Prognostic Meteorological Discussion
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000
FXUS10 KWNH 270434
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1233 AM EDT WED AUG 27 2014

VALID AUG 27/0000 UTC THRU AUG 30/1200 UTC

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


00Z MODEL EVALUATION...INCLUDING THE NAM AND GFS

...UPPER TROUGH AND ASSOCIATED COLD FRONT CROSSING THE NORTHEAST...

PREFERENCE: NON-NAM CONSENSUS
CONFIDENCE: ABOVE AVERAGE

THE 00Z NAM IS A SLIGHTLY STRONG OUTLIER WITH THE DETAILS OF THE
UPR TROUGH CROSSING THE NORTHEAST AND MOVING OFFSHORE INTO THE
ATLANTIC OCEAN OVER THE NEXT COUPLE OF DAYS. AT THE SFC...THE NAM
APPEARS TO BE JUST A TAD SLOWER WITH THE ADVANCE OF ITS SFC COLD
FRONT. THE GLOBAL MODELS ARE WELL CLUSTERED OTHERWISE...AND SO
WILL PREFER A NON-NAM CONSENSUS.


...UPPER-LEVEL TROUGH/LOW MOVING FROM THE ROCKIES IN THE PLAINS...
...SURFACE COLD FRONT DEVELOPING LATE WED IN THE LEE OF THE
CENTRAL ROCKIES...

PREFERENCE: NON-NAM CONSENSUS
CONFIDENCE: ABOVE AVERAGE

THE 00Z NAM AND 00Z GFS ARE IN REASONABLY GOOD AGREEMENT WITH THE
12Z UKMET/12Z GEM AND 12Z ECMWF IN HOW THEY HANDLE THE EVOLUTION
OF THE UPR LOW/TROUGH THAT EXITS THE ROCKIES OVER THE NEXT COUPLE
OF DAYS AND ADVANCES EAST ACROSS THE PLAINS AND TWD THE MIDWEST.
THE MODELS SHOW THAT A COLD FRONT WILL ADVANCE EAST AS WELL AND
THERE SHOULD BE A WAVE OF LOW PRESSURE THAT EVOLVES OVER THE
MIDWEST BY LATE FRI AND SAT. HOWEVER...THE 00Z NAM BECOMES A
FASTER AND WEAKER OUTLIER SOLN FROM 72 HRS ONWARD. THE GLOBAL
MODELS OVERALL SHOW VERY GOOD LARGE SCALE AGREEMENT AND CLUSTER
WELL. WILL PREFER A NON-NAM CONSENSUS AS A RESULT.


...EASTERLY WAVE ADVANCING WEST ALONG THE GULF COAST...

PREFERENCE: NON-NAM CONSENSUS
CONFIDENCE: ABOVE AVERAGE

THE 00Z NAM IS A SLIGHTLY DEEPER OUTLIER WITH THIS SYS AS IT MOVES
INTO CNTRL/SRN TX OVER THE NEXT COUPLE OF DAYS. WILL PREFER A
NON-NAM CONSENSUS SOLN GIVEN SOLID GLOBAL MODEL AGREEMENT SEEN
OTHERWISE..


...NORTHERN STREAM TROUGH CLIPPING THE NORTHWESTERN U.S./CANADIAN
BORDER BY FRI...

PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF
CONFIDENCE: AVERAGE

MODEL SPREAD WITH RESPECT TO THIS FEATURE HAS DIMINISHED
SOME...BUT THE 00Z NAM STILL APPEARS TO BE TOO STRONG ALOFT. THE
12Z UKMET IS PERHAPS A TAD TOO FAST...WITH THE 12Z GEM A LITTLE
TOO SLOW. THE 00Z GFS AND 12Z ECMWF SPLIT THE DIFF AND CLUSTER
VERY WELL. A BLEND OF THE GFS AND ECMWF WILL BE PREFERRED.


...DEEP TROUGH DIGGING INTO THE NORTHWEST BY FRI AND SAT...

PREFERENCE: 12Z ECMWF
CONFIDENCE: AVERAGE

THE 00Z GFS GRADUALLY BECOMES A SOMEWHAT FASTER OUTLIER WITH THE
NEXT TROUGH ARRIVING IN FROM THE PAC OCEAN FRI AND SAT. THE 12Z
GEM APPEARS A LITTLE TOO SLOW. THE 00Z NAM...12Z ECMWF AND 12Z
UKMET SPLIT THE DIFF. THE LATEST GEFS MEAN AND ESP THE ECENS MEAN
GIVE STRONGER SUPPORT FOR THE 12Z ECMWF...SO THE 12Z ECMWF WILL BE
PREFERRED ATTM.


...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...
...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

ORRISON

$$





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