Small Craft Advisory 425, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM ADT WED MAY 9 2007

.MODEL DISCUSSION...
ALL AVAILABLE NWP MODELS FAIRLY CONSISTENT WITH SURFACE LOW MOVING
SOUTHEAST ACROSS KODIAK INTO THE CENTRAL GULF OF ALASKA LATER THIS
AFTERNOON AND EVENING. THIS IS ALSO REFLECTED IN THE TIGHT...
CONSISTENT SET OF ENSEMBLE MEMBERS OUT OF THE GFS THROUGH 36 HOURS.
THIS IS ALSO FAIRLY EVIDENT IN THE HANDLING OF THE UPSTREAM LOW
CURRENTLY OVER KAMCHATKA. THE SCREAMING MESSAGE IS THAT THE SYSTEM
WILL DRIVE EAST INTO THE CENTRAL ALEUTIANS ON FRIDAY MORNING AND THEN
TURN ON A MORE SOUTHEAST TRACK OVER THE WEEKEND INTO THE NORTH
PACIFIC. THIS IS DUE TO THE REORGANIZATION OF THE LONGWAVE PATTERN IN
THE WESTERN HEMISPHERE AND THE DEVELOPMENT OF A HIGH AMPLITUDE RIDGE
NEAR 130W BY SUNDAY. THE NOSE OF THE RIDGE SHOULD PARALLEL THE SOUTH
CENTRAL ALASKA COAST LEADING TO A RETURN TO THE STRONG EAST WINDS.

.ANALYSIS AND UPPER LEVELS...
CLOSED UPPER LOW WITH ASSOCIATED SURFACE LOW DROPPING SOUTHEAST INTO
THE GULF OF ALASKA THIS AFTERNOON AND EVENING LOOKS WELL HANDLED.
AIRMASS UNSTABLE FOR SHOWERS BUT DOES NOT LOOK UNSTABLE ENOUGH FOR
ANY WIDESPREAD THUNDERSTORMS THIS EVENING. ANOTHER NEGATIVELY TILTED
DIFFLUENT TROUGH DROPPING SOUTH INTO BRISTOL BAY IN A WEAKLY
RETROGRESSIVE PATTERN AS REORGANIZATION OF THE HEMISPHERE UNDERWAY
AND DOMINANT WAVE NUMBER CHANGING. AIRMASS EXPECTED TO DESTABILIZE A
BIT MORE TOMORROW WITH THIS LOW INCREASING PROBABILITY OF
THUNDERSTORMS IN THE INTERIOR. FREEZING LEVELS POPPING UP IN
SOUTHWEST OVERNIGHT CHANGING THE PRECIPITATION TYPE OVER TO GENERALLY
LIQUID.

.SHORT TERM FORECAST...
SHOWERS AND ISOLATED INTERIOR THUNDERSTORMS TO DIMINISH OVERNIGHT.
STRATUS AND AREAS OF FOG WILL CONTINUE ACROSS MOST THE COASTAL AREAS
OF SOUTHWEST AND WEST ALASKA IN ONSHORE FLOW. PRECIPITATION TYPE
SHOULD SWITCH OVER TO PREDOMINANTLY LIQUID OVERNIGHT.

.LONG TERM FORECAST...
MORE OF THE SAME. 500MB HEIGHTS LOOK TO REMAIN AT OR BELOW SEASONABLE
LEVELS FOR THE FORSEEABLE FUTURE. THE CENTERS OF ACTION SHOULD REMAIN
ALONG THE SOUTH CENTRAL COAST AND THE WESTERN AND CENTRAL BERING SEA
AND ALEUTIANS.

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

CAS MAY 07