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000
FXAK68 PAFC 251249
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
449 AM AKDT SAT OCT 25 2014

.ANALYSIS AND UPPER LEVELS...
THE PATTERN ALOFT CONTINUES TO BE ANCHORED BY A DEEP LOW PRESSURE
CENTERED OVER EASTERN RUSSIA. THE POLAR JET STREAM IS ZONALLY
ORIENTED FROM THE KAMCHATKA PENINSULA STRETCHING INTO THE BERING
SEA JUST OVER 100 KT. THE FLOW BECOMES MUCH MORE DIFLUENT TO THE
EAST OVER MAINLAND ALASKA WITH A COUPLE OF WEAK EMBEDDED
DISTURBANCES EVIDENT ON WATER VAPOR THIS MORNING. THE FIRST OF
WHICH BROUGHT FLURRIES AND LIGHT SNOW TO ANCHORAGE AND THE
MATANUSKA VALLEY...IS PROGRESSING INTO THE COPPER RIVER BASIN. A
STRONGER WAVE CURRENTLY RESIDES OVER THE CENTRAL BERING
SEA...PROGRESSING TOWARD THE SOUTHWEST MAINLAND.

A WEAK CIRCULATION IN THE LOW LEVELS SITS OVER THE NORTHERN GULF
KEEPING NUMEROUS SHOWERS IN THE AREA AS WELL AS PUMPING SOME
MOISTURE ALOFT OVER THE COPPER RIVER BASIN. THE COOK INLET REGION
IS SEEING DECREASING CLOUDINESS BEHIND THE DEPARTING TROUGH WITH
LIGHT WINDS AND SEASONABLE TEMPERATURES. LOW PRESSURE IN THE GULF
KEEPS AN ENHANCED SURFACE PRESSURE GRADIENT ALONG THE COASTAL
MOUNTAINS...FORCING SOME MODERATE STRENGTH "OUTFLOW" WINDS FROM
WESTERN PRINCE WILLIAM SOUND THROUGH THE NORTHEAST GULF COAST.

&&

.MODEL DISCUSSION...
GUIDANCE IS IN PRETTY GOOD AGREEMENT WITH THE UPCOMING SYNOPTIC
PATTERN. THE NEXT MAJOR FEATURE IN THE FLOW IS A SHORTWAVE TROUGH
UNDER THE JET IN THE BERING SEA. MODELS HAVE THIS FEATURE CROSSING
THE SOUTHWEST MAINLAND TODAY AND THE SOUTHERN MAINLAND EARLY
SUNDAY. MUCH LIKE THE LAST WAVE...GUIDANCE IS NOT VERY HOT ON THIS
ONE EITHER. THERE DOES APPEAR TO BE A STRONGER AREA OF LIFT
ASSOCIATED WITH THIS WAVE PASSING OVER THE SOUTHERN EDGE OF THE
KENAI PENINSULA BUT MOISTURE APPEARS LACKING AND THERE IS NOT A
WHOLE LOT GOING ON IN THE LOW LEVELS TO ACCOMPANY THIS FEATURE SO
THE LACK OF SIMULATED PRECIPITATION IS NOT SURPRISING. BOTH
DOMAINS PREFERRED A TRANSITION FROM THE 00Z NORTH AMERICAN MODEL
TO THE 00Z EUROPEAN MODEL.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...LOWER CLOUDS WILL BE DECREASING TODAY AS THE
UPPER TROUGH MOVES OFF AND DRIER AIR FILTERS INTO THE
COOK INLET REGION. HIGHER CLOUDS WILL STREAM INTO THE
SOUTHCENTRAL TODAY BUT MOST OF THE REGION WILL SEE SOME GOOD
SUNSHINE TO GO ALONG WITH SEASONABLE TEMPERATURES AND LIGHT WINDS.
LIGHT SNOW WILL LINGER OVER THE COPPER RIVER BASIN TODAY AND INTO
SUNDAY AS THE NEXT TROUGH KEEPS THE AREA UNDER FAVORABLE DYNAMICS.
RAIN SHOWERS WILL CONTINUE ALONG THE NORTHERN GULF AS THE LOW
LEVEL CIRCULATION THAT IS IN PLACE WILL LINGER THROUGH SUNDAY
BEFORE MOVING AWAY. GUSTY WINDS WILL REMAIN ALONG THE NORTH GULF
COAST THROUGH THE WEEKEND.

