Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
244 PM EDT Tue May 15 2018

Valid May 15/1200 UTC thru May 19/0000 UTC

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

12Z model evaluation and final preferences
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GFS/NAM initialization errors do not seem to degrade their short
range forecasts.


...Pair of closed lows impacting the West through Friday...
...Eventual cold front reaching the northern Plains Friday morning
with accompanying surface low/trough...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: General model blend
Confidence: Slightly above average

A closed low currently over Nevada is expected to weaken toward
the north through Wednesday and Thursday while a second closed low
enters central California from the west. The models show similarly
with the mid-level and surface evolution of this system.


...Broad upper level trough over the Great Lakes/Northeast...
...Pair of fronts affecting the Ohio
valley/Mid-Atlantic/Northeast...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: General model blend
Confidence: Slightly above average

The models show similarly with this feature and broad agreement
with the frontal boundary(s) across the
Northeast/Mid-Atlantic/Ohio valley.


Closed low over the eastern Gulf of Mexico, slowly lifting north
while weakening through the end of the week...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: Non 12Z CMC blend
Confidence: Average

While the 12Z CMC fits in with its mid-level low center in the
vicinity of the Gulf Coast, it is displaced westward of the
remaining model guidance regarding its 850-750 mb low moving into
the Ohio valley on Friday. The lack of agreement from the
deterministic models is a concern for favoring the 12Z CMC. Detail
differences remain with the non 12Z CMC models, but they are in
broad agreement on the larger scale details.


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

Otto