Prognostic Meteorological Discussion
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FXAK02 KWNH 211949
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ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
248 PM EST TUE FEB 21 2017

VALID 12Z SAT FEB 25 2017 - 12Z WED MAR 01 2017

RATHER GOOD AGREEMENT WITH THE OPERATIONAL AND ENSEMBLE GUIDANCE
THROUGH THIS WEEKEND INTO EARLY NEXT WEEK FOR AK. AN EXTREMELY
POWERFUL UPPER JET AND ANOMALOUS MOISTURE SURGE WILL ARRIVE INTO
WESTERN AK ON SAT AND SPREAD ACROSS THE STATE ON SUN. THIS WILL
SHIFT SHARP SHORT WAVE RIDGING PROGRESSIVELY DOWNSTREAM AND ALLOW
MORE UPSTREAM UPPER DYNAMICS TO CROSS THE STATE TOWARD THE NERN
PAC/GULF OF AK ON MON/TUES. THE 12Z GFS AND 00Z/21 ECMWF ARE IN
VERY GOOD AGREEMENT WITH THIS SCENARIO. IN FACT... ITS MEANS
INDICATE A LONG FETCH OF PWS 2 TO 2.5 TIMES ABOVE AVG INUNDATING
THE STATE... AS 850MB TEMPS ARE SLIGHTLY ABOVE AVG FOR THE
WEEKEND. THEN EARLY NEXT WEEK... THE PASSING UPPER DYNAMICS
REACHING THE NERN PAC WILL ALLOW COLD ADVECTION TO SWEEP ACROSS
THE STATE. THE OPERATIONAL GUIDANCE VARIES ON THE DEVELOPMENT OF
LOW PRESSURE OVER THE NERN PAC AND BUILDING OF UPPER HEIGHTS OVER
THE ALEUTIANS AND WESTERN PORTION OF THE STATE. THUS THE LATTER
PORTION OF THE MEDIUM RANGE PERIOD IS MOSTLY BASED ON THE GEFS AND
ECMWF MEAN THAN OPERATIONAL SOLUTIONS.

MUSHER


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