Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 021412
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
612 AM AKDT TUE SEP 2 2014

.ANALYSIS AND UPPER LEVELS...
A COLD UPPER LOW OFF THE NORTHWEST COAST IS STREAMING ABUNDANT
MOISTURE AROUND THE BASE OF ITS TROUGH WITH THE HEAVY
PRECIPITATION ACROSS THE CENTRAL INTERIOR. THE COLD FRONT ALONG
THE NORTHWEST COAST YESTERDAY RACED ACROSS THE NORTHERN HALF OF
THE STATE AND IS NOW STALLED ALONG A LINE FROM JUST NORTH OF EAGLE
IN EASTERN ALASKA TO THE YUKON DELTA. CLOUDS ARE INCREASING ACROSS
THE SOUTHERN AREAS OF THE STATE WITH DEEP LEVEL MOISTURE AND THE
WARMEST AIR MASS SLIDING INTO THE SOUTHWEST FROM THE BERING. THE
WARM AIR MASS BROUGHT RECORD BREAKING WARM TEMPERATURES TO SAINT
PAUL IN THE PRIBILOF ISLANDS YESTERDAY...HIGH 56/LOW 51. PATCHY
FOG AND LIGHT RAIN DEVELOPED ALONG THE FRONTAL BOUNDARY OVERNIGHT
AROSS THE KUSKOKWIM AND WESTERN AREAS OF BRISTOL BAY. RAIN ALSO
ALONG THE WESTERN ALASKA RANGE AND SOUTH TO TALKEETNA.

&&

.MODEL DISCUSSION...
MODELS WERE IN GOOD AGREEMENT WITH THE GENERAL SYNOPTIC PATTERN THROUGH
FRIDAY MORNING. THE ARCTIC LOW SHIFTS EAST ACROSS THE BEAUFORT
SEA WITH THE RIDGE ACROSS THE BERING MOVING TO THE NORTHEAST
PACIFIC. ENERGY FROM THE UPPER LOW WORKS ON MOVING THE COLD FRONT
SOUTH TODAY AND TONIGHT. THE BIGGEST CHALLENGE IN THE SHORT TERM
FORECAST IS THE FRONTAL PROGRESSION THROUGH TONIGHT. THE NAM WAS
FAVORED MODEL ACROSS SOUTHCENTRAL AND ITS SURROUNDING WATERS AS IT
KEEPS THE FRONT ALONG THE ALASKA RANGE TODAY WITH MOST OF THE RAIN
ACTIVITY ALONG THE MOUNTAINS. BETTER FORCING MOVES ACROSS THE
SUSITNA AND COPPER RIVER VALLEYS TONIGHT AS THE COLD FRONT SAGS
FURTHER SOUTH...THEREFOR PRECIPITATION WAS ADJUSTED TO INCLUDE A
SNOW MIX WITH MINOR ACCUMULATIONS TONIGHT.

THE GFS WAS THE MODEL CHOICE FOR THE SOUTHWEST MAINLAND AND
BERING/ALEUTIANS AS IT INCLUDED A GENERAL BLEND OF ALL THE
OPERATIONAL SOLUTIONS. THE LOW SOUTH OF THE EASTERN ALEUTIANS
SENDS A SHORT WAVE ACROSS OF THE ALASKA PENINSULA TONIGHT. ZONAL
FLOW ACROSS THE BERING AND RIDGING OVER THE PACIFIC STEER THE
ENERGY ALONG THE SOUTHERN GULF TODAY NOT GENERATING MUCH
PRECIPITATION. AS THE RIDGE SHIFTS EAST A STRONGER WAVE MOVES
NORTH ACROSS THE ALASKA PENINSULA AND INTO THE WESTERN GULF
SPREADING RAIN NORTH ACROSS THE SOUTHWESTERN MAINLAND.

THE UPPER WEATHER PATTERN SHIFTS FOR THE SECOND HALF OF THE WEEK
WITH A BROAD TROUGH ACROSS THE WESTERN BERING SENDING MULTIPLE
WAVES EAST BREAKING DOWN THE RIDGE OVER THE NORTHEAST PACIFIC.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...
RAIN CONTINUES TO DEVELOP ALONG THE ALASKA RANGE TODAY WITH
DOWNSLOPING KEEPING THE VALLEYS DRY UNTIL THE MAIN WAVE FORCES THE
FRONT TOWARD THE COAST OVERNIGHT. RAIN MIXED WITH SNOW IS POSSIBLE
ALONG THE ALASKA RANGE AND JUST SOUTH WITH ONLY MINOR ACCUMULATIONS
EXPECTED. PRECIPITATION TAPERS OFF ON WEDNESDAY AS THE SHORTWAVE
EXITS TO THE EAST. AS FOR WINDS...GENERALLY A LIGHT FLOW ACROSS
THE INLAND LOCATIONS AND GUSTY WINDS ACROSS THE WESTERN GULF AND
COOK INLET. WINDS TAPER OFF TONIGHT AS THE PRESSURE GRADIENT
RELAXES...HOWEVER THE SOUTHERN GULF KEEPS A STRONGER SOUTH TO
WESTERLY FLOW BETWEEN 20 TO 30 MPH. THE NEXT FRONT MOVES INTO THE
WESTERN GULF WEDNESDAY NIGHT SPREADING RAIN INTO THE NORTHERN GULF
THURSDAY AFTERNOON.

SOUTHWEST ALASKA...
THE FRONT BRINGS RAIN ACROSS THE SOUTHWESTERN MAINLAND THROUGH
TONIGHT AS IT SAGS SOUTHWARD. THE ALASKA PENINSULA WILL SEE
INCREASING CLOUDS THROUGH TODAY WITH RAIN CHANCES INCREASING
WEDNESDAY NIGHT AS A FRONT MOVES NORTH FROM THE PACIFIC. THIS
FRONT SPREADS RAIN INTO BRISTOL BAY THURSDAY AND THEN BECOMES
SCATTERED AS IT MOVES NORTH TOWARD THE ALASKA RANGE AND THE
KUSKOKWIM DELTA.


BERING SEA/ALEUTIANS...
QUIET WEATHER CONDITIONS CONTINUE THROUGH THE END OF THE WEEK AS
RIDGING OVER THE BERING BLOCKS LOW PRESSURE.

&&

.LONG TERM FORECAST...
THE PATTERN SHIFT FOR THE UPCOMING WEEKEND BRINGS INCREASED
CHANCES FOR PRECIPITATION ACROSS THE SOUTHERN MAINLAND AND
SURROUNDING WATERS. COOLER TEMPERATURES FILTER BACK ACROSS THE
WESTERN BERING THIS WEEKEND AS THE LONG WAVE TROUGH DEEPENS. WARM
AIR ADVECTION CONTINUES ALONG THE EASTERN BERING AND SOUTHERN
MAINLAND ON SATURDAY AND THEN POSSIBLE COOLER THAN NORMAL
TEMPERATURES SUNDAY AS A COOLER AIR MASS MOVES FROM NORTHERN
ALASKA.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.
&&

$$

KH SEP 14



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