Brisk Wind Advisory 42, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
400 PM ADT FRI APR 4 2008

.MODEL DISCUSSION...OVERALL PATTERN OF THE MODELS HAS BEEN CONSISTENT
THE LAST NUMBER OF RUNS. THERE IS SOME DIFFERENCES IN THE DETAILS IN
THE EASTERN PART OF THE AREA THAT WILL MAKE A DIFFERENCE IN THE
FORECAST HOWEVER. THE DIFFERENCE OCCURS IN COMPARING THE 00Z MODEL
RUN OF THE GFS TO THE PREVIOUS ONES AND THIS MORNINGS 12Z GFS RUN.
THE 00Z TRIED TO SPLIT THE ENERGY OF THE TRIPLE POINT LOW DEVELOPING
SOUTHEAST OF KODIAK AND SEND SOME OF IT SOUTHEAST AND THE OTHER PART
INTO THE YUKON TERRITORIES BY WAY OF PRINCE WILLIAM SOUND. THE OTHER
RUNS INCLUDING THE MORE CURRENT 12Z RUN ELONGATES THE LOW BEFORE IT
SPLITS IT AND THEN HAS THE NORTHERN LOW STAY JUST SOUTH OF PRINCE
WILLIAM SOUND THROUGH SUNDAY AFTERNOON WHEN IT THEN PULLS
SOUTHEASTWARD. THIS DIFFERENCE WILL HAVE A LARGE IMPACT ON THE MARINE
FORECASTS AROUND THE GULF AS WELL AS SNOWFALL AMOUNTS OVER SOUTH
CENTRAL ALASKA. THE NAM MODEL IS DOING THE SAME THING AS THE GFS BUT
BRINGS THE LOW TO THE SOUTHEASTERN KENAI PENINSULA.

.ANALYSIS AND UPPER LEVELS...AN UPPER LEVEL LOW NEAR THE BERING
STRAIT IS ANCHORING A SURFACE LOW AND COLD FRONT THAT IS MOVING
THROUGH BRISTOL BAY AND THE KUSKOKWIM VALLEY THIS AFTERNOON. AS
DISCUSSED EARLIER A TRIPLE POINT LOW IS DEVELOPING SOUTHEAST OF
KODIAK ISLAND AND WILL MOVE TO THE NORTH GULF COAST BY SATURDAY
MORNING.

.SHORT TERM FORECAST...PRECIPITATION IN SOUTHWEST ALASKA WILL BE ALL
SNOW FOR THE REMAINDER OF THIS SYSTEM WITH THE EXCEPTION OF EASTERN
BRISTOL BAY UNTIL THE COLD FRONT MOVES THROUGH THIS EVENING. THIS
FRONT WILL MOVE INTO SOUTH CENTRAL ALASKA LATE TONIGHT AFTER A SLIGHT
DELAY ALONG THE ALASKA AND ALEUTIAN RANGES. THIS WILL BRING COLDER
AND WINDY CONDITIONS TO KODIAK. SOUTHWEST ALASKA WILL BE IN DRIER AIR
BUT SNOW SHOWERS MAY PERSIST INTO TOMORROW. THIS WILL ALSO BE THE
CASE FOR THE ALASKA PENINSULA AND ALEUTIAN ISLANDS.
ANCHORAGE AND NEARBY AREAS WILL LIKELY SEE SNOW WITH THIS SYSTEM. THE
BIG QUESTION IS HOW MUCH. SNOW MAY BEGIN A LITTLE EARLIER THAN
ORIGINALLY THOUGHT WITH PRECIPITATION BEGINNING LATE TONIGHT AND
CONTINUING THROUGH AT LEAST SATURDAY NIGHT. THE 850 MB ISOTHERMS ARE
NICELY ALIGNED NORTH TO SOUTH AS ARE THE 1000-500 MB THICKNESS
VALUES. WHILE THE SURFACE LOW IS NOT IN IDEAL POSITION BEING JUST
SOUTH OF THE SOUND INSTEAD OF IN THE SOUND IT SHOULD SUFFICE TO PUSH
PLENTY OF MOISTURE OVER THE COLD ADVECTION OVER THE ANCHORAGE AREA
WHICH WILL PRODUCE SNOW.

.LONG TERM FORECAST...COLD UPPER LEVEL TROUGH WILL REMAIN OVER THE
CHUKCHI SEA INTO THE MIDDLE OF NEXT WEEK. THIS WILL KEEP THINGS ON
THE COOL SIDE THROUGH THAT TIME.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 120 130 132 140 150 155 180 185.
FIRE WEATHER...NONE.

APR 08