Storm Warning 92, NWS Anchorage, AK

011 
FZAK62 PAFC 121202
OFFALU

OFFSHORE WATERS FORECAST
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 AM AKDT MON APR 12 2010

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.

PKZ499-130200-
400 AM AKDT MON APR 12 2010
.SYNOPSIS FOR CENTRAL BERING SEA...

A WEATHER FRONT OVER THE CENTRAL GULF DISSIPATES MON. A STRONG
SECONDARY FRONT MOVES INTO THE WESTERN GULF MONDAY AND DISSIPATES
ALONG THE NORTH GULF COAST BY TUE MORNING. AN AREA OF LOW PRESSURE
MOVES INTO THE WESTERN GULF TUE AND REMAINS THROUGH TUE NIGHT.

$$

PKZ411-130200-
BERING SEA OFFSHORE WEST OF 180 AND EAST OF THE INTERNATIONAL
DATELINE
400 AM AKDT MON APR 12 2010

...GALE WARNING TODAY...

.TODAY...W WIND 40 KT. SEAS 21 FT. FREEZING SPRAY. 
.TONIGHT...W WIND 30 KT. SEAS 18 FT. FREEZING SPRAY. 
.TUE...W WIND 30 KT. SEAS 15 FT. FREEZING SPRAY. 
.TUE NIGHT...W WIND 30 KT. SEAS 14 FT. 
.WED...S WIND 40 KT. SEAS 13 FT. 
.THU...SW WIND 35 KT. SEAS 17 FT. 
.FRI...W WIND 30 KT. SEAS 17 FT.  

$$

PKZ412-130200-
BERING SEA OFFSHORE 171W TO 180 AND NORTH OF 56N
400 AM AKDT MON APR 12 2010

...STORM WARNING TODAY...

.TODAY...W WIND 50 KT. SEAS 24 FT. PATCHY FOG. SNOW AND RAIN SHOWERS.
.TONIGHT...W WIND 35 KT. SEAS 20 FT. 
.TUE...W WIND 30 KT. SEAS 17 FT. FREEZING SPRAY. 
.TUE NIGHT...NW WIND 25 KT. SEAS 14 FT. 
.WED...S WIND 35 KT. SEAS 11 FT. 
.THU...S WIND 40 KT. SEAS 13 FT. 
.FRI...SW WIND 25 KT. SEAS 14 FT.  

$$

PKZ413-130200-
BERING SEA OFFSHORE 171W TO 180 AND SOUTH OF 56N
400 AM AKDT MON APR 12 2010

...STORM WARNING TODAY...

.TODAY...W WIND 50 KT DIMINISHING TO 40 KT IN THE AFTERNOON. SEAS
26 FT. RAIN AND SNOW SHOWERS. 
.TONIGHT...W WIND 35 KT. SEAS 20 FT. SNOW AND RAIN SHOWERS. 
.TUE...W WIND 30 KT. SEAS 17 FT. 
.TUE NIGHT...W WIND 30 KT. SEAS 14 FT. 
.WED...SW WIND 40 KT. SEAS 12 FT. 
.THU...SW WIND 40 KT. SEAS 14 FT. 
.FRI...SW WIND 30 KT. SEAS 15 FT.  

$$

PKZ414-130200-
BERING SEA OFFSHORE EAST OF 171W
400 AM AKDT MON APR 12 2010

...STORM WARNING TODAY...

.TODAY...SW WIND 50 KT. SEAS IN ICE FREE WATERS 24 FT. PATCHY FOG.
RAIN SHOWERS WITH SNOW. 
.TONIGHT...SW WIND 35 KT. SEAS IN ICE FREE WATERS 22 FT. SNOW AND
RAIN SHOWERS. 
.TUE...SW WIND 25 KT. SEAS IN ICE FREE WATERS 15 FT.
.TUE NIGHT...W WIND 25 KT. SEAS IN ICE FREE WATERS 12 FT. 
.WED...W WIND 20 KT. SEAS IN ICE FREE WATERS 9 FT. 
.THU...S WIND 40 KT. SEAS IN ICE FREE WATERS 12 FT. 
.FRI...SW WIND 25 KT. SEAS IN ICE FREE WATERS 11 FT.  

$$

750 
FZAK62 PAFC 122315
OFFALU

OFFSHORE WATERS FORECAST
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 PM AKDT MON APR 12 2010

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.

PKZ499-131400-
400 PM AKDT MON APR 12 2010
.SYNOPSIS FOR CENTRAL BERING SEA...

