Small Craft Advisory 843, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
150 PM AKDT FRI OCT 31 2008

.ANALYSIS/UPPER LEVELS...AT THE UPPER LEVELS WE HAVE HIGH PRESSURE
BEING CUT-OFF OVER NORTHERN ALASKA WITH A TROUGH UNDERNEATH IT
STRETCHING FROM THE INTERIOR TO WELL SOUTH INTO THE PACIFIC. LOW
PRESSURE ALSO EXISTS IN THE BERING IN THE FORM OF A COLD FRONT
STRETCHED FROM A LOW WEST OF ST. LAWRENCE ISLAND TO THE ALASKA
PENINSULA. HIGH PRESSURE AT THE SFC HOLDS FIRM PROMOTING ANOTHER
CLEAR DAY ACROSS SOUTHCENTRAL.

.MODEL DISCUSSION...MODELS IN REASONABLY GOOD AGREEMENT THROUGH 84
HOURS. ONE MINOR DIFFERENCE BETWEEN THE GFS AND NAM CROPS UP LATER
TONIGHT AS A WEAK TRIPLE POINT LOW FORMS SOUTH OF CHIGNIK. WE ARE
GOING WITH A SOLUTION CLOSER TO THE NAM WHICH MOVES THE LOW QUICKLY
SOUTH AND EAST OF KODIAK ISLAND AS IT GETS ABSORBED INTO A LARGER LOW
IN SE ALASKA.

.SHORT TERM FORECAST...A 994 MB LOW WELL SOUTH OF YAKUTAT WILL MOVE
UP ALONG THE COAST SPREADING CLOUDS BACK INTO SOUTHCENTRAL FOR THE
WEEKEND. THE LOW WILL RAPIDLY WEAKEN AS IT MOVES NORTH ENCOUNTERING
THE HIGH PRESSURE CENTER IN THE INTERIOR. SNOW WILL BE CONFINED TO
THE EASTERN COPPER RIVER BASIN AND EASTERN PRINCE WILLIAM SOUND.
MEANWHILE...FURTHER WEST, A TRIPLE POINT LOW WILL FORM ON THE SOUTH
END OF A DECAYING FRONT NEAR CHIGNIK AND MOVE SE. RAIN WILL SKIRT
KODIAK ISLAND TONIGHT AND SUNDAY. AN TIGHTENING PRESSURE GRADIENT
ACROSS THE GULF IN RESPONSE TO A DEEPENING LOW IN SE ALASKA WILL
YIELD GUSTY NORTHWEST WINDS (I.E. GALE FORCE IN MARINE AREAS) SAT
NIGHT THROUGH SUN NIGHT.

FURTHER WEST...PLENTY OF LOW CLOUDS AND FOG HANGING AROUND SW ALASKA.
A FRONT DRAPED ALONG THE SW COAST HAS STALLED OUT AND WILL CONTINUE
TO WEAKEN. RAIN AND SNOW SHOWERS WILL CONTINUE ALONG THE ALASKA
PENINSULA WITH ONLY SCATTERED SHOWERS REACHING INLAND. NORTHWEST
WINDS AND SNOW SHOWERS WILL PERSIST IN THE BERING ON THE PERIPHERY OF
A LARGE RIDGE OVER THE SW BERING SEA.

.LONG TERM FORECAST...THE GENERAL TRANSITION OF THE UPPER LEVEL
PATTERN TO ONE WITH A CLOSED LOW OVER THE MAINLAND MEANS THAT THE
EASTERN MAINLAND WILL GET ITS FIRST REAL CHANCE FOR SNOW IN A LONG
TIME AT THE BEGINNING OF NEXT WEEK. IN THE WEST SNOW SHOULD CONTINUE
ON THE MAINLAND WITH THAT UNSTABLE UPPER LOW OVERHEAD...WHILE WEATHER
IN THE ALEUTIANS WILL BE CALMER AS A STRONG NORTH PACIFIC RIDGE
SETTLES IN.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 185.
FIRE WEATHER...NONE.

JCA/LF