Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 010036
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
436 PM AKDT FRI OCT 31 2014

.ANALYSIS AND UPPER LEVELS...
THE MAIN FEATURE CONTINUES TO BE THE STORM CENTER NEAR SAINT PAUL
ISLAND THIS AFTERNOON. GALE TO STORM FORCE WINDS ASSOCIATED WITH
THIS CENTER WERE OBSERVED OVERNIGHT AND THIS MORNING OVER MUCH OF
THE EASTERN BERING SEA/ALEUTIANS. FREQUENT GUSTS IN EXCESS OF 60
MPH WERE OBSERVED ALONG THE ALEUTIAN CHAIN WITH A FEW GUSTS TO
NEAR 85 MPH IN UNALASKA BAY THIS MORNING. THE FRONTAL TROUGH
ASSOCIATED WITH THIS LOW EXTENDS EAST THROUGH BRISTOL BAY TO JUST
SOUTH OF KODIAK ISLAND. RADAR IMAGERY SHOWS PRECIPITATION
SPREADING NORTH IN BRISTOL BAY...AND AS OF NOON RAIN WAS REPORTED
OVER THE SOUTHERN AK PEN WITH SOME SNOW AND BLOWING SNOW NEAR THE
WESTERN CAPES. TRIPLE POINT LOW DEVELOPMENT ALONG THE FRONT SOUTH
OF KODIAK IS LIKELY THIS AFTERNOON AS A STRONG UPPER WAVE IS
MOVING OVER THE AREA (MARINE 150). AN UPPER WAVE MOVING ACROSS THE
NORTH GULF AND WEAK SURFACE CENTER SOUTH OF THE KENAI PEN ARE
PRODUCING RAIN AND SNOW SHOWERS ALONG THE GULF WITH SOME SPILL
OVER SNOW SHOWERS WEST OF THE KENAI/CHUGACH MOUNTAINS.


&&

.MODEL DISCUSSION...
THE MAIN MODEL CHALLENGE CONTINUES TO BE THE STORM SYSTEM OVER
THE EASTERN BERING SEA AND ITS EVOLUTION OVER THE NEXT COUPLE OF
DAYS. THE ECMWF HAS BEEN MORE CONSISTENT OVERALL AND DID
INITIALIZE FAIRLY WELL THIS MORNING...SO WILL BE LEANING THAT
DIRECTION WITH THE AFTERNOON PACKAGES. WILL ALSO INCORPORATE SOME
GEM REGIONAL/NAM FOR MESOSCALE WINDS.


&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...
SHOWERS ARE EXPECTED TO CONTINUE ACROSS THE NORTH GULF COAST AND
KENAI TONIGHT WITH SOME SPILL OVER SNOW SHOWERS WEST OF THE
CHUGACH AS THE SURFACE LOW MOVES WEST AND WEAKENS. EAST WINDS WILL
INCREASE ACROSS TURNAGAIN ARM/PORTAGE TONIGHT AS THE SURFACE LOW
MOVES WEST INTO COOK INLET FOLLOWED BY A LULL ON SAT MORNING. THE
PRESSURE GRADIENTS WILL INCREASE AGAIN SAT AFTERNOON...SO EXPECT
THE TURNAGAIN WINDS TO COME BACK UP. STEADY RAIN WITH SNOW MIX
SHOULD SPREAD TO MUCH OF THE COAST LATE TONIGHT AND SAT AS THE
FRONTAL TROUGH NEAR KODIAK ISLAND HEADS TOWARD THE COAST. THE
BRUNT OF THE PRECIPITATION WILL LIKELY BE ALONG THE COASTS AS
INCREASING CROSS BARRIER FLOW SHOULD DAMPEN PRECIPITATION TO THE
WEST. BETTER SHOT AT RAIN AND SNOW WEST OF THE COASTAL MOUNTAINS
WILL OCCUR LATER SAT WAS THE FRONT MOVES INLAND. SHOWERS LIKELY TO
CONTINUE ACROSS THE REGION THROUGH THE REMAINDER OF THE WEEKEND AS
BROAD CYCLONIC FLOW CONTINUES.

SOUTHWEST ALASKA...
THE FRONTAL TROUGH APPROACHING THE COAST THIS AFTERNOON WILL MOVE
INLAND AND WEAKEN OVERNIGHT. OVERRUNNING SNOW SHOULD CONTINUE THE PUSH
NORTH TONIGHT INTO THE BRISTOL BAY MAINLAND WITH SOME UPSLOPE
ENHANCEMENT INLAND WITH SOUTHERLY WINDS IN THE LOW LEVELS.
OVERRUNNING WARM AIR AHEAD OF FRONT WILL INCREASE THE FREEZING
RAIN THREAT THIS EVENING NORTH OF KING SALMON AS THE COLD SURFACE
AIR WILL BE SLOW TO ERODE. PRECIPITATION SHOULD TURN TO RAIN AND
BECOME SHOWERY ALONG THE COASTS AND MIXED INLAND AFTER FRONTAL
PASSAGE. SHOWERY CONDITIONS WITH GRADUAL DRYING OVER THE SW
MAINLAND IS EXPECTED THROUGH THE REMAINDER OF THE WEEKEND. STRONG
WINDS ALONG THE AK PEN WILL GRADUALLY DIMINISH SAT NIGHT AND SUN.
HIGH SEAS GENERATED BY THIS LOW COUPLED WITH HIGH TIDES TONIGHT
WILL PROBABLY CREATE SOME ROUGH SURF CONDITIONS IN BRISTOL BAY
COAST FROM PORT HEIDEN TO GOOD NEWS BAY.


