Prognostic Meteorological Discussion
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000
FXUS02 KWBC 151600
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1159 AM EDT MON SEP 15 2014

VALID 12Z THU SEP 18 2014 - 12Z MON SEP 22 2014


...SW US TROPICAL DOWNPOUR THREAT WITH MOISTURE THEN SPREADING TO
THE S-CENTRAL US...

MODELS AND ENSEMBLES OFFER REASONABLY SIMILAR MID-LARGER SCALE
FLOW PATTERN EVOLUTIONS ACROSS THE NOAM MID-UPPER LATITUDES INTO
THE WEEKEND. THIS BOLSTERS FORECAST CONFIDENCE WITH A BLEND OF THE
COMPATABLE 00 UTC GFS/ECMWF AND 00 UTC GFS/ECMWF ENSEMBLES TO WEED
OUT THE LESS PREDICTABLE SMALLER SCALE MASS FIELD AND SYSTEM
TIMING/STRENGTH ISSUES TO A CERTAIN DEGREE. THIS LEADS TO MORE
AMPLIFIED FLOW INTO DAYS 6/7 WITH FURTHER DEVELOPMENT OF A WRN
NOAM RIDGE AND E-CENTRAL NOAM TROUGH ALOFT AND ASSOCIATED AND WELL
DEFINED LOW/FRONTAL SYSTEM EMERGENCE ACROSS THE CENTRAL AND ERN US
THAT WILL FOCUS LEAD PCPN POTENTIAL AND POST FRONTAL AIRMASS.
PREFER A SIMPLER 50-50 BLEND OF THE STILL COMPATABLE 00 UTC
GFS/ECMWF ENSEMBLE MEAN AT THESE LONGER TIME FRAMES IN A PERIOD
WITH MORE SIGNIFICANT DETERMINISTIC MODEL RUN TO RUN CONTINUITY
CONSIDERATIONS.

IMPORTANTLY...A SPECIAL FOCUS SEEMS MERITED OVER THE SOUTHWEST
WHERE TROPICAL MOISTURE IS ONCE AGAIN POISED TO FLOW INTO THE
REGION AS A LEADING CURRENT MID-LATITUDE TROUGH OFF THE UNITED
STATES WEST COAST KICKS INLAND. VERY HIGH PRECIPITABLE-WATER
VALUES MAY WELL BE WRUNG OUT WITH AND AHEAD BY A SERIES OF
SMALL-SCALE SHORTWAVES WIGGLING NORTHWARD FROM THE GULF OF
CALIFORNIA ASSOCIATED WITH CURRENT HURRICANE ODILE WHOSE WEAKENS
WHILE TRACKING INTO THE NRN GULF OF CA OVER THE NEXT 3-4 DAYS. I
ALSO SUSPECT THAT THIS MOISTURE WILL SUBSEQUENTLY FEED NEWD INTO
THE S-CENTRAL US AND COULD FUEL ADDITIONAL AND HARD TO PINPOINT
HEAVY CONVECTION/DOWNPOURS IN ADVANCE OF AN APPROACHING WEEKEND
FRONT.

SCHICHTEL

$$





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