Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
118 PM EDT Sun Mar 31 2019

Valid Mar 31/1200 UTC thru Apr 04/0000 UTC

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

12Z NAM/GFS Evaluation With Preliminary Preferences and Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Deep trough lifting through the Northeast tonight...
...Cold front crossing the Eastern Seaboard...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 
Preference: General model blend
Confidence: Above average

The models show similarly with this system.


...Four Corners to Southern Plains trough/closed low...
...Reaching the Gulf Coast/Southeast by Mon/Tues...
...Cyclogenesis near the Southeast Coast by Tues...
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Preference: near the 00Z ECMWF through 00Z/03
            12Z GFS/00Z ECMWF blend 00Z/03-00Z/04
Confidence: Average

Ensemble spaghetti heights and low plots have shown a slight trend
to be faster and north with the surface low. Through 00Z/03, the
00Z ECMWF is closest to the best ensemble clustering while the 12Z
NAM and 00Z CMC are closer to the Southeast coast. The 12Z GFS is
slightly farther offshore through 00Z/03 while the 00Z UKMET is a
bit south of the better model clustering. Beyond 00Z/03 and up
until 00Z/04, the 00Z ECMWF and 12Z GFS show the best agreement
with the latest low clustering off of the northern Mid-Atlantic
and New England coasts, with the ensemble spread largely
north-south versus west-east.


...Trough/Low approaching the West Coast on Mon...
...Surface low approaching the Pacific Northwest...
...Energy reaching the Four Corners by Wed...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: 12Z GFS/00Z ECMWF blend
Confidence: Slightly above average

Ensemble spaghetti heights and low plots show the best overall
blend for this system is a 12Z GFS/00Z ECMWF blend. The 00Z CMC
stands out from the remaining consensus with a flatter shortwave
into the Four Corners region through early Wednesday. Outside of
the differences in the upper trough, a surface low will develop
across the southern high plains with a front draped northeastward
through the Midwest. Some latitude differences exist with the
frontal boundary and surface low in/near the the Texas Panhandle
Wednesday afternoon. Ensemble scatter low plots support a low
position nearer to the 00Z ECMWF with a 700-500 mb trough
depth/timing closer to a 00Z ECMWF/12Z GFS blend.


...Upper trough over the Northern Plains/Midwest Tues...
...Surface cold front crossing the Midwest...
...Initial surface low track through the Upper Mississippi Valley
into the Great Lakes Monday...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: General model blend, led by the 00Z ECMWF
Confidence: Above average

Minor differences remain with this system as a shortwave moves
through a broader upper trough covering south-central Canada. The
12Z GFS remains a bit faster while the 12Z NAM is north of the
remaining model consensus, though the difference is relatively
minor. The 00Z ECMWF appears to be well placed with respect to the
middle of the deterministic/ensemble spread. As mid-level height
falls overspread the north-central U.S. Tuesday, there is
reasonable agreement with the timing and related cold front. A
general model blend is recommended to represent the middle of
these relative small scale differences.


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

Otto