A 976 MB LOW NEAR 62N 169W MOVES NORTH TOWARD NORTON SOUND TONIGHT. A
988 MB LOW NEAR 59N 179E MOVES EAST TOWARD 60N 172W AND DISSIPATES
TUESDAY MORNING. A FRONTAL BOUNDARY APPROACHES THE WESTERN ALEUTIANS
WEDNESDAY AFTERNOON.

$$

PKZ411-131400-
BERING SEA OFFSHORE WEST OF 180 AND EAST OF THE INTERNATIONAL
DATELINE
400 PM AKDT MON APR 12 2010

...GALE WARNING THROUGH TUESDAY NIGHT...

.TONIGHT...W WIND 25 TO 35 KT. SEAS 12 TO 19 FT. SNOW SHOWERS.
FREEZING SPRAY. 
.TUE...NW WIND 25 TO 35 KT. SEAS 11 TO 18 FT. SNOW SHOWERS. FREEZING
SPRAY. 
.TUE NIGHT...NW WIND 20 TO 35 KT. SEAS 10 TO 16 FT. FREEZING SPRAY. 
.WED...S WIND 45 KT. SEAS 12 FT. 
.WED NIGHT...S WIND 45 KT. SEAS 14 FT. 
.THU...SW WIND 35 KT. SEAS 20 FT. 
.FRI...W WIND 30 KT. SEAS 19 FT. 
.SAT...NW WIND 25 KT. SEAS 15 FT.  

$$

PKZ412-131400-
BERING SEA OFFSHORE 171W TO 180 AND NORTH OF 56N
400 PM AKDT MON APR 12 2010

...GALE WARNING THROUGH TUESDAY...

.TONIGHT...SW WIND 25 TO 35 KT. SEAS 15 TO 22 FT. SNOW. FREEZING
SPRAY. 
.TUE...W WIND 20 TO 35 KT. SEAS 12 TO 19 FT. SNOW. FREEZING SPRAY. 
.TUE NIGHT...NW WIND 20 TO 30 KT. SEAS 10 TO 16 FT. FREEZING SPRAY. 
.WED...W WIND 20 KT. SEAS 11 FT. 
.WED NIGHT...S WIND 45 KT. SEAS 12 FT. 
.THU...SW WIND 40 KT. SEAS 14 FT. 
.FRI...SW WIND 25 KT. SEAS 16 FT. 
.SAT...NW WIND 20 KT. SEAS 15 FT.  

$$

PKZ413-131400-
BERING SEA OFFSHORE 171W TO 180 AND SOUTH OF 56N
400 PM AKDT MON APR 12 2010

...GALE WARNING THROUGH TUESDAY...

.TONIGHT...W WIND 20 TO 35 KT. SEAS 17 TO 21 FT. SNOW.
.TUE...W WIND 25 TO 35 KT. SEAS 15 TO 18 FT. SNOW SHOWERS. 
.TUE NIGHT...W WIND 30 KT. SEAS 15 FT. SNOW SHOWERS. FREEZING SPRAY.
.WED...W WIND 30 KT. SEAS 13 FT. 
.WED NIGHT...S WIND 45 KT. SEAS 13 FT. 
.THU...SW WIND 40 KT. SEAS 15 FT.
.FRI...SW WIND 30 KT. SEAS 18 FT. 
.SAT...W WIND 25 KT. SEAS 16 FT.  

$$

PKZ414-131400-
BERING SEA OFFSHORE EAST OF 171W
400 PM AKDT MON APR 12 2010

...GALE WARNING TONIGHT...

.TONIGHT...SW WIND 20 TO 40 KT. SEAS IN ICE FREE WATERS 17 TO 23 FT.
.TUE...SW WIND 20 TO 30 KT. SEAS IN ICE FREE WATERS 14 TO 17 FT. SNOW
SHOWERS. 
.TUE NIGHT...W WIND 20 TO 30 KT. SEAS IN ICE FREE WATERS 11 TO 16 FT.
.WED...NW WIND 25 KT. SEAS IN ICE FREE WATERS 11 FT. 
.WED NIGHT...SW WIND 35 KT. SEAS IN ICE FREE WATERS 9 FT. 
.THU...S WIND 45 KT. SEAS IN ICE FREE WATERS 14 FT. 
.FRI...SW WIND 25 KT. SEAS IN ICE FREE WATERS 12 FT. 
.SAT...SW WIND 15 KT. SEAS IN ICE FREE WATERS 13 FT.  

