Prognostic Meteorological Discussion
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FXUS10 KWNH 241840
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
239 PM EDT SUN JUL 24 2016

VALID JUL 24/1200 UTC THRU JUL 28/0000 UTC

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

12Z MODEL EVALUATION - INCLUDING THE ECMWF


***WEAK UPPER LEVEL LOW CROSSING THE NORTHERN GULF OF MEXICO***

PREFERENCE: NON-NAM CONSENSUS
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

A WEAK UPPER LOW CROSSING THE FLORIDA PENINSULA WILL CONTINUE
TRACKING WESTWARD THROUGH TUESDAY, TRAVERSING THE GULF OF MEXICO
BEFORE REACHING THE TEXAS COAST BY TUESDAY NIGHT.  THE 12Z NAM HAS
LOWER OVERALL 500MB HEIGHTS THAN THE MODEL CONSENSUS, ALONG WITH
ITS PREVIOUS RUNS.  THE REMAINING MODELS REMAIN RATHER WELL
CLUSTERED WITH THE UPPER LEVEL LOW.  THEREFORE A NON-NAM
COMPROMISE IS RECOMMENDED WITH THIS FEATURE.


***SUNDAY TROUGH OVER THE UPPER MIDWEST REACHING NEW ENGLAND
TUESDAY MORNING***

PREFERENCE: 12Z GFS/12Z ECMWF COMPROMISE
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

A PROGRESSIVE MID LEVEL TROUGH WILL TRACK ACROSS THE UPPER GREAT
LAKES THROUGH MONDAY MORNING AND THEN REACHING QUEBEC CANADA ON
TUESDAY.  THIS WILL RESULT IN A SURFACE COLD FRONT TO ADVANCE
ACROSS THE GREAT LAKES AND NORTHEAST STATES.  THE 12Z NAM IS MORE
AMPLIFIED WITH THE UPPER LEVEL HEIGHTS AND SURFACE PRESSURES WITH
THIS SYSTEM.  THE 12Z UKMET IS CLOSER TO THE MODEL CONSENSUS WITH
THE MAIN UPPER LEVEL LOW CROSSING FROM ONTARIO TO QUEBEC COMPARED
TO ITS PREVIOUS RUN.  THE GLOBAL MODELS AND THE RESPECTIVE
ENSEMBLE MEANS ARE IN GOOD AGREEMENT ON THIS FEATURE AND THE
SURFACE FRONTAL BOUNDARY AND THUS A GFS AND ECWMF COMPROMISE IS
RECOMMENDED.


***LOW-AMPLITUDE SHORTWAVE CROSSING THE MIDWEST THROUGH MIDWEEK***

PREFERENCE: 12Z GFS/12Z ECMWF/00Z EC MEAN
CONFIDENCE: AVERAGE

THE GUIDANCE SHOWS A LOW-AMPLITUDE SHORTWAVE EMBEDDED WITHIN THE
WESTERLIES NORTH OF THE SUBTROPICAL RIDGE, CROSSING THE MIDWEST ON
TUESDAY AND INTO WEDNESDAY MORNING.  A WEAK SURFACE COLD FRONT
CROSSING THE NORTHERN PLAINS IS WELL-AGREED BY THE MODELS.  THE
12Z NAM CONTINUES TO APPEAR TO BE TOO AMPLIFIED WITH THIS SYSTEM
AS WELL, AND THE 12Z UKMET SLIGHTLY WEAKER.  THE STRONGER MODEL
CLUSTERING RESIDES WITH THE 12Z GFS AND 12Z ECMWF THAT ARE CLOSE
TO THE MODEL CONSENSUS, AND SO A BLEND OF THESE SOLUTIONS WILL BE
PREFERRED.


***TROUGH OVER THE PACIFIC NORTHWEST***

PREFERENCE: 12Z ECMWF/12Z UKMET/12Z NAM
CONFIDENCE: ABOVE AVERAGE

THE MODELS HAVE A TROUGH LINGERING OVER THE NORTHWEST TUESDAY AND
WEDNESDAY. ONLY MINOR DIFFERENCES WITH TIMING/DEPTH EXIST WITH
THIS SYSTEM, WITH THE GFS A LITTLE MORE AMPLIFIED AND THE CMC
FLATTER WITH THE UPPER LEVEL PATTERN.  THEREFORE, A BLEND OF THE
ECMWF, NAM, AND UKMET SHOULD WORK WELL.

HAMRICK

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

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

$$





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