Blizzard in Alaska, November 26, 2011

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
130 PM AKST SAT NOV 26 2011

.ANALYSIS AND UPPER LEVELS...
MUCH QUIETER WEATHER PATTERN THIS WEEKEND THAN THE PREVIOUS DAYS AS
THE STATE TRANSITIONS FROM ONE STORM SYSTEM TO THE NEXT. A COLD CORE
UPPER LEVEL LOW STILL RESIDES OVER MUCH OF THE CENTRAL INTERIOR WHILE
A TRANSITORY RIDGE RACES TOWARDS SOUTHWEST ALASKA. OUT WEST...A FRONT
IS NEAR THE EASTERN ALEUTIANS AND PRIBILOFS WHICH IS STEMMING FROM A
LARGE LOW PRESSURE SYSTEM OVER THE FAR WESTERN BERING. SATELLITE AND
SURFACE OBS ARE INDICATING THAT A TRIPLE POINT LOW IS DEVELOPING NEAR
DUTCH HARBOR EARLY THIS AFTERNOON.

.MODEL DISCUSSION...THE MODELS AGAIN AGREE ON THE OVERALL PATTERN BUT
DIFFER ON THE DETAILS AS THE LOWS PROGRESS EAST. THE FIRST CHALLENGE
WILL BE THE TRIPLE POINT LOW DEVELOPING NEAR THE EASTERN ALEUTIANS.
WE HAVE PREFERRED THE OVERALL STRUCTURE OF THE FRONT AND DEVELOPING
LOW OF THE NAM...BUT IT APPEARS TOO FAST. THE GFS AND ECMWF ARE IN
EXCELLENT AGREEMENT ON THE TIMING BUT SEEM TO NOT CAPTURE THE
COMPLEXITY OF THE FRONT INTERACTING WITH THE TERRAIN THE WAY THE
HIGHER RESOLUTION NAM DOES. FOR THIS REASON...HAVE MAINLY GONE WITH
THE GFS/EC SOLUTION BUT HAVE ADJUSTED THE FORECAST TO ACCOUNT FOR THE
MORE COMPLEX STRUCTURE THAT WE HAVE COME TO EXPECT WITH THIS TYPE OF
SYSTEM.

THE PICTURE AGAIN IS A BIT MUDDLED AS THE OCCLUDED LOW MOVES
NORTHEAST TOWARD PRINCE WILLIAM SOUND EARLY NEXT WEEK. AT THIS
TIME...DID A BLEND OF THE INHERITED FORECAST WITH THE GFS WHICH
RESULTED IN A FORECAST THAT CLOSELY RESEMBLES THE ENSEMBLE MEAN.

.SHORT TERM FORECAST...THE SHORT TERM FORECAST CHALLENGES IN THE
EASTERN DOMAIN MAINLY INVOLVE STRATUS AND THE CHANCE OF FOG AROUND
SOUTHCENTRAL OVERNIGHT AHEAD OF THE NEXT SYSTEM. STRATUS WAS VERY
SLOW TO BURN OFF IN THE MATANUSKA VALLEY THIS MORNING AND SUSPECT
THAT IT WILL RETURN OVERNIGHT. THERE SHOULD BE JUST ENOUGH MIXING TO
PREVENT FOG FROM SETTLING IN...BUT WILL BE MENTIONING THAT
POSSIBILITY MAINLY ALONG KNIK ARM DOWN COOK INLET THROUGH SUNDAY
MORNING.

MID AND UPPER LEVEL CLOUDS INVADE SOUTHCENTRAL SUNDAY AFTERNOON AND
EVENING AHEAD OF THE TRIPLE POINT LOW. THERE DOES NOT APPEAR TO BE A
SIGNIFICANT THREAT OF SNOW OVER THE INTERIOR SECTIONS OF THE STATE
UNTIL LATER ON MONDAY AS THE UPPER TROF FINALLY APPROACHES THE
REGION. THE EXCEPTION ARE COASTAL COMMUNITIES INCLUDING
KODIAK...WHERE THE POSSIBILITY EXISTS FOR SIGNIFICANT SNOWFALL WITH
THIS STORM. WILL CONTINUE TO ADVERTISE THIS POSSIBILITY KEEPING IN
MIND A SLIGHT SHIFT IN THE POSITION OF THE LOW TO THE WEST WOULD
RESULT IN WARMER TEMPERATURES AND NO SNOW. GIVEN THE UNCERTAINTY WITH
THE MODELS DEVELOPING THE TRIPLE POINT...WILL STAY AWAY FROM AN
ADVISORY FOR KODIAK ISLAND UNTIL THE PICTURE BECOMES A LITTLE MORE
CLEAR.