$$

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AKDT SUN APR 11 2010

.ANALYSIS AND UPPER LEVELS...
A SHARP UPPER LEVEL RIDGE LIES OVER MUCH OF EASTERN ALASKA AND
NORTHWESTERN CANADA WHILE A TROUGH FOLLOWS QUICKLY ON ITS HEELS OVER
THE EASTERN BERING SEA. THIS TROUGH BRANCHES OUT FROM A LARGE
KAMCHATKA LOW PRESSURE SYSTEM THAT IS RESPONSIBLE FOR MULTIPLE
WEATHER SYSTEMS AFFECTING THE BERING SEA AND NORTHEASTERN RUSSIA. A
160 KT ZONAL JET RACES ACROSS THE BERING SEA BEFORE ABRUPTLY
SWITCHING TO A MERIDIONAL FLOW AS IT NAVIGATES AROUND THE
AFOREMENTIONED HIGH AMPLITUDE TROUGH AND RIDGE.

AT THE SURFACE...A ONCE IMPRESSIVE LOW PRESSURE SYSTEM THAT BROUGHT
ACTIVE WEATHER TO THE BERING SEA OVER THE PAST FEW DAYS IS RAPIDLY
FILLING AS IT MOVES ONSHORE OVER THE FAR EASTERN TIP OF RUSSIA. THE
OCCLUDED FRONT PUSHES NORTH INTO THE CENTRAL ARCTIC OCEAN BEFORE
DIVING SOUTHEASTWARD AND CUTTING THROUGH THE MAINLAND FROM NORTHEAST
TO SOUTHWEST. A SURFACE SHORTWAVE ACCOMPANYING THE OCCLUSION IS
PROGRESSING VERY SLOWLY ACROSS THE WESTERN GULF AND SOUTH CENTRAL
ALASKA THIS AFTERNOON. RESULTANT WIDESPREAD SNOW CONTINUES ACROSS THE
KENAI PENINSULA AND THE SUSITNA VALLEY...WITH HIGHER AMOUNTS IN
UPSLOPED TERRAIN. THE ANCHORAGE BOWL HAS SO FAR REMAINED DOWNSLOPED
BY SOUTHEASTERLY FLOW FOR THIS EVENT. AN ADDITIONAL SURFACE SHORTWAVE
IN COMBINATION WITH THE UPPER LEVEL TROUGH BACK OVER THE EASTERN
BERING IS INSTIGATING SNOW SHOWERS OVER PORTIONS OF SOUTHWEST ALASKA.
A NEW 979 MB LOW PRESSURE SYSTEM IS JUST ENTERING THE SOUTHWESTERN
BERING SEA NEAR THE WESTERN TIP OF THE ALEUTIANS AND HASTILY
TRACKING NORTHEASTWARD. A SHORTWAVE PRESSING OUT AHEAD OF THIS SYSTEM
IS BRINGING SHOWERS TO THE EASTERN ALEUTIANS.

.MODEL DISCUSSION...
IN GENERAL THE MODELS ARE IN GOOD AGREEMENT WITH THE PROGNOSIS OF THE
FRONTAL SYSTEM OVER SOUTH CENTRAL ALASKA AND THE NEXT LOW CURRENTLY
TRACKING INTO THE BERING SEA. THE GFS IS THE MOST AGGRESSIVE WITH THE
STRENGTH OF THE LOW BOTH IN TERMS OF THE CENTRAL PRESSURE AND THE
WIND FIELD AROUND THE SYSTEM. BUT OVERALL...CONSIDERING HOW FAST THE
STORM IS TRAVELING...MODEL ALIGNMENT IS VERY GOOD. THERE ARE SOME
NAGGING QUESTIONS...HOWEVER...AS TO THE STRUCTURE AND SPEED OF A
TRAILING FRONTAL BAND THAT WILL WRAP UP INTO THE GULF OF ALASKA ON
TUESDAY MORNING AND INTO SOUTHERN ALASKA ON WEDNESDAY. MODELS HAVE
SHOWN DECENT RUN-TO-RUN CONSISTENCY...BUT CONTINUE TO DIFFER FROM
ANOTHER. THE GFS SOLUTION IS MUCH FASTER THAN THE ECMWF AND THE NAM
BY A GOOD 12 TO 18 HOURS AND DEVELOPS A TRIPLE POINT LOW FURTHER
NORTH THAN THE ECMWF. WITH AN ACTIVE WEATHER PATTERN IN
PLACE...BLENDED WITH THE ECMWF AND THE NAM IN THE SHORT TERM AND MADE
MINIMAL CHANGES TO THIS MORNING'S LONG RANGE FORECAST (WHICH WAS A
GFS AND ECMWF COMPROMISE).

