Small Craft Advisory 678, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM ADT WED AUG 2 2006

.DISCUSSION...
THE POLAR JET IS COMING SOUTHEASTWARD OFF OF THE NORTHEAST SIBERIA
AND THE SUB-TROPICAL JET WESTWARD OFF OF NORTHERN JAPAN. THE TWO JET
STREAMS MERGE SOUTH OF THE WESTERN ALEUTIANS WHERE A ROBUST LOW IS
SPINNING UP AND MOVING EASTWARD ALONG THE STORM TRACK...WHICH IS
FAIRLY ZONAL AT AROUND 50N. THE STORM TRACK THEN SPLITS NEAR KODIAK
ISLAND WITH SOME OF THE ENERGY GOING EAST INTO BRITISH COLUMBIA AND
WASHINGTON...AND THE REST ALMOST STRAIT NORTH INTO ALASKA PROPER AS
A BLOCKING RIDGE IS FIRMLY IN PLACE OVER THE NORTHWEST TERRITORIES.
THERE IS A FRONT CENTERED NEARLY OVER ANCHORAGE THAT IS WEAKENING AS
IT TRANSITIONS THROUGH THE JET STREAM SPLIT.

MODELS STILL IN SOME DISAGREEMENT ON WHERE TO SEND THE ALEUTIAN LOW
OVER THE NEXT 48 HOURS. THE NAM IS THE FASTEST AND FURTHEST SOUTH...
WITH OTHER MODEL SOLUTIONS PROGRESSIVELY SLOWER AND FURTHER NORTH.
THE GFS ENSEMBLE MEAN AND THE MAJORITY OF THE MODEL SOLUTIONS AND
ENSEMBLE MEMBERS ARGUE FOR A TRACK THAT WILL TAKE THE NOW NEARLY
VERTICALLY STACKED LOW ALMOST DIRECTLY TO KODIAK ISLAND THURSDAY
AFTERNOON/EVENING. THIS ALSO IS CONSISTENT WITH PREVIOUS FORECAST
PACKAGES AND WILL BE CONTINUED FOR THE AFTERNOON MARINE AND PUBLIC
FORECASTS.

INTO THE WEEKEND THE LOW WILL SLOWLY DRIFT EAST INTO THE NORTHERN
GULF OF ALASKA WHILE A RIDGE BUILDS OVER THE BERING SEA. THE STORM
TRACKS WILL BE WELL DIVIDED BY THIS TIME WITH THE POLAR JET
RECEDING TO 65N AND THE SUB-TROPICAL JET SLIDING SOUTH TO 45N. THE
BLOCKING RIDGE OVER NORTHERN CANADA WILL STUBBORNLY REMAIN THROUGH
THE WEEKEND FORCING THE GULF LOW SOUTHEASTWARD WHERE IT WILL
INTERACT WITH THE SUB-TROPICAL JET BY EARLY NEXT WEEK AND DEVELOP
INTO A MAJOR STEERING LOW JUST OFF THE WESTERN CANADIAN COAST. THIS
WILL ALLOW THE BERING RIDGE TO PUSH WESTWARD INTO SOUTHWEST AND
SOUTH CENTRAL ALASKA BY EARLY NEXT WEEK...BUT WITH THE QUESTIONABLE
STRENGTH OF THIS RIDGE AND AUGUST CLIMATOLOGY THERE IS STILL A RISK
OF PRECIPITATION IN SOME AREAS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM WARNING MARINE ZONE 120.
         GALE WARNINGS MARINE ZONES 130 138 140.
FIRE WEATHER...NONE.

LUDWIG AUG 06