Brisk Wind Advisory 37, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
1235 PM AKDT FRI MAR 15 2013

.ANALYSIS AND UPPER LEVELS...A STRONG BLOCKING HIGH IS CENTERED OVER
THE BEAUFORT SEA WITH AN EQUALLY STRONG ANCHOR LOW CENTERED OVER THE
SEA OF OKHOTSK. ENERGY IS EJECTING OUT OF THE ANCHOR LOW AND DRIVING
A SURFACE FRONTAL SYSTEM EASTWARD ACROSS THE CENTRAL BERING SEA AND
ALEUTIANS THIS MORNING. DOWNSTREAM OVER SOUTHWEST ALASKA A TROUGH IS
SHEARING APART AS THE NORTHERN SECTION HEADS NORTHWESTWARD BETWEEN
THE UPPER HIGH AND LOW AND THE SOUTHERN SECTION HEADS EASTWARD INTO
THE GULF OF ALASKA. CORRESPONDINGLY AN AREA OF SNOW SITTING OVER
SOUTHWEST ALASKA FROM AROUND KING SALMON NORTHWEST TO ANIAK IS
DIMINISHING. FINALLY A WEAK TO MODERATE STRENGTH LOW OVER THE
EASTERN GULF IS TRACKING NORTHWARD HAS BEGUN TO SLOW ITS PROGRESS
AND TURN NORTHWESTWARD THANKS TO THE RIDGE SITTING TO THE NORTH.

.MODEL DISCUSSION...MODELS CONTINUE TO DISPLAY MINOR DIFFERENCES
WITH LOW OVER THE EASTERN GULF AND THE TWO TRIPLE POINT LOWS WHICH
FORM ALONG THE BERING FRONT TODAY AND TONIGHT. ECMWF SHOWS THE BEST
RUN-TO-RUN CONSISTENCY AND IS PREFERRED. MODELS HAVE ALSO COME INTO
GOOD AGREEMENT (WITH THE ECMWF) IN TRACK OF NEXT LOW CROSSING THE
NORTHERN BERING AND DEEP LOW DEVELOPING SOUTH OF THE ALEUTIANS
OVER THE WEEKEND. THUS...FORECAST CONFIDENCE FOR THE SHORT-TERM
IS ABOVE AVERAGE.

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...THE EASTERN GULF LOW WILL STALL AND WEAKEN
OVER THE NORTHERN GULF. THIS LOW IS QUIET COMPACT...SO WINDS AND
PRECIP WILL STAY CLOSE TO THE LOW CENTER AND HAVE LITTLE OR NO
IMPACT ON LAND AREAS ALONG PRINCE WILLIAM SOUND. MEANWHILE AS THE
BERING SEA FRONT CROSSES THE ALASKA PENINSULA A TRIPLE POINT LOW
WILL DEVELOP AND TRACK EASTWARD ACROSS THE SOUTHERN GULF. THIS
WILL CAUSE THE FRONT TO QUICKLY FALL APART AS IT ENTERS THE WESTERN
GULF...ONCE AGAIN KEEPING PRECIP OUT OF SOUTHCENTRAL. ONE MORE
TROUGH WILL QUICKLY CROSS THE BERING THIS WEEKEND AND MOVE INTO
THE GULF MONDAY...AGAIN STAYING TO THE SOUTH. BOTTOM LINE...MOST
OF SOUTHCENTRAL WILL STAY COOL AND DRY.

SOUTHWEST ALASKA...THE BERING SEA FRONT WILL ARRIVE ALONG THE
SOUTHWEST COAST THIS EVENING AND THEN QUICKLY WEAKEN TONIGHT
THROUGH SATURDAY MORNING AS THE ENERGY SPLITS...SOME HEADING
NORTHWARD ALONG THE WEST COAST OF ALASKA AND SOME MOVING EASTWARD
INTO THE GULF. THEREFORE...ANY SNOW THAT DOES MAKE ITS WAY INLAND
WILL BE LIGHT. A WINTER WEATHER ADVISORY FOR BLOWING SNOW IS IN
EFFECT FOR THE KUSKOKWIM DELTA COAST BEGINNING THIS EVENING. BASED
ON THE SPEED OF THE FRONT AS WELL AS THE FACT THAT IT WILL BE
QUICKLY WEAKENING...THE WORST CONDITIONS WILL NOT BE VERY LONG-LIVED.
ANOTHER SYSTEM CROSSING THE BERING WILL RAPIDLY MOVE THROUGH ON
SUNDAY WITH SIMILAR IMPACTS AS THE FRONT MOVING THROUGH TONIGHT.
DRY AND COLD WEATHER IS ON TAP AFTER THIS SYSTEM AS A BLOCKING
RIDGE SETS UP OVER THE BERING SEA NEXT WEEK.

BERING SEA/ALEUTIANS...SYSTEMS WILL RAPIDLY MOVE ACROSS THE BERING
THROUGH SUNDAY THANKS TO STRONG WESTERLIES ALOFT. THE PATTERN WILL
SHIFT EARLY NEXT WEEK AS A HIGH AMPLITUDE BLOCKING RIDGE SETS UP
OVER THE BERING SEA. THIS WILL PUSH THE STORM TRACK SOUTH AND WEST
OF THE FORECAST AREA. THE ALEUTIANS WILL BE RIGHT BETWEEN THE RIDGE
AND STORMS PASSING TO THE SOUTH AND WEST...SO WILL STILL SEE SOME
IMPACT AT TIMES ALONG THE PERIPHERY OF THESE STORMS.

.LONG TERM FORECAST...GUIDANCE FROM THE WEATHER PREDICTION CENTER
AND CLIMATE PREDICTION CENTER INDICATE SUPPORT FOR A LONG-LIVED
BLOCKING RIDGE OVER THE BERING SEA. THEREFORE...EXPECT DRY AND COOL
CONDITIONS TO PERSIST ON THE EAST SIDE OF THIS RIDGE OVER MAINLAND
ALASKA. AS ARCTIC AIR SURGES SOUTHWARD THERE IS ALSO GOOD POTENTIAL
FOR STRONG WIND EVENTS ALONG THE GULF COAST. THE ALEUTIANS WILL
OCCASIONALLY SEE MORE ACTIVE WEATHER AS STORMS PASS BY...BUT WILL
LIKELY ALSO SEE SOME QUIET PERIODS IN BETWEEN.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE WARNING...176.
FIRE WEATHER...NONE.

SEB MAR 13