High Wind Watch 24, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AST MON DEC 3 2007

.ANALYSIS AND UPPER LEVELS...

PATTERN CHANGE ABOUT HALFWAY COMPLETE THIS MORNING. THE WESTERN FLANK
OF THE UPPER LEVEL CUT-OFF HIGH EXTENDS SOUTH INTO THE NORTHERN
BERING...WHILE THE INCREASINGLY POSITIVE TILT OF THE FEATURE HAS
BROUGHT THE EASTERN FLANK TO NORTH OF HUDSON BAY. THE WESTERN CUT-OFF
LOW REMAINS AROUND THE KAMCHATKA PENINSULA...AND THE EASTERN CUT-OFF
ENCOMPASSES THE GULF OF ALASKA. AT THE SURFACE...MAINLAND AK IS
COVERED WITH HIGH PRESSURE WITH LOWS NEAR THE EASTERN ALEUTIANS AND
OVER KAMCHATKA.

.MODEL DISCUSSION...

MODELS IN AGREEMENT IN BRINGING GULF UPPER CUT-OFF LOW INTO THE
BERING BY TUE AND MERGING IT WITH THE KAMCHATKA FEATURE WEST OF THE
BERING WED INTO THU. THIS WILL ALLOW AN UPPER RIDGE TO FORM OVER THE
GULF DURING THE SAME PERIOD. AT THE SURFACE...THE LOW NEAR THE
EASTERN ALEUTIANS TRACKS UP SHELIKOF STRAIT AND THEN DISSIPATES LATER
ON TUE. HIGH PRESSURE THEN BUILDS IN OVER THE GULF THROUGH THU. IN
THE WEST...A MASSIVE NORTH PACIFIC LOW WILL CROSS ATTU TUE AFTERNOON
AND THEN SLOWLY MOVE TO THE BERING STRAIT BY LATE THU. AN ASSOCIATED
FRONT WILL REACH WESTERN AK WED. THE FORECAST FOLLOWS THE GFS
SOLUTION FOR THE FIRST THREE DAYS. AT THAT POINT CONFIDENCE IN THAT
MODEL DIMINISHES RAPIDLY AS THE SOLUTION SHOWS LITTLE RUN TO RUN
STABILITY. THE REST OF THE FORECAST THEN USES THE EUROPEAN MODEL.

.SHORT TERM FORECAST...

OVER THE WEST...DECAYING FRONTS IN THE FAR WEST WILL KEEP SOME SNOW
SHOWERS OVER THE AREA TODAY. AS THE NORTH PAC LOW MOVES TO THE
WESTERN ALEUTIANS TUE IT WILL BE PRECEDED BY A STRONG FRONT PRODUCING
STORMS AND HURRICANE FORCE WINDS...AND SNOW. THESE CONDITIONS WILL
SPREAD ACROSS THE BERING THROUGH THU AS THE LOW MOVES TO EASTERN
RUSSIA.

OVER SW AK...SNOW SHOWERS WILL MOVE ACROSS THE ALEUTIAN RANGE UNTIL
THE EASTERN ALEUTIAN LOW DISSIPATES LATE TUE. MOST OF THE SHOWERS
WILL FALL SOUTH OF THE KUSKOKWIM. AS THE LOW WEAKENS INTO A TROUGH
OVER THE SOUTHERN MAINLAND...SHOWERS WILL BE MORE WIDESPREAD OVER THE
SOUTHWEST WITH ONLY A BRIEF BREAK TUE NIGHT BEFORE THE BERING FRONT
MOVES ONSHORE. SOUTHWEST FLOW MEANS THIS WILL BE A SNOW MAKER FOR THE
AREA UNTIL LATE WED WHEN CONDITIONS ALOFT WARM TO AT LEAST CREATE A
MIX OF RAIN AND SNOW FOR BRISTOL BAY. THE LOW MOVES EAST AND PRECIP
BECOMES SPOTTY ON THU.

SOUTH AND EAST OF THE AK RANGE...COLD CONDITIONS OVER THE INTERIOR
WILL PERSIST FOR SEVERAL DAYS. AS THE EASTERN ALEUTIAN LOW MOVES
TOWARD SHELIKOF....THE GRADIENT WILL TIGHTEN AND GALES AND STORM
FORCE WINDS SHOULD AFFECT MARINE AREAS AS FAR NORTH AS COOK INLET.
EAST FLOW WILL KEEP THE WESTERN GULF COAST IN LINE FOR SNOW THROUGH
TUE AFTERNOON. AMOUNTS ON WINDWARD SLOPES COULD BE SIGNIFICANT.
DURING THIS TIME THE FLOW BECOMES SOUTH AND BRINGS SNOW TO THE NORTH
GULF COAST. EXCEPT FOR SOME POSSIBLE MIX OF RAIN AND SNOW TUE
EVENING...THIS SHOULD REMAIN SNOW UNTIL RIDGING BUILDS IN ON WED. A
NEAR REPEAT FOR THE WESTERN GULF BEGIN LATER ON WED AS THE BERING
FRONT ARRIVES. SNOW ON THE WESTERN COAST WILL CHANGE TO RAIN THU
MORNING BUT WILL REMAIN SNOW FOR THE KENAI. THROUGHOUT THIS PERIOD
WINDS ALOFT ARE SUFFICIENT TO CREATE LEEWARD DOWNSLOPING SO MAJOR
SNOWFALL IS NOT EXPECTED INLAND FROM THE COASTAL MOUNTAINS.

.LONG TERM FORECAST...

IN THE WEST THERE WILL BE A BRIEF BREAK AFTER THE LOW MOVES INTO
RUSSIA. ON FRI THE NEXT NORTH PAC LOW CROSSES THE EASTERN ALEUTIANS
AND THEN STALLS IN THE EASTERN BERING THROUGH THE WEEKEND. GALES WILL
ACCOMPANY THIS SYSTEM AND SNOW WILL CHANGE TO RAIN DURING THE
WEEKEND. IN THE SOUTHWEST...SCATTERED SNOW SHOWERS AND GUSTY GAP
WINDS WILL ACCOMPANY THE SECOND LOW. IN THE EAST...THE FRONT
ASSOCIATED WITH THE SECOND LOW WILL AGAIN BRING ONSHORE FLOW TO
COASTAL AREAS. TEMPERATURES SHOULD REMAIN COLD ENOUGH FOR ANOTHER
ROUND OF MOUNTAIN SNOW AND INLAND SHOWERS FOR THE WEEKEND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...
MARINE...HEAVY FREEZING SPRAY 121 125 130 140 180
         GALES 125 132 138 141 150 160 170 172 175
         STORMS 120 130 140 141
         HURRICANE FORCE 176
FIRE WEATHER...NONE

DS DEC 07