Blizzard Watch 24, NWS Anchorage, AK

866 
WWAK41 PAFC 200330
WSWAER

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE ANCHORAGE AK
630 PM AKST MON DEC 19 2011

AKZ131-201630-
/X.CON.PAFC.BZ.A.0024.111221T0300Z-111221T1300Z/
NORTHEAST PRINCE WILLIAM SOUND-
INCLUDING THE CITIES OF...VALDEZ...THOMPSON PASS
630 PM AKST MON DEC 19 2011

...BLIZZARD WATCH REMAINS IN EFFECT FROM TUESDAY EVENING THROUGH
LATE TUESDAY NIGHT FOR THOMPSON PASS...

A BLIZZARD WATCH REMAINS IN EFFECT FROM TUESDAY EVENING THROUGH
LATE TUESDAY NIGHT. 

* LOCATION...THROUGH THOMPSON PASS.

* VISIBILITY...MAY BE LESS THAN ONE QUARTER MILE AT TIMES.

* WIND...SOUTHEAST WIND 20 TO 35 MPH.

* TIMING...LIGHT SNOW WILL DEVELOP TUESDAY AFTERNOON AND THEN 
  BECOME HEAVY AT TIMES TUESDAY NIGHT. WINDS WILL INCREASE EARLY 
  TUESDAY EVENING AND LIKELY PEAK DURING THE MID TO LATE EVENING 
  HOURS WHICH IS WHEN THE WORST VISIBILITIES ARE EXPECTED. 

* IMPACTS...SNOWFALL COMBINED WITH STRONG WINDS AND BLOWING SNOW 
  MAY PRODUCE WHITE-OUT CONDITIONS AT TIMES. DRIVING MAY BECOME 
  VERY DIFFICULT. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A BLIZZARD WATCH MEANS THERE IS A POTENTIAL FOR FALLING AND/OR
BLOWING SNOW WITH STRONG WINDS AND EXTREMELY POOR VISIBILITIES.
THIS CAN LEAD TO WHITE-OUT CONDITIONS AND MAKE TRAVEL VERY
DIFFICULT.

&&

$$

797 
WWAK41 PAFC 201336
WSWAER

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE ANCHORAGE AK
436 AM AKST TUE DEC 20 2011

AKZ131-210245-
/X.UPG.PAFC.BZ.A.0024.111221T0300Z-111221T1300Z/
/X.NEW.PAFC.BZ.W.0049.111221T0300Z-111221T1300Z/
NORTHEAST PRINCE WILLIAM SOUND-
INCLUDING THE CITIES OF...VALDEZ...THOMPSON PASS
436 AM AKST TUE DEC 20 2011

...BLIZZARD WARNING IN EFFECT FROM 6 PM THIS EVENING TO 4 AM AKST
WEDNESDAY FOR THOMPSON PASS...

THE NATIONAL WEATHER SERVICE IN ANCHORAGE HAS ISSUED A BLIZZARD
WARNING...WHICH IS IN EFFECT FROM 6 PM THIS EVENING TO 4 AM AKST
WEDNESDAY. THE BLIZZARD WATCH IS NO LONGER IN EFFECT. 

* LOCATION...THROUGH THOMPSON PASS.

* VISIBILITY...WILL BE LESS THAN ONE QUARTER MILE AT TIMES DUE TO
  BLOWING SNOW.

* WIND...SOUTHEAST WIND 25 TO 40 MPH.

* TIMING...SNOW WILL DEVELOP THIS AFTERNOON AND THEN BECOME HEAVY
  AT TIMES TONIGHT. WINDS WILL INCREASE EARLY THIS EVENING AND
  LIKELY PEAK BY LATE EVENING THEN DECREASE TOWARD MORNING.
  POOREST VISIBILITIES WILL OCCUR WITH  THE STRONGEST WINDS.

