Prognostic Meteorological Discussion
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000
FXUS10 KWNH 251842
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
141 PM EST THU DEC 25 2014

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

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

12Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/GEM AND ECMWF


...UPPER TROUGH DIGGING ACROSS THE INTERMOUNTAIN WEST/FOUR CORNERS
REGION THROUGH FRI...
...ENERGY EJECTING OUT ACROSS THE CENTRAL PLAINS AND UPPER MIDWEST
THROUGH SAT...

PREFERENCE: 12Z GFS
CONFIDENCE: AVERAGE

THE MODELS DEPICT A STRONG UPPER TROUGH DIGGING THROUGH THE
INTERMOUNTAIN WEST THROUGH FRI...WITH A PORTION OF THIS ENERGY
FORECAST TO EJECT EAST ACROSS THE CENTRAL PLAINS AND UPPER MIDWEST
THROUGH SAT. THIS ENERGY WILL FOSTER THE DEVELOPMENT OF A SURFACE
LOW THAT WILL CROSS FROM THE MID MS VALLEY TO THE GREAT LAKES
REGION THROUGH SAT. MOST OF THE MODELS SHOW VERY GOOD AGREEMENT
WITH THE HEIGHT FALL DETAILS...ALTHOUGH THE 12Z GEM IS A TAD
SLOWER AND DEEPER THAN THE MULTI-MODEL CONSENSUS. REGARDING THE
SURFACE LOW...THE 12Z GEM IS THE SLOWEST SOLN FOLLOWED BY THE 12Z
ECMWF. THE 12Z GFS/12Z UKMET AND 12Z NAM ARE ALL FASTER. THE TREND
OVER THE LAST DAY OR SO HAS BEEN TO BE MORE PROGRESSIVE WITH THIS
ENERGY...AND THE 00Z ECENS MEAN SUGGESTS THE 12Z ECMWF IS A TAD
TOO SLOW. BASED ON THE OVERALL TRENDS TO BE MORE PROGRESSIVE AND
COUPLED WITH THE 12Z GEFS MEAN WHICH FAVORS THE MORE PROGRESSIVE
CAMP...THE ECMWF AND GEM SOLNS WILL BE DISCOUNTED. WILL PREFER THE
12Z GFS ATTM.


...SHORTWAVE ENERGY SHEARING OVER THE FOUR CORNERS REGION/SOUTHERN
PLAINS...

PREFERENCE: 12Z ECMWF
CONFIDENCE: AVERAGE

SHORTWAVE ENERGY LEFT BEHIND OVER THE FOUR CORNERS REGION BY LATE
SAT WILL SHEAR EAST OUT ACROSS THE SOUTHERN PLAINS ON SUN. THE 12Z
NAM/12Z UKMET AND ESP THE 12Z GEM ARE THE SLOWEST/DEEPEST SOLNS.
THE 12Z ECMWF AND ESP THE 12Z GFS ARE MORE SHEARED/FLATTER AND
FASTER WHICH IS SUPPORTED BY THE LATEST GEFS MEAN AND ECENS MEAN.
THE UPSTREAM PATTERN FAVORS A FLATTER AND MORE PROGRESSIVE
SHORTWAVE EJECTING EAST ACROSS THE SOUTHERN PLAINS...HOWEVER NO
MODEL IS QUITE AS WEAK AND PROGRESSIVE AS THE GFS. WILL LEAN TWD
THE 12Z ECMWF AS A COMPROMISE SOLN AT THIS POINT.


...SHORTWAVE TROUGH DIGGING TOWARD THE PACIFIC NORTHWEST ON SAT...

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

THE MODELS INDICATE A SHORTWAVE TROUGH DIGGING SOUTHEAST FROM THE
GULF OF AK AND INTO SOUTHWEST BRITISH COLUMBIA AND THE PACIFIC
NORTHWEST BY LATER SAT. THE 12Z NAM AND 12Z UKMET ARE JUST A TAD
MORE PROGRESSIVE THAN THE 12Z GFS AND 12Z ECMWF. THE 12Z GEM
APPEARS TO BE TOO FLAT WITH THE SHORTWAVE. THE STRONGER MODEL
CLUSTERING AND ENSEMBLE SUPPORT WOULD FAVOR A BLEND OF THE 12Z GFS
AND 12Z ECMWF 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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