Prognostic Meteorological Discussion
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000
FXUS10 KWNH 251613
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1212 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 AND PRELIMINARY PREFERENCES

CLOSED LOW OVER THE PACIFIC NORTHWEST...

PREFERENCE: NAM OR GFS
CONFIDENCE: AVERAGE

THE 00Z ECMWF MOVES THE LEADING EDGE OF THE TROUGH FURTHER INTO
THE ROCKIES COMPARED TO THE NAM/GFS DUE TO ITS FASTER UPSTREAM
SOLUTION ACROSS WESTERN CANADA...WHICH IS MUCH FASTER THAN ITS OWN
ENSEMBLE MEAN.  GIVEN MINIMAL SUPPORT FOR THIS FASTER
SOLUTION...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...THUS RECOMMEND THE NAM DUE TO GREATER MODEL
SUPPORT.

SHORTWAVE TROUGH OVER WEST TEXAS...

PREFERENCE: GFS OR ECMWF
CONFIDENCE: ABOVE AVERAGE

THE NAM INITIALIZES THE CENTER OF THE TROUGH SLIGHTLY WEST OF ITS
DEPICTED LOCATION ACCORDING TO SATELLITE IMAGERY...WHILE THE GFS
IS MUCH CLOSER.  ONE RESULT OF THE SLIGHTLY MORE WESTWARD NAM IS
ITS SLOWER EASTWARD MOTION.  GIVEN BETTER ALIGNMENT WITH THE
IMAGERY AS WELL AS AGREEMENT FROM THE ECMWF...THE GFS OR ECMWF ARE
PREFERRED.  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: BELOW AVERAGE

OTHER THAN THE 00Z CANADIAN (FASTER) AND 00Z UKMET (SLOWER)...THE
NAM/GFS/ECMWF SHOW GOOD LARGE-SCALE AGREEMENT THROUGH THE PERIOD
WITH BELOW AVERAGE CONFIDENCE DUE TO THE MODEST 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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