* IMPACTS...SNOWFALL COMBINED WITH STRONG WINDS AND BLOWING SNOW
  WILL PRODUCE WHITE-OUT CONDITIONS AT TIMES. DRIVING MAY BECOME
  VERY DIFFICULT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A BLIZZARD WARNING MEANS SEVERE WINTER WEATHER CONDITIONS ARE
EXPECTED OR OCCURRING. FALLING AND BLOWING SNOW WITH STRONG WINDS
AND POOR VISIBILITIES ARE LIKELY. THIS WILL LEAD TO WHITE-OUT
CONDITIONS...MAKING TRAVEL VERY DIFFICULT. ALL TRAVEL AND OUTDOOR
ACTIVITY IS STRONGLY DISCOURAGED.

&&

$$

AKZ125-210245-
/X.NEW.PAFC.BZ.W.0049.111221T0000Z-111221T0900Z/
WESTERN PRINCE WILLIAM SOUND-
INCLUDING THE CITIES OF...WHITTIER...SEWARD...GIRDWOOD...
MOOSE PASS
436 AM AKST TUE DEC 20 2011

...BLIZZARD WARNING IN EFFECT FROM 3 PM THIS AFTERNOON TO
MIDNIGHT AKST TONIGHT FOR PORTAGE VALLEY AND TURNAGAIN ARM...

THE NATIONAL WEATHER SERVICE IN ANCHORAGE HAS ISSUED A BLIZZARD
WARNING...WHICH IS IN EFFECT FROM 3 PM THIS AFTERNOON TO MIDNIGHT
AKST TONIGHT. 

* LOCATION...THROUGH PORTAGE VALLEY AND TURNAGAIN ARM.

* SNOW...4 TO 8 INCHES FROM THIS AFTERNOON THROUGH MIDNIGHT TONIGHT.

* VISIBILITY...LESS THAN A QUARTER MILE AT TIME DUE TO BLOWING SNOW.

* WIND...SOUTHEAST 45 TO 60 MPH.

* TIMING...THE SNOW WILL DEVELOP THIS AFTERNOON AND CONTINUE
  THROUGH THIS EVENING BEFORE BECOMING SCATTERED SNOW SHOWERS
  AFTER MIDNIGHT. THE WINDS WILL GRADUALLY INCREASE THIS AFTERNOON
  AND WILL REACH IT MAXIMUM SPEED BY EARLY EVENING. THIS WILL BE
  WHEN VISIBILITIES WILL BE THE POOREST. WINDS WILL DIMINISH THROUGH
  LATE EVENING WITH VISIBILITIES IMPROVING BY MIDNIGHT.

* IMPACTS...SNOWFALL COMBINED WITH STRONG WINDS AND BLOWING SNOW
  WILL PRODUCE WHITE-OUT CONDITIONS AT TIMES. DRIVING MAY BECOME
  VERY DIFFICULT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A BLIZZARD WARNING MEANS SEVERE WINTER WEATHER CONDITIONS ARE
EXPECTED OR OCCURRING. FALLING AND BLOWING SNOW WITH STRONG WINDS
AND POOR VISIBILITIES ARE LIKELY. THIS WILL LEAD TO WHITE-OUT
CONDITIONS...MAKING TRAVEL VERY DIFFICULT. ALL TRAVEL AND OUTDOOR
ACTIVITY IS STRONGLY DISCOURAGED.

&&

$$

AKZ145-210245-
/X.NEW.PAFC.WW.Y.0038.111221T0300Z-111221T1800Z/
SUSITNA VALLEY-
INCLUDING THE CITIES OF...TALKEETNA...WILLOW...CANTWELL
436 AM AKST TUE DEC 20 2011

...WINTER WEATHER ADVISORY IN EFFECT FROM 6 PM THIS EVENING TO
9 AM AKST WEDNESDAY...

THE NATIONAL WEATHER SERVICE IN ANCHORAGE HAS ISSUED A WINTER
WEATHER ADVISORY FOR SNOW...WHICH IS IN EFFECT FROM 6 PM THIS
EVENING TO 9 AM AKST WEDNESDAY.

* LOCATION...HEAVIEST SNOW WILL FALL WEST OF THE PARKS HIGHWAY.

* SNOW...5 TO 10 INCHES.

* TIMING...SNOW WILL BEGIN THIS EVENING AND CONTINUE THROUGH
  EARLY WEDNESDAY MORNING BEFORE CHANGING TO SNOW SHOWERS.

