Brisk Wind Advisory 18, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
150 PM AST WED MAR 5 2008

.ANALYSIS AND UPPER LEVELS...A LARGE DEEP UPPER LOW IS CENTERED
JUST SOUTH OF THE CENTRAL ALEUTIANS WITH A ZONAL JET WELL TO THE
SOUTH DRIVING EASTWARD INTO THE EAST PACIFIC RIDGE...GRADUALLY
PUSHING IT FARTHER EAST. SYSTEMS CONTINUE TO DEVELOP IN THE LEFT
EXIT REGION OF THE MAIN JET AND THEN TRACK NORTHWARD UP THE WEST
SIDE OF THE RIDGE AND NORTHWESTWARD AROUND THE ALEUTIAN LOW. THE
LATEST SYSTEM IS A 970 MB LOW OVER BRISTOL BAY WITH OCCLUSION
EXTENDING EASTWARD TO TRIPLE POINT NORTHEAST OF KODIAK ISLAND AND
COLD FRONT EXTENDING SOUTHWARD ACROSS GULF. STRONG EASTERLY FLOW
AHEAD OF THE FRONTAL SYSTEM IS PRODUCING IN STORM FORCE WINDS OVER
THE NORTHERN GULF WATERS. HIGH WIND WARNINGS ARE IN EFFECT FROM
CORDOVA TO PORTAGE VALLEY AND TURNAGAIN ARM. STRONG LIFT ASSOCIATED
WITH THIS SYSTEM IS PRODUCING A LOT OF PRECIPITATION WHICH IS
OVERCOMING SOME OF THE DOWNSLOPE AFFECTS. ABOVE FREEZING TEMPERATURES
ACROSS MUCH OF SOUTHCENTRAL AND SOUTHWEST ALASKA IS PRODUCING RAIN
OR RAIN/SNOW MIXED MOST PLACES. SNOW IS FALLING ON THE BACK SIDE OF
THE SYSTEM FROM THE KUSKOKWIM DELTA TO THE SOUTHERN ALASKA PENINSULA.
GUSTY NORTH WINDS ARE PRODUCING BLIZZARD CONDITIONS ALONG THE
KUSKOKWIM DELTA COAST. THE NEXT SYSTEM IN LINE IS DEVELOPING DOWN
OVER THE NORTH PACIFIC NEAR 42N 160W.

.MODEL DISCUSSION...MODELS HAVE STRUGGLED MIGHTILY WITH TRACK OF
RECENT LOWS. THE CURRENT SYSTEM ENDED UP TRACKING MUCH FARTHER SOUTH
AND WEST THAN WAS DEPICTED IN YESTERDAYS MODEL SOLUTIONS. MANY
FORECAST UPDATES WERE PERFORMED TODAY TO ACCOUNT FOR THE NEW TRACK.
18Z MODEL RUNS CONTINUED TO TREND JUST SLIGHTLY SOUTHWEST OF 12Z
POSITIONS AS LOW MOVES ACROSS THE EASTERN BERING TONIGHT AND
THURSDAY. SOLUTIONS FOR TRACK OF NEXT LOW ARE ALL CLUSTERED TOGETHER
AS IT MOVES ACROSS THE GULF THURSDAY NIGHT AND FRIDAY AND THEN
DIVERGE IN MOVING THE LOW INLAND FRIDAY AFTERNOON. IT MAKES SENSE
THAT THE TRACK OF THIS LOW WILL BE FARTHER EAST THAN THE CURRENT
LOW SINCE THE RIDGE TO THE EAST IS GRADUALLY PUSHED FARTHER AND
FARTHER EASTWARD. HOWEVER...HAVE LOW CONFIDENCE IN THE EXACT TRACK
ACROSS THE GULF...WHICH MAKES ALL THE DIFFERENCE IN THE DETAILS OF
THE FORECAST ACROSS SOUTHCENTRAL. FOR NOW STUCK WITH CURRENT
FORECAST WHICH WAS BASED OFF OF YESTERDAY AFTERNOONS GFS RUN.

