Gale Warning 325, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
300 PM AKDT WED MAR 25 2009

.MODEL DISCUSSION...
MODELS ARE IN GOOD AGREEMENT THROUGH 00Z SATURDAY. DIFFERENCES ARISE
CONCERNING DETAILS OF THE NEXT NORTH PACIFIC LOW EXPECTED TO IMPACT
THE AREA THIS WEEKEND. CONSENSUS IS GOOD AND DETAILS WELL RESOLVED
PERTAINING TO THE LOW CURRENTLY IN THE GULF OF ALASKA. THE GFS WAS
THE PREFERRED MODEL FOR CONSTRUCTING THE FORECASTS THIS AFTERNOON DUE
TO CONTINUED CONSISTENCY.

.ANALYSIS AND UPPER LEVELS...THE STRONG LOW PRESSURE SYSTEM TRACKING
INTO THE GULF IS VERY WELL FORMED WITH THE UPPER LEVEL CENTER
SOUTHWEST OF THE PRIBILOF ISLANDS AND THE SURFACE LOW SOUTHWEST OF
KODIAK ISLAND IN THE UPPER LEFT EXIT REGION OF THE JET STREAM. THE
LOW WILL BECOME VERTICALLY STACKED AS THE NIGHT GOES ON AS THE UPPER
LEVEL LOW REACHES THE SURFACE LOW POSITION. THIS WILL LEAVE THE UPPER
LEVEL TROUGH EXTENDING FROM THE CENTRAL ALEUTIANS TO THE KENAI
PENINSULA AND THEN NORTHWARD TOWARD BARROW.
THE VISIBLE SATELLITE SHOWS THE STRONG COLD ADVECTION IN THE COLD AIR
CUMULUS TO THE SOUTHWEST OF IT. THE SMALL CLEAR SLOT IN ADVANCE OF
THE LOW IS INDICATIVE OF GOOD DOWNWARD MOTION. BOTH OF THESE ARE GOOD
SIGNS OF A STRONG AND WELL DEVELOPED SYSTEM.
WHILE THE 50 MB JET REMAINS SOUTH OF THE AREA IT IS STILL A STRONG
DRIVER OF THIS SYSTEM.

.SHORT TERM FORECAST...BLIZZARD WARNINGS ARE IN EFFECT FOR THE
KSUKOKWIM DELTA AS WELL AS THE ALASKA PENINSULA AND PORTIONS OF THE
BRISTOL BAY ZONE. WINDS ALONG THE ALASKA PENINSULA AND BRISTOL BAY
AREA HAVE BEEN GUSTING BETWEEN 40 AND 60 MPH TODAY AND WILL BE SLOW
TO COME DOWN.
PORTAGE VALLEY HAS ALSO BEEN EXPERIENCING WHITEOUT CONDITIONS TODAY
IN GUSTS NEAR 70 MPH. WHILE THESE CONDITIONS WERE INITIALLY EXPECTED
TO HAVE ENDED THIS MORNING THE BARRIER JET ALONG THE GULF COAST AND
CONSTANT MOISTURE ADVECTION INTO THAT AREA WILL KEEP IT GOING UNTIL
THE EARLY EVENING. IT IS POSSIBLE IT COULD GO EVEN LONGER IF THE
WARMER AIR TRULY STALLS AND DOES NOT MAKE IT MUCH FARTHER NORTH.
KODIAK ISLAND HAS BEEN EXPERIENCING HEAVY RAIN ALL DAY WHICH IS
FALLING ON TOP OF THE LARGE SNOWFALL FROM MONDAY. THIS HAS RAISED
CONCERNS FOR FLOODING ALONG THE ROAD SYSTEM AND THEREFORE THERE IS A
FLOOD ADVISORY FOR THAT AREA SINCE THE RAINFALL HAS NOWHERE TO GO.

.LONG TERM FORECAST...
THE SIBERIAN BLOCK WILL CONTINUE TO RETROGRADE OVER THE WEEKEND AND
INTO NEXT WEEK. AS A RESULT...MAINLAND ALASKA WILL REMAIN WITHIN THE
MEAN TROUGH POSITION. THEREFORE EXPECT A CONTINUED PROGRESSIVE AND
ACTIVE STORM TRACK ACROSS THE ALEUTIANS AND INTO THE GULF OF ALASKA.
THE NEXT IN A SERIES OF NORTH PACIFIC LOWS WILL BEGIN TO IMPACT THE
AREA OF RESPONSIBILITY OVER THE WEEKEND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD 125 155 161 181 185.
MARINE...GALE 125 132 140 150 155 160 165 170 171 172 179 180 185.
         STORM 120 130.
         HEAVY FREEZING SPRAY 165 179.
FIRE WEATHER...NONE.

EZ/NRH MAR 09