Small Craft Advisory 220, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
400 PM AKDT TUE MAR 10 2009

.MODEL DISCUSSION...MODELS ARE IN VERY GOOD AGREEMENT FROM THE 12Z
RUN UNTIL AROUND 72 HOURS. ONE ITEM TO WATCH IS THAT THE 18Z RUN OF
THE NAM IS BRINGING THE LOW INTO THE GULF WED NIGHT QUITE A BIT
FARTHER WEST THAN ANY OF THE 12Z RUNS. THE NEXT FEW RUNS WILL NEED TO
BE WATCHED TO SEE IF THIS IS A GLITCH OR IF THE OTHER MODELS AND RUNS
START TO MOVE IT IN THIS DIRECTION. THE MORE SIGNIFICANT IMPACT IS
THE IT WOULD BRING THE LOW INTO PRINCE WILLIAM SOUND THURSDAY. THE
CURRENT TRACKS BRING IT BETWEEN CORDOVA AND YAKUTAT SO THERE IS A BIT
OF DIFFERENCE IN WHAT WEATHER IT WOULD BRING. AT THIS TIME WE ARE
GOING WITH THE MORE EASTERLY SOLUTION.

.ANALYSIS AND UPPER LEVELS...THE CURRENT UPPER LEVEL PATTERN HAS A
TROUGH OVER THE EASTERN BERING SEA AND A RIDGE OVER THE ALCAN BORDER.

THE TROUGH WILL MOVE SLOWLY EASTWARD AND BREAK DOWN THE RIDGE BY
THURSDAY. A WEAK FRONT IS POSITIONED BETWEEN THESE FEATURES AND IS
BRINGING SOME SNOW TO AREAS AROUND THE ALASKA AND ALEUTIAN RANGE IN
THE SUSITNA VALLEY AND KUSKOKWIM VALLEY.

THE JET STREAM WILL REMAIN SOUTH OF THE EASTERN PART OF THE AREA BUT
WILL BE A FACTOR IN THE WEATHER IN THE WESTERN AREAS. THE 250 MB JET
IS CURRENTLY RIDING OVER UN UPPER RIDGE IN THE WESTERN BERING SEA BUT
WILL FLATTEN OUT WEDNESDAY AND THURSDAY WITH WESTERLY FLOW BETWEEN
140 AND 180 KT OVER THE ALEUTIANS.

.SHORT TERM FORECAST...THERE IS A MIX OF RAIN AND SNOW IN THE GULF OF
ALASKA AREA WITH RAIN IN THE KODIAK AREA AND MOSTLY SNOW IN PRINCE
WILLIAM SOUND.
THE SNOW ALONG THE ALASKA RANGE AND ALEUTIAN RANGE AS FAR WEST AS
KING SALMON LOOKS TO PERSIST WELL INTO TONIGHT OR WEDNESDAY MORNING.
SCATTERED SNOW SHOWERS WILL PERSIST OVER THE BERING SEA THROUGH THE
NIGHT INTO WEDNESDAY.

.LONG TERM FORECAST...BIG QUESTION WILL CENTER OVER THE LOW MOVING
INTO THE NORTH GULF COAST THURSDAY. THIS WILL BRING SOME SNOW INTO
THE AREA BUT HOW FAR WEST WILL BE THE BIG CONCERN.
AFTER THE LOW MOVES INTO EASTERN ALASKA AN UPPER LEVEL TROUGH WILL
DEVELOP OVER THE INTERIOR INTO SOUTH CENTRAL ALASKA. THIS WILL BRING
COLDER TEMPERATURES BACK INTO THE ALASKA MAINLAND THIS WEEKEND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE
FIRE WEATHER...NONE.

MAR 09