Gale Warning 341, NWS Anchorage, AK

909 
FZAK62 PAFC 051113
OFFALU

OFFSHORE WATERS FORECAST
NATIONAL WEATHER SERVICE ANCHORAGE AK
313 AM AKDT SAT APR 5 2014

OFFSHORE WATERS FORECAST FOR THE BERING SEA

WIND FORECASTS REFLECT THE PREDOMINANT SPEED AND DIRECTION
EXPECTED. SEA FORECASTS REPRESENT AN AVERAGE OF THE HIGHEST
ONE-THIRD OF THE COMBINED WIND WAVE AND SWELL HEIGHT.

PKZ499-060130-
313 AM AKDT SAT APR 5 2014
.SYNOPSIS FOR CENTRAL BERING SEA...

A 990 MB LOW 53N 162W WILL EXIT TO THE NORTH PACIFIC THIS
AFTERNOON. A FRONT OVER THE NORTHWEST PACIFIC WILL MOVE ACROSS
THE WESTERN BERING SEA AND ALEUTIANS TONIGHT THROUGH LATE SUN.

$$

PKZ411-060130-
BERING SEA OFFSHORE WEST OF 180 AND EAST OF THE INTERNATIONAL
DATELINE-
313 AM AKDT SAT APR 5 2014

.TODAY...NW WIND UP TO 15 KT BECOMING SW IN THE AFTERNOON. SEAS 3
TO 8 FT. FREEZING SPRAY.
.TONIGHT...SE WIND 15 TO 25 KT. SEAS 3 TO 8 FT.
.SUN...S WIND 20 TO 30 KT. SEAS 6 TO 11 FT. PATCHY FOG. RAIN AND SNOW.
FREEZING SPRAY N OF 58N.
.SUN NIGHT...SW WIND 10 TO 25 KT. SEAS 10 FT.
.MON THROUGH TUE...SE WIND 20 TO 35 KT. SEAS 9 TO 16 FT.
.WED...E WIND 15 TO 25 KT. SEAS 9 TO 13 FT.

$$

PKZ412-060130-
BERING SEA OFFSHORE 171W TO 180 AND NORTH OF 56N-
313 AM AKDT SAT APR 5 2014

...HEAVY FREEZING SPRAY WARNING THROUGH TONIGHT...

.TODAY...N WIND 15 TO 30 KT. SEAS 4 TO 9 FT. HEAVY FREEZING SPRAY.
.TONIGHT...NE WIND 10 TO 25 KT. SEAS 3 TO 6 FT. HEAVY FREEZING
SPRAY.
.SUN...E WIND 10 TO 20 KT. SEAS 4 FT. PATCHY FOG. RAIN AND SNOW.
FREEZING SPRAY IN THE MORNING.
.SUN NIGHT...SE WIND 10 TO 25 KT. SEAS 3 TO 8 FT.
.MON THROUGH WED...E WIND 20 TO 35 KT. SEAS 8 TO 13 FT.

$$

PKZ413-060130-
BERING SEA OFFSHORE 171W TO 180 AND SOUTH OF 56N-
313 AM AKDT SAT APR 5 2014

.TODAY...N WIND 15 TO 30 KT. SEAS 8 TO 13 FT. FREEZING SPRAY.
.TONIGHT...N WIND 10 TO 25 KT. SEAS 4 TO 9 FT. FREEZING SPRAY.
.SUN...SE WIND 10 TO 25 KT. SEAS 3 TO 7 FT. PATCHY FOG. RAIN AND SNOW.
.SUN NIGHT...S WIND 10 TO 25 KT. SEAS 3 TO 8 FT.
.MON THROUGH WED...SE WIND 20 TO 35 KT. SEAS 7 TO 12 FT.

$$

PKZ414-060130-
BERING SEA OFFSHORE EAST OF 171W-
313 AM AKDT SAT APR 5 2014

...HEAVY FREEZING SPRAY WARNING THROUGH SUNDAY...