BERING SEA/ALEUTIANS... STRONG WINDS ACROSS THE ALEUTIANS WILL
GRADUALLY DIMINISH FROM THE WEST THROUGH SAT AND SUN. RAIN WILL
CONTINUE ALONG THE FRONT TODAY AS IT MOVES TOWARDS THE SOUTHWEST
MAINLAND...FOLLOWED BY A TRANSITION TO A MORE SHOWERY REGIME AS
NORTHWEST FLOW COMMENCES ON THE BACKSIDE OF THE SYSTEM. COLD
ADVECTION WILL ALLOW FOR A CHANGEOVER TO SNOW LATER TODAY FOR THE
PRIBILOF ISLANDS...WITH A COUPLE INCHES OF ACCUMULATION POSSIBLE
BY SATURDAY MORNING. PRECIPITATION  TYPE LOOKS TO REMAIN MOSTLY
RAIN ALONG THE ALEUTIANS...ALTHOUGH SOME SNOW WILL START TO MIX IN
DURING THE DAY ON SATURDAY.


&&

.LONG TERM FORECAST (TUE THROUGH FRI)...THIS TIME PERIOD STARTS
WITH A STRONG AND VERY MERIDIONAL JET CENTERED OVER THE BERING. IT
ENTERS OUR DOMAIN NEAR THE WESTERN ALEUTIANS AT 170 KTS. IT MAKES
A SHARP TURN OVER EXTREME NORTHEASTERN RUSSIA BEFORE DIVING
QUICKLY DOWN TO NEAR 35N. IT THEN TURNS BACK TO THE NORTHEAST AND
PLOWS INTO THE BRITISH COLUMBIA COAST AT AROUND 145 KTS. THIS JET
PAINTS THE STORY OF OUR PATTERN IN THIS TIME FRAME FOR SEVERAL
REASONS. ONE...THE STRONG WESTERLY PORTION WILL CONTINUE TO PUSH
MODEST STORMS ACROSS THE WESTERN ALEUTIANS. TWO...THE "DIVE" DOWN
TO 35N WILL ALLOW PLENTY OF COLD AIR TO SPILL INTO THE BACKSIDE OF
THE TROUGH OVER THE GULF OF AK. THIS WILL EFFECTIVELY DEEPEN AND
ENTRENCH THIS TROUGH THERE. THREE...THE JET SUPPORTING THIS TROUGH
WILL STAY WELL SOUTH OF THE MAINLAND. SO WHILE THE MAINLAND WILL
HAVE SOME UNSETTLED WEATHER...NO MAJOR STORMS APPEAR ON THE
HORIZON THROUGH FRIDAY.

TOWARDS THE END OF NEXT WEEK...THE PACIFIC JET CRANKS UP TO 200
KTS AND BECOMES MUCH MORE ZONAL. THIS CUTS OFF A CLOSED HIGH OVER
THE ARCTIC. THIS CLOSED HIGH WORKS IN CONJUNCTION WITH A WEAK LOW
OVER THE GULF OF AK TO FORM A MODIFIED VERSION OF A BLOCKING
PATTERN. SO...MOST OF THE "ACTIVE" WEATHER WILL REMAIN CONFINED
TO THE BERING SEA...BUT EVEN OUT THERE THINGS DON`T APPEAR OVERLY
IMPRESSIVE WITH JUST MINIMUM GALES. THE KEY TO THE PATTERN WILL BE
FIGURING OUT HOW THE STRONG JET WILL INTERACT WITH THE LOW IN THE
GULF LATER IN THE WEEK. MODELS ARE STARTING TO INDICATE THE
POTENTIAL FOR A STRONG PHASING LOW DEVELOPING BY NEXT WEEKEND NEAR
THE EASTERN ALEUTIANS AND ALASKA PENINSULA. DUE TO MODEL
UNCERTAINTY THAT FAR OUT...THERE IS LOW CONFIDENCE IN THAT PORTION
OF THE FORECAST AT THIS TIME.


&&


AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE
MARINE...STORM WARNING 172 174
GALE WARNING 119 120 130 132 139 150 155 165 170 171 173 175-185
FIRE WEATHER...NONE


$$

RMC/MO OCT 14



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