Heavy Freezing Spray Warning 39, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 PM AKST TUE FEB 8 2011

.MODEL DISCUSSION...MODELS ARE IN REASONABLE AGREEMENT...ESPECIALLY
BETWEEN THE GFS AND ECMWF. NAM IS HAVING A LITTLE MORE TROUBLE WITH
THE TRIPLE POINT LOW DEVELOPING IN THE BERING SEA. OVERALL THE MODELS
SEEM TO HAVE CAUGHT THE DEVELOPING PATTERN QUITE WELL.

.ANALYSIS AND UPPER LEVELS...THERE IS A SOMEWHAT PROGRESSIVE PATTERN
OVER THE REGION TODAY. A LARGE UPPER LEVEL RIDGE OVER THE WEST COAST
OF NORTH AMERICA EXTENDS NORTHWARD AND OVER THE AL-CAN BORDER AND A
LONG WAVE TROUGH HAS DUG DOWN THE WESTERN COAST OF THE STATE AND OVER
THE ALASKA PENINSULA. THESE FEATURES WILL BE MOVING SLOWLY BUT
STEADILY EASTWARD OVER THE NEXT FEW DAYS AS ANOTHER UPPER LEVEL RIDGE
BUILDS OVER THE CENTRAL BERING SEA BY THURSDAY.
A SURFACE LOW SOUTHWEST OF KODIAK IS MOVING NORTHWARD TODAY WITH A
FRONT EXTENDING FROM IT INTO THE NORTHERN GULF OF ALASKA.

.SHORT TERM FORECAST...
SOUTH CENTRAL ALASKA...A STACKED LOW WILL MOVE THROUGH BRISTOL BAY
TONIGHT AND WEAKEN. A RESULTANT SOUTHEASTERLY FLOW ALOFT BRINGING
PLENTY OF MOISTURE INTO THE AREA OFF THE GULF OF ALASKA. WE ARE
EXPECTING CONTINUED SNOWFALL UP THE SUSITNA VALLEY ENOUGH FOR AN
ADVISORY. WITH THE SURFACE LOW AND SOUTHEAST FLOW ALOFT...TURNAGAIN
ARM WINDS ARE CONTINUING NEAR 45 TO 60 MPH. THIS IS RESULTING IN THE
TYPICAL PRECIPITATION FREE AREAS OF THE WESTERN KENAI...MAT VALLEY
AND ANCHORAGE BOWL. HOWEVER...PLENTY OF PRECIPITATION ALONG THE COAST
AND IN THE WESTERN SUSITNA VALLEY. COMBINED WITH HIGH WINDS AND
PRECIPITATION...PORTAGE VALLEY WILL REMAIN IN BLIZZARD CONDITIONS FOR
THE EVENING. THE SURFACE LOW AND UPPER LEVEL WAVE TO PASS THROUGH THE
AREA WEDNESDAY CHANGING THE FLOW TO MORE SOUTHWEST AND BRINGING MORE
WIDESPREAD PRECIPITATION. THE SYSTEM WILL MOVE THROUGH BY TOMORROW
NIGHT WITH PRECIP BECOMING ISOLATED. ANOTHER LOW TO MOVE OUT OF THE
NORTH PACIFIC AND INTO THE GULF LATE THURSDAY. THIS LOW WILL BE
MAINLY IN THE EASTERN GULF WITH THE BULK OF THE PRECIPITATION VALDEZ
EASTWARD. HOWEVER...MODERATE TO STRONG GAP WINDS ARE POSSIBLE FROM
THE BARREN ISLANDS SOUTHWEST THROUGH SHELIKOF STRAIT.

SOUTHWEST ALASKA...THE STACKED LOW TO MOVE THROUGH THE AREA TONIGHT.
STILL EXPECTING STRONG GAP WINDS NEAR THE LOW THIS EVENING BEFORE IT
WEAKENS CONSIDERABLY OVERNIGHT. THE LOW WILL SWING INTO SOUTH CENTRAL
TOMORROW AND INTO EASTERN ALASKA WEDNESDAY NIGHT. THIS WILL MEAN
WIDESPREAD PRECIPITATION OVER THE AREA THROUGH MUCH OF WEDNESDAY.
PRECIPITATION TO END OVER THE AREA WEDNESDAY NIGHT WITH LITTLE CHANCE
OF PRECIPITATION THROUGH THURSDAY BEFORE A LOW MOVES INTO THE
NORTHERN BERING FRIDAY AND BRINGS A CHANCE TO THE WEST COAST FRIDAY
AFTERNOON.

ALEUTIANS AND BERING...THE LOW IN BRISTOL BAY BRINGING SHOWERS ALL
THE WAY INTO THE CENTRAL BERING. A WEAK LOW OVER NORTHWEST BERING SEA
BRINGING MODERATE WINDS AND RAIN TO SHEMYA. THE FRONT WILL WORK TO
THE CENTRAL BERING BY WEDNESDAY AFTERNOON AND HIT HIGH PRESSURE AND
WEAKEN. ANOTHER LOW TO PUSH ACROSS THE KAMCHATKA PENINSULA THURSDAY
AND BRING ANOTHER SHOT OF MODERATE WINDS AND PRECIPITATION TO THE
WESTERN BERING AND ALEUTIANS THURSDAY AND RIDE THROUGH THE CENTRAL
BERING THURSDAY NIGHT. THE LOW WILL REMAIN OVER THE NORTHERN BERING
SEA FRIDAY WITH WIDESPREAD LIGHT TO MODERATE PRECIPITATION OVER THE
BERING AND ISOLATED TO SCATTERED PRECIPITATION ALONG THE ALEUTIANS.
WINDS WILL BE NEAR GALE FORCE CLOSER TO THE LOW.

.LONG TERM FORECAST...A MORE STABLE PATTERN SETS UP OVER THE WEEKEND
WITH A LARGE LOW IN THE GULF AND A LARGE LOW NEAR THE KAMCHATKA
PENINSULA. A SKINNY RIDGE TO REMAIN OVER THE CENTRAL AND EASTERN
BERING INTO EARLY NEXT WEEK. THE BIG QUESTION IS THE BREAK THROUGH OF
THE RIDGE BY A FRONT BY TUESDAY. THE MORE STABLE SOLUTION WOULD
SUGGEST THE RIDGE HOLDING AND WEAKENING THE FRONT. THE RIDGE WILL
THEN REBOUND. SO...MORE OF A WET PANHANDLE WITH STRONG WESTERLY GAP
WINDS IN SOUTH CENTRAL OVER THE LATER WEEKEND INTO MID WEEK RIGHT
NOW. FOR THE SOUTHWEST...DRY WITH AKPEN GAP WINDS. FOR THE ALEUTIANS
AND BERING...STRONG WINDS AND LOTS OF PRECIPITATION AND WARMER THAN
NORMAL OVER THE CENTRAL AND WESTERN BERING. DRY AND COOL FOR THE MOST
PART OF THE EASTERN BERING.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...WINTER WEATHER ADVISORY FOR SNOW 145.
MARINE...GALE 120 125 129 130 132 140 150 170 172 175 176 179.
         HEAVY FREEZING SPRAY 179 185.
FIRE WEATHER...NONE.

FEB 11