Small Craft Advisory 1048, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
505 AM AST THU DEC 13 2007

.MODEL DISCUSSION...
MODELS ARE IN BETTER AGREEMENT THAN THEY HAVE BEEN IN THE LAST FEW
DAYS. THE ONLY DISCREPANCY IS WITH THE SPEED OF A LOW TRACKING SOUTH
OF THE ALEUTIAN CHAIN AND THEN SOUTH OF THE GULF FRIDAY. ITS NOT A
CONCERN NOW SINCE IT IS OUT OF THE FORECAST AREA...HOWEVER IT COULD
COME INTO PLAY LATER IN THE WEEKEND OVER THE EASTERN GULF AS IT
MERGES WITH A LOW NEAR SOUTHEAST ALASKA.

.ANALYSIS AND UPPER LEVELS...
THE DENSE FOG AROUND SOUTHCENTRAL IS DISSIPATING AS NORTHERLY FLOW
PULLS IN DRIER AIR. THEREFORE HAVE CANCELED THREE OF THE FOUR DENSE
FOG ADVISORIES THAT WERE TO CONTINUE UNTIL NOON TODAY. HOWEVER PATCHY
FOG WILL STILL BE PRESENT UNDER THE STABLE CONDITIONS CAUSED BY THE
RIDGE OVER THE NORTHERN ALASKA RANGE. THE COMBINATION OF AN UPPER
LEVEL TROUGH AND A WEAK SURFACE LOW SOUTHWEST OF KODIAK IS PRODUCING
SCATTERED SHOWERS MAINLY OVER KODIAK AND BRISTOL BAY. A RIDGE OVER
THE CENTRAL ALEUTIANS AND BERING IS BEING PUSHED TO THE EAST BY THE
STRONG LOW SOUTHWEST OF THE CHAIN.

A WEAK UPPER LEVEL RIDGE OVER THE EASTERN MAINLAND WILL BE REPLACED
BY A WEAK TROUGH BY FRIDAY. THIS TROUGH WILL BE DEEPENED THROUGH THE
WEEKEND AS ANOTHER TROUGH OVER THE BERING WILL SLIDE EAST AND MERGE
WITH IT. AS A RIDGE OVER THE BERING NUDGES EAST AGAINST THIS DEEPENED
TROUGH...COLD AIR FROM THE ARCTIC WILL SLIDE DOWN OVER SOUTHCENTRAL.

.SHORT TERM FORECAST...
SOUTHCENTRAL...AS STATED ABOVE FOG CONDITIONS WILL CONTINUE
DIMINISHING AS DRIER AIR SETTLES IN. COPPER RIVER BASIN WILL REMAIN
IN THE ADVISORY AS MOIST AIR CONTINUES TO POOL IN THE VALLEYS. A
STRONG PACIFIC LOW WILL MOVE NORTH INTO THE EASTERN GULF FRIDAY AS
THE RIDGE OVER THE INTERIOR AND SOUTHWEST ALASKA HOLDS...THIS WILL
HELP ENHANCE THE COLDER AIR FROM THE NORTH POUR OVER THE ALASKA RANGE
AS THE UPPER LEVELS SET UP AS STATED ABOVE. TEMPERATURES LOOK TO DIP
BELOW CLIMATOLOGICAL VALUES.
SOUTHWEST ALASKA...BRISTOL BAY WILL CONTINUE TO SEE SHOWERS TODAY AS
AN UPPER LEVEL TROUGH INTERACTS WITH A WEAK LOW JUST SOUTHWEST OF
KODIAK. OTHERWISE AS THE BERING AND INTERIOR RIDGE CLOSES IN...LOOK
FOR CALM CONDITIONS WITH AREAS OF LOW STRATUS AND PATCHY FOG. COLD
TEMPERATURES WILL ALSO BE DROPPING OVER SOUTHWEST ALASKA THROUGH THE
WEEKEND TO BELOW CLIMATOLOGICAL VALUES AS WELL.
ALEUTIANS/BERING...THE LOW TO THE SOUTHWEST OF THE CHAIN WILL BE
BRINGING GALE FORCE WIND AND A MIX OF RAIN AND SNOW TO THE CENTRAL
AND EASTERN ALEUTIANS THROUGH FRIDAY NIGHT BEFORE IT HEADS SOUTHEAST
AWAY FROM THE CHAIN INTO THE NORTH PACIFIC. THE RIDGE WILL QUICKLY
BUILD IN BEHIND THE LOW BEFORE A STRONG FRONT NEARS THE WESTERN
ALEUTIANS LATE FRIDAY NIGHT TO ADVANCE ALONG THE CHAIN AND BERING
THROUGH SUNDAY.

.LONG TERM FORECAST...
THE MODELS ARE HAVING MORE DIFFICULTY IN THE LONG RANGE. AS IT LOOKS
NOW...THE UPPER LEVEL TROUGH OVER THE EASTERN MAINLAND BRINGING THE
COLD TEMPERATURES SOUTH WILL PULL NORTH AND SPREAD WEST EARLY NEXT
WEEK. THIS WILL MOVE THE COLDER TEMPERATURES OVER THE BERING AND
ALLOW NORTH PACIFIC SYSTEMS TO HEAD FURTHER NORTH INTO THE GULF BY
MID NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 150 155 170 172 175
FIRE WEATHER...NONE

LR DEC 07