Prognostic Meteorological Discussion
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FXAK02 KWNH 301815
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
114 PM EST FRI JAN 30 2015

VALID 12Z TUE FEB 03 2015 - 12Z SAT FEB 07 2015

THE LATTER HALF OF THIS PARTICULAR MEDIUM RANGE PERIOD---FEBRUARY
3-6---SHOULD BE AN ACTIVE ONE FOR THE GULF OF ALASKA WITH A
LONG-WAVE UPPER-LEVEL TROUGH POSITIONED ALONG 150W-160W AND A
SERIES OF ACTIVE SHORTWAVES/SURFACE CYCLONES MIGRATING
NORTHEASTWARD ALONG THE SOUTHEASTWARD QUADRANT OF THIS UPPER-LEVEL
TROUGH.

BY DAY 5...THE BROAD FETCH OF ZONAL WESTERLY FLOW ALOFT---ALONG
35N-40N---WILL ATTEMPT TO SHEAR EASTWARD---`RE-DIRECTING`--- AREAS
OF MODERATE-TO-HEAVY PRECIPITATION INTO THE EASTERN GULF OF ALASKA
AND SOUTHWEST CANADA. THE BULK OF THIS CONCENTRATED...JET-DRIVEN
PRECIPITATION---IS PROJECTED TO "STEER AWAY" FROM THE SOUTHEAST
COAST AND PANHANDLE.

THE 30/00Z ECENS AND GEFS MEANS CONTINUE TO FEATURE THIS
UPPER-LEVEL PATTERN---WITH SOME SPREAD IN THE INDIVIDUAL SHORTWAVE
DETAILS---WITH RESPECT TO DEPTH AND TIMING. HOWEVER...THE
DETERMINISTIC RUNS DO IDENTIFY THE PRIMARY FEATURES AND THE SOURCE
REGIONS FOR CYCLOGENESIS IN THIS PATTERN---WITH THE ENSEMBLES
SEEMINGLY `LOCKED-IN` WITH THE AMPLITUDE OF THE LONG WAVE. THIS
LONG-WAVE TROUGH IS POISED TO DISLODGE THE NORTH AMERICAN
UPPER-LEVEL RIDGE AND MIGRATE THE RIDGE DOWNSTREAM---A GOOD 10-20
DEGREES EAST OF ITS CURRENT LOCATION---HEADING INTO THE DAY8+ TIME
FRAME---BETWEEN 35N-55N LATITUDE.

VOJTESAK

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