Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 251434
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
534 AM AKST SUN JAN 25 2015

.ANALYSIS AND UPPER LEVELS...
THE LONGWAVE TROUGH RESPONSIBLE FOR THE ARCTIC AIR INTRUSION OVER
THE SOUTHERN MAINLAND HAS BEEN DIVIDED INTO A COUPLE DIFFERENT
TROUGH AXIS. THE FIRST IS PROPAGATING OVER THE COPPER RIVER BASIN
AND REPRESENTS MOST OF THE ENERGY OF THIS LONGWAVE. BEHIND THE
WAVE...DRYING IS OCCURRING OVER THE COOK INLET REGION WITH SOME
LOW/MID CLOUDS BANKING UP AGAINST THE CHUGACH. OUTFLOW WINDS ARE
CRANKING IN WHITTIER AND SEWARD AS ARCTIC AIR FLOWS THROUGH THE
CHUGACH. SOME OF THE COLDEST TEMPERATURES OF THE SEASON ARE
SETTLING IN OVER COOK INLET...EXAGGERATED WHERE CLEARING HAS
ALLOWED FOR EFFICIENT RADIATIONAL COOLING. HOW FAR TEMPERATURES
FALL BEFORE SUNRISE WILL BE DEPENDENT ON AMOUNT OF CLEARING OVER
THE AREA.

FURTHER OUT WEST...A LARGE MATURE LOW SPINS SOUTH OF THE ALEUTIAN
ISLANDS WITH A FRONT DRAPED OVER THE CHAIN. THIS SYSTEM IS NOT
MAKING MUCH NORTHWARD PROGRESS AS RIDGING TO ITS NORTH IS MAKING A
NEAR REX BLOCK OVER THE BERING SEA. OUTFLOW WINDS AND BELOW NORMAL
TEMPERATURES CONTINUE FOR THE SOUTHWEST MAINLAND.

