutions
is preferred at this time.


...Upper trough moving from the Rockies into the northern plains
today/tonight, and upper MS Valley Sat night...

Preference: GFS/ECMWF blend
Confidence: Average

The NAM/GFS handle this features similarly to the model/ensemble
consensus through tonight, and by Saturday the NAM becomes
slightly faster than consensus while the GFS/UKMET/ECMWF were
slower. A GFS/ECMWF blend should represent consensus well.


...Mid-level vorticity maximum entering the Southwest U.S. on
Saturday...

Preference: General model blend
Confidence: Slightly above average

The 12Z models handle this feature similarly, tracking it along
the periphery of the broad upper ridge anchored across the
southern tier. The consensus brings it across the Four Corners
region by Sun and into the central plains, by Mon.


...Upper trough reaching the Pacific Northwest Sunday/Monday...

Preference: General model blend
Confidence: Above average

The models show minor differences with this system. Given the
relatively small spread, a general model blend is preferred to
smooth out these smaller scale differences.


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

Ryan