.SHORT TERM FORECAST...THE OCCLUDED FRONT WILL MOVE ONSHORE THIS
EVENING AND QUICKLY FALL APART AT THE SURFACE AS IT MOVES INLAND
TONIGHT. FLOW WILL SHIFT TO SOUTH TO SOUTHEAST AND BECOME GUSTY
ACROSS THE SOUTHERN MAINLAND DUE TO PRESSURE RISES AS RIDGE BRIEFLY
BUILDS IN AHEAD OF NEXT SYSTEM. THE STRONGEST PRESSURE RISES WILL
BE DIRECTLY BEHIND THE LOW FROM THE ALASKA PENINSULA AND BRISTOL BAY
TO THE KUSKOKWIM VALLEY AND KUSKOKWIM DELTA. THESE GUSTY WINDS WILL
KEEP TEMPERATURE IN THE 30S TONIGHT FOR MOST PLACES. WINDS WILL DROP
OFF THURSDAY MORNING ACROSS SOUTHCENTRAL AND EASTERN PORTIONS OF
SOUTHWEST ALASKA AS FLOW BEGINS TO SHIFT AROUND TO EAST AHEAD OF
THE NEXT SYSTEM APPROACHING THE GULF. BLIZZARD CONDITIONS AHEAD
OF THE LOW OVER THE KUSKOKWIM DELTA WILL END BY LATE THIS EVENING
AS THE LOW NEARS AND WINDS DIMINISH. HOWEVER...SNOW WILL PUSH
WESTWARD INTO THE PRIBILOF ISLANDS AND WINDS WILL INCREASE TO ABOUT
35 MPH.  SO EXPECT BLIZZARD CONDITIONS TO DEVELOP THERE AND CONTINUE
THROUGH THE OVERNIGHT HOURS.

THE NEXT SYSTEM WILL PUSH UP INTO THE GULF FRIDAY. THERE IS LOW
CONFIDENCE IN STORM TRACK...BUT LOOKS LIKE ANOTHER STRONG LOW WITH
THE POTENTIAL FOR STORM FORCE WINDS OVER THE NORTHERN GULF AND HIGH
WIND CONDITIONS FROM CORDOVA TO TURNAGAIN ARM. AIR ON THE EAST SIDE
OF THE LOW LOOKS VERY WARM...SO IF TRACK TO BARREN ISLANDS IS CORRECT
SOUTHCENTRAL WILL SEE ANOTHER WARM-UP FRIDAY WITH PRECIPITATION
MAINLY IN THE FORM OF RAIN WHILE MOST OF SOUTHWEST WILL REMAIN ON
THE COLD SIDE OF THE LOW. AS THIS NEXT LOW MOVES NORTHWARD ACROSS
THE GULF COLD AIR WILL ADVECT SOUTHWARD ACROSS THE BERING SEA
PRODUCING SNOW SHOWERS. OTHERWISE...IT WILL REMAIN QUIET OUT WEST.

.LONG TERM FORECAST...EACH NEW LOW WILL TRACK PROGRESSIVELY EASTWARD
DURING THE EXTENDED PERIOD AS THE UPPER RIDGE CONTINUES TO BE PUSHED
FARTHER EASTWARD. THIS WILL ALLOW TEMPERATURES ACROSS MAINLAND ALASKA
TO COOL BACK DOWN TO NEAR CLIMATOLOGICAL NORMALS. STORM TRACK WILL BE
LESS ACTIVE SO THINGS WILL QUIET DOWN...AT LEAST TEMPORARILY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING 101 125 135.
         BLIZZARD WARNING 155 195.
MARINE...GALE WARNING 120 125 129 130 132 138 140 150 155
                      160 165 180.
         HEAVY FREEZING SPRAY 179 185.
FIRE WEATHER...NONE.

SEB MAR 08