&&

.MODEL DISCUSSION...
IN THE UPPER LEVELS GUIDANCE IS IN GREAT AGREEMENT WITH THE HEIGHT
FIELD THROUGH MID-WEEK. SLIGHT DIFFERENCES IN LOW CENTER POSITIONS
STILL EXIST AS WELL AS TRIPLE POINT LOW FORMATION DIFFERENCES BUT
FOR THE MOST PART GUIDANCE SHOWING THE SAME GENERAL SOLUTION. THE
BIGGEST DIFFERENCES ARE IN FRONTAL POSITION OVER THE BERING SEA
AND HOW MUCH PRECIPITATION FALLS OVER THE PRIBILOF ISLANDS THEN
EVENTUALLY THE SOUTHWESTERN MAINLAND.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
LINGERING CLOUDS OVER THE MATANUSKA AND SUSITNA VALLEY WILL
DIMINISH TODAY LEADING TO CONTINUED COLDER CONDITIONS. OUTFLOW
WINDS WILL CONTINUE ACROSS THE NORTH GULF COAST AS THE PRESSURE
GRADIENT REMAINS FAVORABLE AND ARCTIC AIR IS ENTRENCHED OVER THE
MAINLAND. THE COPPER RIVER BASIN WILL HAVE LOW AND MID LEVEL
CLOUDS LINGER THE LONGEST TODAY BUT SHOULD CLEAR OUT BY THE
NIGHTTIME HOURS WHEN TEMPERATURE WILL PLUMMET UNDER LIGHT WINDS.
DRY...CLEAR...AND COLD CONDITIONS WILL CONTINUE FOR THE NEXT
COUPLE DAYS. A FRONT WILL ENTER THE GULF LATE MONDAY.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
NOW THAT THE ARCTIC AIRMASS HAS SET UP OVER THE INTERIOR
SOUTHWEST TEMPERATURES WILL STRUGGLE TO RECOVER MUCH TODAY WITH
LITTLE CHANGE IN WIND OR CLOUDCOVER EXPECTED. THIS WILL CHANGE
TONIGHT AS A WAVE DEVELOPS IN THE BERING...INCREASING THE OFFSHORE
WINDS THROUGHOUT THE KUSKOKWIM DELTA AND BRISTOL BAY. THIS WILL
CREATE DANGEROUSLY LOW WIND CHILLS LATE TONIGHT AND TOMORROW
MORNING...ESPECIALLY FOR THE KUSKOKWIM DELTA WHERE A WIND CHILL
ADVISORY HAS BEEN ISSUED FOR WIND CHILLS AS LOW AS 45 BELOW ZERO.
TEMPERATURES WILL THEN SLOWLY RISE ON MONDAY AS WINDS AND CLOUDS
INCREASE. THIS INCREASING CLOUDCOVER WILL MOVE IN AS A RESULT AS A
SHORTWAVE MOVING IN FROM THE AKPEN. THIS WILL BRING ACCUMULATING
SNOW TO THE WESTERN BRISTOL BAY FROM LATE MONDAY INTO TUESDAY.
THIS WAVE HAS TO POTENTIAL TO BRING SIGNIFICANT ACCUMULATIONS TO
THE DILLINGHAM AREA BY TUESDAY MORNING...HOWEVER DUE TO SOME
DISAGREEMENT IN HOW FAR EAST THE SNOW WILL REACH AND STRENGTH OF
THE UPPER LEVEL WAVE...ITS TOO SOON TO SAY EXACTLY HOW MUCH SNOW
COULD FALL.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
THE FRONT ASSOCIATED WITH THE LOW CURRENTLY JUST SOUTH WILL
CONTINUE TO BRING RAIN AND SNOW FROM THE CENTRAL
ALEUTIANS...BECOMING SNOW AS IT SPREADS INTO THE EASTERN ALEUTIANS
AND AKPEN BY THIS LATE THIS AFTERNOON. THIS SYSTEM WILL THEN
SPREAD INTO THE BERING AND TOWARDS THE PRIBILOFS THIS
EVENING...HOWEVER THE MODELS HAVE TRENDED FURTHER SOUTH AND MUCH
LIGHTER WITH THE SNOWFALL AS IT APPROACHES THE ISLANDS BY MONDAY
MORNING. IT IS FOR THIS REASON...AND BECAUSE OF THE LACK OF
CURRENT TRANSPORTABLE SNOW AND UNSEASONABLY WARM WATERS IN THE
BERING THAT THE BLIZZARD WATCH THERE WAS CANCELLED THIS MORNING.
THERE STILL WILL BE AREAS OF BLOWING SNOW AS STRONG WINDS KICK UP
WHATEVER DOES FALL...HOWEVER AT THIS POINT IT DOES NOT APPEAR THIS
WILL BE ENOUGH TO CREATE BLIZZARD CONDITIONS.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
AN UPPER LEVEL RIDGE BEGINS TO AMPLIFY OVER SOUTHCENTRAL
TUESDAY...THEN PUSH EAST OVER SOUTHEASTERN ALASKA AS A COMPLEX
LOW OVER THE NORTH PACIFIC TRACKS FURTHER EAST BY THE END OF THE
WEEK. MULTIPLE WAVES ASSOCIATED WITH THIS COMPLEX SYSTEM OVER THE
NORTH PACIFIC WILL TRACK INTO PARTS OF THE SOUTHERN MAINLAND
THROUGH THE END OF THE WEEK...BRINGING PRECIPITATION AND LOCALLY
GUSTY WINDS TO THE AREA. FURTHER WEST...THERE IS AN UPPER LEVEL
BLOCKING PATTERN SETTING UP WITH AN AMPLIFIED POSITIVE TILTED
RIDGE BUILDING INTO THE WESTERN ALEUTIANS/BERING SEA BY TUESDAY.
THIS RIDGE WILL EXTEND THROUGH THE WESTERN ALEUTIANS NORTHWARD
INTO THE EASTERN SIBERIAN REGION. TO THE EAST OF THE HIGH PRESSURE
SET UP OVER THE WESTERN BERING...COLDER AIR WILL FILTER DOWN OVER
THE BERING AND CENTRAL/WESTERN ALEUTIANS WEDNESDAY AND TRACK
EASTWARD OVER THE EASTERN ALEUTIANS BY FRIDAY MORNING. ANOTHER
FRONTAL SYSTEM WILL TRACK OVER THE WESTERN ALEUTIANS
FRIDAY...BRINGING IN SOME GUSTY SOUTHERLY WINDS AND MIXED
PRECIPITATION OVER THE AREA AND PERSISTING INTO THE WEEKEND.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WIND CHILL ADVISORY 155.
MARINE....GALE WARNING 129 130 131 160 165 170 175 177 179 180
          HEAVY FRZ SPRAY 121 127 129 130 131 138 139 140 141
            160 165 179 180 185
FIRE WEATHER...NONE.

&&

$$

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



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