Prognostic Meteorological Discussion
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000 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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