Blizzard and High Wind in Alaska, January 11, 2012

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 PM AKST TUE JAN 10 2012

.ANALYSIS AND UPPER LEVELS...
A VERY ACTIVE PATTERN CONTINUES FOR MOST OF THE SOUTHERN MAINLAND
TODAY. THE DOMINANT FEATURE RESPONSIBLE FOR MOST OF THE SENSIBLE
WEATHER IS A DEEP NORTHERN PACIFIC LOW PRESSURE. AN UPPER LEVEL
SHORTWAVE TROUGH AND THE ATTENDANT TRIPLE POINT LOW FORMING OFF OF
THE PARENT LOW HAS MOVED ASHORE THE ALASKAN PENINSULA AND PUSHED A
FRONT UP INTO THE NORTHERN GULF COAST BRINGING WIDESPREAD SNOW AND
WIND FROM THE KENAI PENINSULA THROUGH THE ANCHORAGE BOWL. BLIZZARD
CONDITIONS HAVE BEEN PREVALENT ACROSS THE EASTERN AND SOUTHWESTERN
KENAI PENINSULA AS WELL AS FURTHER WEST AROUND BETHEL AND KING
SALMON. COLD NORTHERLY FLOW OVER THE BERING BRINGS SNOW TO SAINT PAUL
AND THE EASTERN ALEUTIANS.

.MODEL DISCUSSION...
GUIDANCE REMAINS IN GOOD AGREEMENT WITH THE UPPER LEVEL PATTERN
THROUGH THE SHORT TERM. AT THE SURFACE MODELS AGREE ON TAKING THE
TRIPLE POINT LOW FROM THE ALASKAN PENINSULA UP INTO THE CENTRAL
INTERIOR WHILE WEAKENING FOR THE NEXT 24 HOURS. THERE IS VERY GOOD
AGREEMENT ON THE TRACK AND STRENGTH OF THE PARENT LOW AS IT WORKS UP
INTO THE WESTERN GULF AND EVENTUALLY TO PRINCE WILLIAM SOUND...THOUGH
GUIDANCE AS A WHOLE HAS SLOWED THE ARRIVAL BY ABOUT HALF A DAY OR SO.
THE EXACT TRACK OF THE LOW WILL DETERMINE INTENSITY AND DURATION OF
SNOW FOR THE ANCHORAGE BOWL. FURTHER OUT WEST MUCH OF THE ALEUTIANS
WILL SEE A BIT OF A BREAK FROM THE ACTIVE WEATHER AS HIGH PRESSURE
BUILDS IN. A WEAK LOW PRESSURE WILL CROSS THE WESTERN ALEUTIANS BUT
GUIDANCE IS HAVING A HARD TIME RESOLVING THE SMALL WEAK FEATURE.
THERE IS MORE AGREEMENT ON A LARGER KAMCHATKA LOW DEVELOPING LATER IN
THE WEEK WHICH WILL DRAG A FRONT OVER THE WESTERN CHAIN.

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...HIGH WINDS AND BLIZZARD CONDITIONS CONTINUE FOR
THE HIGHER ELEVATIONS IN THE ANCHORAGE BOWL BUT WILL BEGIN TO
DIMINISH THIS EVENING IS THE PRESSURE GRADIENT SLACKENS AND WINDS
TAPER OFF. AS THE FRONTAL BOUNDARY STALLS OVER THE NORTHERN GULF
COAST SNOW WILL CONTINUE FOR PRINCE WILLIAM SOUND. WEDNESDAY ANOTHER
LOW PRESSURE SYSTEM AND ATTENDANT FRONTAL BOUNDARY WILL MOVE INTO THE
NORTHERN GULF BRINGING ANOTHER ROUND OF SNOW...FIRST TO KODIAK ISLAND
THEN SPREADING NORTHWARD TO THE EASTERN KENAI PENINSULA AND UP INTO
PRINCE WILLIAM SOUND. THE EXACT POSITION OF THE SURFACE LOW PRESSURE
WILL FIRST INITIATE DOWNSLOPING IN FAVORED AREAS OF THE CHUGACH AND
THEN LATER WEDNESDAY RELAX THE WINDS ALLOWING FOR SNOW TO WORK INTO
THE WESTERN KENAI PENINSULA AND ANCHORAGE BOWL.

SOUTHWEST ALASKA...GUSTY NORTHWESTERLY WINDS CONTINUE BLIZZARD
CONDITIONS FOR THE KUSKOKWIM DELTA REGION THIS EVENING AS LOW
PRESSURE MOVES UP THE ALASKAN PENINSULA. SNOW ACCUMULATION WILL
CONTINUE FOR THE BRISTOL BAY REGION AND KUSKOKWIM VALLEY AS THE UPPER
LEVEL ENERGY MOVES UP THE ALASKA RANGE. SNOWFALL WILL CONTINUE FOR
UPSLOPE FAVORED REGIONS OF THE ALASKA RANGE AS THE NEXT LOW PRESSURE
WORKS UP INTO THE GULF OF ALASKA.

BERING SEA AND ALEUTIANS...A WEAK QUICK MOVING LOW PRESSURE WILL
BRING SNOW TO THE WESTERN CHAIN ON WEDNESDAY. A MORE POTENT LOW
DEVELOPS OFF KAMCHATKA WHICH WILL BRING A FRONTAL BOUNDARY EASTWARD
TOWARD THE END OF THE WEEK.

.LONG TERM FORECAST...
THE EXTENDED PERIOD WILL BRING A CHANGE OF SCENERY TO MOST OF ALASKA
AS A RIDGE BUILDS OVER THE EASTERN BERING SEA/WESTERN ALASKA. THE
EXACT POSITION OF THE RIDGE WILL HAVE AN AFFECT ON NORTHERLY WINDS
OVER THE CENTRAL PORTION OF THE STATE. THIS BLOCKING PATTER WILL KEEP
HOLD THROUGH NEXT WEEK AND KEEP THE PATTERN STAGNANT FOR A WHILE.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING....101 125 131 135 155 161 181
         WINTER WEATHER ADVISORY...145
         WIND CHILL ADVISORY...155
MARINE...STORM...120 125 130
         GALE...132 138 140 150 155 160 165 170 171 172 175 176 179
180
         HEAVY FREEZING SPRAY...130 132 138 140 141
FIRE WEATHER...NONE

MTL JAN 12