Prognostic Meteorological Discussion
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FXUS10 KWNH 251826
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
225 PM EDT MON MAY 25 2015

VALID MAY 25/1200 UTC THRU MAY 29/0000 UTC

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

12Z NAM/GFS EVALUATION INCLUDING THE UKMET/CANADIAN/ECMWF AND
PREFERENCES

CLOSED LOW OVER THE PACIFIC NORTHWEST...

PREFERENCE: NAM OR GFS
CONFIDENCE: AVERAGE

THE NEW ECMWF HAS TRENDED SLOWED FROM ITS PREVIOUS RUN...THUS
MOVING CLOSER TO ITS OWN ENSEMBLE MEAN AS WELL AS THE 12Z
DETERMINISTIC GUIDANCE.  GIVEN THIS TREND AND AGREEMENT FOR A
SLOWER OUTCOME...RECOMMEND EITHER THE NAM OR GFS.

SHORTWAVE TROUGH OVER ARIZONA...

PREFERENCE: GFS OR ECMWF
CONFIDENCE: AVERAGE

THE NAM DRIFTS TOWARD THE SLOW SIDE OF THE GUIDANCE BY WED
NIGHT/THURSDAY WHILE THE GFS/ECMWF REMAIN IN GOOD AGREEMENT
THROUGH THE PERIOD AND HAVE GOOD SUPPORT FROM THE UKMET/CANADIAN...
THUS RECOMMEND THE GFS OR ECMWF DUE TO GREATER MODEL SUPPORT.

SHORTWAVE TROUGH OVER WEST TEXAS...

PREFERENCE: GFS
CONFIDENCE: AVERAGE

THE NAM INITIALIZES THE CENTER OF THE TROUGH SLIGHTLY WEST OF ITS
DEPICTED LOCATION ACCORDING TO SATELLITE IMAGERY...WHICH
CONTRIBUTES TO ITS SLOWER SOLUTION OVER TIME...AND THUS IS
CONSIDERED A LOW PROBABILITY SOLUTION.  THE GFS INITIALIZATION
ALIGNS BETTER WITH SATELLITE IMAGERY AND IS GENERALLY NEAR THE
CONSENSUS THROUGH THE ENTIRE PERIOD...WHILE THE ECMWF MOVES TOWARD
THE STRONG EDGE OF THE GUIDANCE BY LATE TUESDAY DUE TO PHASING
WITH A NORTHERN STREAM SHORTWAVE TROUGH...BUT HAS VERY LITTLE
SUPPORT FROM OTHER GUIDANCE.  THUS...RECOMMEND THE GFS.
REFER TO THE QPFPFD FOR MORE INFORMATION ON RAINFALL.

LOW PRESSURE OVER MINNESOTA AND ASSOCIATED WARM FRONT...

MODELS SHOW GOOD LARGE-SCALE AGREEMENT.

SHORTWAVE TROUGH REACHING THE SOUTHWEST NEXT THURSDAY...

PREFERENCE: NAM OR GFS OR ECMWF
CONFIDENCE: AVERAGE

OTHER THAN THE CANADIAN (FASTER)...THE NAM/GFS/ECMWF SHOW
REASONABLE LARGE-SCALE AGREEMENT THROUGH THE PERIOD WITH AVERAGE
CONFIDENCE DUE TO THE GROWING SPREAD.

...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...

...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

JAMES

$$




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