Small Craft Advisory 510, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 PM AKDT SAT JUL 23 2011

.ANALYSIS AND UPPER LEVELS...
AN UPPER LOW OVER THE SOUTHEAST BERING SEA CONTINUES TO MOVE EAST
TOWARD SOUTHWEST ALASKA. THE UPPER RIDGE OVER THE WESTERN GULF IS
BEING PUSHED SOUTHEAST BY THE UPPER LOW. A SURFACE LOW SITS NEAR
NUNIVAK ISLAND WITH A WEATHER FRONT OVER THE NORTHERN BERING SEA,
SEWARD PENINSULA, THE MIDDLE YUKON VALLEY, THE SUSITNA VALLEY AND
COOK INLET. AREAS OF RAIN HAVE SPREAD INTO BRISTOL BAY, KODIAK
ISLAND, THE KENAI PENINSULA AND SUSITNA VALLEY. CLOUDS AND SHOWERS
REMAIN OVER REMAIN OVER THE REST OF SOUTHWEST ALASKA AND THE BERING
SEA.

.MODEL DISCUSSION...
THE MODELS ARE IN GOOD AGREEMENT THROUGH SUNDAY AFTERNOON BY BEGIN TO
HAVE DIVERGENT SOLUTION ESPECIALLY AT THE UPPER LEVELS BEYOND THAT
POINT. ALL THE MODELS MOVE THE 500 MB LOW INTO THE SOUTHWEST MAINLAND
TONIGHT, BUT THEN THE EC AND NAM MOVES IT EAST OVER THE KENAI
PENINSULA WHILE THE GFS KEEPS IT NEARLY STATIONARY OVER THE SOUTHWEST
INTERIOR MONDAY AFTERNOON. THE GFS APPEARS TO BE OUT OF SYNC WITH THE
OTHER MODELS AND LESS WEIGHT GIVEN TO ITS SOLUTION.

.SHORT TERM FORECAST...
.UPPER LEVELS...THE UPPER LOW OVER THE SOUTHEAST BERING SEA WILL MOVE
INTO SOUTHWEST ALASKA TONIGHT THEN MOVE OVER THE KENAI PENINSULA
MONDAY AFTERNOON AND NEAR YAKUTAT MONDAY NIGHT. OTHERWISE A BROAD
AREA OF LOW PRESSURE WILL COVER MOST OF MAINLAND ALASKA SUNDAY AND
MONDAY.

THE WEAKENING SURFACE LOW NEAR NUNIVAK ISLAND WILL MOVE NORTH INTO
THE SEWARD PENINSULA WHERE IT WILL MERGE WITH THE THERMAL TROUGH OVER
THE NORTHERN INTERIOR SUNDAY. THE WEATHER FRONT OVER THE SUSITNA
VALLEY AND COOK INLET WILL MOVE EAST AND WEAKEN OVER THE COPPER RIVER
BASIN AND PRINCE WILLIAM SOUND TONIGHT AND EARLY SUNDAY MORNING.

.SOUTHCENTRAL ALASKA...AREAS OF RAIN MAINLY WEST OF THE TALKEETNA
MOUNTAINS WILL SPREAD INTO THE COPPER RIVER BASIN AND PRINCE WILLIAM
SOUND TONIGHT. THE RAIN WILL CHANGE TO SHOWERS SUNDAY AND MONDAY.
LOCALLY GUSTY WINDS ALONG CHANNELED TERRAIN WILL DIMINISH TONIGHT.

.SOUTHWEST ALASKA...A PERSISTENT WEST TO SOUTHWEST FLOW WILL CONTINUE
TO FEED MOISTURE INTO THE AREA. AREAS OF RAIN WILL CONTINUE THROUGH
TONIGHT ESPECIALLY ALONG WESTERN SIDE OF TERRAIN THEN WILL BECOME
SHOWERS SUNDAY.

.BERING SEA AND THE ALEUTIANS...CLOUDS AND SHOWERS WILL REMAIN OVER
THIS REGION THROUGH MONDAY. GALE FORCE WINDS ALONG THE EASTERN
ALEUTIANS AND THE ALASKA PENINSULA WILL DIMINISH TONIGHT.

.LONG TERM FORECAST...
THE BROAD AREA OF LOW PRESSURE WILL REMAIN OVER MAINLAND ALASKA
THROUGH THE MIDDLE OF NEXT WEEK, SO WE CAN EXPECT THE CLOUDS AND
SHOWERS TO REMAIN OVER SOUTHERN ALASKA UNTIL THEN.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...155 170
FIRE WEATHER...RED FLAG WARNING FOR THE COPPER RIVER BASIN THIS
AFTERNOON THROUGH THIS EVENING.

NM JUL 11