Storm Warning 54, NWS Anchorage, AK

307 
FZAK62 PAFC 091123
OFFALU

OFFSHORE WATERS FORECAST
NATIONAL WEATHER SERVICE ANCHORAGE AK
323 AM AKDT THU APR 9 2015

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.

PKZ499-100145-
323 AM AKDT THU APR 9 2015
.SYNOPSIS FOR CENTRAL BERING SEA...
A 978 MB LOW NEAR 58N 160W MOVES INLAND INTO SOUTHWEST ALASKA THIS
MORNING. THE BERING SEA WILL REMAIN IN WESTERLY FLOW THROUGH SAT
AFTERNOON.

$$

PKZ411-100145-
BERING SEA OFFSHORE WEST OF 180 AND EAST OF THE INTERNATIONAL
DATELINE-
323 AM AKDT THU APR 9 2015

.TODAY...W WIND 20 TO 30 KT. SEAS 12 FT. SNOW SHOWERS. FREEZING
SPRAY.
.TONIGHT...W WIND 20 TO 30 KT. SEAS 10 TO 13 FT. SNOW SHOWERS.
FREEZING SPRAY.
.FRI...W WIND 15 TO 30 KT. SEAS 9 TO 12 FT. SNOW SHOWERS. FREEZING
SPRAY.
.FRI NIGHT...NW WIND 15 TO 30 KT. SEAS 8 TO 11 FT.
.SAT THROUGH MON...NW WIND 10 TO 25 KT. SEAS 5 TO 10 FT.

$$

PKZ412-100145-
BERING SEA OFFSHORE 171W TO 180 AND NORTH OF 56N-
323 AM AKDT THU APR 9 2015

...GALE WARNING THROUGH TONIGHT...

.TODAY...W WIND 15 TO 25 KT INCREASING TO 20 TO 35 KT IN THE
AFTERNOON. SEAS 7 TO 12 FT. SNOW SHOWERS. FREEZING SPRAY.
.TONIGHT...NW WIND 20 TO 35 KT DIMINISHING TO 15 TO 25 KT AFTER
MIDNIGHT. SEAS 7 TO 12 FT. SNOW SHOWERS. FREEZING SPRAY.
.FRI...NW WIND 10 TO 25 KT. SEAS 7 TO 12 FT. SNOW SHOWERS.
FREEZING SPRAY.
.FRI NIGHT...NW WIND 15 TO 25 KT. SEAS 5 TO 10 FT.
.SAT THROUGH MON...N WIND 10 TO 25 KT. SEAS 4 TO 9 FT.

$$

PKZ413-100145-
BERING SEA OFFSHORE 171W TO 180 AND SOUTH OF 56N-
323 AM AKDT THU APR 9 2015

...GALE WARNING TONIGHT...

.TODAY...W WIND 20 TO 30 KT. SEAS 11 TO 16 FT. SNOW SHOWERS.
.TONIGHT...W WIND 20 TO 35 KT. SEAS 13 FT. SNOW SHOWERS.
.FRI...W WIND 20 TO 30 KT. SEAS 13 FT. SNOW SHOWERS. FREEZING SPRAY.
.FRI NIGHT...W WIND 30 KT. SEAS 12 FT.
.SAT...NW WIND 20 TO 30 KT. SEAS 9 TO 13 FT.
.SUN...NW WIND UP TO 20 KT. SEAS 4 TO 9 FT.
.MON...N WIND 10 TO 25 KT. SEAS 4 TO 9 FT.

$$

PKZ414-100145-
BERING SEA OFFSHORE EAST OF 171W-
323 AM AKDT THU APR 9 2015

...GALE WARNING THROUGH TONIGHT...
...HEAVY FREEZING SPRAY WARNING THROUGH FRIDAY...

.TODAY...NW WIND 30 TO 45 KT. SEAS 10 TO 18 FT. SNOW SHOWERS.
HEAVY FREEZING SPRAY NEAR THE ICE EDGE.
.TONIGHT...NW WIND 25 TO 40 KT. SEAS 8 TO 13 FT. HEAVY FREEZING
SPRAY NEAR THE ICE EDGE.
.FRI...W WIND 15 TO 30 KT. SEAS 7 TO 12 FT. SNOW SHOWERS. HEAVY
FREEZING SPRAY NEAR THE ICE EDGE.
.FRI NIGHT...W WIND 15 TO 30 KT. SEAS 5 TO 10 FT.
.SAT THROUGH SUN...NW WIND 15 TO 30 KT. SEAS 5 TO 10 FT.
.MON...N WIND 10 TO 20 KT. SEAS 3 TO 7 FT.

$$

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
442 AM AKDT WED APR 8 2015

.ANALYSIS AND UPPER LEVELS...
AN UPPER LEVEL NEGATIVELY TILTED TROUGH IS POSITIONED OVER THE
WESTERN GULF EXTENDING THROUGH THE SOUTHERN KENAI PENINSULA
INTO THE ALASKA RANGE. RADAR IMAGERY IS SHOWING NUMEROUS RAIN
SHOWERS ACROSS THE SOUTHCENTRAL REGION AND THE NORTHERN GULF
COASTAL AREAS. THE ANCHORAGE BOWL CONTINUES TO DOWNSLOPE-OUT
RESULTING IN DRIER CONDITIONS. WHILE...UPSTREAM THERE IS A WEAK
RIDGE OVER THE BRISTOL BAY REGION WITH A CLOSED LOW OVER THE
CENTRAL BERING SEA. THE SATELLITE IMAGERY IS SHOWING LOW STRATUS
OVER THE EASTERN BERING AND BRISTOL BAY REGION THIS MORNING.

