Prognostic Meteorological Discussion
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FXUS10 KWNH 190445
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1244 AM EDT FRI SEP 19 2014

VALID SEP 19/0000 UTC THRU SEP 22/1200 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 19/00Z NAM/GFS AND 18/12Z ECMWF/UKMET
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

OVERALL THE NAM/GFS/ECMWF APPEAR CONSISTENT WITH ONE ANOTHER IN
TERMS OF QPF WHILE THE OLD CANADIAN WAS ON THE FAST SIDE OF THE
GUIDANCE.

...DEEP UPPER TROUGH/CLOSED LOW AFFECTING THE WESTERN STATES
THROUGH SAT...

PREFERENCE: BLEND OF THE 18/12Z ECMWF/UKMET AND THE 20/00Z CANADIAN
CONFIDENCE: ABOVE AVERAGE

FEW MODEL DIFFERENCES EXIST HERE. THE NAM GOT INTO A LITTLE BETTER
AGREEMENT WITH OTHER GLOBAL MODELS IN TERMS OF HOW IT HANDLES A
SHORTWAVE TROF NEAR THE BASE OF THE LOW AND SWING THE LARGER SCALE
LOW. THE GLOBAL MODELS...HOWEVER...SHOW STRONG AGREEMENT.

...UPPER TROUGH DIGGING INTO THE EASTERN U.S THIS WEEKEND...
...SURFACE LOW DEVELOPING OFF THE SOUTHEAST UNITED STATES COAST
FRI/SAT...

PREFERENCE: BLEND OF 18/12Z GEFS MEAN WITH 18/12Z ECMWF
CONFIDENCE: AVERAGE

BY DAY 3...THE NAM BECOMES A WEAK/SLOW OUTLIER COMPARED WITH THE
GFS AND PREVIOUS ECMWF/UKMET/GEFS.  THE 19/00Z GFS CERTAINLY
SLOWED DOWN THE EASTWARD PROGRESSION OF THE TROF BY SUNDAY
NIGHT/MONDAY MORNING APPARENTLY IN RESPONSE TO THE TROF BEING MORE
AMPLIFIED THAN IN EARLIER RUNS. THINK THAT OVERALL THE 18/12Z GEFS
DEPICTS THE POSITION AND EVOLUTION OF THE TROF BEST.

...LEAD SHORTWAVE INTO THE PACIFIC NORTHWEST THIS WEEKEND...

PREFERENCE: BLEND OF THE OPERATIONAL MODELS
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.

...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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