Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
324 AM EDT Sat Apr 06 2019

Valid Apr 06/0000 UTC thru Apr 09/1200 UTC

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

00Z Model Evaluation with Preferences and Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Northern Tier of CONUS...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: Blend of 00Z GFS/ECMWF
Confidence: Average

Main concerns are the timing of the northern stream shortwave
arrival into the Pacific NW Saturday and subsequent axis of the
Atmospheric River there into Day 3 as well as the northern stream
shortwave crossing the Great Lakes Sunday night and its associated
effects into the Northeast Monday.

The 00Z GFS and 00Z ECMWF are in good agreement in terms of
northern stream amplitude with some differences with the
progression of the trough over the Great Lakes and eastern Canada
on Days 2/3. On Day 2 the GFS more progressive with southern
stream energy getting out ahead of the Canadian Prairies trough
which pushes QPF to the New England Coast while the ECMWF is
farther west. On Day 3 the QPF axis over Maine became in better
agreement as the 00Z ECMWF shifted south slightly becoming more in
line with the 00Z GFS. A compromise of these two models for Days
2/3 is warranted

The 00Z NAM/CMC are more zonal with the trough over the Great
Lakes by Day 3 while the 00Z UKMET remains the most amplified
solution with the northern stream.


...Southern Stream Shortwave from Texas to TN Valley Sunday
through Monday night.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: Blend of 00Z GFS/ECMWF/UKMET
Confidence: Average

The southern stream trough digging over north-central Mexico
tonight shifts northeast across Texas Sunday night and approaches
the southern Appalachians late Monday night. The 00Z ECMWF slowed
considerably as it digs farther into Mexico. The 00Z GFS had also
slowed, but is now more progressive as well as deeper than the 00Z
ECMWF. The 00Z UKMET is a good hedge between the GFS and ECMWF
with timing and strength through Days 2/3.

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

Jackson