SOUTHWEST ALASKA...A QUICK MOVING DISTURBANCE ALOFT WILL TRAVERSE
THE MAINLAND TODAY BRINGING A QUICK SHOT OF RAIN AND SNOW ALONG
THE KUSKOKWIM DELTA COAST WITH SNOW INLAND. AN ABOVE FREEZING
LAYER JUST OFF THE SURFACE COULD PROMOTE SOME SLEET OR FREEZING
RAIN PROVIDED SURFACE TEMPERATURES STAY COLD ENOUGH. THIS
DISTURBANCE WILL WEAKEN AS IT MOVES EASTWARD OVERNIGHT BRINGING
LIGHT SNOW TO THE LOWER KUSKOKWIM VALLEY AND INTERIOR BRISTOL
BAY. THE ACTIVE PATTERN CONTINUES ON SUNDAY WHEN ANOTHER FRONT
COMES ASHORE THE DELTA BRINGING MORE RAIN AND SNOW.

BERING SEA/ALEUTIANS...A SMALL LINGERING LOW PRESSURE KEEPS SOME
SHOWERS IN THE FORECAST FOR THE EASTERN ALEUTIANS AND ALASKA
PENINSULA THIS MORNING. WINDS WILL LIGHTEN UP OVERNIGHT WITH THE
CHANCE FOR PATCHY FOG. A DEVELOPING SYSTEM IN THE WESTERN BERING
WILL STRENGTHEN WINDS FROM WEST TO EAST THROUGH THE WEEKEND WHILE
A FRONTAL BOUNDARY TRAVERSES THE BERING SEA BRINGING A PERIOD OF
RAIN AND SNOW.


&&

.LONG TERM FORECAST...
WHILE MODEL AGREEMENT BEYOND EARLY NEXT WEEK REMAINS QUITE POOR...THERE
HAVE BEEN SOME SMALL IMPROVEMENT IN THE MODELS SINCE YESTERDAY.
THERE IS NOW GOOD AGREEMENT THAT REMAIN THE REMNANTS OF TROPICAL
STORM ANA MOVE ONSHORE SOUTH OF THE PANHANDLE...WELL SOUTH AND
EAST OF OUR AOR. THE WEAK LOW THAT WILL FORM BEHIND THIS SYSTEM
WILL ALSO QUICKLY DIVE SOUTHWARD INTO THE NORTH PACIFIC TUESDAY-
WEDNESDAY...KEEPING PRECIPITATION CONFIDED TO THE GULF COAST AND
WESTERN BERING THROUGH WEDNESDAY.

BECAUSE OF THE POOR MODEL AGREEMENT WITH LOW LOCATION...THE LONG
TERM FORECAST ONCE AGAIN HEAVILY USED WPC GUIDANCE TODAY (WHICH
USED MOSTLY ENSEMBLES AND THE 00Z EC THROUGH TUESDAY).


&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 177 178 181 185.
FIRE WEATHER...NONE. &&

$$

MTL OCT 14





000
FXAK68 PAFC 242147
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
147 PM AKDT FRI OCT 24 2014

.ANALYSIS AND UPPER LEVELS...
AN ELONGATED UPPER LEVEL LOW OVER EASTERN RUSSIA INTO NORTHERN
ALASKA IS BRINGING ZONAL FLOW ALOFT OVER SOUTHERN ALASKA FROM THE
BERING SEA THROUGH THE GULF OF ALASKA. AN UPPER LEVEL DISTURBANCE
IS MOVING INTO SOUTHCENTRAL ALASKA FROM SOUTHWEST ALASKA. THIS
WAVE IS DISSIPATING AS IT MOVES TO THE EAST.
THIS PATTERN WILL BEGIN TO SHIFT ON SUNDAY AND SUNDAY NIGHT AS
THE LOW IN EASTERN RUSSIA DIGS SOUTHWARD INTO THE BERING SEA WHICH
WILL ALSO AMPLIFY AN UPPER LEVEL RIDGE OVER THE COPPER RIVER BASIN
NEAR THE ALCAN BORDER.

