Small Craft Advisory 979, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AST WED NOV 21 2007

.ANALYSIS AND UPPER LEVELS...
A SIGNIFICANT UPPER LEVEL TROUGH IS PRESENT THIS MORNING OVER THE
BERING SEA...WITH A SIGNIFICANT UPPER LEVEL RIDGE CENTERED OVER
BRITISH COLUMBIA AND THE YUKON. COLD AIR AND SNOW SHOWERS ARE PRESENT
OVER THE BERING. OVER THE MAINLAND...VERY WARM...MOIST AIR IS PRESENT
IN SOUTHERLY FLOW WHICH EXTENDS ALL THE WAY NORTH FROM THE TROPICS.
AT THE SURFACE...A DISSIPATING LOW IS PRESENT OVER THE SOUTHWEST
MAINLAND THIS MORNING. A SURFACE TROUGH AXIS EXTENDS SOUTHWEST FROM
THIS LOW TO ANOTHER SURFACE LOW PRESSURE IN THE NORTH PACIFIC SOUTH
OF THE ALASKA PENINSULA. WIDESPREAD PRECIPITATION...MOSTLY RAIN...IS
PRESENT OVER THE SOUTHERN MAINLAND EAST OF THE LOW. RAINFALL HAS BEEN
VERY HEAVY OVER COASTAL REGIONS. FOR EXAMPLE...PORTAGE HAS RECEIVED
OVER 8 INCHES OF RAIN SINCE MONDAY AFTERNOON ALONG WITH HURRICANE
FORCE WIND GUSTS. SMALL STREAM FLOODING REMAINS A CONCERN OVER
PORTIONS OF THE SOUTHERN AND EASTERN KENAI PENINSULA DUE TO HEAVY
RAIN COUPLED WITH SNOWMELT.

.MODEL DISCUSSION...
MODEL CONFIDENCE IS BUILDING FOR THE NEXT MAJOR LOW TO MOVE NORTHWEST
THROUGH THE WESTERN GULF OF ALASKA AND INTO THE SOUTHWEST MAINLAND
THURSDAY. FAVORING GFS MODEL FOR THIS LOW. FOR THE NEXT MAJOR LOW TO
MOVE INTO THE WESTERN ALEUTIANS THURSDAY NIGHT...MODEL CONFIDENCE IS
ALSO BUILDING AND WE ARE ALSO FAVORING THE GFS. FROM FRIDAY
ONWARD...MODEL CONFIDENCE DECREASES SOMEWHAT ESPECIALLY REGARDING THE
EXACT POSITION OF LOW PRESSURE IN THE BERING. HOWEVER...CONFIDENCE IS
HIGH FOR GENERALLY CYCLONIC FLOW TO PERSIST OVER THE BERING FRIDAY
ONWARD.

.SHORT TERM FORECAST...
SOUTHCENTRAL...
VERY MOIST ONSHORE FLOW TO CONTINUE FOR SEVERAL DAYS. THROUGH
THURSDAY NIGHT...EXPECT FAIRLY SMALL CHANGES IN THE LOCATION OF THE
PRECIPITATION...WITH THE SOUTHERN/EASTERN KENAI AND PRINCE WILLIAM
SOUND RECEIVING THE HEAVIEST PRECIPITATION...AND COOK INLET REGION
AND COPPER RIVER BASIN RECEIVING LESS PRECIP DUE TO DOWNSLOPING. ALSO
EXPECT CONTINUED MILD TEMPERATURES. WINDS WILL NOT BE AS STRONG TODAY
AND TONIGHT OVER MOST AREAS...AS THE LOW OVER THE SOUTHWEST MAINLAND
WEAKENS AND THE PRESSURE GRADIENT RELAXES. HOWEVER...ANOTHER STRONG
LOW IS POISED TO FOLLOW A SIMILAR TRACK AS ITS PREDECESSOR...MOVING
THROUGH THE WESTERN GULF THURSDAY MORNING AND INTO THE SOUTHWEST
MAINLAND THURSDAY AFTERNOON. THIS WILL BRING INCREASING WINDS TO THE
USUAL AREAS...AND A HIGH WATCH WATCH HAS BEEN HOISTED FOR PORTAGE
VALLEY...TURNAGAIN ARM...AND THE HIGHER ELEVATIONS NEAR ANCHORAGE FOR
THURSDAY. COOLER AIR WILL BEGIN TO WORK INTO THE REGION FROM THE
SOUTHWEST LATE THURSDAY NIGHT INTO FRIDAY...WITH PERHAPS SOME BETTER
PRECIPITATION CHANCES FOR INLAND AREAS...AS WELL AS MAYBE A SHOT OF
SNOW.

SOUTHWEST MAINLAND...
LOW PRESSURE OVER THE BRISTOL BAY REGION THIS MORNING WILL DISSIPATE
TODAY. AREAS OF MOSTLY LIGHT RAIN AND SNOW CAN BE EXPECTED FROM
BRISTOL BAY NORTH INTO THE KUSKOKWIM VALLEY...WHILE THE KUSKOKWIM
DELTA WILL BE COLD ENOUGH FOR ANY PRECIP TO MAINLY FALL AS SNOW. A
SIMILAR SETUP WILL PERSIST THROUGH THURSDAY NIGHT...EXCEPT THAT A BIT
HEAVIER PRECIPITATION AND STRONGER WINDS ARE EXPECTED THURSDAY AND
THURSDAY NIGHT AS LOW PRESSURE CROSSES THE ALEUTIAN RANGE AND MOVES
THROUGH THE SOUTHWEST MAINLAND. THIS LOW SHOULD HAVE MORE PUNCH THAN
THE PRESENT LOW FOR THE SOUTHWEST MAINLAND...AS IT IS EXPECTED TO
HAVE MORE UPPER LEVEL JET SUPPORT. COLDER AIR AND CALMER WEATHER WILL
WORK INTO THE SOUTHWEST MAINLAND FRIDAY AND FRIDAY NIGHT AS WEAK HIGH
PRESSURE BUILDS IN FROM THE WEST.

BERING SEA/ALEUTIANS...
COLD NORTHERLY FLOW WILL BE PRESENT OVER THE BERING/ALEUTIANS TODAY
WITH GENERALLY SCATTERED SNOW SHOWER ACTIVITY. WARMER AIR WILL
GRADUALLY WORK INTO THE REGION FROM WEST TO EAST. TONIGHT...A FAIRLY
WEAK FRONT WILL MOVE INTO THE WESTERN ALEUTIANS...BRINGING MOSTLY
RAIN. A STRONG LOW PRESSURE THEN MOVES INTO THE WESTERN ALEUTIANS
THURSDAY NIGHT AND INTO THE WESTERN BERING FRIDAY. THIS WILL BRING
WARMER...WET WEATHER TO THE ENTIRE REGION.

.LONG TERM FORECAST...
AREAS OF STRONG LOW PRESSURE ARE LIKELY TO PERSIST IN THE
BERING/ALEUTIANS THROUGH EARLY NEXT WEEK. MILD TEMPERATURES AND WET
WEATHER LIKELY TO PERSIST OVER MOST OF THE FORECAST AREA WITH THE
POSSIBLE EXCEPTION OF THE KUSKOKWIM VALLEY AND INLAND SOUTHCENTRAL.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WATCH 101 AND 125.
MARINE...STORM WARNINGS ZONES 120 130 132 138 140 351 352.
         GALE WARNINGS ZONES 125 129 141 150 155 160 165 180 414.
         HEAVY FREEZING SPRAY WARNING ZONES 180 185.
FIRE WEATHER...NONE.

FOISY NOV 07