Prognostic Meteorological Discussion
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000
FXUS10 KWNH 250429
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1228 AM EDT TUE APR 25 2017

VALID APR 25/0000 UTC THRU APR 28/1200 UTC

...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...

00Z NAM/GFS EVALUATION WITH PRELIMINARY MODEL PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT
RANGE FORECASTS.


SYSTEM MOVING INTO THE WEST WEDNESDAY
LARGE SCALE TROF IN INTERMOUNTAIN WEST THURSDAY
CONSOLIDATING CYCLONE MOVING UP THE EAST COAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
THE GUIDANCE SHOWS GOOD AGREEMENT WITH THESE FEATURES.  THE
PREFERENCE IS FOR A GENERAL MODEL COMPROMISE -- SIMILAR TO THE
PARALLEL VERSION OF THE NATIONAL BLEND OF MODELS -- WITH ABOVE
AVERAGE CONFIDENCE.


SYSTEM MOVING NORTHWARD THROUGH THE PLAINS INTO SE CANADA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-GFS COMPROMISE
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE 00Z GFS SHOWS AN ARRAY OF CONVECTIVE/FEEDBACK BULL`S EYES
WHICH INITIALLY DEEPEN THE BASE OF ITS VERSION OF THE UPPER TROUGH
06Z WEDNESDAY, AND THEN BROADEN IT OUT ON ITS EASTERN PERIPHERY
SPEEDING UP THE FRONT AND SPEEDING THE NORTH TO NORTHEAST EJECTION
OF THE CYCLONE, WHICH AT TIMES IS COMPLETELY OUTSIDE THE 12Z
GLOBAL ENSEMBLE SPREAD ON THE NORTHEAST SIDE.  THE 00Z GFS
RESEMBLES THE 24/00Z NAM RUN, WHICH IS TROUBLING AS THE NAM HAS
SINCE ABANDONED THAT SOLUTION.  THE REMAINDER OF THE GUIDANCE
SHOWS INCREASING AGREEMENT WHEN COMPARED TO YESTERDAY WITH 12Z
GLOBAL ENSEMBLE SPREAD SHRINKING AS WELL.  WITH THE SUPPORT OF THE
ENSEMBLE GUIDANCE, PREFER A COMPROMISE OF THE 00Z NAM, 12Z
CANADIAN, 12Z UKMET, AND 12Z ECMWF WITH SLIGHTLY ABOVE AVERAGE
CONFIDENCE.


WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML... /ALL LOWER CASE/
WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML... /ALL LOWER CASE/

ROTH

$$





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