.SOUTHWEST AK AND BERING SEA...THE SOUTHWEST INTERIOR WILL SEE VERY
LITTLE IN THE WAY OF WEATHER THROUGH EARLY NEXT WEEK. THE ONLY
CONCERN AT THIS POINT IS WIND CHILLS NEAR THE KUSKOKWIM DELTA. RECORD
COLD TEMPERATURES WILL COMBINE WITH INCREASING WINDS RESULTING IN THE
DANGEROUS CONDITIONS OVERNIGHT.

OTHERWISE...THE TRACK OF THE LOW WILL STAY FAR ENOUGH SOUTH TO
PREVENT ANY SIGNIFICANT WEATHER TO INVADE THE REGION. THIS WILL BE
THE CASE UNTIL TUESDAY EVENING WHEN THE NEXT STORM SYSTEM APPROACHES
THE ALASKA PENINSULA AND SPREADS SNOW OVER THE BRISTOL BAY ZONE.

FARTHER WEST...MOST OF THE ACTIVE WEATHER IS ALONG THE ALEUTIANS AND
BERING SEA WHERE A FRONT IS CURRENTLY APPROACHING THE PRIBILOFS.
BLIZZARD CONDITIONS HAVE NOT DEVELOPED AS THOUGHT...SLIGHTLY WARMER
TEMPERATURES AND PRECIPITATION ALONG THE BOUNDARY HAS NOT BEEN QUITE
AS HEAVY. THE SOURCE OF MOISTURE QUICKLY BECOMES CUT OFF THIS EVENING
AS THE TRIPLE POINT LOW DEVELOPS AND MOVES TOWARD THE WESTERN GULF.
THIS WILL LEAD TO WIDESPREAD SNOW ALONG THE BOUNDARY BECOMING SHOWERS
THROUGH TONIGHT AND THE REST OF THE WEEKEND. THE REMNANTS OF THE
PARENT LOW TO THE WEST SLOWLY DRIFTS SOUTHEAST TOWARD THE CENTRAL
ALEUTIANS EARLY NEXT WEEK.

MEANWHILE...A POTENT NORTH PACIFIC LOW DEVELOPS MONDAY NIGHT WITH
EYES FOR THE PENINSULA BY TUESDAY. THIS LOW WILL LIKELY BE A PATTERN
CHANGER FOR MUCH OF THE STATE AS THE UPPER LEVEL TROF RETROGRADES
BACK TO THE WESTERN INTERIOR ALLOWING FOR WARMER AIR TO STREAM
NORTHWARD OVER SOUTHCENTRAL. THIS WARMER AIRMASS WILL LEAD TO
TEMPERATURES REBOUNDING MUCH CLOSER TO NORMAL AROUND THE STATE AFTER
NEARLY 3 WEEKS OF BELOW NORMAL TEMPS. AT THIS TIME...IT LOOKS LIKE
RAIN WILL BE LIMITED TO THE COAST WHILE THE INTERIOR STAYS JUST COLD
ENOUGH FOR SNOW BUT WE WILL HAVE TO WATCH CLOSELY SINCE RAIN AFTER AN
EXTENDED PERIOD OF EXTREME COLD RESULTS IN VERY TREACHEROUS DRIVING
CONDITIONS.

EXTENDED...WATCHING A PATTERN CHANGE EARLY NEXT WEEK WITH SIGNIFICANT
MOISTURE BEING PUSHED UP TOWARD SOUTHCENTRAL ALASKA. THE EC AND GFS
IN GOOD AGREEMENT AND HAVE BEEN CONSISTENTLY ADVERTISING A SIMILAR
PICTURE. TEMPERATURES ALONG THE IMMEDIATE COAST WILL WARM UP
RESULTING IN RAIN...BUT JUST INLAND AND OVER THE MOUNTAINS THE PRECIP
WILL FALL IN THE FORM OF SNOW AND WILL BE VERY HEAVY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 181
MARINE...STORM WARNING 185
         GALES 120 121 130 132 138 351 352 150 155 160 165 170 171
               172 175 176 179 411 412 414
FIRE WEATHER...NONE.

AB NOV 11