AT THE SURFACE THERE IS A LARGE AND COMPLEX LOW OVER THE NORTHWEST
BERING SEA THROUGH EASTERN RUSSIA. A FRONT ASSOCIATED WITH THIS
LOW COMPLEX IS KEEPING A FAIRLY TIGHT PRESSURE GRADIENT OVER THE
BERING SEA AS IT PUSHES INTO THE RIDGE OVER SOUTHWEST ALASKA. A
LOW NEAR THE NORTH GULF COAST WILL REMAIN IN THE AREA THROUGH
SATURDAY AND IS BRINGING SOME MOISTURE INTO THE COASTAL AREA AND
COPPER RIVER BASIN.

&&

.MODEL DISCUSSION...
MODEL INITIALIZATION WAS GOOD ON THE 12Z RUNS FOR ALL MODELS.
MODELS CONTINUE TO SHOW GOOD CONSENSUS UNTIL SATURDAY NIGHT WHEN
THE SOLUTION FOR THE LOW STRENGTHENING IN THE NORTHWEST BERING
SEA BEGINS TO DIVERGE. THE ECMWF MODEL IS SHOWING THE LOW STRONGER
AND FARTHER EAST ON SUNDAY AND THEN IS MOVE NORTHWARD FASTER THAN
DO THE GFS OR NAM MODELS. BY SUNDAY NIGHT THERE IS NEARLY 250
MILES DIFFERENCE IN LOCATION OF THE LOW WITH THE ECMWF MOVING IT
ALMOST TO THE BERING STRAIT WHILE THE NAM AND GFS HAVE IS
SOUTHWEST OF ST LAWRENCE ISLAND. WHILE THE CENTER OF THE LOW IS
FAR ENOUGH NORTH TO MITIGATE THE EFFECT IT WILL HAVE ON THE SOUTHWEST
ALASKA MAINLAND IT IS STRONG ENOUGH THAT THE TRACK WILL BE
IMPORTANT. IN SHORT...THERE WILL BE A STRONG LOW IN THE BERING
SEA THROUGH THE WEEKEND BUT THE DETAILS RELATED TO THE TRACK OF
THE LOW MAY CHANGE SOME AS THE STORM DEVELOPS.

&&

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
THE UPPER LEVEL WAVE THAT IS MOVING ACROSS THE ALASKA RANGE THIS
AFTERNOON IS RAPIDLY WEAKENING AS IT MOVES EASTWARD. THIS IS
DIMINISHING THE CHANCE FOR SNOW SHOWERS ACROSS THE COOK INLET TO
SUSITNA VALLEY REGIONS. THE LOW IN THE NORTHERN GULF IS PRODUCING
SOME RAIN AND SNOW SHOWERS NEAR THE COASTAL LOCATIONS. THIS LOW IS
ALSO PUSHING SOME MOISTURE INTO THE COPPER RIVER BASIN WHICH WILL
CAUSE SOME PERIODS OF SNOW THROUGHOUT THE BASIN INTO TOMORROW
MORNING. SKIES SHOULD BEGIN TO CLEAR OUT OVER SOUTHCENTRAL AGAIN
AS THE SURFACE LOW IN SOUTHWEST ALASKA MOVES OVER SOUTHCENTRAL
TOMORROW.

SOUTHWEST ALASKA...
THE RIDGE OVER SOUTHWEST ALASKA WILL GIVE WAY TO A WEATHER FRONT
WHICH WILL START TO BRING IN SNOW TO THE KUSKOKWIM DELTA TOMORROW
MORNING WHICH WILL SPREAD EASTWARD THROUGHOUT THE DAY. COASTAL
AREAS OF THE DELTA WILL ALSO SEE SOME GUSTY WINDS WITH THIS FRONT.

