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Model Diagnostics Discussion
(Caution: Version displayed is not the latest version. - Issued 1858Z Sep 24, 2018)
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Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
258 PM EDT Mon Sep 24 2018

Valid Sep 24/1200 UTC thru Sep 28/0000 UTC

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

12Z Final Model Evaluation...with Preferences and Forecast

...Overall preference for the entire CONUS...
Preference: Blend of the 12Z GFS/ECMWF (more weight to ECMWF
Confidence: Slightly above average

The synoptic scale pattern over the lower 48 through Thursday will
feature ridging over the northeastern Pacific with a longwave
trough slowly advancing east across Canada and the central U.S.
Embedded shortwaves within the flow will drive a series of cold
fronts which are forecast to track south and east.

Differences across the lower 48 were relatively minor concerning
an area of low pressure forecast to organize across the Great
Lakes Tuesday night and track into eastern Canada while deepening
and dragging a cold front through the eastern U.S. The 12Z GFS was
noted to be a little faster with the front over the East, with a
slower timing nearer to the 00Z/12Z ECMWF preferred given the
slower timing has better support from the remaining model
consensus. Elsewhere, similar timing differences were noted with a
second shortwave forecast to reach the north-central U.S.
Wednesday evening with the slower 12Z ECMWF/UKMET/CMC timing
preferred over the faster 12Z NAM/GFS.

Model trends at
500 mb forecasts at