.TODAY...N WIND 20 TO 30 KT. SEAS 6 TO 11 FT. HEAVY FREEZING SPRAY.
.TONIGHT...N WIND 30 KT. SEAS 4 TO 9 FT. HEAVY FREEZING SPRAY.
.SUN...N WIND 10 TO 25 KT. SEAS 3 TO 7 FT. HEAVY FREEZING SPRAY.
.SUN NIGHT...N WIND UP TO 20 KT. SEAS 3 TO 6 FT.
.MON THROUGH WED...E WIND 15 TO 30 KT. SEAS 4 TO 9 FT.

$$

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
1250 PM AKDT FRI APR 4 2014

.ANALYSIS AND UPPER LEVELS...A LARGE MULTI-CENTERED UPPER LEVEL
CLOSED LOW IS CENTERED NEAR THE EASTERN ALEUTIANS AND SOUTHERN
ALASKA PENINSULA. A BUILDING UPSTREAM RIDGE HAS CAUSED ENERGY
TO DIVE SOUTHWARD ON THE BACK SIDE OF THE UPPER LOW RESULTING IN
AMPLIFICATION OF THE LONG-WAVE TROUGH. THIS IN TURN IS HELPING TO
PUSH A TRIPLE POINT LOW AND FRONTAL SYSTEM NORTHWARD ACROSS THE
GULF OF ALASKA TOWARD SOUTHCENTRAL. THE BULK OF PRECIP WITH THIS
IS OFFSHORE AT THE MOMENT...BUT WILL OVERSPREAD THE NORTH GULF
COAST THIS AFTERNOON AND EVENING. MEANWHILE...A SHORT-WAVE TROUGH
WHICH MOVED OUT OF SIBERIA IS DIGGING SOUTHEASTWARD TOWARD WESTERN
ALASKA...BRINGING ARCTIC AIR WITH IT.

&&

.MODEL DISCUSSION...MODELS INITIALIZED WELL AND GENERALLY SHOW
GOOD AGREEMENT WITH SYNOPTIC SCALE FEATURES AFFECTING THE FORECAST
AREA. THE 12Z NAM IS AN OUTLIER WITH ITS DEPICTION OF A MORE
ELONGATED TRIPLE POINT LOW ALONG THE NORTHWEST GULF
COAST...ALTHOUGH THE 18Z RUN NOW LOOKS MORE SIMILAR TO THE OTHER
MODELS. MODELS HAVE BEGUN TO SHOW SOME RUN-TO-RUN CONSISTENCY
WITH SECONDARY ARCTIC TROUGH DIGGING ACROSS MAINLAND ALASKA SUNDAY
NIGHT AND MONDAY. THUS...FORECAST CONFIDENCE FOR ACCUMULATING SNOW
OVER PORTIONS OF SOUTHCENTRAL (INCLUDING ANCHORAGE AND THE MAT-SU)
SUNDAY NIGHT AND MONDAY IS INCREASING.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...THE SHORT-WAVE TROUGH MOVING OUT OF THE
ARCTIC WILL CROSS WESTERN ALASKA TONIGHT AND SATURDAY AND HELP TO
SLOW THE NORTHWARD PROGRESSION OF THE SYSTEM OVER THE GULF. IN
FACT THE FRONTAL SYSTEM WILL DISSIPATE JUST OFFSHORE WHICH WILL
CONFINE THE BULK OF PRECIPITATION TO COASTAL AREAS. THE ARCTIC
TROUGH WILL STALL OVER INTERIOR ALASKA...BUT WILL COME CLOSE
ENOUGH TO SOUTHCENTRAL LATE SATURDAY TO GENERATE SOME WEAK
VERTICAL MOTION. THUS...EXPECT AREAS OF LIGHT PRECIPITATION TO
DEVELOP ACROSS INLAND AREAS OF SOUTHCENTRAL SATURDAY AFTERNOON
THROUGH SUNDAY. WEAK WAVES WILL ALSO CONTINUE TO MOVE UP FROM THE
GULF AND CONTRIBUTE TO PRECIPITATION. TEMPERATURES DURING THE DAY
WILL BE WARM ENOUGH FOR ALL RAIN ALONG THE COAST. LOW LEVEL
THICKNESSES SUPPORT MAINLY SNOW INLAND...ALTHOUGH SURFACE
TEMPERATURES WILL RISE ABOVE FREEZING IN MANY LOCATIONS SO EXPECT
LITTLE OR NO ACCUMULATION...ESPECIALLY ON PAVED SURFACES.

