Small Craft Advisory 978, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM AST TUE NOV 20 2007

.MODEL DISCUSSION...
THE MODEL ARE IN GENERALLY GOOD AGREEMENT THROUGH WEDNESDAY AFTERNOON
BUT START TO HAVE DIVERGENT SOLUTION BEYOND THAT POINT. THE PROBLEM
LIES WITH THE NEXT LOW THAT WILL DEVELOP OVER THE CENTRAL NORTH
PACIFIC WEDNESDAY AFTERNOON AND MOVE NEAR KODIAK ISLAND THURSDAY. THE
GFS AND UKMET MOVES IT INTO BRISTOL BAY THURSDAY AFTERNOON WHILE THE
NAM AND ECMWF HAD NEAR OR JUST SOUTH OF KODIAK ISLAND AT THE SAME
TIME. THE CONSENSUS IN THE OFFICE IS TO LEAN CLOSER TO THE ECMWF
SOLUTION.

.ANALYSIS AND UPPER LEVELS...
AN UPPER RIDGE OVER WESTERN CANADA AND A COMPLEX UPPER LOW OVER THE
BERING SEA IS STEERING THE 300 MB JET STREAM NORTH THROUGH THE GULF
OF ALASKA AND WESTERN MAINLAND. THIS PATTERN HAD BEEN GUIDING THE
PATH OF THE STORM SYSTEM SINCE MONDAY.

AT THE SURFACE...A LARGE INTENSE LOW SOUTH OF KODIAK ISLAND IS MOVING
NORTH TOWARD KODIAK ISLAND. THE ASSOCIATED FRONT ACROSS THE THE
SOUTHERN GULF AND KODIAK ISLAND IS CONTINUING TO MOVE NORTH.

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA AND THE GULF OF ALASKA...
THE LOW SOUTH OF KODIAK ISLAND WILL MOVE THROUGH KODIAK ISLAND THIS
EVENING THEN TURN NORTHWEST INTO NORTHERN BRISTOL BAY LATE TONIGHT.
THE WEATHER FRONT IS EXPECTED TO MOVE ONSHORE ALONG THE CENTRAL GULF
COAST LATE TONIGHT AND DISSIPATE OVER THE CENTRAL INTERIOR WEDNESDAY.
STRONG EAST TO SOUTHEAST WINDS WILL GRADUALLY INCREASE ALONG THE GULF
COAST AND THROUGH CHANNELED TERRAIN IN THE CHUGACH MOUNTAINS UNTIL
FRONTAL PASSAGE. RAIN ALONG THE COAST AND THE LOWER KENAI PENINSULA
WILL CHANGE TO SHOWERS BEHIND THE FRONT. AREAS OF SNOW MAINLY OVER
THE WESTERN SUSITNA VALLEY WILL DIMINISH TONIGHT.

A SECOND STORM SYSTEM DEVELOPING OVER THE CENTRAL NORTH PACIFIC
WEDNESDAY WILL MOSTLY LIKELY MOVE THROUGH KODIAK ISLAND LATE THURSDAY
AND INTO SOUTHWEST ALASKA FRIDAY. MORE RAIN WILL MOVE INTO THE GULF
COAST AND SNOW INTO THE SUSITNA VALLEY. LOCALLY GUSTY WINDS WILL
DEVELOP AGAIN ALONG THE GULF COAST AND THROUGH CHANNELED TERRAIN IN
THE CHUGACH MOUNTAINS AHEAD OF THE FRONT.

SOUTHWEST ALASKA...
LOW PRESSURE SYSTEM IN THE WESTERN GULF WILL MOVE INTO NORTHERN
BRISTOL BAY TONIGHT AND WILL DISSIPATE OVER SOUTHWEST ALASKA
WEDNESDAY. THE SECOND LOW FORMING SOUTH OF KODIAK WEDNESDAY WILL TAKE
A SIMILAR TRACK INTO SOUTHWEST ALASKA FRIDAY. THE RAIN-SNOW LINE WILL
LIE OVER THE EASTERN KUSKOKWIM VALLEY AND EASTERN BRISTOL BAY. RAIN
WILL CONTINUE TO FALL ALONG THE BASE OF THE ALASKA RANGE, WHILE THE
REST OF THE AREA WILL REMAIN SNOW.

BERING SEA AND ALEUTIANS...
A RIDGE OF HIGH PRESSURE LOVE THE WESTERN BERING SEA WILL MOVE INTO
THE EASTERN BERING SEA THURSDAY. LOW PRESSURE WILL PERSIST OVER THE
WESTERN MAINLAND. NORTHERLY FLOW OVER THE EASTERN BERING WILL
DIMINISH THURSDAY.

A NEW STORM SYSTEM WILL MOVE INTO THE WESTERN ALEUTIANS FRIDAY. GALE
TO POSSIBLE STORM FORCE WINDS WILL MOVE INTO THE WESTERN ALEUTIANS
THURSDAY NIGHT.

.LONG TERM FORECAST...
THE UPPER LONG WAVE PATTERN BEGINS TO PROGRESS TO THE EAST AGAIN AS
THE BLOCK RIDGE OVER WESTERN CANADA BREAKS DOWN. AN UPPER RIDGE WILL
MOVE INTO THE ALASKA MAINLAND OVER THE WEEKEND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING 101 AND 125.
MARINE...STORM 120, 125, 130, 140,
         GALE 121, 129, 132, 138, 141
FIRE WEATHER...NONE

NM NOV 07