ALASKA EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
200 PM EST TUE FEB 09 2010
 
VALID 12Z SAT FEB 13 2010 - 12Z WED FEB 17 2010
 
THE DAVIS STRAIT BLOCK IS STILL FORECAST TO BE GOING STRONG IN THE
MEDIUM RANGE PERIOD OVER THE FAR NORTH ATLANTIC AND ITS AFFECTS
WILL EMANATE WESTWARD TO ALASKA... KEEPING ABOVE NORMAL HEIGHTS
OVER MOST OF THE STATE. ANOTHER POSITIVE HEIGHT ANOMALY IS
FORECAST NEAR 35N/150E... EAST OF JAPAN... WITH A NEGATIVE ANOMALY
OVER THE WESTERN ALEUTIANS AND POINTS SOUTHEASTWARD. THIS KEEPS A
STORM TRACK WELL SOUTH OF THE MAINLAND BEFORE CURVING TOWARD/INTO
THE GULF VIA THE PANHANDLE /OR JUST OFFSHORE/. SYNOPTIC PATTERN
REMAINS IN GOOD AGREEMENT OVERALL AMONG THE ENSEMBLES. 

TIMING DIFFERENCES CONTINUE TO BE A PROBLEM FROM RUN TO RUN... BUT
ATTEMPTED TO RUN WITH THE LATEST CLUSTERING TODAY. ON SAT/D4...
THE 12Z GFS AND 00Z UKMET/CANADIAN AND 06Z GEFS MEAN CLUSTER BEST
WITH ONE SYSTEM MOVING TOWARD THE GULF WHILE THE ECMWF AND ITS
ENSEMBLE MEAN ARE FARTHER NORTH AND WEST. STUCK CLOSER TO THE
BROADER CONSENSUS INCLUDING THE 12Z GFS. THEREAFTER... THE 12Z GFS
AND 00Z ECMWF SHOW GOOD AGREEMENT IN THE NORTHEAST PACIFIC WEST OF
BC... BUT THE 12Z GFS APPEARS TOO FAST NEAR THE ALEUTIANS AND ALSO
HAS MUCH LOWER PRESSURES OVER THE NORTH SLOPE THAN WHAT THE
ENSEMBLES AND OTHER OPERATIONAL MODELS WOULD SUGGEST. PREFERRED TO
HAVE ARCTIC HIGH PRESSURE STAY THE DOMINANT FEATURE THERE. HAD TO
THROW OUT THE 12Z GFS BY MON/D6 SINCE IT DID NOT FIT IN A MAJORITY
OF THE DOMAIN. A 00Z ECMWF/ECMWF ENSEMBLE MEAN BLEND SEEMED TO
SUFFICE FOR THE BALANCE OF THE FORECAST. 12Z UKMET/CANADIAN SHOWED
A NUDGE IN THE DIRECTION OF THE 00Z ECMWF AND THE MANUAL FORECAST.
THIS IS A BIT SLOWER THAN CONTINUITY 24 HRS AGO.

12Z ECMWF IS CLOSE TO ITS 00Z RUN THROUGH MON/D6 EXCEPT IT TAKES A
MUCH STRONGER LOW INTO THE GULF ON TUE/D7 MORE IN LINE WITH THE
00Z ECMWF ENSEMBLE MEAN AND FARTHER WEST THAN THE MANUAL PROGS.

FRACASSO