THE BIGGER EVENT LOOKS TO BE SUNDAY NIGHT INTO MONDAY AS A
REINFORCING TROUGH DIGS OUT OF THE ARCTIC AND ACROSS SOUTHWEST
ALASKA INTO THE WESTERN GULF AND COOK INLET. WITH DEEP MOISTURE
ALREADY IN PLACE AT THE ONSET AND COLD AIR FILTERING IN FROM THE
WEST THERE IS POTENTIAL FOR SEVERAL INCHES OF SNOW ALONG THE COOK
INLET TO MAT-SU CORRIDOR. THERE IS STILL SOME UNCERTAINTY IN THE
EXACT ORIENTATION AND AMPLITUDE OF THE TROUGH WHICH WILL DETERMINE
WHICH AREAS SEE THE MOST SNOW OUT OF THIS.

SOUTHWEST ALASKA...AS THE LONG-WAVE TROUGH CONTINUES TO AMPLIFY
TONIGHT AND SATURDAY THE LOW OVER THE EASTERN ALEUTIANS AND
ALASKA PENINSULA WILL DROP SOUTHWARD INTO THE NORTH PACIFIC AND
THE FRONT CURRENTLY SITTING OVER THE BRISTOL BAY WILL RAPIDLY
DISSIPATE. THE APPROACHING ARCTIC TROUGH WILL GENERATE SOME LIGHT
SNOW AS IT MOVES THROUGH LATE TONIGHT THROUGH SATURDAY...BUT SWIFT
MOVEMENT MEANS SNOW WILL BE SHORT-LIVED IN ANY ONE AREA. THE
SECOND TROUGH WILL MOVE THROUGH ON MONDAY PROVIDING A REINFORCING
SHOT OF ARCTIC AIR AND SETTING UP COLDER AND DRIER CONDITIONS AS
WE HEAD INTO THE NEW WEEK.

BERING SEA/ALEUTIANS...AS THE CURRENT LOW/TROUGH SHIFTS SOUTH AND
EASTWARD A RIDGE WILL BUILD IN FROM THE WEST. THIS WILL BE SHORT-
LIVED AS ANOTHER LARGE CLOSED LOW MOVES OUT OF ASIA INTO THE
WESTERN BERING SUNDAY AND MONDAY. THIS SYSTEM WILL SET UP SHOP
OVER THE BERING SEA NEXT WEEK.

&&

.LONG TERM FORECAST...THE UPPER TROUGH OVER MAINLAND ALASKA THIS
WEEKEND WILL EXIT EARLY NEXT WEEK WITH THE UPPER LEVELS REMAINING
FAIRLY PROGRESSIVE. PRIOR MODEL RUNS HAD INDICATED A FAIRLY ROBUST
BLOCKING RIDGE SETTING UP OVER WESTERN ALASKA AND KEEPING THE
MAINLAND DRY THROUGH ALL OF NEXT WEEK. THE LATEST SOLUTIONS HAVE
BACKED OFF ON THE STRENGTH OF THE RIDGE...ALLOWING THE BERING
TROUGH TO PENETRATE THE MAINLAND BY LATE NEXT WEEK. IN EITHERCASE...THERE
WILL BE A FEW DAYS OF DRY AND COOL WEATHER OVER THE MAINLAND WHILE
WEATHER ACROSS THE BERING SEA AND ALEUTIANS WILL REMAIN UNSETTLED.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING...119 120 131 170 171 173 174 175 176 177
                        179 181 185.
         HEAVY FREEZING SPRAY 179 180 185.
FIRE WEATHER...NONE.
&&

SEB APR 14