Prognostic Meteorological Discussion
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000
FXUS10 KWNH 200445
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1245 AM EDT SAT SEP 20 2014

VALID SEP 20/0000 UTC THRU SEP 23/1200 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/ECMWF/UKMET
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

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.


...CLOSED LOW INITIALLY OVER CALIFORNIA...

PREFERENCE: ANY OF THE 19/12Z OR 20/00Z OPERATIONAL MODELS
CONFIDENCE: ABOVE AVERAGE

FEW MODEL DIFFERENCES EXIST INTO DAY 2...WITH THE 00Z NAM LAGGING
A BIT BEHIND THE GFS/EC OR GEFS ON DAY 3.  THE DIFFERENCES BY DAY
3 ARE MINOR IN THE MID LEVELS.

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

PREFERENCE: BLEND OF 19/12Z ECMWF WITH 20/00Z ECMWF OR GEFS/ECMWF
ENSEMBLE MEANS
CONFIDENCE: AVERAGE

THE UKMET JOINED THE CANADIAN IN BEING A STRONG OUTLIER IN TERMS
OF BRINGING A COASTAL LOW PRESSURE ALONG OR INLAND 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. LITTLE CHANGED FROM EITHER THE 20/00Z NAM OR THE
GFS TO ALTER THE PREVIOUS WPC PREFERENCE.

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

PREFERENCE: ANY OF 20/00Z NAM/GFS OR 19/12 ECMWF/UKMET
CONFIDENCE: ABOVE AVERAGE

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 20/00Z GFS GOT TO BE A BIT FASTER THAN THE OTHER
GLOBAL MODELS BY DAY 3 BUT THE DIFFERENCES WERE MINOR.

...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...
...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

BANN

$$





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