Prognostic Meteorological Discussion
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000
FXUS10 KWNH 191652
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1252 PM EDT FRI SEP 19 2014

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

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

==============================================
00Z MODEL EVALUATION AND PREFERENCES
==============================================
NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TO
SIGNIFICANTLY AFFECT THEIR LARGE SCALE OUTPUT.
==============================================

...REMNANTS OF ODILE...

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

THE LOWER TO MIDDLE LEVEL REMNANTS OF PACIFIC TROPICAL CYCLONE
ODILE...DEFINED AS EITHER A SMALL CIRCULATION OR SHEAR AXIS...ARE
FORECAST TO STALL OVER EASTERN NM AND WEST TX...TRAPPED WITHIN A
BUILDING UPPER LEVEL RIDGE. THE NAM/GFS/ECMWF SHOW THE GREATEST
SIMILARITY TO ONE ANOTHER AND KEEP GOOD CONTINUITY WITH WPC QPF.


...CLOSED LOW INITIALLY OVER CALIFORNIA...

PREFERENCE: ANY OF 12Z NAM/GFS AND 00Z ECMWF/CANADIAN

FEW MODEL DIFFERENCES EXIST HERE. THE 00Z UKMET WAS SLIGHTLY
FASTER THAN CONSENSUS IN EJECTING THIS SYSTEM TOWARD THE NORTHERN
HIGH PLAINS ON MONDAY.


...UPPER TROUGH DIGGING INTO THE EASTERN U.S THIS WEEKEND...
...SURFACE LOW DEVELOPING OFF THE SOUTHEAST U.S. COAST SATURDAY...

PREFERENCE: 12Z GFS

THE ONLY STRONG OUTLIER HERE IS THE 00Z CANADIAN...WHICH BROUGHT
COASTAL LOW PRESSURE ONSHORE DURING PARTS OF ITS JOURNEY FROM THE
CAROLINAS TOWARD NEW ENGLAND. THE CONSENSUS OVER MULTIPLE MODEL
CYCLES IS FOR A POSITION FARTHER OFFSHORE AND REMAINING OFFSHORE
WHILE BEING ABSORBED BY SYNOPTIC LOW PRESSURE OVER NEW ENGLAND.
RECENT GFS AND GEFS FORECASTS...AS WELL AS THE UKMET...HAVE
SUPPORTED THESE IDEAS. THE 00Z ECMWF WAS SIMILAR...ALTHOUGH IT
LOST ANY SENSE OF THE COASTAL LOW BEYOND SUNDAY MORNING. GIVEN
THAT THE 12Z GFS FITS NICELY WITH THE 06Z GEFS MEAN...WE RECOMMEND
THE 12Z GFS AS THE BEST STARTING POINT FOR THIS SYSTEM.


...DEEP TROUGH LEANING INTO THE PACIFIC NORTHWEST...

PREFERENCE: BLEND OF 12Z NAM/GFS

A DEEP LONGWAVE TROUGH OFFSHORE SHOULD HAVE LITTLE IMPACT THROUGH
SUNDAY NIGHT/MONDAY MORNING...BUT MODELS DO BRUSH THE PACIFIC NW
COAST WITH LOW PRESSURE ASSOCIATED WITH A LEAD SHORTWAVE THIS
WEEKEND. THE 12Z NAM AND GFS WERE CONSISTENT WITH A RECENT TREND
TOWARD GREATER AMPLIFICATION WITHIN THE BASE OF THE TROUGH
OFFSHORE...AND BETTER DEFINITION OF THE LEAD SHORTWAVE AND
ASSOCIATED WEAK HEIGHT FALLS OVER THE PACIFIC NORTHWEST.

...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
$$





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