* IMPACTS...TRAVEL MAY BE DIFFICULT. VISIBILITIES MAY BE LIMITED
  IN HEAVY SNOWFALL.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER WEATHER ADVISORY FOR SNOW MEANS THAT PERIODS OF SNOW
WILL CAUSE PRIMARILY TRAVEL DIFFICULTIES. BE PREPARED FOR SNOW
COVERED ROADS AND LIMITED VISIBILITIES...AND USE CAUTION WHILE
DRIVING.&&

$$

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
520 AM AKST MON DEC 19 2011

.ANALYSIS AND UPPER LEVELS...
THE REGION REMAINS UNDER THE INFLUENCE OF A BROAD LONGWAVE TROUGH
CENTERED OVER THE BERING SEA WITH CORRESPONDING SOUTHERLY FLOW ACROSS
MUCH OF MAINLAND ALASKA. AN 80 KT JET STREAM WITH EMBEDDED 125+ KT
JET MAXES CONTINUE TO STEER FAST-MOVING STORMS INTO THE SOUTHERN
MAINLAND. ON THE MORNING SATELLITE IMAGE...THE STRONG LOW AND FRONT
FROM YESTERDAY HAS WEAKENED AND MOVED RAPIDLY INTO THE INTERIOR...AND
IS NOW A DISTANCE MEMORY. A PAIR OF LOWS APPROACHING THE GULF OF
ALASKA ARE TAKING CENTER STAGE...AND WILL BE THE PRIMARY FEATURES
IMPACTING THE STATE TODAY. THE FIRST LOW IS NEAR THE FAR SOUTHERN
GULF AND WILL PRIMARILY IMPACT SOUTHEAST ALASKA TODAY. THE SECOND AND
SMALLER OF THE TWO LOWS IS DEVELOPING RAPIDLY SOUTHWEST OF KODIAK
ISLAND IN RESPONSE TO A CORRESPONDING MID-LEVEL TROUGH. THE SHIELD OF
RAIN AND SNOW ASSOCIATED WITH THIS LOW HAS JUST BECOME VISIBLE ON THE
KING SALMON RADAR SPREADING FROM SOUTHWEST TO NORTHEAST ALONG THE
ALEUTIAN RANGE. FURTHER WEST...COLD AIR ALOFT HAS HELPED AN AREA OF
SCATTERED HEAVY SNOW SHOWERS DEVELOP ACROSS MOST OF THE ALEUTIAN
ISLANDS AND SOUTHERN BERING SEA. THIS FEATURE IS MOVING NORTHEAST
TOWARD THE MAINLAND AND IS FOLLOWING ON THE HEELS OF THE
AFOREMENTIONED LOW AFFECTING THE BRISTOL BAY AREA.

.MODEL DISCUSSION...
THE MODELS ARE IN GOOD AGREEMENT FOR THE FIRST 24-36 HOURS OF THE
FORECAST PERIOD...TAKING THE LOW NEAR KODIAK NEARLY DUE NORTHEAST AND
GENERALLY PARALLELING THE SPINE OF THE KENAI MOUNTAINS TODAY. BY LATE
TUESDAY NIGHT MODEL AGREEMENT BEGINS TO BREAK DOWN IN DRAMATIC
FASHION AS A MODERATE STRENGTH LOW DEVELOPS IN THE NORTHEAST PACIFIC
AND EITHER MOVES TOWARD PRINCE WILLIAM SOUND (NAM/EC) OR WEAKENS AND
MOVES INTO THE PANHANDLE (GFS). THE SCENE GOES FROM BAD TO WORSE ON
THURSDAY AS A STRONG LOW DEVELOPS SOMEWHERE SOUTH OF THE CENTRAL
ALEUTIANS. SUCH MODEL DISAGREEMENT IS NOT TERRIBLY SURPRISING GIVEN
THE SIGNS OVER THE LAST SEVERAL DAYS THAT THIS PERSISTENT LONGWAVE
PATTERN IS BECOMING MORE UNSTABLE. OVERALL...THE NAM/EC SOLUTION WAS
PREFERRED FOR THE FIRST 3 DAYS OF THE FORECAST...WITH A QUICK
TRANSITION TO THE LATEST GUIDANCE FROM HPC FOR THE MID AND LONG
RANGE.

