Small Craft Advisory 830, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
415 AM AKDT SUN OCT 26 2008

.ANALYSIS AND UPPER LEVELS...
THE UPPER LEVEL JET STREAM THIS MORNING STRETCHES FROM JAPAN
NORTHEAST TO NEAR THE WESTERN ALEUTIANS...THEN DIVES SOUTHEAST TO
AROUND 35N 160W...AND FINALLY HEADS BACK NORTHEAST INTO SOUTHEAST
ALASKA AND THE YUKON. A 988 MB LOW PRESSURE ABOUT 200 NM SOUTH OF
KODIAK EARLY THIS MORNING IS RIDING NORTHEAST ALONG THE WEST SIDE
JET STREAM AND BRINGING STORM FORCE WINDS TO THE NORTHERN GULF OF
ALASKA ALONG A FRONT EXTENDED OUT AHEAD OF THE LOW. HIGH PRESSURE IS
PRESENT OUT WEST THIS MORNING...CENTERED OVER THE WEST CENTRAL
BERING/ALEUTIANS.

THE GULF LOW WILL WEAKEN AS IT MOVES NORTHEAST TO JUST SOUTHEAST OF
CORDOVA MONDAY AFTERNOON AND THEN BECOME STATIONARY. A SIGNIFICANT
PATTERN CHANGE WILL TAKE PLACE OUT WEST OVER THE NEXT FEW
DAYS...WITH THE JET STREAM WORKING NORTHEAST INTO THE WEST/CENTRAL
BERING/ALEUTIANS BRINGING WARMER TEMPERATURES...RAIN...AND WIND AS A
SIGNIFICANT LOW PRESSURE SYSTEM MOVES NORTHEAST THROUGH THE WESTERN
BERING.

.MODEL DISCUSSION...
MODELS ARE IN VERY NICE AGREEMENT ALL THE WAY THROUGH ABOUT THURSDAY
AFTERNOON AND THEN BEGIN TO DIVERGE. WEDNESDAY THROUGH
THURSDAY...GFS HAS COME IN LINE WITH THE MORE CONSISTENT ECMWF IN
HOW FAR EAST THE SYSTEM MOVING EAST ACROSS THE BERING/ALEUTIANS WILL
MAKE IT BEFORE BEING SHEARED APART BY THE BLOCKING HIGH PRESSURE
OVER THE MAINLAND. THE NEW GFS AND THE MORE CONSISTENT ECMWF ARE
BRINGING THE SYSTEM FURTHER EAST BEFORE SHEARING APART AND WE HAVE
GONE WITH THIS SOLUTION.

.SHORT TERM FORECAST...
SOUTHCENTRAL...
THE 988 MB LOW SOUTH OF KODIAK IS STILL BRINGING STORM FORCE WINDS
THIS MORNING ALONG A FRONT RUNNING OUT AHEAD OF THE LOW.
HOWEVER...AS THE LOW MOVES NORTHEAST TOWARD CORDOVA IT WILL
GRADUALLY WEAKEN AS WILL ITS ASSOCIATED WINDS. THE LOW WILL REACH
THE AREA JUST OFF THE COAST BETWEEN CORDOVA AND YAKUTAT MONDAY
AFTERNOON...AND THEN BECOME NEARLY STATIONARY AND SLOWLY DISSIPATE.
THE WEST EDGE OF THE PRECIPITATION WITH THE LOW IS JUST GRAZING THE
EASTERN KENAI PENINSULA AND KODIAK ISLAND THIS MORNING...AND THE
WEST EDGE WILL MOVE EASTWARD THIS AFTERNOON. FROM THIS AFTERNOON
ONWARD...MOST OF THE PRECIPITATION WILL BE FROM CORDOVA NORTH TO THE
SOUTHEAST PORTION OF THE COPPER RIVER BASIN. SNOWFALL TOTALS ARE A
CONCERN FOR THE SOUTHEAST PORTION OF THE COPPER RIVER BASIN AND A
WINTER WEATHER ADVISORY FOR SNOW IS BEING ISSUED. ALSO OF CONCERN
ARE NORTHERLY WINDS THROUGH CHANNELED TERRAIN AS COLD ADVECTION
KICKS BACK IN FROM NORTHWEST TO SOUTHEAST LATE TODAY THROUGH MONDAY
NIGHT. SOME AREAS WHICH WILL RECEIVE THE GUSTIER WINDS INCLUDE BROAD
PASS...THOMPSON PASS AND VALDEZ...AND THE COPPER RIVER DELTA. ALSO
KICKING IN WITH THE COLD ADVECTION WILL BE MOSTLY CLEAR
SKIES...WHICH WILL TAKE OVER SOUTHCENTRAL FROM WEST TO EAST
BEGINNING LATE TODAY. SO ALTHOUGH TEMPERATURES WILL BE COOLER THAN
NORMAL THROUGH TUESDAY AND LOCALLY WINDY...MANY PLACES WILL SEE A
GOOD DOSE OF SUNSHINE.

