Blizzard in Alaska, January 9 to 10, 2012

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
515 AM AKST MON JAN 9 2012

.ANALYSIS AND UPPER LEVELS...
IN THE WEST...A 967 MB LOW 350 MILES SOUTH OF ATKA IS MOVING
EAST-NORTHEAST. AN ASSOCIATED FRONT IS DRAPED THROUGH THE CENTRAL AND
EASTERN ALEUTIAN CHAIN MOVING TOWARDS THE SW MAINLAND AND GULF OF AK.
SNOW AND BLOWING SNOW IS OCCURRING FROM ADAK EAST TOWARDS COLD
BAY...THOUGH WARMER AIR IS POKING NORTH WITH THE FRONT...PUSHING
SURFACE TEMPERATURES INTO THE LOWER 30S FAHRENHEIT. HIGH PRESSURE IS
STAMPED OVER SW MAINLAND...WITH A FEW WEAK UPPER-DISTURBANCES
SQUEEZING OUT SOME PASSING FLURRIES/SNOW SHOWERS.

IN THE EAST...A RESIDUAL LOW JUST NORTHEAST OF MIDDLETON ISLAND IS
DRIFTING EAST TOWARDS YAKUTAT AND FILLING QUICKLY...THOUGH SOME GUSTY
NORTH TO WEST GAP WINDS PERSIST THROUGH AREAS SUCH AS WHITTIER AND
SEWARD. RADAR STILL SHOWS SOME COLD-ADVECTION SNOW SHOWERS PUSHING
ASHORE SOUTHEASTERN PRINCE WILLIAM SOUND BUT THESE ARE ON THE DECLINE
CONCURRENT WITH THE LOW WEAKENING. IN THE WAKE OF THIS
FEATURE...THERE IS DECREASING CLOUDINESS ALLOWING FOR SOME
SUNSHINE...THOUGH CLOUDS ARE ON THE INCREASE ACROSS KODIAK ISLAND
AHEAD OF THE PACIFIC/ALEUTIAN FRONT.

.MODEL DISCUSSION...
MODELS SATISFACTORILY CAPTURE THE SYNOPTIC PICTURE. OUT WEST...THEY
CAPTURE A LOW DEVELOPING ALONG THE FRONT NEAR CHIGNIK LATE TONIGHT
THEN MOVE IT UP TO BRISTOL BAY ON TUESDAY. THE 00Z ECMWF AND UKMET
WERE DEEPER WITH THIS FEATURE THAN THE GFS AND NAM...AND WHILE THE
FORECAST DID GO QUITE THAT STRONG...THE 06Z RUNS OF THE NAM AND GFS
APPEAR TOO WEAK...WITH BARELY A WAVE ALONG THE FRONT. SATELLITE
IMAGERY SHOWS A DECENT SHORTWAVE ALREADY ROUNDING THE BASE OF THE LOW
MOVING UP TOWARDS THE AREA OF CONCERN...AND THIS SHOULD PROMOTE A
TRIPLE POINT LOW. FURTHER WEST...MODELS SHOW A STORM-FORCE FRONT
ADVANCING TOWARDS THE FAR WESTERN BERING/CHAIN MID-WEEK...BUT DIFFER
ON THE POSITION OF THE PARENT LOW WHICH LAGS OFF THE KAMCHATKA
PENINSULA. HAVE KEPT CLOSE TO THE GFS BUT ACKNOWLEDGE LOW CONFIDENCE
IN THE SOLUTION.

FOR THE EAST...THE AFOREMENTIONED FRONT WILL MOVE TO THE NORTHERN
GULF TUESDAY AFTERNOON...AND THE PARENT PACIFIC LOW WILL MOVE TO
AROUND 200 MILES SOUTH OF KODIAK ISLAND WEDNESDAY MORNING. MODELS
AGREE ON STRONG EAST GAP FLOW AND BARRIER JET DEVELOPMENT OVER THE
NORTH GULF COAST. BEYOND WEDNESDAY...MODELS DIVERGE WITH THE TRACK OF
THE LOW. THE GFS TENDS TO KEEP A CONSOLIDATED LOW MOVING UP JUST EAST
OF KODIAK ISLAND AND EVENTUALLY TO THE SOUTHCENTRAL MAINLAND
MID-WEEK. HAVE TENDED TO FAVOR THE ECMWF DEPICTION OF A MORE COMPLEX
LOW WITH MULTIPLE LOBES OF ENERGY. THE MAIN THING AT LEAST IS THAT
THE MODELS AGREE ON A SUBSTANTIAL AMOUNT OF MOISTURE/QPF SLAMMING THE
SOUTHERN MAINLAND.

