Prognostic Meteorological Discussion
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FXUS10 KWNH 011619
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1219 PM EDT MON SEP 01 2014

VALID SEP 01/1200 UTC THRU SEP 05/0000 UTC

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

12Z MODEL EVALUATION...INCLUDING THE NAM AND GFS


...TROUGH SLIDING FROM THE MIDWEST TO THE NORTHEAST THROUGH WED...

PREFERENCE: BLEND OF THE 00Z UKMET/00Z GEM AND THE 00Z ECMWF
CONFIDENCE: ABOVE AVERAGE

THIS TROUGH CONSISTS OF A LEAD SHORTWAVE AND A SMALLER SHORTWAVE
THAT QUICKLY FOLLOWS OVER THE NEXT COUPLE OF DAYS. THE COMBINATION
OF THE TWO WILL DRIVE A COLD FRONT THROUGH THE NORTHERN AND
NORTHEASTERN U.S...WHILE THE TAIL END STALLS IN THE MID MS VLY AND
CNTRL PLAINS. IN GENERAL THERE IS GOOD MODEL MASS FIELD AGREEMENT
WITH THE LARGER SCALE TROUGH AXIS. HOWEVER...THE 12Z GFS IS SEEN
AS BEING A TAD SLOWER THAN THE 12Z NAM AND THE REMAINING NON-NCEP
SOLNS INCLUDING THE 00Z UKMET AND 00Z GEM. THE 12Z GFS ALSO
REFLECTS SOME NOTABLE DIFFS WITH RESPECT TO THE SFC LOW THAT
IMPACTS THE ST LAWRENCE RIVER VALLEY AND SRN QUEBEC AS THE GFS IS
A BIT WEAKER AND LESS DEFINED WITH IT. THE 12Z NAM IS ALSO WEAKER
AND LESS DEFINED. ALL OF THE NON-NCEP MODELS REFLECT A STRONGER
SFC LOW CENTER LIFTING NEWD THROUGH THIS REGION. A BLEND OF THE
NON-NCEP SOLNS WILL BE PREFERRED.


...PACIFIC TROUGH AFFECTING THE WEST AND SPILLING INTO THE
NORTHERN PLAINS LATE WED...
...LINGERING TROUGH/WEAKNESS LEFT OVER THE NORTHWEST...

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

THE MODELS INDICATE A PROGRESSIVE BUT RATHER VIGOROUS TROUGH
DIGGING INTO THE NORTHWEST ON TUES AND THEN MOVING EAST OUT INTO
THE NRN PLAINS BY WED. MEANWHILE...ALL OF THE MODELS BY WED AND
THURS SHOW A TAIL OF ENERGY OR WEAKNESS LEFT BEHIND THE MAIN
SHORTWAVE TROUGH THAT WILL BE SITUATED OVER THE NORTHWEST AND DOWN
INTO NRN CA WHERE IT WILL BE ATTEMPTING TO INTERACT WITH ENERGY
OFFSHORE OF CA. THE 00Z UKMET AND 00Z GEM ARE FASTER WITH THE
HEIGHT FALLS THAT EJECT OUT ACROSS THE NRN PLAINS. THE SAME
APPLIES TO THE SFC LOW EVOLUTION THROUGH THE PERIOD...ALTHOUGH THE
12Z NAM IS SEEN MOST TIME FRAMES AS BEING A TAD NORTH OF THE
GLOBAL MODEL CONSENSUS. THE LATEST GEFS MEAN AND ECENS MEAN FAVOR
A SOMEWHAT SLOWER SOLN AND SUPPORT THE DETERMINISTIC GFS AND ECMWF
CAMP. OVER THE NORTHWEST ON WED AND THURS...THERE IS NOT AS MUCH
SPREAD WITH THE GUIDANCE. BASED ON THE CURRENT DEGREE OF SPREAD
AND CLUSTERING...FEEL LIKE A BLEND OF THE 12Z GFS AND 00Z ECMWF
WILL SUFFICE FOR THE TIME BEING.


...BROAD AREA OF LOW PRESSURE ENTERING THE BAY OF CAMPECHE...

PREFERENCE: LATEST NHC TROPICAL WEATHER OUTLOOK

A BROAD AREA OF LOW PRESSURE IS ADVANCING INTO THE BAY OF CAMPECHE
FROM THE YUCATAN PENINSULA THIS MORNING. THE NATIONAL HURRICANE
CENTER FORECASTS A 60 PERCENT CHANCE OF TROPICAL CYCLONE FORMATION
WITHIN THE NEXT 48 HOURS. THE MODEL SPREAD REMAINS RATHER MINIMAL
REGARDING THE TRACK...WITH THE GUIDANCE SUGGESTING THAT THE LOW
CENTER MOVES INTO NERN MEXICO BY WED. HOWEVER...IT SHOULD BE NOTED
THAT THE 12Z NAM AND THE 00Z UKMET/00Z GEM SOLNS SHOW CONSIDERABLY
MORE VERTICAL DEVELOPMENT AND ORGANIZATION COMPARED TO THE 12Z GFS
AND 00Z ECMWF. PLS CONSULT THE LATEST NHC TROPICAL WEATHER OUTLOOK
FOR MORE INFORMATION ON THIS SYS.


...EASTERLY WAVE APPROACHING FLORIDA...

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

AN EASTERLY WAVE APPROACHING THE BAHAMAS WILL BE ADVANCING ACROSS
SRN FL AND THE FL KEYS BY WED. THE 12Z NAM APPEARS TO BE TOO
STRONG WITH THE WAVE AXIS...WITH THE 00Z UKMET SEEN AS TOO FAR
SOUTH AND POSSIBLY TOO WEAK. THE 00Z GEM/00Z ECMWF AND 12Z GFS ALL
SPLIT THE DIFF...BUT CLUSTER REASONABLY WELL WITH A TRACK
GENERALLY OFF TO THE WEST.

...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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