Gale Warning 296, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
242 PM AKDT WED MAR 31 2010

.ANALYSIS AND UPPER LEVELS...AN UPPER LEVEL TROUGH REGION EXTENDS
FROM THE KAMCHATKA PENINSULA AND TILTS NEGATIVELY INTO THE NORTH
PACIFIC. TO THE SOUTHEAST OF THIS LOW...A RIDGE IS LOCATED WITHIN THE
GULF OF ALASKA WHILE A SEPARATE RIDGE IS BUILDING INTO MAINLAND
ALASKA FROM WESTERN CANADA. A FORMIDABLE 185 KT JET SITS JUST SOUTH
OF THE EASTERN ALEUTIANS AND ALASKA PENINSULA...ALONG THE BORDER
BETWEEN THE GULF RIDGE AND NEGATIVELY TILTED TROUGH.

AT THE SURFACE...A SURFACE LOW PRESSURE IS SITTING UNDERNEATH THE
SOUTHEASTERN CORNER OF THE NEGATIVELY TILTED UPPER LEVEL
TROUGH...JUST SOUTHEAST OF DUTCH HARBOR. SUCH A SET UP INDICATES THAT
THE SURFACE LOW PRESSURE HAS REACHED ITS PEAK INTENSITY AND WILL
SLOWLY BEGIN TO DISSIPATE. THIS IS CONFIRMED BY MODELS WHICH SHOW THE
LOW MOVING INTO THE GULF BY TONIGHT AND DECAYING AS IT LOSES UPPER
LEVEL JET SUPPORT. AN ASSOCIATED SURFACE TROUGH WITHIN THE GULF IS
APPROACHING THE GULF COAST...WHILE HIGHER PRESSURE COVERS MUCH OF THE
MAINLAND.

.MODEL DISCUSSION...TODAY THERE IS GREAT AGREEMENT AMONG THE MODELS
IN THE SHORT TERM. THE MODELS ALL INDICATE THAT THE SURFACE LOW
PRESSURE NEAR DUTCH HARBOR WILL MOVE TO THE GULF AND DISSIPATE OVER
THE NEXT SEVERAL DAYS. SO FAR TODAY THE MODELS ALSO APPEAR TO BE
CAPTURING PRECIPITATION AMOUNTS ACROSS THE SOUTHCENTRAL REGION MUCH
MORE ACCURATELY THAN THEY HAVE FOR THE PAST SEVERAL DAYS. THERE WERE
NO DRASTIC CHANGES IN THE NEW LONG TERM MODEL SOLUTIONS SO THE ECMWF
WAS USED.

.SHORT TERM FORECAST...NUMEROUS SHOWERS ALONG THE COAST AND WESTERN
PRINCE WILLIAM SOUND ARE EXPECTED TO CONTINUE TODAY ACROSS THE
REGION. AS THE SURFACE TROUGH IN THE GULF MOVES TOWARDS THE COAST
...THE PRESSURE GRADIENT BETWEEN THE INLAND HIGH PRESSURE AND
GULF TROUGH SHOULD BE SUFFICIENT FOR TURNAGAIN ARM WINDS TO DEVELOP
ALONG THE ARM AND HIGHER ELEVATIONS FROM THIS AFTERNOON INTO TONIGHT.
STEADY RAIN AND SNOW SHOWERS ARE EXPECTED TO CONTINUE ALONG WESTERN
PRINCE WILLIAM SOUND...EASTERN KENAI PENINSULA...AND KODIAK ISLAND
THROUGH FRIDAY MORNING AS THE DUTCH HARBOR LOW APPROACHES THE GULF.

SOUTHWEST ALASKA...MUCH OF THE SOUTHWEST WILL REMAIN CLOUDY TODAY AS
THE DUTCH HARBOR LOW PROGRESSES EASTWARD BUT THE LOW WILL REMAIN TOO
FAR SOUTH FOR WIDESPREAD PRECIPITATION. HOWEVER...A TROUGH ASSOCIATED
WITH THE LOW WILL MOVE FROM THE SOUTHEAST TO THE NORTHWEST BRINGING
THE CHANCE FOR STEADIER PRECIPITATION EAST OF KING SALMON THIS
AFTERNOON AND NEAR KILBUCK THIS EVENING. SNOW WITH RAIN WILL IMPACT
MUCH OF THE MAINLAND FROM THIS EVENING INTO TOMORROW EVENING AS THIS
SHORTWAVE STALLS.

BERING SEA AND ALEUTIANS...THE WINDS AND PRECIPITATION ASSOCIATED
WITH THE DUTCH HARBOR LOW WILL DIMINISH TODAY AS THE LOW PRESSURE
CONTINUES TO MOVE TO THE EAST. ONLY SCATTERED OR ISOLATED SHOWERS ARE
EXPECTED AS A SERIES OF WEAK DISTURBANCES MOVE ACROSS THE ALEUTIANS
ALTHOUGH GALE FORCE WINDS ARE A POSSIBILITY.

.LONG TERM FORECAST...AN ACTIVE PATTERN WILL CONTINUE OVER THE NEXT
WEEK AS A SERIES OF UPPER LEVEL WAVES MOVE ACROSS THE ALASKA. THE
PROXIMITY OF THE JET WILL CONTINUE TO SUPPORT THE DEVELOPMENT OF
SURFACE LOWS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE...120 125 132 138 150 155 170 171 172 175 176
         HEAVY FREEZING SPRAY...160 165
FIRE WEATHER...NONE.

ELN MAR 10