.SHORT TERM FORECAST...
SOUTHCENTRAL...GUSTY SOUTHERLY WINDS ACROSS MUCH OF THE REGION WILL
BE DIMINISHING THIS MORNING AS A WEAK RIDGE OF HIGH PRESSURE MOVES
QUICKLY INTO THE AREA. THIS FEATURE WILL ALLOW MANY AREAS TO SEE SOME
BREAKS OF SUN TODAY BEFORE CLOUDS RETURN THIS EVENING. THE EXCEPTION
WILL BE KODIAK ISLAND WHERE CLOUDS AND A MIX OF RAIN AND SNOW WILL
DEVELOP THIS MORNING. THE FAST-MOVING LOW RACES ACROSS THE KENAI
PENINSULA TODAY AND INTO WESTERN PRINCE WILLIAM SOUND TONIGHT MOST
AREAS FROM HOMER TO THE MATANUSKA VALLEY SHOULD SEE A BRIEF PERIOD OF
MODERATE SNOW THIS EVENING AND OVERNIGHT. NOT EXPECTING SIGNIFICANT
ACCUMULATIONS AT THIS TIME...SIMPLY DUE TO THE VERY FAST FORWARD
SPEED OF THIS LOW. AFTER ANOTHER VERY BRIEF BREAK SNOW AND WIND
RETURN TO SOUTHCENTRAL TUESDAY AFTERNOON AS A SIGNIFICANT LOW MAKES
LANDFALL IN BRISTOL BAY. THIS STORM SEEMS TO BE SHAPING UP SIMILAR TO
THE WIND STORM YESTERDAY THAT AFFECTED EAST ANCHORAGE AND THE
HILLSIDE. THE ONE NOTABLE DIFFERENCE WITH THIS LOW IS THAT UPPER
LEVEL WINDS ARE MORE SOUTHWESTERLY WITH THIS STORM THAN WITH THE
PREVIOUS...A SCENARIO WHICH CAN SOMETIMES MAKE WIND EVENTS WORSE AT
THE LOWER ELEVATIONS OF ANCHORAGE. THIS POTENTIALLY SIGNIFICANT EVENT
WILL BE MONITORED CLOSELY THROUGHOUT THE DAY. STAY TUNED TO THE
LATEST FORECAST FOR THE MOST CURRENT INFORMATION.

SOUTHWEST AND BERING SEA...THE LOW NEAR KODIAK WILL BRING A PERIOD OF
SNOW TO PARTS OF THE BRISTOL BAY ZONE EAST OF DILLINGHAM TODAY WITH A
FEW INCHES OF ACCUMULATION LIKELY. ELSEWHERE SNOW SHOWERS AND ONSHORE
FLOW WILL CONTINUE FOR THE REMAINDER OF SOUTHWEST AS WELL AS THE
ALEUTIANS. THE LOW WELL SOUTH OF SHEMYA IS THE STORM THAT WILL GROW
AND AFFECT THE MAINLAND IN A MAJOR WAY ON TUESDAY. AS THIS LOW MOVES
EAST LOCATIONS FROM DUTCH HARBOR EASTWARD WILL EXPERIENCE GALE TO
STORM FORCE WINDS IN ADDITION TO RAIN AND SNOW BEGINNING THIS
EVENING.

.LONG TERM FORECAST...
AS MENTIONED IN THE MODEL DISCUSSION ABOVE THERE IS CONSIDERABLE
DISAGREEMENT AMONG THE LONG RANGE WEATHER MODELS. THE COMMON ELEMENT
SEEMS TO BE A GRADUAL SHIFT EASTWARD IN THE LONGWAVE TROUGH BY THE
END OF THE WEEK. THIS IS A MORE TYPICAL PATTERN FOR ALASKA THIS TIME
OF YEAR AND WOULD ALLOW COLDER AIR TO INFILTRATE BACK INTO MOST PARTS
OF THE STATE.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...STORM 150 155 170
         GALE 120 130 132 138 140 160 165 171 172 179 185
         HEAVY FREEZING SPRAY 185
FIRE WEATHER...NONE

AMD DEC 11