Prognostic Meteorological Discussion
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000
FXAK02 KWNH 271836
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
135 PM EST TUE JAN 27 2015

VALID 12Z SAT JAN 31 2015 - 12Z WED FEB 04 2015

A DEEP CYCLONE IS EXPECTED TO LOOP ACROSS THE NORTHEAST PACIFIC
THIS PERIOD,  AHEAD OF ANOTHER SLOW-MOVING DEEP CYCLONE MOVING BY
THE INTERNATIONAL DATELINE.  OTHERWISE, AN ARCTIC HIGH ACROSS
NORTHWESTERN NORTH AMERICA WILL SLOWLY WANE AS THE MID-LEVEL RIDGE
ACROSS THE REGION IS PUSHED ASIDE BY AN UPPER TROUGH MOVING ACROSS
THE BERING SEA/STRAIT BY LATE TUESDAY.  ALOFT, THE NON-CANADIAN
GUIDANCE WAS IN GOOD AGREEMENT WITH THIS SCENARIO AND HAD THE
SUPPORT OF THE RELATED 06Z GEFS AND 00Z ECMWF ENSEMBLE MEANS.
USED A COMPROMISE OF THE 00Z UKMET/00Z ECMWF/06Z GFS THROUGH THE
WEEKEND BEFORE SHIFTING TO AN EVEN 00Z ECMWF/06Z GEFS MEAN
COMPROMISE FOR LATE SUNDAY THROUGH LATE TUESDAY.

THERE IS SIGNIFICANT UNCERTAINTY REGARDING THE MOVEMENT OF THE
CYCLONE ACROSS THE NORTHEAST PACIFIC AFTER SUNDAY, WITH THE 00Z
ECMWF/12Z GFS RACING THE SYSTEM NORTHEAST INTO SOUTHERN ALASKA
TUESDAY NIGHT.  OUT OF RESPECT FOR THEIR SPEED, NUDGED THE
ENSEMBLE MEAN COMPROMISE SOLUTION NORTHEASTWARD TO ACCOUNT FOR THE
UNCERTAINTY.  FRESH EAST WINDS ARE EXPECTED ACROSS THE GULF OF
ALASKA THIS PERIOD, WHICH COULD BE STRONGER THAN EXPECTED LATE
MONDAY INTO TUESDAY IF THE OPERATIONAL GFS/ECMWF SOLUTIONS VERIFY.

ROTH
$$





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