.SHORT TERM FORECAST...
.SOUTH CENTRAL ALASKA...THE SYSTEM RESPONSIBLE FOR THE ADVISORY LEVEL
SNOW NORTH OF HOMER AND THE NORTHERN SUSITNA VALLEY WILL MAKE LITTLE
HEADWAY THROUGHOUT THE REST OF THE DAY AS IT RUNS UP AGAINST THE
RIDGE OVER EASTERN ALASKA. EVENTUALLY THIS SHORTWAVE AND ACCOMPANYING
UPPER LEVEL TROUGH WRAP UP INTO SOUTHERN ALASKA ON MONDAY AND
DISSIPATE AS A NEW SYSTEM PRESSES INTO SOUTHWEST ALASKA. THUS EXPECT
AREAS OF SNOW AND RAIN TO CONTINUE ACROSS PORTIONS OF SOUTHERN ALASKA
THROUGH THE NIGHT AND TAPER OFF BY MORNING. SOUTHEASTERLY WINDS WILL
LIKELY KEEP ANCHORAGE DOWNSLOPED FOR THE REMAINDER OF THIS
EVENT...THOUGH AS THE SHORTWAVE PASSES OVERHEAD THE CITY MAY SEE A
BRIEF SHOT OF SNOW. A SHORTWAVE TRACKING INTO THE NORTHWESTERN GULF
ON TUESDAY MORNING WILL BRING ANOTHER ROUND OF ACTIVE WEATHER FOR
SOUTH CENTRAL ALASKA. A SUPPORTIVE UPPER LEVEL JET AND SOUTHWESTERLY
LOW LEVEL FLOW COULD LEAD TO A RESPECTABLE AMOUNT OF PRECIPITATION
FALLING IN THE ANCHORAGE AREA ON TUESDAY.

.SOUTHWEST ALASKA...SNOW SHOWERS WILL CONTINUE TO HANG AROUND
SOUTHWESTERN ALASKA TODAY AS THE UPPER LEVEL TROUGH PASSES THROUGH. A
SHORTWAVE ASSOCIATED WITH THE NEXT LOW MOVING UP INTO THE BERING WILL
SWEEP ACROSS SOUTHWESTERN ALASKA ON MONDAY...BRINGING WITH IT A
RENEWED THREAT OF HIGH WINDS AND HEAVY SNOW. A BLIZZARD WATCH HAS
BEEN ISSUED FOR THE COAST OF SOUTHWEST ALASKA FOR MONDAY MORNING IN
ANTICIPATION OF THESE DANGEROUS CONDITIONS. AS WITH THE LAST
STORM...THE BIG QUESTION WILL BE HOW FAR NORTH THE NOSE OF THE WARM
AIR WILL REACH INTO THE REGION. CURRENTLY THE FORECAST CALLS FOR SNOW
ACROSS MUCH OF SOUTHWEST ALASKA...BUT ANY NORTHWARD DEVIATION OF THE
WARM AIR COULD RESULT IN SIGNIFICANTLY DIFFERENT CONDITIONS THAN ARE
CURRENTLY FORECAST.

.ALEUTIANS AND BERING SEA...WINDS WILL RAPIDLY INCREASE TO STORM
FORCE ACROSS THE ALEUTIAN ISLAND CHAIN AND SOUTHERN BERING THIS
EVENING AS A NEW LOW PRESSURE SYSTEM QUICKLY TRACKS ACROSS THE
CENTRAL BERING SEA THIS AFTERNOON AND TOMORROW. PRECIPITATION AMOUNTS
WILL BE LIMITED OVER THE ISLAND CHAIN DUE TO THE FAST FORWARD MOTION
OF THE STORM...BUT EXPECT LINGERING SHOWERS TO CONTINUE THROUGH
MIDWEEK.

.LONG TERM FORECAST...
THE JET STREAM WILL FERRY ADDITIONAL WEATHER SYSTEMS ACROSS THE
FORECAST AREA THROUGH THE REST OF THE WORK WEEK WHILE TEMPERATURES
REMAIN SLIGHTLY COLDER THAN NORMAL. LONGER RANGE MODELS DEPICT THE
DEVELOPMENT OF A RIDGE OVER WESTERN CANADA NEXT WEEKEND...WHICH WOULD
BRING CALMER WEATHER AND WARMER TEMPERATURES TO EASTERN ALASKA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WATCH 155 161.
MARINE...STORM WARNING...172 175 176 179.
         GALE WARNING...150 155 160 165 170 171 180 185.
FIRE WEATHER...NONE.

KS APR 10