Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
129 PM EST Thu Feb 27 2020
Valid Feb 27/1200 UTC thru Mar 02/0000 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
12z Model Evaluation with Model Preferences and Forecast Confidence
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CONUS and Canada
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Preference: General model blend
Confidence: Average
Three are three systems of note across the US and Canada during
the period.
Concerning the exiting surface system and closed mid level low
over Quebec and Northern New England, the 12z NAM/GFS are close to
the consensus with the placement of the various redevelopments of
surface lows from New Brunswick/Nova Scotia and further south
through 01/00z. After that time, there is some model spread
concerning the placement of the surface lows along the extended
frontal boundary, but by that time the sensible weather effects on
the CONUS are limited.
The second system is the short wave that comes ashore over WA
state around 29/00z. Unlike the past few cycles, there is better
agreement on the timing of the short wave as it tracks into
western Ontario by the end of the period. The 12z ECMWF continues
to be slower than the consensus, while the 12z CMC has joined the
remainder of the guidance to form a tight cluster with the mid
level system and its attendant surface low over western Ontario at
02/00z. For this system, a non-ECWMF solution may be a better
choice.
Finally, for the short wave near 45N 137W at 23/12z, there is good
model agreement as it evolves into a long wave trough over CA
before closing off by 02/00. While there are some minor timing
differences late in the period, there is enough clustering to
recommend a general model blend here.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Hayes