ALASKA EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
125 PM EST MON FEB 13 2012
 
VALID 12Z FRI FEB 17 2012 - 12Z TUE FEB 21 2012
 
UPPER PATTERN ACROSS THE PACIFIC OCEAN WILL FEATURE A VANISHING
RIDGE SOUTH OF JAPAN BUT A STABLE RIDGE OVER THE EASTERN PACIFIC
NEAR 35N/145W. A BROAD UPPER LOW WILL REPOSITION ITSELF OVER
NORTHEASTERN ASIA BUT WILL STRETCH ALL THE WAY INTO WESTERN ALASKA
THROUGH THE MEDIUM RANGE PERIOD. THIS WILL KEEP A FAIRLY
ACTIVE/STORMY PATTERN FOR SOUTHERN COASTAL AREAS. THE ENSEMBLE
SYSTEMS ARE GENERALLY SPLIT BETWEEN THE SLOWER AND MORE AMPLIFIED
ECMWF VERSUS THE QUICKER AND FLATTER GFS MEMBERS... ESPECIALLY
COMING OUT OF THE CENTRAL PACIFIC BY THIS WEEKEND. OTHERWISE...
BOTH THE UKMET AND CANADIAN OFFER FAIR SUPPORT TOWARD EITHER
SOLUTION BUT PERHAPS SIDE MORE WITH THE ECMWF. GIVEN THE BETTER
RECENT PERFORMANCE OF THE ECMWF/ECMWF ENSEMBLE MEAN COMBINED WITH
BETTER CONTINUITY... FELT COMPELLED TO STICK WITH AN ECMWF
SOLUTION IN THE MEDIUM RANGE. FORECASTER CONFIDENCE IS ABOUT
AVERAGE.

ON FRI/D4... THE 12Z GFS BRINGS A LOW MUCH FARTHER NORTH INTO THE
GULF THAN THE 00Z ECMWF/UKMET/CANADIAN WHICH TAKE IT INTO THE PAC
NW... THOUGH THE GFS DOES SPIN UP ANOTHER LOW IN THE SAME PLACE
LATER ON. BY THE WEEKEND... THE GFS BEGINS TO SPEED AHEAD OF THE
ECMWF/UKMET AS AN OCCLUSION PUSHES THROUGH THE ALEUTIANS AND INTO
THE GULF... THOUGH THE GFS LAGS ITS FORMER PARENT LOW IN THE
BERING. 06Z GEFS MEAN IS A CLOSE PARALLEL TO THE GFS. THE NEXT
SYSTEM ENTERING THE MAP ON SUN/D6 SHOWS THE MOST SPREAD AND FELT
THE 00Z ECMWF ENSEMBLE MEAN WAS THE BEST BET FOR NOW AS IT WAS NOT
AS SLOW AS THE 00Z ECMWF. POTENTIAL EXISTS FOR A FAIRLY DEEP
SYSTEM WITH THE MEAN PMSL IN THE 960S MB AND THE OP ECMWF/CANADIAN
IN THE 950S MB. 



FRACASSO