Heavy Freezing Spray Warning 55, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKST THU JAN 26 2012

.MODEL DISCUSSION...MODEL INITIALIZATIONS ARE REASONABLE BUT
CONSENSUS IS POOR. MODELS SIMILARLY HANDLE THE LONG WAVE TROUGH
MOVING ACROSS THE MAINLAND AND THE UPPER LOW SOUTH OF THE ALEUTIANS.
THE ECMWF PUTS A GREATER EMPHASIS ON SECONDARY WAVE DEVELOPMENT NORTH
OF THE CENTER SOUTH OF THE ALEUTIANS THAN THE GFS/GEMGLB/NAM.
COMPLICATING MATTERS...IS A SERIES OF LOW AMPLITUDE WAVES MOVING
ACROSS THE NORTHEAST PACIFIC. THE RESULTING SURFACE PATTERN HAS
UNDERGONE NUMEROUS CHANGES AMONG THE MODELS IN THE LAST COUPLE OF
DAYS. FOR NOW IT APPEARS THE GFS/GEMGLB HAVE A SOMEWHAT REALISTIC
SOLUTION THROUGH THE SHORT TERM ON SYNOPTIC FEATURES. THE NAM EARLY
ON DOES A FAIR JOB WITH THE DETAILS ACROSS SOUTH CENTRAL ALASKA.

.UPPER LEVELS...
THE LONG WAVE MOVES ACROSS THE MAINLAND TONIGHT AND IS FOLLOWED BY A
COUPLE OF SHORT WAVES FRI. THE WESTERLY FLOW SETS UP FRI NIGHT
THROUGH SAT. WEAK RIDGING BUILDS OVER THE EASTERN BERING SEA FRI
NIGHT AND SAT. A LOW OVER THE WESTERN NORTH PACIFIC MOVES SOUTH OF
THE WESTERN ALEUTIANS FRI NIGHT AND BECOMES GENERALLY STATIONARY
THROUGH SAT. A SERIES OF WAVES MOVE ACROSS THE NORTH PACIFIC EAST OF
THE CENTER TO SOUTH OF THE GULF OF ALASKA.

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
THE LOW OVER PRINCE WILLIAM SOUND CONTINUES TO WEAKEN AND WILL DRIFT
SOUTH FRI AND WEAKEN. SNOW SQUALLS AND GUSTY WINDS ACROSS SOUTHERN
COOK INLET AND KACHEMAK BAY WILL DIMINISH OVERNIGHT AS THE PRINCE
WILLIAM SOUND LOW DRIFTS SOUTH AND PRESSURE GRADIENTS DIMINISH. THE
CHANCES OF SNOW WILL DIMINISH ACROSS MUCH OF THE AREA AFTER THE MORE
SIGNIFICANT OF THE UPPER WAVES MOVE ACROSS THE REGION TONIGHT.
HOWEVER...SOUTHWEST FLOW ALOFT AND A WEAKENING LOW OVER THE GULF WILL
CONTINUE THE THREAT OF SOME SNOW SHOWERS THROUGH FRI. CONDITIONS LOOK
TO BE SOMEWHAT DRIER AND WINDY ON SAT.

SOUTHWEST ALASKA...
WEAK RIDGING MOVES OVER SW ALASKA TONIGHT AND CONTINUES THROUGH FRI.
THE FLOW BECOMES PROGRESSIVELY OFFSHORE FRI NIGHT AND SAT AS THE
RIDGE RETREATS NORTH AND A FRONTAL WAVE MOVES TOWARD THE EASTERN
ALEUTIANS. WIND CHILLS WILL BECOME A CONCERN ACROSS THE REGION FRI
NIGHT AND SAT WITH INCREASING NORTHERLY FLOW.

ALEUTIANS...
THE BERING SEA RIDGE CONTINUES TO RETREAT NORTH AS A LOW COMPLEX
MOVES NORTH. THE MAIN LOW ANCHORS WELL SOUTH OF THE ALEUTIANS AS THE
FRONTAL TROUGH AND DEVELOPING WAVES MOVE NORTH TOWARD THE CHAIN. THE
INITIAL SURGE OF MOISTURE FRI WILL LIKELY BE SNOW...PROBABLY MIXING
WITH RAIN IN THE CENTRAL AND EASTERN ALEUTIANS ON SAT. STRONG WINDS
WILL ACCOMPANY SNOW...SO BLIZZARD CONDITIONS ARE POSSIBLE.

.LONG TERM FORECAST...
THE ALASKAN UPPER LOW WILL DRIFT WESTWARD INTO THE BERING SEA BY THE
END OF THE WEEK AND THROUGH THE WEEKEND. THERE IS A FAIR AMOUNT OF
UNCERTAINTY DURING THE EXTENDED FORECAST PERIOD...HOWEVER A MORE
ACTIVE PATTERN LOOKS TO BE IN STORE WITH THE ZONAL FLOW ALOFT SETTING
UP FOR A FEW DAYS ACROSS SOUTHERN AK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WATCH 187.
MARINE...STORM 175. GALE 130 138 155 165 170 172 176 179.
FIRE WEATHER...NONE.

RMC JAN 12