WHILE...REFLECTED AT THE SURFACE...THERE IS A STORM FORCE LOW IN
THE WESTERN BERING SEA WITH A FRONTAL BOUNDARY EXTENDING THROUGH
THE PRIBILOF ISLAND SOUTHWARD EXTENDING THROUGH THE EASTERN
ALEUTIANS EAST OF DUTCH HARBOR THIS MORNING. THIS SYSTEM HAS GOOD
SUPPORT WITH A STRONG 160 KNOT ZONAL JET STREAM LOCATED FROM THE
WESTERN ALEUTIANS EXTENDING THROUGH THE LOWER CENTRAL/EASTERN
BERING SEA. THE SATELLITE IMAGERY IS SHOWING LARGE SWATH OF
MOISTURE WITH THE AFOREMENTIONED SYSTEM WITH RAIN/SNOW
MIXTURE ALONG THE ALEUTAINS. AS YOU MOVE FARTHER NORTH INTO THE
BERING THE PRECIPITATION TURNS TO ALL SNOW SHOWERS WITH GUSTY
WESTERLY WINDS AS THE KAMCHATKA LOW MOVES EASTWARD ACROSS THE
BERING.

&&

.MODEL DISCUSSION...
THE MODELS WERE IN GOOD AGREEMENT WITH THE STORM FORCE LOW OVER
THE WESTERN GULF AND THE FRONTAL BOUNDARY POSITIONED OVER THE
PRIBILOF ISLAND THIS MORNING. THE NAM/GEM-REG WERE THE PREFERRED
MODELS. THE FORECAST CONFIDENCE REMAINS ABOVE AVERAGE HEADING INTO
THE END OF THE WEEK.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
AN UPPER LEVEL TROUGH WILL PUSH THROUGH SOUTH CENTRAL ALASKA TODAY
FROM THE WEST. THIS SYSTEM IS FAIRLY COLD ALOFT AND WILL PROVIDE
GOOD CHANCES OF SNOW TO MUCH OF THE AREA. THE EXCEPTION IS THE
COPPER RIVER BASIN WHERE POPS ARE FAIRLY LOW...AS BY THE TIME THE
TROUGH REACHES THAT AREA (TONIGHT) IT WILL HAVE WEAKENED
CONSIDERABLY. A FRONT ASSOCIATED WITH A LOW RACING EASTWARD ACROSS
THE BERING SEA WILL MOVE INTO KODIAK ISLAND AND THE WESTERN GULF
THIS EVENING...THEN PUSH EAST INTO THE REST OF SOUTH CENTRAL LATE
TONIGHT INTO THURSDAY. THE LOW ITSELF WILL CONTINUE TO DRIVE EAST
AND WILL BE CENTERED JUST NORTH OF KODIAK ISLAND BY LATE THURSDAY
NIGHT. THIS SYSTEM IS ALSO FAIRLY COLD (ALOFT) BUT DUE TO THE
LOCATION OF ITS TRACK AND ITS ORIENTATION THE FRONT ITSELF WILL
NOT PUSH VERY FAR INLAND. THIS CREATES A BIT OF A CHALLENGE FOR
PRECIPITATION FORECASTS FOR THURSDAY AND THURSDAY NIGHT...IN JUST
HOW FAR NORTH THE PRECIPITATION WILL REACH.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (TODAY THROUGH FRI NIGHT)...

PRECIPITATION CHANCES WILL BE ON THE RISE LATE THIS MORNING AS A
RAPIDLY DEVELOPING AREA OF LOW PRESSURE IN THE BERING SEA PUSHES
A FRONT ACROSS SOUTHWEST ALASKA THIS AFTERNOON. THE MAJORITY OF
THE PRECIPITATION IS EXPECTED TO FALL AS SNOW ACROSS SOUTHWEST
ALASKA WITH THE EXCEPTION OF THE ALASKA PENINSULA WHERE SFC
TEMPERATURES SHOULD WARM ENOUGH ABOVE FREEZING TO MELT ANY SNOW TO
RAIN PRIOR TO REACHING THE GROUND. THE AFOREMENTIONED AREA OF LOW
PRESSURE WILL MOVE INLAND NEAR BRISTOL BAY EARLY THURSDAY MORNING
AND CONTINUE INTO SOUTHCENTRAL ALASKA. AS THIS HAPPENS...THE
PRESSURE GRADIENT WILL FLIP AND THE SOUTHEASTERLY WINDS SEEN WITH
THE FRONT MOVING INLAND WILL FLIP TO THE NORTHWEST AND BRING SOME
GUSTY WINDS TO THE KUSKOKWIM DELTA THURSDAY AFTERNOON AND
PERSISTING INTO FRIDAY. WHILE PRECIPITATION IS EXPECTED TO BE MORE
SHOWERY AS COLDER AIR FILTERS IN AND MAKES THE ATMOSPHERE QUITE
UNSTABLE...THE GUSTY NORTHERLY WINDS SHOULD CREATE SOME BLOWING
SNOW CONDITIONS ACROSS COASTAL REGIONS OF THE KUSKOKWIM DELTA.
VISIBILITIES COULD OCCASIONALLY DROP TO ONE MILE OR LESS AT
TIMES...BUT NOTHING SIGNIFICANT ENOUGH TO WARRANT AN ADVISORY OR
WARNING AT THIS TIME.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (TODAY THROUGH FRI NIGHT)...