SOUTHWEST MAINLAND...
DRY AND COLD UPPER LEVEL NORTHERLY FLOW IS PRESENT OVER THE
SOUTHWEST MAINLAND TODAY TO THE WEST OF THE GULF LOW PRESSURE AND TO
THE EAST OF THE BERING HIGH PRESSURE. HOWEVER...THE LOW LEVELS ARE
STILL FAIRLY MOIST WITH SOME LOW CLOUDS AND FOG. THE BERING HIGH
PRESSURE WILL MOVE EAST INTO THE SOUTHWEST MAINLAND MONDAY KEEPING
CONDITIONS DRY. A FRONT MOVING EAST ACROSS THE BERING WILL BRING
WARMER TEMPERATURES AND RAIN AND SNOW TO THE SOUTHWEST COAST
BEGINNING TUESDAY.

BERING SEA/ALEUTIANS...
TRANQUIL SETUP TODAY OUT IN THE BERING AND ALEUTIANS. HIGH PRESSURE
IS POSITIONED IN THE WESTERN/CENTRAL BERING/ALEUTIANS. THE HIGH
PRESSURE WILL CONTINUE TO MOVE EAST AS A SIGNIFICANT PATTERN CHANGE
OVERTAKES THE REGION...A CHANGE TO MUCH WARMER...WET AND WINDY. THE
RAIN AND WIND IS ALREADY AFFECTING THE WESTERN ALEUTIANS TODAY...BUT
AS A LOW PRESSURE INTENSIFIES JUST NORTH OF ATTU TONIGHT THE WINDS
AND RAIN IN THE WESTERN ALEUTIANS/BERING WILL FURTHER INCREASE. THE
LOW INTENSIFIES TO ABOUT 975 MB AS IT MOVES TO AROUND SAINT MATTHEW
TUESDAY MORNING. A STRONG FRONT WITH GALE FORCE WINDS AND POSSIBLY
STORM FORCE WINDS WILL MOVE FROM THE WESTERN BERING/ALEUTIANS LATE
TONIGHT TO THE CENTRAL BERING/ALEUTIANS MONDAY AND TO THE EASTERN
BERING/ALEUTIANS MONDAY NIGHT. RAIN WILL BE THE PREDOMINANT
PRECIPITATION TYPE WITH THIS SYSTEM.

.LONG TERM FORECAST...
ON TUESDAY AND WEDNESDAY...THE FRONT WHICH HAD BEEN MOVING ACROSS
THE BERING IS EXPECTED TO MOVE INLAND TO THE KUSKOKWIM VALLEY WITH
THE ENERGY THEN SPLITTING AND AN AREA OF LOW PRESSURE FORMING OVER
THE GULF OF ALASKA. THE ENERGY WILL SPLIT BECAUSE OF A BLOCKING AREA
OF HIGH PRESSURE OVER THE CENTRAL TO EASTERN INTERIOR OF ALASKA
WHICH WILL INTENSIFY IN THE SHORT TERM AND PERSIST INTO THE LONG
TERM. GENERALLY SPEAKING FOR THE EXTENDED...EXPECT PROGRESSIVE WET
AND WARM WESTERLY FLOW ACROSS THE BERING/ALEUTIANS WITH
SEMIPERMANENT LOW PRESSURE OVER THE GULF OF ALASKA. GENERALLY DRY
CONDITIONS ARE EXPECTED INLAND WITH THE POSSIBLE EXCEPTION OF THE
ABOVE MENTIONED FRONT WHICH MAY MAKE IT EAST TO THE KUSKOKWIM VALLEY
ON WEDNESDAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM WARNING ZONES 120 130 132 138 175 176 412 413.
         GALE WARNING ZONES 125 140 150 172 179 185 351 352 411 414.
FIRE WEATHER...NONE.

FOISY OCT 08