Prognostic Meteorological Discussion
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FXUS02 KWBC 310704
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
304 AM EDT TUE MAY 31 2016

VALID 12Z FRI JUN 03 2016 - 12Z TUE JUN 07 2016


...PATTERN OVERVIEW...

THE PATTERN OVER THE LOWER 48 WILL TRANSITION BACK TO A RIDGE IN
THE WEST AND TROUGH IN THE EAST THIS WEEKEND AND INTO EARLY NEXT
WEEK.  WITHIN THE MEAN FLOW...THE REMNANTS OF BONNIE SHOULD
FINALLY LIFT AWAY FROM THE CAROLINA COAST ON FRIDAY...AHEAD OF A
COLD FRONT PRESSING TOWARDS THE EASTERN SEABOARD.  AN UPSTREAM
SHORTWAVE DIGGING INTO THE UPPER MIDWEST AND GREAT LAKES SATURDAY
AND SUNDAY SHOULD HELP REINFORCE A BROAD TROUGH IN THE EAST.
MEANWHILE...AN UPPER LOW OVER TEXAS WILL GRADUALLY WEAKEN AND
MEANDER EASTWARD...AND AN AMPLIFYING UPPER RIDGE AND POTENTIAL
UPPER TROUGH LIFTING INTO CALIFORNIA WILL BE THE MAIN FEATURES IN
THE WESTERN U.S..


...MODEL EVALUATION/PREFERENCES...

MODELS ARE IN UNUSUALLY GOOD AGREEMENT WITH THE GENERAL FLOW
PATTERN EVOLVING OVER THE CONUS THIS FRIDAY THROUGH NEXT
TUESDAY...AND THE COMBINATION OF RELATIVELY STEADY DETERMINISTIC
RUNS AND MINIMAL SPREAD IN ENSEMBLE MEMBERS GIVES EVEN EXTRA
CONFIDENCE IN THE LARGE SCALE FORECAST.  THERE IS STILL SOME
UNCERTAINTY WITH THE EXACT TIMING AND AMPLITUDE OF THE SHORTWAVE
DIGGING INTO THE UPPER MIDWEST/GREAT LAKES THIS WEEKEND AND THE
UPPER TROUGH LIFTING INTO CALIFORNIA SUNDAY INTO MONDAY.
ALSO...DETAILS OF THE REMNANTS OF BONNIE LIFTING AWAY FROM THE
CAROLINA COAST AND THE WEAKENING UPPER LOW OVER TEXAS HAVE YET TO
BE RESOLVED.  THE WPC FORECAST STARTED WITH THE ECMWF ENSEMBLE
MEAN SINCE IT APPEARED TO BEST REPRESENT THE MIDDLE OF THE SUBTLE
MODEL SPREAD WITH SOME OF THE SMALLER SCALE FEATURES OF THE
FORECAST.


...SENSIBLE WEATHER HIGHLIGHTS...

CONDITIONS WILL REMAIN WARM AND DRY BENEATH AN UPPER RIDGE IN THE
WEST...WITH DAYTIME TEMPERATURES APPROACHING RECORD HIGHS ACROSS
THE PACIFIC NORTHWEST AND NORTHERN ROCKIES THIS WEEKEND.
WIDESPREAD SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE ALONG A
FRONTAL BOUNDARY LINGERING FROM THE WESTERN GULF COAST TO THE
CAROLINAS FRIDAY THROUGH SUNDAY.  THE GREATEST THREAT FOR HEAVY
RAINS SHOULD BE ACROSS TEXAS AND THE LOWER MISSISSIPPI
VALLEY...WHERE ANOMALOUS GULF MOISTURE SURGING NORTHWARD AHEAD OF
THE CLOSED LOW OVER TEXAS COULD FEED INTO DEVELOPING STORMS.


GERHARDT













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