Prognostic Meteorological Discussion
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FXAK02 KWNH 301915
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
314 PM EDT SUN APR 30 2017

VALID 12Z THU MAY 04 2017 - 12Z MON MAY 08 2017

MODELS AND ENSEMBLES REMAIN IN VERY GOOD AGREEMENT IN THE MEDIUM
RANGE, OFFERING ABOVE AVERAGE CONFIDENCE. A LEAD UPPER LOW WILL
WEAKEN IN THE GULF (ASSOCIATED WITH A FAIRLY STRONG SYSTEM IN THE
SHORT RANGE) AS ANOTHER UPPER LOW MOVES JUST NORTH OF DUE EAST
ALONG 50N. THIS WILL CARRY A SURFACE LOW AND FRONTAL BOUNDARIES
EASTWARD AND NORTHEASTWARD THROUGH THE PERIOD, FOCUSING RAINFALL
ALONG THE ALEUTIANS INITIALLY AND THEN THROUGH SOUTH CENTRAL AND
TOWARD THE PANHANDLE BY THE END OF THE PERIOD. THE LEAD SYSTEM ON
THURSDAY WILL BE WELL INTO CANADA BUT THE UPPER TROUGH WILL
SUPPORT SHOWERS THROUGH THE PANHANDLE THU/FRI. A CONSENSUS BLEND
OF THE 12Z GFS, 06Z GEFS, AND 00Z ECMWF/EC-ENS MEAN OFFERED A
REASONABLE STARTING POINT THAT FIT WELL WITH CONTINUITY. THIS
SMOOTHED OUT THE EVOLUTION OF THE MAIN SYSTEM AS IT MAY CONTAIN
SFC WAVES OR PERHAPS TRIPLE POINT RE-DEVELOPMENT LATER ON, BUT
THESE DETAILS CANNOT YET BE RESOLVED.


FRACASSO


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