Prognostic Meteorological Discussion
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FXUS10 KWNH 021845
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
244 PM EDT WED SEP 02 2015

VALID SEP 02/1200 UTC THRU SEP 06/0000 UTC

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

12Z MODEL EVALUATION INCLUDING THE CMC/UKMET/ECMWF

UPPER TROUGH FORMING ACROSS THE PACIFIC NORTHWEST...

PREFERENCE: MODEL CONSENSUS...MOVING AWAY FROM ECMWF BY DAY 3.
CONFIDENCE: AVERAGE

THE GFS BACKED OFF ON THE DEPTH OF THE TROF AND CLOSED LOW BY 12Z
SAT WHILE THE 12Z NAM IS STRONGER/DEEPER THAN IT WAS ON ITS 02/00Z
RUN.  THE 02/00Z ECMWF WAS SLIGHTLY WEAKER AND NORTH BY OF THE
MODEL CONSENSUS AT THIS POINT...WITH LITTLE CHANGE IN POSITION OR
STRENGTH FROM ITS 12Z RUN. WILL SUGGEST THAT A MODEL CONSENSUS
SHIFTED TOWARDS THE 12Z GFS REMANIS THE BEST APPROACH AT THIS
POINT.

SHORTWAVE TROUGH ACROSS THE UPPER MIDWEST...

PREFERENCE: BEFORE 12Z THU...EQUAL BLEND GFS/ECMWF DAY 1 LEANING
GFS DAY 2/3
CONFIDENCE: BEFORE 12Z THU...BELOW AVERAGE

THE 12Z NCEP RUNS STILL POINT TO A CONSENSUS EARLY IN THE FORECAST
PERIOD WITH A SHIFT TO THE GFS PRIMARILY IN THE DAY 2/3 CYCLE.
THE HI-RES SOLUTIONS LOSE THEIR SOUTHWARD QPF EMPHASIS BY TONIGHT
AND SHIFT CONVECTION NORTHWARD ALONG THE STATIONARY BOUNDARY.  THE
GLOBAL MODELS TENDED TO PUT MORE EMPAHSIS ON A SOUTHERLY
SOLN...PERHAPS DUE TO THEIR CONVECTIVE PARAMETERIZATIONS THAT
ALLOW FOR EASIER TRIGGERING.  THE CURRENT PREFERENCE FOR MASS
FIELDS REMAINS TOWARDS A MORE SOUTHWARD ORIENTED SOLUTIONS.  REFER
TO THE QPFPFD/FXUS04 KWBC FOR DETAILS RELATED TO THE DETAILS OF
THE WPC QPF.

SHORTWAVE TROUGH MOVING FROM THE SOUTHWEST TO THE PLAINS THU-FRI...

PREFERENCE:  NAM OR GFS OR ECMWF
CONFIDENCE:  AVERAGE

THE NAM AND GFS HAVE TRENDED WESTWARD WITH ITS TRACK AND SHOW
FAIRLY GOOD AGREEMENT WITH EACH OTHER THROUGH 84 HRS...WITH
SUPPORT FROM THE 00Z ECMWF.

...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...

...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

BANN


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