FXAK68 PAFC 151228
AFDAFC

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKDT MON MAR 15 2010

.ANALYSIS AND UPPER LEVELS...

MASSIVE UPPER LEVEL TROUGH EAST OF KAMCHATKA AND AN EQUALLY MASSIVE
CLOSED LOW OVER THE GULF AND NORTHEAST PACIFIC THIS MORNING. A STRONG
RIDGE PERSISTS OVER THE CENTRAL ALEUTIANS AND BERING AND OVER THE
CANADIAN ROCKIES. AT THE SURFACE...LOWS ARE OVER THE EXTREME WESTERN
BERING AND THE SOUTHERN GULF OF ALASKA. A SURFACE RIDGE HAS MOVED
JUST WEST OF BRISTOL BAY. A WEATHER FRONT IS OVER THE WESTERN
ALEUTIANS WITH STRONG SOUTH FLOW MOVING TOWARD NIKOLSKI AND THE
PRIBILOFS. MANY WAVES ARE ROTATING AROUND THE GULF LOW...BRINGING
SNOW SHOWERS TO COASTAL LOCATIONS AND EAST FACING SLOPES OF THE
ALASKA AND ALEUTIAN RANGES.

.MODEL DISCUSSION...

MODELS ARE IN GOOD AGREEMENT THROUGH MIDWEEK. IN THE BERING...A WEAK
LOW DEVELOPS TODAY ALONG THE FRONT OVER THE CENTRAL ALEUTIANS AND
DISSIPATES TUE EVENING OVER THE BERING. THE NEXT FRONT MOVES INTO THE
WESTERN BERING TUE NIGHT AND REACHES THE CENTRAL BERING BEFORE
DISSIPATING LATE WED. IN THE EAST...POORLY TIMED WAVES WILL CONTINUE
TO ROTATE AROUND THE DECAYING GULF LOW UNTIL TUE NIGHT. AT THAT TIME
A LOW MOVING FROM THE NORTH PACIFIC WILL BRING SIGNIFICANT ONSHORE
FLOW LATER ON WED AND CONTINUING UNTIL THE WEEKEND. THE FORECAST IS A
BLEND WITH THE GFS THROUGH MIDWEEK...WITH HPC GUIDANCE BEING ADDED
INTO THE WEEKEND.

.SHORT TERM FORECAST...

IN THE WEST...THE WESTERN ALEUTIANS WILL HAVE SNOW SHOWERS THROUGH
TUE WHILE THE CENTRAL AND EASTERN ISLANDS WILL HAVE GALE FORCE SOUTH
WINDS AND A MIX OF RAIN AND SNOW. ON WED THE SECOND FRONT BRINGS
ANOTHER ROUND OF GALES AND SNOW CHANGING TO RAIN. THIS WILL CHANGE
BACK TO SNOW SHOWERS IN THE COLD ADVECTION BEHIND THE FRONT WHICH
MOVES ACROSS THE CHAIN BY THU NIGHT.

FOR SOUTHWEST AK...LINGERING NORTH WINDS WILL DIMINISH TODAY AS HIGH
PRESSURE BUILDS INTO THE AREA. CLEAR AND DRY CONDITIONS WILL THEN
PERSIST THROUGH WED...EXCEPT FOR CLOUDS ALONG THE ALASKA AND ALEUTIAN
RANGES. A FRONT ASSOCIATED WITH A NORTH PACIFIC LOW WILL BRING
SHOWERS ACROSS THE RANGES THU.

SOUTH AND EAST OF THE AK RANGE...POORLY TIMED WAVES WILL CONTINUE TO
ROTATE AROUND THE GULF LOW...WITH BANDS OF SNOW AND RAIN SHOWERS
BRUSHING COASTAL AREAS UNTIL WED MORNING. THE NEXT NORTH PACIFIC LOW
MOVING TOWARD THE AK PEN WED NIGHT WILL BRING ONSHORE FLOW AND MORE
COASTAL PRECIPITATION BEGINNING THU.

.LONG TERM FORECAST...

IN THE WEST...SHOWERS WILL DIMINISH FRI AS HIGH PRESSURE BUILDS OVER
THE BERING. THE NEXT LOW TO TRANSIT SOUTH OF THE CHAIN WILL BRING
SNOW TO THE ALEUTIANS FOR THE WEEKEND. SOUTHWEST AK WILL HAVE SNOW
SHOWERS FRI BEFORE HIGH PRESSURE DRIES OUT THE AREA FOR THE WEEKEND.
SOUTHEAST OF THE AK RANGE...ONSHORE FLOW WITH RAIN AND SNOW PERSISTS
FRI AND THEN TAPERS OFF FOR THE WEEKEND BENEATH WEAK HIGH PRESSURE,

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALES 150 155 170 172 176 179 185
HEAVY FREEZING SPRAY 138 150 155 165
FIRE WEATHER...NONE

DS MAR 10

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