Prognostic Meteorological Discussion
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FXUS02 KWBC 301504
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1103 AM EDT THU JUL 30 2015

VALID 12Z SUN AUG 02 2015 - 12Z THU AUG 06 2015

THE BASIC PATTERN THROUGH THE MEDIUM RANGE IS A DEVELOPING UPPER
TROUGH OVER THE NORTHWEST...A MEAN RIDGE FROM THE SOUTHWEST ACROSS
THE ROCKIES...AND A MEAN TROUGH OVER THE MIDWEST AND NORTHEAST.
WITHIN THE ENSEMBLE MEANS...THE EUROPEAN ENSEMBLE MEANS ARE LESS
AMPLIFIED AND SLOWER THAN THE CORRESPONDING  GEFS/NAEFS/CANADIAN
MODELS.  MEANWHILE...THE OPERATIONAL MODELS ARE NOT NECESSARILY
CONSISTENT WITH THE MEANS WITH THE GREATEST ISSUE TODAY SEEMING TO
BE WHETHER OR NOT THE AMPLITUDE OF THE ABOVE PATTERN IS WEAKER OR
STRONGER. THE MAIN IMPLICATION IS THAT A STRONGER PATTERN WILL
BRING COOLER AIR ACROSS MUCH OF THE MIDWEST AND NORTHEAST INTO THE
EAST LATER IN THE FORECAST.  AT PRESENT...KEPT A LESS AMPLIFIED
PATTERN CONSISTENT WITH RECENT TRENDS SO MINIMIZED ANY ONE
OPERATIONAL SOLUTION AND DID NOT BRING THE COOLER AIR AS FAR
SOUTHWARD AS EITHER THE GFS OR ECMWF MODELS SUGGESTED.

THE ONLY DAY ELECTED TO GO WITH A MAJORITY OPERATIONAL BLEND WAS
ON DAY 3...WHICH USED A COMBO OF THE 06Z GFS/00Z ECMWF AND THE
EUROPEAN  ENSEMBLE MEANS.  BY DAY 4...USED A 50/50 COMBO
OPERATIONAL/ENSEMBLE MEAN BLEND...AGAIN USING THE EUROPEAN
ENSEMBLE MEAN WITH A COMBINATION OF THE 06Z GFS AND 00Z ECMWF.
AFTER DAY 5...THE OPERATIONAL RUNS BECOME MUCH LESS RELIABLE SO
USED MORE OF A COMBINATION OF THE EUROPEAN ENSEMBLE MEANS AND THE
NAEFS ENSEMBLE MEANS...AS WELL AS A LESSER CONTRIBUTION FROM THE
06Z GFS OR 00Z ECMWF.  WITH THE OPERATIONAL RUNS....NO MODEL WAS
CONSIDERED SUPERIOR TO ANY OTHER OPERATIONAL MODEL.

KOCIN

$$





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