Gale Warning 689, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKDT SUN SEP 26 2010

.MODEL DISCUSSION...
MODELS IN EXCELLENT AGREEMENT IN THE SHORT TERM. MODELS ARE EVEN IN
GOOD AGREEMENT FURTHER OUT WITH THE GFS AND ECMWF NOT GETTING OUT OF
PHASE UNTIL AFTER 168 HOURS (SATURDAY AFTERNOON).

.ANALYSIS AND UPPER LEVELS...
UPPER LEVEL LOW CENTERED NORTH OF ALASKA WITH THE TROUGH AXIS
STRETCHING SOUTHWARD ACROSS THE EASTERN HALF OF THE STATE TO A LOW
ALONG THE NORTHERN GULF COAST. ANOTHER LOW IN THE SOUTHWESTERN GULF
IS MOVING TOWARD THE NORTHEAST. HIGH PRESSURE OVER WESTERN ALASKA
THROUGH THE CENTRAL BERING SEA. A RAPIDLY DEVELOPING CYCLONE
(REMNANTS OF TROPICAL CYCLONE MALAKA) IS SOUTHEAST OF THE KAMCHATKA
PENINSULA RACING TOWARD THE WESTERN ALEUTIANS.

.SHORT TERM FORECAST...
BERING SEA AND ALEUTIANS...MAJOR CYCLONE MOVING INTO THE WESTERN
ALEUTIANS TODAY AND CENTRAL ALEUTIANS TONIGHT. CENTER OF STORM WILL
TRACK JUST NORTH OF SHEMYA LATE TONIGHT AND BE NEAR DUTCH HARBOR
LATE MONDAY NIGHT. SURFACE PRESSURE IN THE CENTER OF THE LOW IS
EXPECTED TO STAY BELOW 970 MB THROUGH AT LEAST EARLY MONDAY
AFTERNOON...AND HIGH WINDS ARE EXPECTED WITH THIS STORM. ON TUESDAY
THIS STORM WILL CROSS SOUTH OF THE ALEUTIANS/ALASKA PENINSULA AND
INTO THE WESTERN GULF OF ALASKA...LEAVING SHOWERY WEATHER UNDER
NORTHERLY FLOW IN ITS WAKE.

SOUTHWEST ALASKA...
HIGH PRESSURE WILL REMAIN OVER SOUTHWEST ALASKA THROUGH MONDAY. ON
TUESDAY AS THE BERING/ALEUTIAN LOW DROPS INTO THE GULF THE HIGH
PRESSURE WILL WEAKEN SUBSTANTIALLY...WITH SOME SHOWERS POSSIBLE IN
THE BRISTOL BAY ZONE.

SOUTH CENTRAL ALASKA AND THE GULF...
WITH AN UPPER LEVEL TROUGH STRETCHED ACROSS SOUTH CENTRAL ALASKA
EXPECT DRY WEATHER TO THE WEST OF THE TROUGH AXIS AND CLOUDS AND
PRECIPITATION TO THE EAST. THIS DIVIDING NORTH/SOUTH LINE SHOULD
MOVE WEST TO JUST EAST OF ANCHORAGE LATER TODAY BEFORE RETREATING
EASTWARD TONIGHT AND MONDAY.

THE PRECIPITATION WILL FALL AS SNOW IN THE COPPER RIVER BASIN.
DECENT ACCUMULATIONS ARE EXPECTED...ESPECIALLY TONIGHT...DUE TO THE
SLOW MOVEMENT OF THE TROUGH AND THE ISENTROPIC LIFT AHEAD OF IT.

ON TUESDAY THE ABOVE MENTIONED SYSTEM MOVING INTO THE GULF WILL
BRING PRECIPITATION TO MAINLY COASTAL AREAS AS SOUTHWESTERLY FLOW
ALOFT DEVELOPS ACROSS SOUTHERN ALASKA.

.LONG TERM FORECAST...
THE MEAN UPPER LEVEL TROUGH POSITION WILL SETTLE IN OVER WESTERN
ALASKA. THIS WILL BRING CYCLONIC FLOW AND MOIST CONDITIONS TO
SOUTHERN ALASKA...WITH SOUTHERLY FLOW OVER SOUTH CENTRAL. A FAST
ZONAL JET STREAM WILL BE ACROSS THE NORTHERN PACIFIC THAT WILL THEN
SLOW AND TURN NORTHWARD IN THE GULF.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING 191.
         HIGH WIND WATCH 187.
MARINE...STORM WARNING 127 130 172 175 176.
         GALE WARNING 120 121 126 128 132 150 160 179 185.
FIRE WEATHER...NONE.

LUDWIG SEP 10