Small Craft Advisory 671, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
520 AM ADT SAT AUG 18 2007

.MODEL DISCUSSION...
GFS REMAINS THE MODEL OF CHOICE WITH ITS HANDLING OF THE BERING LOWS
AND ITS AGREEMENT WITH ENSEMBLES. USED THE NEW RUN AS GUIDANCE
THROUGH ABOUT 60 HOURS...THEN TRENDED TOWARD THE PREVIOUS RUN AS ITS
PERSISTENCE IS POOR ON THE LOW NEARING THE ALASKA PENINSULA SUNDAY.

.ANALYSIS AND UPPER LEVELS...
UPPER LOW NEAR THE KAMCHATKA PENINSULA IS MOVING SOUTH TOWARD THE
WESTERN ALEUTIANS. UPPER LOW OVER THE CENTRAL ALEUTIANS IS MOVING
EAST AND ABSORBING THE UPPER LOW CURRENTLY OVER WESTERN BRISTOL BAY
ZONE. RIDGE OVER THE CENTRAL GULF STRETCHES NORTH OVER THE ALCAN
BORDER AND THEN NORTHEAST TO THE BEAUFORT SEA.
AT THE SURFACE...A LOW OVER THE CENTRAL BERING IS EXTENDING ITS
OCCLUDED FRONT EAST ACROSS THE AKPEN. A RIDGE IS HOLDING STEADY ALONG
THE NORTHEASTERN GULF COAST. A WEAK THERMAL TROUGH SITS OVER THE
INTERIOR. THIS TROUGH AND THE UPPER LOW OVER BRISTOL BAY HAS HELPED
SUSTAIN THE THUNDERSTORMS IN THE KUSKOKWIM VALLEY AND NORTH THROUGH
THE NIGHT.

.SHORT TERM FORECAST...
SOUTHCENTRAL...THE FRONT WILL MOVE OVER KODIAK THIS MORNING THEN
REACH THE KENAI PENINSULA THIS AFTERNOON AND CONTINUE NORTHEAST
STRETCHING ALONG THE NORTHERN GULF COAST THROUGH TUESDAY. WINDS WILL
REACH GALE FORCE OVER THE SOUTHERN GULF AND NEAR THE BARREN ISLANDS
TODAY AND TONIGHT AS THE FRONT PUSHES AGAINST THE RIDGE OVER THE
EASTERN GULF. MOIST SOUTHERLY FLOW THROUGH THE FIRST PART OF NEXT
WEEK WILL KEEP THE NORTHERN GULF COASTAL AREAS IN A MOSTLY CLOUDY AND
WET REGIME THROUGH THE WEEKEND...WITH THE CONDITIONS SPREADING
INLAND TOWARDS THE COPPER RIVER BASIN IN THE FIRST PART OF NEXT WEEK.
COASTAL ZONES WILL SEE MORE STEADY RAIN WHEREAS INLAND ZONES WILL SEE
MORE OF A SHOWERY PATTERN.

WESTERN MAINLAND...THUNDERSTORMS WILL PUSH NORTH OUT OF THE KUSKOKWIM
VALLEY AS A VORTICITY MAX FROM THE UPPER LOW OVER BRISTOL BAY SWINGS
NORTH. AS THE FRONT PUSHES NORTH ALONG THE AKPEN...EXPECT GUSTY GAP
WINDS TO BE FUNNELED THROUGH THE ALEUTIAN RANGE OVER BRISTOL BAY.
MOST OF THE FRONTAL ACTIVITY WILL BE CONFINED TO BRISTOL BAY AND
SOUTHERN PARTS OF THE KUSKOKWIM DELTA AND VALLEY AS THE UPPER RIDGE
HOLDS TO THE NORTH. THE UPPER AND SURFACE LOWS LOOK TO REMAIN OVER
THE EASTERN BERING AND BRISTOL BAY AREA...THEREFORE EXPECT GENERALLY
CLOUDY AND SHOWERY WEATHER THROUGH THE FIRST PART OF NEXT WEEK.

BERING/ALEUTIANS...THE UPPER LOW NEAR THE KAMCHATKA PENINSULA WILL
HEAD SOUTH TOWARD THE WESTERN ALEUTIANS AND MOVE TOWARD THE BRISTOL
BAY LOW AND MERGE EARLY NEXT WEEK. THIS WILL KEEP THE BERING AND
ALEUTIANS IN A RAINY AND CLOUDY REGIME FOR SEVERAL DAYS. GALE FORCE
WINDS WILL BE AHEAD OF AND DESCENDING AROUND THE BACK SIDE OF THE
CURRENT CENTRAL BERING LOW TO AFFECT BRISTOL BAY AND THE CENTRAL
ALEUTIANS TODAY.

.LONG TERM FORECAST...
A GENERALLY CLOUDY AND SHOWERY PATTERN IS PROGGED FOR THE UPCOMING
WEEK AS THE BROAD UPPER LOW OVER THE EASTERN BERING LOOKS TO HOLD
THROUGH WEDNESDAY NIGHT THEN MOVE INTO THE SOUTHERN GULF.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 130 160 172 180
FIRE WEATHER...NONE

LR AUG 07