Blizzard in Alaska, April 8 to 10, 2009

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKDT WED APR 8 2009

.ANALYSIS AND UPPER LEVELS...
BY FAR THE STRONGEST FEATURE OVER THE FORECAST AREA EARLY THIS
MORNING IS A STRENGTHENING STORM FORCE SURFACE LOW PRESSURE NEARING
THE WESTERN ALEUTIANS. THIS LOW HAS GOOD UPPER LEVEL JET SUPPORT. A
WEAKER NEARLY STATIONARY VERTICALLY STACKED LOW PRESSURE IS LOCATED
NEAR SAINT LAWRENCE ISLAND THIS MORNING...TO MOVE INLAND OVER THE
SEWARD PENINSULA TONIGHT. A WEAKENING UPPER LEVEL SHORTWAVE TROUGH
AND WEAK SURFACE FRONT CONNECTED TO THE SAINT LAWRENCE LOW IS
POSITIONED OVER THE SOUTHWEST MAINLAND THIS MORNING WITH SOME LIGHT
SNOW PERSISTING. THIS SYSTEM WILL CONTINUE TO WEAKEN AS IT SLOWLY
PROGRESSES EAST.

.MODEL DISCUSSION...
MODELS ARE IN PRETTY GOOD AGREEMENT EVEN INTO THE EXTENDED.

.SHORT TERM FORECAST...
BERING SEA/ALEUTIANS...
A STRONG LOW PRESSURE SYSTEM WITH STORM FORCE WINDS WILL MOVE EAST
ALONG THE ALEUTIANS THROUGH THE SHORT TERM. THE LOW WILL REACH
AMCHITKA THIS EVENING...THEN MOVE EAST TO JUST SOUTH OF SAND POINT
THURSDAY EVENING. A FRONT WILL STRETCH WELL OUT AHEAD OF THE LOW
WITH A TRIPLE POINT LOW PERHAPS DEVELOPING ALONG THE FRONT JUST
SOUTH OF THE PRIBILOFS THURSDAY MORNING AND THEN MOVING EAST INTO
BRISTOL BAY AS THE MAIN LOW PASSES JUST SOUTH OF THE ALEUTIAN CHAIN
AND AKPEN. BESIDES THE OBVIOUS STRONG WINDS...THE MAIN CONCERN IS
POTENTIAL BLIZZARD CONDITIONS FOR THE WESTERN ALEUTIANS TODAY AND
TONIGHT ON THE NORTHWEST SIDE OF THE LOW...AND THE PRIBILOFS TONIGHT
AND THURSDAY ON THE NORTH SIDE OF THE FRONT/TRIPLE POINT LOW. WE ARE
JUST GOING TO PUT IN AREAS OF BLOWING SNOW AT THIS POINT RATHER THAN
ANY BLIZZARD WARNING OR WATCH AS CONFIDENCE ON CONDITIONS GETTING
THAT BAD ARE NOT HIGH ENOUGH.

SOUTHWEST MAINLAND...
TWO DIFFERENT WEAK SYSTEMS WILL IMPACT THE SOUTHWEST MAINLAND
THROUGH THIS EVENING...ONE BEING THE SAINT LAWRENCE LOW WHICH WILL
CONTINUE TO SEND SCATTERED SNOW SHOWERS INTO THE KUSKOKWIM DELTA
UNTIL IT MOVES INLAND TONIGHT OVER THE SEWARD PENINSULA...THE SECOND
BEING A DYING FRONT BANKED UP AGAINST THE ALASKA/ALEUTIAN RANGE
WHICH WILL ALLOW SOME LIGHT SNOW TO PERSIST IN THOSE AREAS. THE
STRONG LOW MOVING EAST THROUGH THE ALEUTIANS WILL BEGIN TO BRING
PRECIP TO THE WEST COAST THURSDAY MORNING. PRECIPITATION SHOULD
CONTINUE INTO FRIDAY AS THE MAIN LOW SLIDES INTO THE WESTERN GULF OF
ALASKA. PRECIPITATION SHOULD FALL MAINLY AS SNOW OVER THE KUSKOKWIM
VALLEY AND DELTA...WITH RAIN MIXING IN NEAR BRISTOL BAY. WILL HAVE
TO KEEP AN EYE OUT FOR POTENTIAL BLIZZARD CONDITIONS FOR THE
KUSKOKWIM DELTA COAST WITH THIS SYSTEM.

SOUTHCENTRAL...
PRETTY QUIET WEATHER OVER SOUTHCENTRAL THROUGH TONIGHT. THE WEAK
SHORTWAVE TROUGH WEST OF THE ALASKA/ALEUTIAN RANGE WILL TRY TO CROSS
THE RANGE LATER TODAY AND INTO TONIGHT. SOUTHWEST FLOW WILL DEVELOP
IN THE COOK INLET REGION WITH PERHAPS SOME INCREASED CLOUDCOVER LATE
THIS AFTERNOON INTO TONIGHT WITH MAYBE A FEW LIGHT SHOWERS...BUT
THATS ABOUT IT FOR THE EFFECTS OF THIS WEAK SYSTEM. ON THURSDAY AN
OCCLUDED FRONT MOVING WELL OUT AHEAD OF THE ALEUTIAN LOW WILL BRING
SNOW MIXING WITH OR CHANGING TO RAIN FOR KODIAK. PRECIPITATION
SHOULD REACH THE NORTH GULF COAST THURSDAY AFTERNOON OR EVENING AS
THE GALE FORCE FRONT APPROACHES...AND CONTINUE INTO FRIDAY. SOUTH TO
SOUTHEAST FLOW WILL KEEP MOST OF THE MAJOR POPULATION CENTERS
GENERALLY DRY WITH THIS SYSTEM.

.LONG TERM FORECAST...
LOW PRESSURE WILL STALL OUT IN THE GULF OF ALASKA INTO SUNDAY AND
THEN DISSIPATE. HIGH PRESSURE OVER THE BERING/ALEUTIANS THIS WEEKEND
WILL WEAKEN EARLY NEXT AS LOW PRESSURE SYSTEMS MOVE EAST ALONG THE
ALEUTIANS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM WARNING ZONES 176.
         GALE WARNING ZONES 130 132 138 150 155 170 172 175 179 351
          352 411 412 413.
         HEAVY FREEZING SPRAY WARNING ZONES 412.
FIRE WEATHER...NONE.

FOISY APR 09