Prognostic Meteorological Discussion
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000
FXUS10 KWNH 300430
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1229 AM EDT TUE JUN 30 2015

VALID JUN 30/0000 UTC THRU JUL 03/1200 UTC

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

00Z NAM/GFS EVALUATION WITH PRELIMINARY MODEL PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT
RANGE FORECASTS.


SHORTWAVE/LOW MOVING THROUGH MS VALLEY EARLY FRI
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GFS
CONFIDENCE: AVERAGE

THERE IS SPREAD IN THE GUIDANCE WITH THIS SYSTEM AS THE 12Z UKMET
IS VERY WEAK AND THE 12Z ECMWF/ITS ENSEMBLE MEAN/00Z NAM/12Z
CANADIAN ARE THE STRONGEST.  WHILE NORMALLY GOING STRONGER ALOFT
EAST OF A CLOSED HIGH CAN BE A SHREWD MOVE, A WEAK UPSTREAM
SHORTWAVE MOVING BY MONTANA THURSDAY NIGHT MUDDIES THE THE
PICTURE.  THE 12Z GLOBAL ENSEMBLE CLUSTERING MOST FAVORED THE 00Z
GFS, WHICH IS PREFERRED WITH AVERAGE CONFIDENCE.


SHORTWAVE/LOW MOVING FROM THE SOUTHERN PLAINS TO THE
VIRGINIA CAPES THURSDAY NIGHT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GFS/UKMET COMPROMISE
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE 00Z NAM AND 12Z ECMWF ARE QUICK IN MOVING THIS CYCLONE OUT TO
SEA DUE TO QUICKER MOVING UPPER LEVEL SHORTWAVES.  THE 18Z
GEFS/12Z ECMWF ENSEMBLE MEAN SOLUTIONS FAVOR THE SLOWER NON-NAM,
NON-ECMWF CONSENSUS.  OF THESE, THE 12Z UKMET/00Z GFS WERE A
REASONABLE MATCH TO THE 12Z GLOBAL ENSEMBLE LOW CLUSTERING, SO
THEY ARE PREFERRED WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE.


MID-LEVEL CYCLONE WEAKENING OVER MEXICO
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CANADIAN COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE 12Z CANADIAN WAS THE WEAKEST WITH THIS FEATURE, TRAPPED IN A
COL BETWEEN THE WESTERN RIDGE NEAR NV AND THE SUBTROPICAL RIDGE
NEAR THE FL STRAITS.  PREFER A NON-CANADIAN COMPROMISE HERE WITH
ABOVE AVERAGE CONFIDENCE.


CYCLONE LIFTING FROM THE GREAT LAKES INTO
QUEBEC & ITS TRAILING COLD FRONT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM COMPROMISE
CONFIDENCE: ABOVE AVERAGE

WHILE THE NAM IS SLOW WITH THE CYCLONE MOVEMENT, THIS DOES NOT
SEEM TO IMPACT ITS FRONTAL PROGRESSION THROUGH THE NORTHEAST.
NEVERTHELESS, PREFER A NON-NAM COMPROMISE HERE WITH ABOVE AVERAGE
CONFIDENCE.


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

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

ROTH
$$





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