Blizzard in Alaska, January 5, 2011

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 AM AKST WED JAN 5 2011

.ANALYSIS AND UPPER LEVELS...

UPPER LEVEL PATTERN SHIFT IS IN FULL SWING THIS MORNING WITH A
WEAKENING RIDGE OVER WESTERN CANADA AND OVER THE EASTERN HALF OF THE
BERING. AN UPPER LOW IS OVER KODIAK ISLAND AND A WEAKENING LOW IS
OVER THE EXTREME WESTERN BERING. AT THE SURFACE...A LOW IS JUST EAST
OF KODIAK ISLAND...ANOTHER IS TRAILING A WEATHER FRONT ACROSS THE
NORTHWESTERN BERING...AND THE NEXT MAIN PLAYER IS A DEEPENING LOW
WELL SOUTH OF THE WESTERN ALEUTIANS.

.MODEL DISCUSSION...

MODELS ARE IN EXCELLENT AGREEMENT FOR THE NEXT SEVERAL DAYS. THE
FORECAST UTILIZES THE NAM INITIALLY FOR FINE DETAIL AND THEN THE EC
FOR RUN TO RUN CONSISTENCY THROUGH THE MID RANGE...WITH HPC ADDED IN
FOR THE EXTENDED.

A WEAK WEATHER FRONT WILL EXIT THE WESTERN BERING THIS AFTERNOON.
HIGH PRESSURE MOVING FROM THE BERING TO WESTERN AK WILL ALLOW A
NORTH PACIFIC LOW....CURRENTLY WELL SOUTH OF THE WESTERN
ALEUTIANS...TO INTENSIFY AND MOVE TO THE CENTRAL ALEUTIANS BY THIS
EVENING. THE LOW WILL THEN WEAKEN AS IT MOVES TO EASTERN RUSSIAN BY
FRI NIGHT. ANOTHER LOW FOLLOWS THE FIRST...REACHING THE CENTRAL
ALEUTIANS SAT AND EASTERN RUSSIA SAT NIGHT.

MEANWHILE...THE LOW EAST OF KODIAK DRIFTS INTO THE CENTRAL GULF
TONIGHT AND THEN TO THE SOUTHEAST GULF BY THU NIGHT. HIGH PRESSURE
FROM THE WEST THEN BUILDS INTO THE GULF AND ALL EXCEPT WESTERN AK ON
FRI WHERE IT PERSISTS THROUGH THE WEEKEND.

.SHORT TERM FORECAST...

IN THE WEST...STRONG WIND WILL AFFECT THE ALEUTIANS TODAY THROUGH THU
NIGHT WITH RAIN OVER THE EASTERN HALF AND SNOW ON THE BACKSIDE OF THE
LOW AS IT MOVES NORTH. A BRIEF BREAK IN WIND AND PRECIPITATION IS
EXPECTED FRI...AND THEN ANOTHER ROUND OF RAIN AND WIND OVER THE
EASTERN ISLANDS WITH SNOW SHOWERS ON THE WEST WILL RETURN LATE FRI
AND PERSIST INTO THE WEEKEND.

FOR SOUTHWEST AK...SOME SNOW SHOWERS WILL PERSIST TODAY ON THE
WESTERN FLANK OF THE KODIAK LOW. PARTIAL CLEARING IS EXPECTED THU AND
THEN STRONG WIND WITH SNOW AND RAIN...ASSOCIATED WITH THE FIRST
BERING LOW..WILL AFFECT THE KUSKOKWIM DELTA AND THEN INLAND SECTIONS
THU NIGHT THROUGH SAT MORNING. DRY CONDITIONS THEN RETURN FOR THE
REST OF THE WEEKEND.

SOUTH AND EAST OF THE AK RANGE...ONSHORE FLOW WITH RAIN ALONG THE
COAST WILL END LATER TONIGHT AS THE LOW MAKES IT WAY ACROSS THE GULF.
THIS MOVEMENT WILL ALSO CREATE A NORTHERLY GRADIENT THAT WILL RETURN
COOLER AIR TO INLAND AREAS. HIGH PRESSURE THEN DRIES OUT THE ENTIRE
AREA WITH CLEAR SKIES INTO THE WEEKEND.

.LONG TERM FORECAST...

IN THE WEST...WINDY CONDITIONS WILL SPREAD ACROSS THE AREA WITH SOME
RAIN INTO THE BEGINNING OF NEXT WEEK. DRY CONDITIONS WILL PERSIST
ACROSS MAINLAND ZONES INTO EARLY NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALES 130 150 155 160 165 170 171 179 185
         STORMS 172 175 176
         HEAVY FREEZING SPRAY 160 165
FIRE WEATHER...NONE

DS JAN 11