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Prognostic Meteorological Discussion
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FXUS10 KWNH 191713
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
112 PM EDT SUN MAY 19 2013

VALID MAY 19/1200 UTC THRU MAY 23/0000 UTC

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

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12Z NAM/GFS EVALUATION AND PRELIMINARY PREFERENCES
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NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TO
SIGNIFICANTLY AFFECT THEIR LARGE SCALE OUTPUT.
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...TROUGH/DEEP CYCLONE MOVING FROM THE WEST INTO THE
PLAINS/MIDWEST...

PREFERENCE: 12Z GFS

RELATIVELY GOOD AGREEMENT ON THE LARGE SCALE. ALL MODELS END UP IN
A SIMILAR PLACE BY THE END OF THE SHORT RANGE...BUT WE ARE
TRUSTING THAT THE 12Z GFS SHOWS LEGITIMATE TRENDS FOR THE TIMING
AND DEPTH OF INDIVIDUAL SHORTWAVES. THE 00Z ECMWF AND CANADIAN
APPEAR SOMEWHAT TOO SLOW WITH THE SHORTWAVE TO ROTATE THROUGH
OKLAHOMA ON DAY 2...AND THE NAM IS ON THE FAST SIDE.


...DEEP CYCLONE DROPPING TOWARDS THE PACIFIC NORTHWEST...

PREFERENCE: ANY OF THE OPERATIONAL MODELS

AGREEMENT IS VERY GOOD HERE FOR THE TIME BEING. THE MAIN ATTRIBUTE
TO RAISE CAUTION IS THE NAM TENDENCY TO ERR ON THE DEEP/STRONG
SIDE WITH ITS 700 MB LOW AND WIND FIELDS. THIS WOULD MAINLY AFFECT
THE OREGON AND NORTHERN CA COAST ON DAY 3.


...SHORTWAVE TROUGH MOVING THROUGH CAROLINAS...
...WEAK UPPER LEVEL SYSTEM FORMING ACROSS FLORIDA...

PREFERENCE: BLEND OF 12Z NAM/GFS AND 00Z ECMWF

THOUGH NOT PERFECT...A BLEND OF THE GFS AND ECMWF TENDS TO CAPTURE
THE MOST LIKELY CONFIGURATION OF THESE SOUTHERN STREAM SYSTEMS
CAUGHT IN WEAK STEERING FLOW. IN THIS CASE THE NAM JOINS THE GFS
AND SEVERAL GEFS AND ECMWF ENSEMBLE MEMBERS IN BETTER DEPICTING
THE HEIGHT FIELD WEAKNESS THAT SHOULD DEVELOP AS A SHORTWAVE DIPS
FROM TEXAS DOWN TO FLORIDA AND TAKES ON A NEGATIVE TILT.


...FRONT/LOW MOVING THROUGH/BY THE NORTHEAST MONDAY/TUESDAY...

PREFERENCE: BLEND OF 12Z NAM AND 00Z ECMWF/CANADIAN

THE 12Z GFS AND 00Z UKMET WERE FLAT WITH THE SHORTWAVE RIDGE
PROGRESSING THROUGH NEW ENGLAND. THE 00Z ECMWF CERTAINLY APPEARS
SLOW AND AMPLIFIED RELATIVE TO OTHER GUIDANCE IN DEPICTING THE
UPSTREAM KICKER TROUGH HUDSON BAY/ONTARIO...BUT OVER NEW ENGLAND
THE ECMWF IS SIMILAR ENOUGH TO THE 12Z NAM AND 00Z CANADIAN TO
FORM AN OPERATIONAL MODEL CLUSTER CLOSE TO THE CONSENSUS SOLUTION.

...MODEL TREND GRAPHICS AT
WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML...
...500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML...

BURKE
$$
National Weather Service Weather Forecast Office