BERING SEA/ALEUTIANS...
THE MOSTLY CLEAR SKIES IN THE EASTERN BERING SEA WILL WAY TO
STORMY WEATHER AS THE WEATHER FRONT MOVES INTO THE AREA. A LOW
WILL DEVELOP NEAR KAMCHATKA SATURDAY AND MOVE RAPIDLY EASTWARD AND
STRENGTHEN BY SUNDAY. THIS WILL BRING SOME STORM FORCE WINDS INTO
SOME OF THE BERING SEA MARINE AREAS. AS THE UPPER LEVEL LOW DIGS
SOUTHWARD OVER THE BRING SEA EARLY NEXT WEEK IT WILL KEEP THE
STORM TRACK OVER THE AREA THROUGH THE MIDDLE OF NEXT WEEK.

&&

.LONG TERM FORECAST...
WHILE MODEL AGREEMENT BEYOND EARLY NEXT WEEK REMAINS QUITE
POOR...THERE HAVE BEEN SOME SMALL IMPROVEMENT IN THE MODELS SINCE
YESTERDAY. THERE IS NOW GOOD AGREEMENT THAT REMAIN THE REMNANTS OF
TROPICAL STORM AND MOVE ONSHORE SOUTH OF THE PANHANDLE...WELL
SOUTH AND EAST OF OUR AOR. THE WEAK LOW THAT WILL FORM BEHIND THIS
SYSTEM WILL ALSO QUICKLY DIVE SOUTHWARD INTO THE NORTH PACIFIC
TUESDAY- WEDNESDAY...KEEPING PRECIPITATION CONFIDED TO THE GULF
COAST AND WESTERN BERING THROUGH WEDNESDAY.

BECAUSE OF THE POOR MODEL AGREEMENT WITH LOW LOCATION...THE LONG
TERM FORECAST ONCE AGAIN HEAVILY USED WPC GUIDANCE TODAY (WHICH
USED MOSTLY ENSEMBLES AND THE 00Z EC THROUGH TUESDAY).

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 178.
FIRE WEATHER...NONE.
&&
$$

OCT 14





000
FXAK68 PAFC 241248
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
448 AM AKDT FRI OCT 24 2014

.ANALYSIS AND UPPER LEVELS...
ON THE LARGE SCALE THE PATTERN ALOFT IS CONTROLLED BY A LARGE
SIBERIAN LOW PRESSURE. THE MAIN FRONTAL BOUNDARY/SHORTWAVE TROUGH
ASSOCIATED WITH THE SYSTEM STRETCHES FROM THE CHUKCHI SEA
SOUTHEASTWARD THROUGH THE SOUTHERN MAINLAND...CURRENTLY BETWEEN
THE SOUTHCENTRAL AND SOUTHWEST MAINLAND. THE JET STREAM CURRENTLY
EXHIBITS A SPLIT FLOW PATTERN WITH THE MAIN BRANCH OF SUBTROPICAL
JET SITTING IN THE NORTHWESTERN PACIFIC AND MERGING WITH THE
NORTHERN STREAM JUST SOUTH OF THE ALASKA PENINSULA.

THE FRONT IS PRODUCING A LARGE AREA OF OVERRUNNING PRECIPITATION
OVER THE LOWER KUSKOKWIM VALLEY AND INTERIOR BRISTOL BAY. ABOVE
FREEZING AIR IN THE SOUTHERLY FLOW AHEAD OF THE FRONT IS LIMITED
TO THE SURFACE AND JUST ABOVE SO FREEZING RAIN IS NOT A CONCERN.
THE WEATHER OVER THE SOUTHCENTRAL IS CURRENTLY BENIGN WITH HIGH
CLOUDS FROM THE FRONT SPREADING OVER MOST AREAS. SHOWERS ARE
BEGINNING TO BLOSSOM OVER THE NORTHERN GULF IN RESPONSE TO
ANTECEDENT INSTABILITY AND WARM AIR ADVECTION DEVELOPING.

