Small Craft Advisory 707, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM ADT SAT SEP 1 2007

.MODEL DISCUSSION...
THE MODELS ARE IN GOOD AGREEMENT AND THE LATEST 12Z RUN OF THE GFS IS
CONSISTENT WITH THE 00Z RUN. SO CONFIDENCE IS HIGHER THAN IT HAS BEEN
IN THE LAST COUPLE OF DAYS.

.ANALYSIS AND UPPER LEVELS...
THE UPPER AIR PATTERN HAS BEEN FAIRLY FLAT OVER MAINLAND ALASKA WITH
ONLY A WEAK AREA OF HIGH PRESSURE OVER SOUTHERN ALASKA AND A WEAK
TROUGH OVER NORTHERN ALASKA. THE HIGH PRESSURE IS EXPECTED TO BUILD A
LITTLE THIS AFTERNOON AND EVENING AS LOW AMPLITUDE RIDGE MOVES ACROSS
THE ALASKA PENINSULA.

LIKE THE UPPER AIR, THE SURFACE PATTERN IS FAIRLY FLAT TODAY.  WEAK
ONSHORE FLOW OFF THE GULF OF ALASKA BROUGHT MORE MOISTURE INTO SOUTH
CENTRAL ALASKA OVERNIGHT. THIS COUPLED WITH A WEAK MID LEVEL
DISTURBANCE PRODUCED THE CLOUDS AND RAIN OVER ANCHORAGE, THE
MATANUSKA VALLEY AND PRINCE WILLIAM SOUND.

SOUTHWEST ALASKA STILL REMAIN FAIRLY UNSTABLE AS THE CONVECTIVE
SHOWERS PERSISTED THROUGH FRIDAY NIGHT AND WILL RE-INTENSIFY TODAY.
ISOLATED THUNDERSTORMS WILL REFORM OVER THE KUSKOKWIM VALLEY AND THE
BRISTOL BAY THIS AFTERNOON AND EVENING.

.SHORT TERM FORECAST...
THE UPPER AIR RIDGE WILL SLOWLY BUILD OVER THE GULF OF ALASKA AND
EASTERN ALASKA THROUGH MONDAY AFTERNOON THEN WILL MOVE INTO WESTERN
CANADA TUESDAY. AN UPPER LOW OVER THE WESTERN BERING SEA WILL RAPIDLY
STRENGTHEN AS IT MOVE EAST ACROSS THE SOUTHERN BERING SEA AND INTO
THE ALASKA PENINSULA MONDAY THEN WILL SLOWLY WEAKEN AS IT MOVES INTO
THE GULF OF ALASKA TUESDAY.

SOUTHCENTRAL ALASKA...
THE SURFACE PATTERN WILL MIRROR THE UPPER AIR PATTERN. A WEAK RIDGE
WILL BUILD INTO THE GULF AND SOUTHCENTRAL ALASKA TONIGHT THROUGH
MONDAY BEFORE IT IS PUSHED EAST BY A STRONG LOW PRESSURE SYSTEM
COMING OUT OF THE WEST. CLOUDS ARE EXPECTED TO BREAK UP TONIGHT BUT
AREAS OF FOG WILL DEVELOP ALONG THE COOK INLET. MORE CLOUDS WILL MOVE
BACK INTO THE KENAI PENINSULA AND SUSITNA VALLEY SUNDAY NIGHT AND
MONDAY AS A STRONG SOUTHERLY FLOW DEVELOPS AHEAD OF THE ONCOMING LOW.
RAIN IS EXPECTED OT MOVE INTO KODIAK ISLAND MONDAY AND INTO THE KENAI
PENINSULA AND COOK INLET MONDAY NIGHT.

SOUTHWEST ALASKA...
CONDITIONS WILL BECOME MORE STABLE OVER THE SOUTHWEST INTERIOR SUNDAY
AS COOLER 850 TEMPS MOVE INTO THE AREA. THERE WILL STILL BE SCATTERED
SHOWERS OVER THE KUSKOKWIM VALLEY AND BRISTOL BAY, BUT THE CHANCE OF
THUNDERSTORMS WILL BE LESS. THE STORM DEVELOPING ALONG THE ALEUTIANS
WILL MOVE UP ALONG THE ALASKA PENINSULA MONDAY. GUSTY WINDS AND RAIN
WILL MOVE INTO BRISTOL BAY MONDAY NIGHT AND WILL SPREAD INLAND
TUESDAY.

BERING SEA AND ALEUTIANS...
THE DEVELOPING LOW SOUTH OF THE WESTERN ALEUTIANS WILL TRACK JUST
SOUTH OF THE CHAIN THROUGH SUNDAY AND WILL MOVE ONTO UNIMAK ISLAND
SUNDAY NIGHT. RAIN AND STRONG WINDS WILL MOVE ALONG THE ALEUTIANS
TONIGHT THROUGH SUNDAY NIGHT. CLOUDY SKIES AND SHOWERS WILL PERSIST
OVER THE BERING SEA.

.LONG TERM FORECAST...
THE SURFACE LOW OVER THE GULF TUESDAY WILL MOVE EAST AND DISSIPATE
NEAR YAKUTAT WEDNESDAY. A BROAD AREA OF LOW PRESSURE WILL PERSIST
OVER THE CENTRAL MAINLAND THROUGH THURSDAY NIGHT. A NEW STORM OVER
THE SEA OF OHKOTSK WILL MOVE INTO THE CENTRAL BERING SEA THURSDAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 170, 171 AND 172.
FIRE WEATHER...NONE.

NM SEP 07