Small Craft Advisory 772, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
400 PM AKDT MON OCT 6 2008

.MODEL DISCUSSION...MODELS STILL DOING FINE IN THE SHORT TERM WITH
CONTINUING PROBLEMS WITH THE COMPLEX LOW MOVING INTO THE ALEUTIANS.
EVEN THERE THE MODELS ARE BEGINNING TO CONVERGE WITH A SOLUTION NOT
TOO FAR OFF FROM WHAT THE GFS HAS BEEN SHOWING.

.ANALYSIS AND UPPER LEVELS...LARGEST FEATURE OVER THE STATE IS THE
LARGE AND COLD UPPER LEVEL LOW CENTERED SOMEWHERE NEAR ILIAMNA. THIS
LOW WILL BEGIN TO CUT OFF OVER THE SOUTHERN KENAI PENINSULA TONIGHT
AND MOVE OVER THE NORTH GULF COAST TOMORROW AND TOMORROW NIGHT. THIS
WILL ALSO VERTICALLY STACK THE SURFACE LOW THAT WILL MOVE NEAR
MONTAGUE ISLAND TONIGHT. BOTH THE SURFACE AND UPPER LEVEL LOW WILL
KICK OUT INTO SOUTHEAST ALASKA WEDNESDAY.
AN UPPER LEVEL RIDGE OVER THE CENTRAL BERING SEA WILL MOVE OVER
SOUTHERN ALASKA WEDNESDAY NIGHT AND THURSDAY AS THE NEXT LARGE LOW
PUSHES IT EASTWARD.

.SHORT TERM FORECAST...THE BIG WEATHER QUESTION FOR TONIGHT AND
TOMORROW IS SNOW AND HOW MUCH IN SOUTH CENTRAL ALASKA INCLUDING THE
ANCHORAGE AREA. THERE IS A SURFACE LOW MOVING INTO THE PRINCE WILLIAM
SOUND AREA OVERNIGHT. HOWEVER THE UPPER LEVEL SET UP IS NOT CONDUCIVE
FOR A LARGE OVER RUNNING SNOW EVENT. THE 500 MB TROUGH IS WEAKLY
CUTTING OFF OVER THE SOUTHERN KENAI PENINSULA AND THE 850 MB THERMAL
STRUCTURE IS NOT PRODUCING A SURFACE THAT WILL ENHANCE SNOW
DEVELOPMENT. WHAT IS LOOKING FAVORABLE IS THE DEVELOPMENT OF SNOW
SHOWERS IN THE STRONG DYNAMICS OVER THE REGION. THESE SHOWERS WILL
HAVE THE POTENTIAL TO DROP A FEW INCHES OF SNOW OVER THE AREA FROM
TONIGHT THROUGH TOMORROW NIGHT. EXACTLY HOW MUCH IS DIFFICULT TO
DETERMINE SINCE THE CONVECTIVE NATURE OF SNOW SHOWERS CAN CAUSE A
LARGE RANGE OF PRECIPITATION AMOUNTS OVER A SMALL AREA.

SOME SNOW SHOWERS WILL PERSIST IN NORTHWEST FLOW OVER THE ALASKA
PENINSULA AND SOUTHWEST ALASKA THROUGH TUESDAY.

.LONG TERM FORECAST...THE LOW MOVING INTO THE ALEUTIANS WEDNESDAY
WILL BRING STRONG WINDS AND WARM AIR INTO THE AREA. THIS LOW WILL
WEAKEN AS IT HEADS INTO THE GULF OF ALASKA BUT STRONG WARM AIR
ADVECTION ASSOCIATED WITH THE FRONT WILL BRING RAIN TO SOUTH CENTRAL
ALASKA AND STRONG WINDS OVER THE GULF OF ALASKA AND TURNAGAIN ARM.
RAIN IS LIKELY IN SOUTHWEST ALASKA AND THE KUSKOKWIM VALLEY AS WELL
WITH THIS SYSTEM. AT THIS TIME IT LOOKS LIKE THE COLD AIR IN ALL
AREAS WILL BE DISPLACED BEFORE PRECIPITATION OCCURS SO RAIN IS MORE
LIKELY THAN SNOW FROM THE ONSET OF THE EVENT.

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

OCT 08