&&

.MODEL DISCUSSION...
GUIDANCE IN DECENT AGREEMENT WITH BOTH THE UPPER LEVELS AND THE
SURFACE IN THE NEAR TERM. OVER THE WEEKEND A STRONG IMPULSE LOOKS
TO ROUND THE BASE OF THE SIBERIAN UPPER LOW AND DEVELOP A STRONG
SYSTEM THAT TRACKS TOWARD THE BERING STRAIT. WHILE THE GUIDANCE
SUITE SHOWS A SIMILAR THEME IN DEVELOPING THIS SYSTEM THERE ARE
DIFFERENCES IN STRENGTH AND TRACK OF BOTH THE SURFACE LOW CENTER
AND FRONTAL BOUNDARY...WHICH WILL AFFECT THE SOUTHWEST MAINLAND BY
THE END OF THE WEEKEND.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...TWO DIFFERENT FEATURES WILL AFFECT THE AREA
TODAY...THE FIRST IS A WEAK SPIN-UP IN THE NORTHEASTERN GULF
WILL SPREAD SNOW AND RAIN SHOWERS OVER THE NORTHEAST GULF COAST
AND SNOW SHOWERS OVER THE COPPER RIVER BASIN LATER TODAY. OVER THE
COOK INLET REGION...THE LOW LEVEL FRONTAL BOUNDARY IS LOSING
STRENGTH AS THE ALASKA/ALEUTIAN RANGE. THE UPPER LEVEL SHORTWAVE
TROUGH ASSOCIATED WITH THE FRONT IS ALSO DE-AMPLIFYING AS IT
CROSSES THE RANGE WHILE THE FLOW ALOFT CONTINUES TO SLACKEN. WITH
NO APPRECIABLE THERMAL ADVECTION AND WEAKENING FORCING IT DOES NOT
LOOK LIKE A FAVORABLE SCENARIO FOR PRECIPITATION. INCREASING CLOUD
COVER AND LIGHT NORTHERLY WINDS WILL BE THE NORM TODAY WITH A
CHANCE FOR SOME FLURRIES...THE BEST CHANCES WILL LIE ALONG
ELEVATED TERRAIN IN THE EASTERN COOK INLET REGION. ANOTHER TROUGH
SLIDES THROUGH ON SUNDAY...THIS ONE A BIT STRONGER BUT LOOKS TO
ONLY AFFECT THE NORTHEAST GULF COAST AND SOUTHEASTERN COPPER RIVER
BASIN.

SOUTHWEST ALASKA...RAIN AND SNOW WILL CONTINUE EARLY THIS MORNING
ALONG THE ALASKA/ALEUTIAN RANGES BEFORE TAPERING OFF BY THE LATE
MORNING. HIGH PRESSURE BUILDING IN AT THE SURFACE AND COLD
ADVECTION ALOFT SHOULD MAKE FOR A MOSTLY CLOUD FREE DAY WITH LIGHT
WINDS ACROSS THE BRISTOL BAY AREA. PRECIPITATION HAS ENDED FOR THE
KUSKOKWIM DELTA BUT LINGERING MOISTURE AND SLACKENING WINDS WILL
MAKE FOR A PERIOD OF FOGGY CONDITIONS THIS MORNING. SOME
DISTURBANCES ALOFT WILL PUSH ACROSS THE DELTA LATE TONIGHT INTO
SATURDAY BRINGING ANOTHER ROUND OF RAIN CHANGING TO SNOW. THAT
WEATHER FRONT WILL PUSH OVER THE REST OF THE SOUTHWEST MAINLAND
LATE SATURDAY INTO SUNDAY.

BERING SEA/ALEUTIANS...A WEAKENING FRONTAL BOUNDARY STRETCHED OVER
THE EASTERN ALEUTIAN AND ALASKA PENINSULA WILL KEEP RAIN SHOWERS
IN THE FORECAST THROUGH THE OVERNIGHT HOURS TONIGHT. ANOTHER FRONT
CROSSES THE BERING LATE TONIGHT BUT SHOULD STAY NORTH OF MOST OF
THE CHAIN. A STRONG LOW PRESSURE WILL DEVELOP OVER THE NORTHWEST
BERING ON SUNDAY AND SEND YET ANOTHER FRONT ACROSS THE BERING
SUNDAY AND MONDAY BRINGING RAIN AND SNOW TO MOST AREAS.

