Gale Warning 181, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 PM AKST FRI FEB 15 2013

.ANALYSIS AND UPPER LEVELS...THE MAIN UPPER LEVEL FEATURE TODAY IS A
TROUGH EXTENDING OUT OF THE CHUKCHI SEA AND OVER SOUTH CENTRAL
ALASKA. THERE IS ALSO AN UPPER LEVEL CLOSED LOW NEAR THE WESTERN
ALEUTIAN ISLANDS. THE UPPER LEVEL RIDGE IS OVER THE ALASKA PENINSULA
AND THE SOUTHWEST MAINLAND SQUEEZED BETWEEN THESE TWO UPPER LOWS.
THE THE STREAM COMING OFF ASIA STILL SPLITS INTO TWO PARTS WELL SOUTH
OF THE ALEUTIAN ISLANDS. THE NORTHERN PART OF THE SPLIT IS EASILY
SEEN ON IR SATELLITE MOVING FROM THE NORTH PACIFIC TOWARD THE
UNALASKA AREA.
AT THE SURFACE THE LARGE LOW OVER MOST OF THE MAINLAND PART OF THE
STATE HAS SEVERAL DISTINCT CENTERS WITH THE STRONGEST ONES BEING IN
PRINCE WILLIAM SOUND AND OVER THE SEWARD PENINSULA.
A LARGE LOW SOUTH OF AMCHITKA WILL CONTINUE TO TRACK TO THE NORTHEAST
WITH A STRONG FRONT MOVING INTO THE EASTERN ALEUTIANS.

.MODEL DISCUSSION...THE MODEL SITUATION IS VERY SIMILAR TO YESTERDAY
WITH MODELS BEING IN GOOD AGREEMENT WITH THE SYNOPTIC PATTERN AND
MOST OF THE SMALLER SCALE FEATURES INTO SUNDAY. ONCE AGAIN THE NAM
AND ECMWF RESOLVE THE WEAK MESO-LOW IN LOWER COOK INLET WHILE THE GFS
DOES NOT SEE THIS FEATURE AT ALL.
BY SUNDAY NIGHT THE UNCERTAINTY INCREASES IN MODEL SOLUTIONS AS THE
GFS AND ECMWF DIFFER BY OVER 400 MILES WITH THE PLACEMENT OF A TRIPLE
POINT LOW IN THE BERING SEA. THE NAM SPLITS THE DIFFERENCE BETWEEN
THEM.

.SHORT TERM FORECAST...THE UPPER LEVEL TROUGH OVER SOUTH CENTRAL IS
SLOWING PROGRESSING EASTWARD. AS IT PASSES THE SNOWFALL WILL END.
THERE WILL BE SOME CLEARING BEHIND THE TROUGH BUT AREAS FARTHER
SOUTH...SUCH AS FROM THE CENTRAL KENAI PENINSULA SOUTHWARD ARE MOST
LIKELY TO SEE GOOD CLEARING. FARTHER NORTH THERE WILL BE A GREATER
CHANCE OF FOG DEVELOPING OR THE FORMATION OF STRATUS. TEMPERATURES IN
SOUTH CENTRAL ALASKA WILL ALSO DROP CONSIDERABLY TONIGHT AS MUCH
COLDER AIR FROM SOUTHWEST ALASKA MOVES INTO THE AREA.

SOUTHWEST ALASKA IS ENTRENCHED IN THE VERY COLD AIR WITH SOME LOW
WIND CHILLS CONTINUING THROUGH THE NIGHT TONIGHT. HOWEVER THEY SHOULD
NOT BE AS BAD AS LAST NIGHT FOR MOST OF THE AREA. THE PRESSURE
GRADIENT WILL INCREASE AGAIN TOMORROW AND BRING IN MORE NORTH TO
NORTHEAST WINDS INTO THE KUSKOKWIM DELTA. WINDS CHILL VALUES MAY DROP
INTO THE 45 TO 55 BELOW RANGE SATURDAY EVENING THROUGH SUNDAY
AFTERNOON AND HAVE PROMPTED THE ISSUING OF A WIND CHILL ADVISORY FOR
ZONE 155.
THE CENTRAL AND WESTERN ALEUTIANS HAVE SEEN STRONG WINDS AND
WIDESPREAD BLOWING SNOW TODAY BUT NOT ENOUGH OF A REDUCTION IN
VISIBILITY TO QUALIFY AS A BLIZZARD. THE BLIZZARD WATCH THAT HAD BEEN
IN EFFECT FOR THE EASTERN ALEUTIANS WAS CANCELED. THIS WAS DONE DUE
TO BOTH THE LATEST SATELLITE DATA AND MODEL DATA. THERE IS ENOUGH OF
A WESTWARD BEND IN THE FRONT APPROACHING THAT AREA TO PUT THEM
FARTHER IN THE WARM SECTOR OF THE SYSTEM. THIS WILL LIKELY KEEP ANY
SIGNIFICANTLY REDUCED VISIBILITIES DUE TO BLOWING SNOW VERY BRIEF.

.LONG TERM FORECAST...THE EXTENDED PERIOD LOOKS TO GET ACTIVE AGAIN
WITH A HIGHLY AMPLIFIED PATTERN SET TO BEGIN NEXT WEEK WITH A LARGE
TROUGH OVER THE BERING AND RIDGE OVER THE WESTERN PORTION OF THE
STATE. A TRANSITION TO A MORE PROGRESSIVE PATTERN WILL TAKE SHAPE
OVER THE COURSE OF THE WEEK WITH A BROAD TROUGH OVER KAMCHATKA AND
STRONG WESTERLIES OVER THE ALEUTIANS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...WIND CHILL ADVISORY 155.
MARINE...GALE 130 150 155 160 165 170 171 172 176 179.
         HEAVY FREEZING SPRAY 130 132 138 140 141 160 179.
FIRE WEATHER...NONE.

FEB 13

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1028 AM AKST FRI FEB 15 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0600 AM     SNOW             1 WNW PETERS CREEK      61.42N 149.45W
02/15/2013  M2.1 INCH                           AK   COCORAHS

0630 AM     SNOW             4 W PALMER              61.61N 149.23W
02/15/2013  M4.6 INCH                           AK   NWS EMPLOYEE

0700 AM     SNOW             1 ENE POTTER MARSH      61.06N 149.75W
02/15/2013  M2.0 INCH                           AK   COCORAHS

0800 AM     SNOW             4 SE WILLOW             61.70N 149.99W
02/15/2013  M1.7 INCH                           AK   COCORAHS

0900 AM     SNOW             2 NNW PALMER            61.62N 149.13W
02/15/2013  M5.0 INCH                           AK   COCORAHS

0900 AM     SNOW             13 NW TRAPPER CREEK     62.39N 150.68W
02/15/2013  M2.0 INCH                           AK   TRAINED SPOTTER

&&

DSTRICKL

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1121 AM AKST FRI FEB 15 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1100 AM     SNOW             3 NNW CASWELL           62.02N 150.06W
02/15/2013  M4.0 INCH                           AK   TRAINED SPOTTER

&&

DSTRICKL

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
345 PM AKST FRI FEB 15 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0344 PM     SNOW             1 ENE POTTER MARSH      61.06N 149.76W
02/15/2013  M3.5 INCH                           AK   TRAINED SPOTTER

&&

DSTRICKL