Prognostic Meteorological Discussion
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FXUS10 KWNH 291847
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
247 PM EDT FRI MAY 29 2015

VALID MAY 29/1200 UTC THRU JUN 02/0000 UTC

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

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

SHORTWAVE TROUGH AND ASSOCIATED COLD FRONT OVER THE
NORTHERN-CENTRAL PLAINS...
MCV OVER THE MIDDLE-LOWER MS VALLEY...

PREFERENCE: GFS
CONFIDENCE: AVERAGE

WHILE ALL MODELS AGREE ON THE STRENGTH AND SPEED OF THE MCV
EXITING TEXAS...ITS INTERACTION WITH THE NORTHERN STREAM IS
DEPICTED QUITE DIFFERENTLY BY THE GUIDANCE...WITH THE NAM MOVING
TOWARD THE FAST SIDE OF THE GUIDANCE BY SUN-MON...THE ECMWF TOWARD
THE DEEP SIDE OF THE GUIDANCE...AND THE GFS REMAINING NEAR THE
CONSENSUS INCLUDING HAVING THE BEST SUPPORT FROM THE ENSEMBLES.
GIVEN THAT THE BEST MODEL SUPPORT EXISTS FOR THE GFS...THE
RECOMMENDATION IS FOR THE GFS WITH AVERAGE CONFIDENCE.

SHORTWAVE TROUGH OVER THE SOUTHERN ROCKIES...

PREFERENCE: EQUAL BLEND GFS/ECMWF
CONFIDENCE: ABOVE AVERAGE

THE NAM AND GFS ALLOW PORTIONS OF THE TROUGH TO SLOW DOWN AND
POSSIBLY BREAK OFF FROM THE WESTERLIES ACROSS THE MIDDLE/LOWER MS
VALLEY COMPARED TO THE ECMWF...WHICH IS SLIGHTLY MORE
PROGRESSIVE...BUT REASONABLE AND WELL CONTAINED WITH THE ENSEMBLE
SOLUTION ENVELOPE.  HOWEVER...THE NAM IS NEARLY AN OUTLIER BY LATE
MONDAY...WHILE THE GFS IS CLOSER TO THE MEANS.  THUS...RECOMMEND
DISCOUNTING THE NAM.  AMONG THE GFS AND ECMWF...THEY APPEAR
EQUALLY REASONABLE AND SUPPORTED BY THE ENSEMBLES.
THEREFORE...RECOMMEND AN INTERMEDIATE SOLUTION INVOLVING THE GFS
AND ECMWF.

SHORTWAVE TROUGH REACHING THE PACIFIC NORTHWEST SUN-MON...

PREFERENCE: NAM OR GFS OR ECMWF
CONFIDENCE: AVERAGE

MODELS SHOW GOOD LARGE SCALE AGREEMENT WITH AVERAGE SPREAD BY DAY
3.

...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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