Prognostic Meteorological Discussion
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000
FXUS10 KWNH 010426
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1225 AM EDT WED JUL 01 2015

VALID JUL 01/0000 UTC THRU JUL 04/1200 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.


DEEP CYCLONE MOVING THROUGH WESTERN CANADA FRI/SAT
FRONT DROPPING INTO MONTANA FRIDAY NIGHT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE GUIDANCE SHOWS GOOD AGREEMENT WITH THIS SYSTEM.


UPPER LOW/WEAKNESS ACROSS CENTRAL MEXICO
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GFS/ECMWF/CANADIAN COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE 12Z UKMET BECOMES A WEAK OUTLIER WITH THIS SYSTEM WHILE THE
00Z NAM IS THE STRONGEST.  A COMPROMISE OF THE 00Z GFS/12Z
ECMWF/12Z CANADIAN APPEARS BEST HERE, AND IS PREFERRED WITH ABOVE
AVERAGE CONFIDENCE.


SECOND WAVE MOVING FROM KS THROUGH THE MID-SOUTH
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: ECMWF ENSEMBLE MEAN
CONFIDENCE: BELOW AVERAGE

THE 00Z GFS/TO SOME DEGREE THE 21Z SREF MEAN WERE THE MOST
AMPLIFIED ALOFT WITH THIS SYSTEM (SIMILAR TO THE 29/12Z ECMWF RUN)
AND BROUGHT THE LOW FARTHEST TO THE NORTH ALONG THE OH RIVER.
THIS IS A PROBLEM AS A WEAK SHORTWAVE UPSTREAM ACROSS ALBERTA LATE
THURSDAY COULD PREVENT A MORE AMPLIFIED SOLUTION ALOFT.  THE 12Z
UKMET WAS THE WEAKEST ALOFT AND WAS SLOWEST/FARTHEST SOUTH WITH
THE SURFACE LOW MOVING IT INTO TN.  THE 12Z ECMWF ENSEMBLE MEAN
SOLUTION WAS IN THE MIDDLE OF THE GUIDANCE SPREAD, AND IS
PREFERRED WITH BELOW AVERAGE CONFIDENCE.


FIRST WEAK WAVE MOVING BY THE VA CAPES FRIDAY MORNING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: ECMWF/UKMET COMPROMISE
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE 00Z GFS WAS TOO WEAK WITH ITS PARENT SHORTWAVE, WHICH LED TO A
WEAKER AND MORE DEPRESSED SURFACE SOLUTION.  THE 12Z CANADIAN WAS
FARTHER NORTH WITH ITS TRACK DUE TO ITS STRONGER SHORTWAVE ACROSS
THE SOUTHERN GREAT LAKES -- ITS USUAL BIAS.  A COMPROMISE OF THE
12Z ECMWF/12Z UKMET IS SUPPORTED BEST BY THE 12Z GLOBAL ENSEMBLE
LOW CLUSTERING AND IS PREFERRED WITH SLIGHTLY 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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