Prognostic Meteorological Discussion
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FXAK02 KWNH 221610
PMDAK

ALASKA EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1209 PM EDT TUE JUL 22 2014

VALID 12Z SAT JUL 26 2014 - 12Z WED JUL 30 2014


SINCE YESTERDAY, BOTH THE GFS AND ECMWF HAVE TRENDED STRONGLY AWAY
FROM THE DEPICTION OF A SURFACE LOW OVER KAMCHATKA 12Z/27 SUNDAY,
NOW INDICATING THAT THE SURFACE RIDGE CENTERED OVER THE INNER
ALEUTIANS SHOULD WRAP WESTWARD ALL THE WAY ACROSS THE BERING SEA.
THEREAFTER, THE ENERGY LIFTING FROM LOWER LATITUDES TOWARD THE
OUTER ALEUTIANS SHOULD MEET CONFLUENT RESISTENCE, WHICH SHOULD
SUBSTANTIALLY STRENGTHEN THE EASTERLY GRADIENT WINDS FOR A TIME.
EVENTUALLY, BOTH MODELS BRING A SPRAWLING SURFACE LOW INTO THE
WESTERN BERING SEA AS PART OF YET ANOTHER BLOCKING VARIATION. THE
BOOKEND VORTEX TO THIS NEW BLOCK SHOULD ANCHOR ITSELF EARLY SOUTH
OF THE GULF OF ALASKA AND WEST OF THE BRITISH COLUMBIA COAST. WITH
TIME, THIS VORTEX SHOULD GET NUDGED CLOSER TO THE CONTINENT AS NEW
ENERGY IMPINGES ON THE BERING SEA VORTEX.

USED THE 00Z/22 EUROPEAN CENTRE ENSEMBLE MEAN FOR THIS PACKAGE,
SINCE THE FUNDAMENTAL SHIFT IN THE FORECAST OF THE FLOW ACROSS THE
REGION AT THE MEDIUM RANGE CASTS A LONG SHADOW OF DOUBT ACROSS ANY
ONE OPERATIONAL SOLUTION. THE GEFS MEANS CONTAIN ELEMENTS GREATLY
AT ODDS WITH THE TRENDS AND THE OPERATIONAL GFS, SO WAS NOT
INCLINED TO GIVE THE GEFS PRODUCTS ANY WEIGHT FOR NOW.


CISCO

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