THE MAIN FEATURE OF NOTE IN THE SHORT-TERM IS A RAPIDLY DEVELOPING
AREA OF LOW PRESSURE CURRENTLY SITUATED NEAR 57N 180. WHILE THE
INTENSITY OF THE LOW (973 MB) IS NOTHING TOO UNUSUAL FOR THE
BERING SEA...A VERY POTENT 500 MB JET (130 KT) AND 300 MB JET
(160+ KT) WILL AID IN BRINGING DOWN STRONG WINDS TO THE SURFACE.
MUCH OF THE BERING SEA WILL OBSERVE GALE FORCE WINDS BUT AREAS
JUST TO THE SOUTH OF THE LOW WILL FEEL THE IMPACT OF THE JET
STREAK WITH 50 TO 55 KT WINDS AT THE SFC. THE PRIBILOF ISLANDS
WILL HAVE A PERIOD OF BLOWING SNOW AS SNOW INTENSITY AND WINDS
GUSTING UPWARDS TO 50 MPH WILL DROP VISIBILITIES TO ONE MILE OR
LESS. THE ONE SAVING GRACE PREVENTING AN ADVISORY OR WARNING IS
THAT SFC TEMPERATURES ARE EXPECTED TO BE NEAR OR ABOVE FREEZING
WHICH SHOULD KEEP THE SNOW WET AND HARDER TO BLOW AROUND.
FOLLOWING THE LOW MOVING INLAND...A MUCH COLDER AIR MASS FROM
SIBERIA WILL BE ADVECTED OVER THE BERING SEA. THIS WILL
DESTABILIZE THE AIR MASS AND KEEP NUMEROUS SNOW SHOWERS IN THE
FORECAST OVER MUCH OF THE BERING SEA THROUGH THE REMAINDER OF THE
WEEK.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...

MODELS ARE IN AGREEMENT WITH THE ONSET OF UPPER LEVEL ZONAL FLOW
THU NIGHT THROUGH SUN. A 120 TO 150 KT JET WILL REMAIN NEAR 45N
AND EXTEND FROM NORTHERN JAPAN TO THE PACIFIC NORTHWEST. THIS
FEATURE WILL KEEP CYCLONIC FLOW OVER THE ENTIRE FORECAST AREA
THROUGH SUN. AT THAT TIME THE JET WILL BUCKLE...AND THE CYCLONIC
CIRCULATION WILL BREAK DOWN INTO A RIDGE OVER THE MAINLAND AND A
DEEP TROUGH SOUTH OF THE BERING BEGINNING ON MON. AT THE
SURFACE...A LOW CROSSING THE AKPEN WILL MOVE TO THE NORTHERN GULF
THU NIGHT. MODELS ARE HAVING A DIFFICULT TIME DETERMINING A TRACK
FOR THIS LOW. WPC USED AN ENSEMBLE APPROACH THAT BY FRI NIGHT
MOVES THE LOW WELL SOUTH OF CAPE SAINT ELIAS AND THEN BROADENS IT
OVER THE NORTH GULF COAST THROUGH EARLY NEXT WEEK. IN THE
WEST...WEST TO NORTHWEST FLOW WILL PERSIST OVER THE BERING AND
ALEUTIANS INTO NEXT WEEK. THE FORECAST UTILIZED THE EC UNTIL FRI
EVENING AND THEN TRANSITIONED TO WPC GUIDANCE.

SNOW SHOWERS WILL PERSIST OVER THE BERING...ALEUTIANS...AND SW AK
WITH WIDESPREAD GALE FORCE WINDS GRADUALLY DIMINISHING TO SMALL
CRAFT BY EARLY NEXT WEEK. IN THE EAST...RAIN IS EXPECTED ALONG THE
COAST...WITH DAYTIME RAIN SHOWERS AND NIGHTTIME SNOW SHOWERS
CROSSING THE KENAI AND CHUGACH MOUNTAINS. THESE WILL DIMINISH IN
INTENSITY AT THE END OF THE WEEKEND AS HIGH PRESSURE MOVES ACROSS
THE MAINLAND.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...STORM WARNING 170 173.
         GALE WARNING 119 120 125 130 131 132 150 155
         160 165 171 172 174175 176 177 178 179 180 181.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...PD
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MC
LONG TERM...DS