Small Craft Advisory 75, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
300 PM AST THU JAN 18 2007

.DISCUSSION...THERE ARE TWO LOW PRESSURE SYSTEMS IMPACTING SOUTHERN
ALASKA TODAY. THE FIRST ON IS A COMPLEX LOW NORTH OF DUTCH HARBOR.
THIS COMPLEX IS SLOWLY WEAKENING AS IT DRIFTS TOWARD NUNIVAK ISLAND
ON SATURDAY. THIS SYSTEM STILL HAS A FEW SHOWERS ASSOCIATED WITH IT
BUT WILL BE DISPLACED BY A RIDGE OF HIGH PRESSURE BUILDING INTO THE
WESTERN BERING SEA. ASSOCIATED WITH THIS CHANGE WILL BE COLDER AIR
MOVING INTO THE BERING SEA AND ALEUTIAN ISLANDS BY THIS WEEKEND.

THE SECOND SYSTEM IS IN THE NORTHERN GULF OF ALASKA AND BEGAN AS A
TRIPLE POINT ON THE LOW COMPLEX IN THE BERING SEA. THIS LOW HAS MORE
UPPER LEVEL SUPPORT ASSOCIATED WITH IT. HOWEVER IT WILL BE SHORT
LIVED AS THE JET STREAM REMAINS WELL SOUTH OF THE GULF OF ALASKA AND
THE LOW IN THE NORTHERN GULF WILL MOVE INTO PRINCE WILLIAM SOUND
TONIGHT AND THEN INLAND FRIDAY MORNING. THIS LOW IS AN INTERESTING
ONE TO WATCH AS IT HAS ELONGATED IN THE NORTHERN GULF. THIS SEEMINGLY
HAS DILUTED THE AMOUNT OF WARM AIR THAT HAS BEEN ABLE TO PENETRATE
INTO SOUTHERN ALASKA PAST SOUTHEASTERN PRINCE WILLIAM SOUND. WHILE
SOME RAIN DID FALL IN EASTERN TURNAGAIN ARM AND WHITTIER EARLIER
TODAY THESE AREAS HAVE ALL TURNED TO SNOW AS THE WARMER AIR WAS
DIVERTED FURTHER EAST. A WEDGE OF WARMER AIR ALOFT REMAINS OVER
PRINCE WILLIAM SOUND TO ANCHORAGE AND IS KEEPING A CHANCE OF FREEZING
RAIN IN THE ANCHORAGE AREA. ANCHORAGE IS THE MOST LIKELY SPOT TO SEE
FREEZING RAIN THROUGH THIS AFTERNOON. AFTER THAT TEMPERATURES ACROSS
THE AREA SHOULD SLOWLY DROP SO THAT THERE IS NO LONGER ANY ABOVE
FREEZING AIR REMAINING IN THE AIR COLUMN EXCEPT FOR AREAS AROUND
SOUTHERN AND EASTERN PRINCE WILLIAM SOUND.

AREAS TO THE IMMEDIATE WEST OF THE KENAI CHUGACH AND TALKEETNA
MOUNTAINS ARE DOWNSLOPEING THIS AFTERNOON. THE DOWNSLOPE EFFECT WILL
REMAIN MOSTLY IN TACT INTO THE EVENING AND STILL HAVE AN EFFECT ON
THE PRECIPITATION OVERNIGHT IN THESE AREAS.

MODELS ARE IN RELATIVELY GOOD AGREEMENT TODAY. THE ONLY DIFFERENCE OF
NOTE IS THE HANDLING OF THE NORTH GULF LOW. THE NAM IS THE ONLY MODEL
THAT HAS DETECTED AND FORECAST THE ELONGATION OF THE LOW WHICH IS
OBVIOUS ON SATELLITE.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 120. HEAVY FREEZING SPRAY 185.
FIRE WEATHER...NONE.

JAN 07