.SHORT TERM FORECAST...
SOUTHCENTRAL...
STEADY PRECIPITATION ASSOCIATED WITH THE FRONT WILL OVERSPREAD KODIAK
ISLAND TODAY AND BEGIN WORKING UP TOWARDS THE SOUTHERN MAINLAND
TONIGHT THROUGH TUESDAY. MARINE AREAS OF THE GULF WILL EXPERIENCE
STORM FORCE WINDS AS THIS OCCURS. MUCH OF THE PRECIPITATION WILL FALL
AS SNOW AND WITH GENEROUS AMOUNTS OF QPF...IT WILL BE HEAVY AT TIMES
ESPECIALLY UP OVER THE SUSITNA VALLEY...EASTERN KENAI PENINSULA AND
PRINCE WILLIAM SOUND. SOME AREAS ALONG THE IMMEDIATE COASTS WILL SEE
A GOOD BIT OF RAIN AS WARM AIR POKES UP FROM THE NORTH. STRONG WINDS
WILL DEVELOP ACROSS PORTAGE VALLEY AND THOMPSON PASS...AND COUPLED
WITH STEADY SNOW...MAY SUPPORT BLIZZARD CONDITIONS...WHERE WATCHES
REMAIN IN EFFECT. WE HAVE UPGRADED THE HIGH WIND WATCH FOR ZONE 101
TO A WARNING AS WELL FOR ALONG TURNAGAIN ARM AND HIGHER ELEVATIONS
WITH GOOD CONFIDENCE BASED ON THE STRENGTH OF THE FRONT AND RESULTING
PRESSURE GRADIENT. THE DEVELOPMENT OF THE TRIPLE POINT LOW NEAR
KODIAK ISLAND/AKPEN TO RESULT IN A DOWN INLET GRADIENT. THIS COUPLED
WITH THE DENSE DOME OF PREEXISTING AIR SHOULD RETARD WINDS FROM
MIXING DOWN INTO THE ANCHORAGE BOWL. PRECIPITATION ACROSS THE
MATANUSKA VALLEY...ANCHORAGE BOWL AND WESTERN KENAI PENINSULA TO BE
RETARDED BY DOWNSLOPING THROUGH TUESDAY. WITH THE LOSS OF THOSE
WINDS...SNOW LOOKS TO FILL IN LATE TUESDAY INTO WEDNESDAY.

SOUTHWEST...
MOISTURE FROM THE FRONT WILL MOVE UP TO BRISTOL BAY AND THE KUSKOKWIM
DELTA THROUGH TODAY AND TONIGHT. SNOW AND BLOWING SNOW COUPLED WITH
STRONG WINDS TO PRODUCE BLIZZARD CONDITIONS...ESPECIALLY FROM AREAS
FROM DILLINGHAM NORTH. BLIZZARD WATCHES IN THESE AREAS HAVE BEEN
UPGRADED TO WARNINGS. THE WORST VISIBILITY IN BLOWING SNOW WILL EBB
EARLY TUESDAY...AS THE PRESSURE GRADIENT RELAXES WITH THE
TRIPLE-POINT LOW MOVING ASHORE. SNOW WILL PERSIST HOWEVER THROUGH
WEDNESDAY...REINFORCED BY A SURGE OF COLD ADVECTION THAT WILL BLEED
BACK SOUTHEAST ACROSS THE SW MAINLAND. SNOW ACCUMULATIONS ACROSS
INTERIOR AREAS OF BRISTOL BAY AND THE KUSKOKWIM VALLEY MAY FLIRT WITH
ADVISORY LEVELS.

BERING SEA/ALEUTIANS...
BLIZZARD WARNINGS REMAIN IN EFFECT FOR ZONES 181 185 AND 187. WARM
AIR WILL MOVE IN FROM THE SOUTH AND HELP MIX RAIN WITH THE SNOW AND
IMPROVE VISIBILITY THROUGH THE DAY. ALL AREAS WILL RETURN TO SNOW AS
THE FLOW SHIFTS NORTHWEST AT GALE FORCE WITH THE LOW PASSING TO THE
SOUTH AND TOWARDS THE GULF. WINDS ARE CURRENTLY STRONGEST OVER THE
CENTRAL ALEUTIANS WITH GUSTS NEAR HURRICANE FORCE. WINDS IN GENERAL
WILL DIMINISH BELOW GALES BY TUESDAY NIGHT.

.LONG TERM FORECAST...
THE FAR WESTERN BERING/ALEUTIANS WHICH HAS BEEN RELATIVELY INACTIVE
WEATHER WISE WILL BECOME MORE UNSETTLED AS AN UPPER-LOW SETTLES IN
NEAR THE KAMCHATKA PENINSULA AND ENERGY SWINGS AROUND IT. A SHARP
RIDGE LOOKS TO DEVELOP OVER THE CENTRAL BERING WHILE AN UPPER-LOW
DROPS TO THE GULF OF AK. LOOK FOR THINGS TO BECOME COOLER AND DRIER
ACROSS THE SOUTHERN MAINLAND LATE WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING...155 161 181 185 187
         BLIZZARD WATCH...125 131
         WINTER WEATHER ADVISORY FOR SNOW...145
         HIGH WIND WARNING...101
MARINE...STORM...120 170 172 175 351 352
         GALE...125 129 130 132 140 141 150 155 160 165 171 179 180
                185 412 413 414
         HEAVY FREEZING SPRAY...127 129 165 179 185 412 413 414
FIRE WEATHER...NONE

JAM