&&

.LONG TERM FORECAST...
MODEL CONSISTENCY...BOTH RUN TO RUN AND BETWEEN MODELS...REMAINS A
PROBLEM. OVERNIGHT OPERATIONAL RUNS RAPIDLY LOST AGREEMENT,
ALTHOUGH THE MORNING RUNS OF THE GFS AND EC WERE MUCH
CLOSER...ESPECIALLY WITH THE LOWS AND FRONTAL SYSTEMS MOVING
ACROSS THE BERING. RELIED HEAVILY ON THE DECISION OF WPC TO BEGIN
WITH A 00Z EC MEAN AS A STARTING POINT. THE GRIDS REPRESENT A
BLEND OF THE WPC GUIDANCE...AND WITH WINDS ENHANCED WITH THE 00Z
EC. THE CONFIDENCE REMAINS FAIRLY LOW...BUT THERE IS SOME HOPE
THAT THE MODELS WILL COME INTO BETTER AGREEMENT IN THE NEXT DAY OR
SO.

THE SOLUTION INVOLVES TWO FRONTAL SYSTEM AFFECTING THE BERING AND
WESTERN AK OVER THE EXTENDED PERIOD. THE INITIAL FRONT...FROM A
BERING STRAIT LOW...MOVES INTO WESTERN AK AND THE EASTERN
ALEUTIANS MON AND DISSIPATES RAPIDLY ON TUE. THE SECOND LOW AND
FRONT AFFECT THE WESTERN BERING TUE NIGHT WITH THE FRONT REACHING
WESTERN AK THU BEFORE DISSIPATING INLAND BY FRI. YET ANOTHER FRONT
MOVES INTO THE WESTERN BERING ON FRI.

WHILE THIS IS HAPPENING THE REMNANTS OF TROPICAL STORM ANA MOVE
INTO SE AK LATER ON MON AND FORM AN ELONGATED TROUGH ALONG THE
NORTHEASTERN GULF COAST THAT PERSISTS THROUGH WED. HIGH PRESSURE
THEN BUILDS OVER THE GULF ON THU.

SHOWERS WILL PERSIST OVER THE BERING AND ALEUTIANS ON MON..AND
THEN RAIN AND SNOW ARE EXPECTED TUE NIGHT BEFORE CHANGING TO SNOW
SHOWERS WED AND THU. MORE RAIN AND SNOW IS EXPECTED FRI. SOME GALES
WILL ACCOMPANY THE FRONTS AS THEY TRANSIT THE BERING.

SOUTHWEST AK WILL HAVE RAIN AND SNOW SHOWERS MON...DRYING ON
TUE...RAIN AND SNOW WED INTO THU...AND SHOWERS LATER ON THU INTO
FRI.

SOUTHCENTRAL WILL BE GENERALLY DRY INLAND THROUGH FRI WITH
SHOWERS ASSOCIATED WITH THE TROUGH ALONG THE COAST TUE AND WED.

&&

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

$$

MTL/DS OCT 14





000
FXAK68 PAFC 232218
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
218 PM AKDT THU OCT 23 2014

.ANALYSIS AND UPPER LEVELS...

500MB...THE PERSISTENT UPPER TROUGH OVER THE MAINLAND AND GULF
MOVE EAST AS THE BERING SEA RIDGE NOSES IN FROM THE WEST. AN UPPER
LOW OVER EASTERN RUSSIA ACTS AS THE FOCAL POINT FOR TROUGHS MOVING
IN FROM THE WEST THROUGH SAT. THE MORE SIGNIFICANT OF THE TROUGHS
CURRENTLY OVER THE EASTERN BERING SEA MOVES OVER THE CENTRAL
MAINLAND FRI AFTERNOON THEN INTO THE YUKON ON SAT. BROAD ZONAL
WESTERLY FLOW SETS UP ACROSS THE BERING SEA TONIGHT AND HOLDS
THROUGH SAT. A FEW MINOR WAVES ARE EXPECTED TO RIPPLE EAST ACROSS
THE BERING SEA. COLD AIR DROPPING SOUTH BEHIND THE EASTERN RUSSIA
LOW SUN DIGS OUT THE TROUGH OVER THE CENTRAL BERING SETTING UP A
FAIRLY BROAD SW JET. AT THE SAME TIME THE RIDGE BUILDS OVER THE
WESTERN/CENTRAL MAINLAND.

.SURFACE...

