Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
245 AM EDT Sun Mar 22 2020
Valid Mar 22/0000 UTC thru Mar 25/1200 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
00Z Model Evaluation with Latest Preferences and Confidence
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General weather pattern across the continental U.S.
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Preference: General model blend through 00Z Tuesday, then 00Z
GFS/00Z UKMET/00Z ECMWF blend
Confidence: Near average
A split flow pattern aloft will initially be in place across the
western U.S. on Sunday with a mid level disturbance crossing the
northern Great Lakes Sunday afternoon, and a second one following
behind it on Monday. A broad shortwave trough crossing the
Central Plains is expected to phase with the second shortwave over
the Great Lakes by early Monday across the Ohio Valley region, and
this is expected to spur surface cyclogenesis off the East Coast
for the beginning of the work week. This is forecast to become a
nor'easter near the New England coast by Monday night as the
phased trough aloft approaches.
Next in line will be a large upper level low that will track
eastward towards central California by Sunday night, and evolve
into an open wave as it crosses the Rockies through Monday. This
feature will also make a transcontinental voyage to the East Coast
by the end of the forecast period Wednesday. Another upper level
low in the northern stream will track southward along the British
Columbia Coast and reach the Pacific Northwest late Monday and
into Tuesday, with a portion of this disturbance crossing southern
Canada through mid-week.
The models are in good agreement through Monday evening. The CMC
becomes slower with the second low pressure system crossing the
central U.S. Tuesday. One of the main differences noted with the
NAM is a much stronger system near New England and faster than the
other guidance. There is good overall agreement with the upper
low approaching the Pacific Northwest, then the NAM is more
amplified with the trough that crosses southern Canada by
mid-week.
7Z Update: The 00Z ECMWF has trended stronger with the coastal
low near eastern New England Monday night and into Tuesday, and
the GFS and its mean track the low farther offshore. The 00Z
UKMET serves as a good middle ground solution with the track of
the low. In regard to the second low crossing the Ohio Valley
region by Tuesday night, the 00Z CMC remains on the slower side of
the guidance, whilst the ECMWF and NAM are most progressive.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Hamrick