Prognostic Meteorological Discussion
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000
FXUS10 KWNH 240642
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
241 AM EDT MON APR 24 2017

VALID APR 24/0000 UTC THRU APR 27/1200 UTC

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

00Z MODEL EVALUATION WITH PREFERENCES/CONFIDENCE INTERVALS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE ITS SHORT
RANGE FORECAST.


SYSTEM MOVING INTO THE WEST WEDNESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
THE GUIDANCE SHOWS GOOD AGREEMENT WITH THE SYSTEM MOVING INTO THE
WEST WEDNESDAY.  A COMPROMISE OF THE AVAILABLE GUIDANCE -- SIMILAR
TO THE PARALLEL VERSION OF THE NATIONAL BLEND OF MODELS -- LOOKS
GOOD HERE TO DEAL WITH ANY LINGERING DETAIL ISSUES WITH ABOVE
AVERAGE CONFIDENCE.


QUASI-PHASED SYSTEM MOVING ACROSS THE WEST INTO THE PLAINS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: CANADIAN/ECMWF COMPROMISE
CONFIDENCE: BELOW AVERAGE

THE GUIDANCE HAS SHOWN MARKED CHANGES SINCE THIS TIME YESTERDAY,
GENERALLY SHOWING A SLIGHTLY SLOWER AND MORE CLOSED SOLUTION.  THE
00Z GFS USES CONVECTIVE/GRIDSCALE FEEDBACK BULL`S EYES TO DRAG ITS
NORTHERN STREAM TROUGH TOO QUICKLY INTO THE GREAT LAKES AND
DEFINES THE NORTHEAST SIDE OF THE 12Z GLOBAL ENSEMBLE SPREAD.  THE
GLOBAL ENSEMBLE SPREAD HERE IS GREATER THAN AVERAGE, REFLECTING
WHAT WE NORMALLY SEE AT THE 5+ DAY RANGE DURING DAY 3.  ALL THE
DETERMINISTIC GUIDANCE DEFINES THE BOUNDARIES SET BY THE 12Z
GLOBAL ENSEMBLE SPREAD -- NOTHING IS IDEAL.  A STRONGER VERSION OF
THE 00Z ECMWF ALOFT, WITH A SOMEWHAT MORE WESTERLY SURFACE LOW
LYING BETWEEN THE 00Z CANADIAN AND 00Z ECMWF, IS AS GOOD AS IT
GETS, AND IS PREFERRED WITH BELOW AVERAGE CONFIDENCE.


DEEP SYSTEM MOVING UP THE EAST COAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE 00Z NAM IS LAGGING IN THE RECURVATURE OF THIS SYSTEM, PERHAPS
DUE TO ITS STRONGER RIDGE IN SOUTHEAST CANADA.  SINCE THE OTHER
GUIDANCE LIES BETWEEN THE 18Z GEFS MEAN AND 12Z ECMWF ENSEMBLE
MEAN, FAVOR A NON-NAM COMPROMISE (00Z GFS, 00Z CANADIAN, 00Z
UKMET, AND 00Z ECMWF) WITH 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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