Prognostic Meteorological Discussion
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000
FXUS10 KWNH 260636
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
235 AM EDT TUE MAY 26 2015

VALID MAY 26/0000 UTC THRU MAY 29/1200 UTC

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

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


TROUGH CROSSING THE ROCKIES LATE THURSDAY/EARLY FRIDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: ECMWF/CANADIAN/UKMET COMPROMISE
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE 00Z GFS WAS UNIQUELY WEAK ALOFT WITH THIS SYSTEM, WHILE THE
00Z NAM SHOWED A STRONGER SHORTWAVE EJECTING INTO THE SOUTHERN
PLAINS -- ITS USUAL BIAS THREE DAYS IN ADVANCE.  THE 00Z ECMWF/00Z
CANADIAN/00Z UKMET FIT IN WELL WITH THE 12Z ECMWF/00Z GEFS
ENSEMBLE MEAN SOLUTIONS, SO THEY ARE PREFERRED WITH SLIGHTLY ABOVE
AVERAGE CONFIDENCE.


LOW NEAR THE CENTRAL US/CAN BORDER THU NIGHT/FRI MORNING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: UKMET/ECMWF COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE GUIDANCE SHOWS A BIT OF SPREAD WITH THIS SURFACE LOW DUE TO
SUBTLE DIFFERENCES ALOFT ACROSS SOUTH-CENTRAL CANADA.  A
COMPROMISE OF THE 00Z UKMET/00Z ECMWF LIES NEAR THE MIDDLE OF THE
BROADER THAN USUAL 12Z GLOBAL ENSEMBLE SPREAD, SO THEY ARE
PREFERRED WITH AVERAGE CONFIDENCE.


CLOSED LOW DROPPING THROUGH BRITISH COLUMBIA
SHORTWAVE GOING THROUGH THE GREAT LAKES WEDNESDAY
LOW MOVING NORTH OF MAINE TUESDAY EVENING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE GUIDANCE IS IN GOOD AGREEMENT WITH THESE FEATURES.


...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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