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000
FXAK68 PAFC 241417
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
517 AM AKST SAT JAN 24 2015

.ANALYSIS AND UPPER LEVELS...
A BROAD TROUGH EXTENDS SOUTHWARD FROM NORTHERN ALASKA SOUTHWARD
THROUGH THE ALASKA RANGE WHERE DRY AIR IS CURRENTLY PUSHING
EASTWARD OVER COOK INLET. AHEAD OF THE TROUGH SOUTHWESTERLY FLOW
STREAMS FROM THE GULF THROUGH THE COPPER RIVER BASIN.  DEEP LAYER
MOISTURE IS QUICKLY MOVING TO THE EAST AS DRY AIR FILTERS IN FROM
THE WEST.

&&

.MODEL DISCUSSION...
GUIDANCE HAS SHOWN THE FULL ENVELOPE OF SOLUTIONS FOR THE LAST
COUPLE DAYS RANGING FROM SNOW AMOUNTS OF EPIC PROPORTIONS TO VERY
MINOR ACCUMULATIONS. THE RECENT TREND HAS BEEN WHISKING THE DEEP
LAYER MOISTURE TO THE EAST DESPITE MOST OF THE COOK INLET AREA
REMAINING UNDER FAVORABLE DYNAMICS...WITH THE UPPER TROUGH STILL
TO THE WEST THROUGH THE AFTERNOON. OTHERWISE GUIDANCE IN GOOD
AGREEMENT WITH THE REMAINDER OF THIS SYSTEM THROUGH THE WEEKEND.
CONSENSUS SAYS A PIECE OF ENERGY WILL MIGRATE FROM THE NORTH TO
THE GULF AND JOIN WITH THE EXISTING TROUGH...MAINLY AFFECTING THE
PRINCE WILLIAM SOUND AREA AS WELL AS COPPER RIVER BASIN.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAY 1 AND DAY 2)...
THE THREAT FOR SNOW TODAY WILL MAINLY BE ALONG THE
CHUGACH/TALKEETNA MOUNTAINS AS A DISTURBANCE MOVES SOME MOISTURE
INTO PRINCE WILLIAM SOUND. TEMPERATURES WILL HOLD STEADY OR FALL
THROUGHOUT THE DAY AS COLD AIR CONTINUES TO INFILTRATE THROUGH THE
ALASKA RANGE. MOST OF THE ACTION TODAY WILL BE ALONG THE NORTH
GULF COAST GULF COAST WITH CONTINUED ONSHORE FLOW AS WELL AS THE
COPPER BASIN WHICH WILL GET BOTH THE INCOMING DISTURBANCE AND THE
CURRENT TROUGH OVERHEAD. SUNDAY TRANSITIONS INTO A COLD OUTFLOW
PATTERN FOR MUCH OF THE SOUTHCENTRAL WITH SOME OF THE COLDEST
TEMPERATURES OF THE SEASON IN MOST AREAS AND GUSTY WINDS ALONG THE
GULF COAST.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAY 1 AND DAY 2)...
CLEAR SKIES THROUGHOUT THE SOUTHWEST MAINLAND WILL ALLOW FOR SOME
OF THE COLDEST OVERNIGHT LOWS OF THE SEASON TO OCCUR OVER THE NEXT
TWO NIGHTS. SOME GUSTY NORTHERLY WINDS WILL ALSO CONTINUE ALONG
THE KUSKOKWIM DELTA COAST INTO THE WESTERN CAPES...CREATING VERY
COLD WIND CHILLS DURING THE OVERNIGHT HOURS...BUT NOT QUITE TO
ADVISORY CRITERIA. THIS COLD TEMPERATURES AND GUSTY WINDS ALONG
THE COAST WILL CONTINUE THROUGH THE WEEKEND BEFORE BEGINNING TO
WARM ON SUNDAY NIGHT AS AN ALEUTIAN FRONT APPROACHES THE ALASKA
PENINSULA.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAY 1 AND DAY 2)...
AN UPPER LEVEL SHORTWAVE TRAVERSING THROUGH THE CENTRAL BERING
WILL BRING SNOW SHOWERS FROM THE PRIBILOFS INTO THE EASTERN
ALEUTIANS TODAY...WITH LIGHT ACCUMULATIONS EXPECTED. A NORTH
PACIFIC LOW WILL THEN BEGIN MOVING INTO THE WESTERN ALEUTIANS BY
THIS EVENING...BRINGING RAIN/SNOW AND GALE FORCE WINDS THAT WILL
SPREAD INTO THE CENTRAL ALEUTIANS FOR SUNDAY.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
A BROAD UPPER LEVEL RIDGE WILL BEGIN TO SET UP OVER THE SOUTHERN
MAINLAND MONDAY MORNING...AND CONTINUE TO AMPLIFY AND PUSH
EASTWARD (OVER SOUTHCENTRAL MAINLAND) THROUGH THE END OF THE WEEK
AS IT INTERACTS WITH A COMPLEX LOW IN THE NORTH PACIFIC. MULTIPLE
WAVES ASSOCIATED WITH THIS COMPLEX SYSTEM WILL TRACK THROUGH THE
SOUTHWEST MAINLAND AND GULF COAST THROUGH THE END OF THE
WEEK...BRINGING WAVE AFTER WAVE OF PRECIPITATION AND LOCALLY GUSTY
WINDS TO THE AREA. OVER THE BERING...A SPLIT PATTERN ALOFT SHIFTS
SLOWLY EAST WITH A RIDGE OVER THE BERING STRAIT AND A CLOSED LOW
SOUTH OF THE ALEUTIANS. THE UPPER RIDGE DRIVES A COLDER AIR MASS
SOUTH ACROSS THE BERING THROUGH MID WEEK. SCATTERED SNOW SHOWERS
ACROSS THE BERING WILL MIX WITH WITH RAIN ALONG THE ALEUTIANS AS
THESE TO SYSTEMS INTERACT WITH EACH OTHER. AS THE SYSTEM OVER THE
NORTH PACIFIC TRACKS EASTWARD...COLDER NORTHERLY FLOW WILL BEGIN
TO FILTER DOWN ON THE BACKSIDE OF THE LOW AND OVER THE WESTERN
ALEUTIANS. SCATTERED SNOW SHOWERS ARE POSSIBLE OVER THE BERING AND
ALEUTIANS DURING THIS TIME...AS THE COLDER AIR MOVING OVER THE
WARMER SEA SURFACE CAN PRODUCE CONVECTIVE SHOWERS. THIS COLDER AIR
AND SHOWERY CONDITIONS WILL TRACK THROUGH THE CENTRAL AND EASTERN
ALEUTIANS BY THE END OF THE WEEK...JUST IN TIME FOR ANOTHER
FRONTAL SYSTEM TO TRACK INTO THE WESTERN ALEUTIANS.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER WEATHER ADVISORY 111 141.
MARINE...GALES 130 131 150
         HEAVY FREEZING SPRAY 121 129 130 131 138 150 160 180 185
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...MTL
SOUTHCENTRAL ALASKA...MTL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DEK
LONG TERM...TP