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000
FXAK68 PAFC 091423
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
520 AM AKST MON DEC 9 2013

.ANALYSIS AND UPPER LEVELS...
AN UPPER LEVEL RIDGE REMAINS OVER THE SOUTHERN MAINLAND THIS MORNING
BUT IS BEGINNING TO NARROW AND WEAKEN AS A SHORTWAVE TROUGH LIFTS
NORTHWARD INTO THE BRISTOL BAY REGION. THE LATTER FEATURE IS
SPREADING LIGHT PRECIPITATION OVER THE SOUTHWEST MAINLAND WITH A
MIXTURE OF RAIN AND SNOW AS WELL AS A FEW POCKETS OF FREEZING RAIN
BEING OBSERVED. DENSE FOG HAS FINALLY BEGUN TO DISSIPATE ACROSS
SOUTHCENTRAL ALASKA AS HIGH PRESSURE WEAKENS AND RETREATS TO THE
SOUTHEAST...WITH MOSTLY JUST A FEW AREAS PATCHY FOG LINGERING OVER
THE AREA. A BROAD COMPLEX UPPER LOW REMAINS CENTERED OVER THE NORTH
CENTRAL PACIFIC BUT IS BEGINNING TO WEAKEN IN PLACE AS IT CONTINUES
TO SEND WEAK DISTURBANCES NORTHWARD INTO THE BERING...SUPPORTING
PERSISTENT AREAS OF RAIN FROM THE AKPEN TO THE EASTERN ALEUTIANS.

.MODEL DISCUSSION...
MODELS REMAIN IN GOOD AGREEMENT IN GRADUALLY WEAKENING THE RIDGE OVER
SOUTHCENTRAL AK THROUGH TUESDAY AND ARE NOW STARTING TO SHOW BETTER
AGREEMENT ON THE UPPER TROUGH THAT WILL BE DROPPING OVER THE SOUTHERN
MAINLAND FROM THE NORTH AS THE RIDGE RETREATS. IN THE
MEANTIME...ANOTHER LOW FORMING OVER THE NORTH PACIFIC AS THE COMPLEX
LOW DISSIPATES WILL BE TRACKING TOWARDS THE GULF BY WEDNESDAY. MODELS
STILL SUGGEST THAT THE MAINLAND TROUGH WILL KEEP THIS LOW OVER THE
FAR SOUTHERN AND EASTERN GULF AND THUS KEEP THE BULK OF THE IMPACTS
OFFSHORE. FURTHER WEST...WEAK LOW PRESSURE LOOKS TO REMAIN OVER THE
BERING THROUGH THE END OF THE SHORT TERM AS AN UPPER LOW FORMS NEAR
THE CENTRAL ALEUTIANS ON WEDNESDAY AND TRACKS SLOWLY EASTWARD.
GENERALLY PREFERRED THE GFS FOR THE FORECAST.

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
WHAT REMAINS OF THE FOG OVER SOUTHCENTRAL WILL DISSIPATE BY LATER
THIS MORNING AS THE RIDGE AND ASSOCIATED SUBSIDENCE INVERSIONS
CONTINUE TO WEAKEN AND LOW LEVEL MOISTURE IS SCOURED OUT. THE
DISTURBANCE PASSING TO THE WEST WILL PROVIDE A CHANCE FOR FEW
ISOLATED SHOWERS THROUGH THE DAY. THE UPPER TROUGH WILL THEN DROP
INTO THE AREA FROM THE NORTH ON TUESDAY...YIELDING A FEW SHOWERS BUT
OTHERWISE HELPING TO KEEP THE AREA DRY AS THE NORTH PACIFIC LOW
REMAINS OVER THE SOUTHERN GULF. LOW PRESSURE OVER THE GULF COUPLED
WITH COLD ADVECTION FROM THE NORTH WILL LEAD TO THE DEVELOPMENT OF
OUTFLOW WINDS THROUGH FAVORED COASTAL AREAS BY MID TO LATE THIS WEEK.


SOUTHWEST ALASKA...
MIXED PRECIPITATION WILL CONTINUE ACROSS THE SOUTHWEST MAINLAND AS A
WEAK FRONT MOVES FROM BRISTOL BAY THIS MORNING TO THE KUSKOKWIM IN
THE AFTERNOON AND THEN DIMINISH. LIGHT FREEZING RAIN WILL AFFECT
BRISTOL BAY THROUGH LATE MORNING AND THE KUSKOKWIM DELTA THROUGH LATE
AFTERNOON. SCATTERED RAIN SHOWERS WILL MOVE ACROSS THE ALASKA
PENINSULA THROUGH THURSDAY AS LOW PRESSURE REMAINS JUST TO THE SOUTH.
THE SURFACE FLOW WILL GENERALLY BE WEAK ACROSS THE MAINLAND THROUGH
MID WEEK. WINDS ACROSS THE ALASKA PENINSULA WILL INCREASE TONIGHT AS
A SURFACE LOW LIFTS NORTH.

ALEUTIANS/BERING SEA...
A FRONT WILL MOVE SLOWLY EAST ACROSS THE WESTERN ALEUTIANS/BERING
TODAY BRINGING RAIN INTO THE CENTRAL ALEUTIANS TONIGHT. TEMPERATURES
ARE EXPECTED TO MODERATE BACK TO SEASONAL NORMALS AS NORTHERLY FLOW
ESTABLISHES BEHIND THE FRONT.

.LONG TERM FORECAST...
MODEL SOLUTIONS ARE ALL SUPPORTING A BROAD UPPER LEVEL TROUGH
CENTERING OVER THE SOUTHERN MAINLAND AT THE END OF THE WEEK WITH A
RIDGE AMPLIFYING OVER KAMCHATKA. COLD TEMPERATURES WILL STAY IN PLACE
ACROSS MUCH OF THE STATE THROUGH THE WEEKEND. HOWEVER...A WARM FRONT
WILL PUSH INTO THE THE GULF WATERS AT THE END OF THE WEEK BRINGING A
WARM MOIST AIR MASS TO THE NORTHERN GULF. DISTURBANCES ASSOCIATED
WITH THE TROUGH BRING INCREASED PRECIPITATION CHANCES ACROSS SOUTHERN
ALASKA AND THE BERING INTO THE WEEKEND.


.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...DENSE FOG ADVISORY 141
         FREEZING RAIN ADVISORY 155 161
MARINE...GALE WARNING 150 155 172
FIRE WEATHER...NONE

CB/KH DEC 13