A FEW SHOWERS WITH WEAK TROUGHING WAS EVIDENT OVER THE NORTH GULF.
SKIES ELSEWHERE ACROSS SOUTHCENTRAL WERE RELATIVELY CLEAR EXCEPT FOR
PERSISTENT STRATUS OVER THE COPPER RIVER BASIN. OUTFLOW WINDS
CONTINUED INTO THE AFTERNOON HOURS OVER THE NORTH GULF COAST AND
WESTERN KENAI PEN. OUT WEST...OVERRUNNING ASSOCIATED WITH A
FRONTAL TROUGH BROUGHT SNOW TO THE DELTA. THIS AFTERNOON...THE
COAST CAME UNDER THE INFLUENCE OF THE WARM SECTOR OF THE FRONT
AND SNOW RAPIDLY CHANGED OVER TO RAIN.


&&

.MODEL DISCUSSION...
MODELS ARE IN RELATIVELY GOOD AGREEMENT IN THE EAST THROUGH THE
SHORT TERM. OUT WEST...THE MODELS STRUGGLE WITH THE PLACEMENT AND
TIMING OF SURFACE FEATURES UNDER STRONG W TO SW FLOW ALOFT. THE
NAM AND EC ARE THE FASTER OF THE SOLUTIONS WITH THE GFS LAGGING
WELL BEHIND. IT SEEMS REASONABLE TO LEAN TOWARD THE FASTER MODEL
SOLUTIONS IN LIGHT OF THE INITIAL STRONG WESTERLY FLOW THEN
DEEPENING SW FLOW ALOFT OVER THE BERING SEA ON SUN.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...
OUTFLOW WINDS ACROSS THE NORTH/WEST GULF WILL SLOWLY DIMINISH
OVERNIGHT. THE FRONTAL TROUGH MOVING INTO COOK INLET FRI LOOKS
LIKE IT COULD HAVE A GREATER IMPACT THAN ORIGINALLY THOUGHT. THE
UPPER TROUGH ASSOCIATED WITH THIS FEATURE IS SOMEWHAT SHARPER AND
THE LOW AND MID LEVEL(850-700MB) FLOWS WILL LIKELY BE MORE SWLY.
THE RESULT COULD BE MORE WIDESPREAD PRECIPITATION ACROSS THE
REGION ON FRI. CURRENT THINKING IS THAT THE CHUGACH AND TALKEETNA
MOUNTAINS WILL LIKELY SEE MEASURABLE SNOWFALL ON FRI WITH LITTLE
MEASURABLE ACCUMULATIONS AT THE LOWER ELEVATIONS. MINOR
ACCUMULATIONS ARE ALSO POSSIBLE WITH SNOW SHOWERS OVER THE COPPER
RIVER BASIN. THE WARMER TEMPS WILL REMAIN ALONG THE COASTS AND
KENAI PEN...SO MOST OF THE PRECIPITATION IN THOSE AREAS WILL BE
RAIN OR A MIX. SHOWERY WEATHER WILL LIKELY CONTINUE INTO SAT WITH
SW FLOW ALOFT.

SOUTHWEST ALASKA...
A FAST MOVING FRONT WILL RAPIDLY TRACK FROM WEST TO EAST THROUGH
TONIGHT...SPREADING RAIN AND SNOW ACROSS THE REGION. WE WILL BE INCREASING
THE SNOW ACCUMULATIONS OVER THE KUSKOKWIM VALLEY AND INTERIOR
BRISTOL BAY TONIGHT WITH UPSLOPE CONDITIONS. COASTAL AREAS WILL
LIKELY SEE RAIN AND SNOW MIXES. THERE IS STILL SOME CONCERN FOR
POCKETS OF LIGHT FREEZING RAIN OVER INTERIOR BRISTOL BAY THIS
EVENING AS WARM AIR OVERRIDES POCKETS OF SHALLOW COLD SURFACE
AIR. WESTERLY ONSHORE FLOW WILL LINGER BEHIND THE FRONT...WITH
EXTENSIVE CLOUD COVER PERSISTING AFTER THE FRONT CLEARS.

BERING SEA/ALEUTIANS...
A FAST MOVING FRONT TRACKING ACROSS THE BERING WILL CLEAR THE
EASTERN BERING TONIGHT LEAVING LARGELY DRY CONDITIONS ACROSS MOST
OF THE ALEUTIANS AND BERING SEA HEADING INTO THE WEEKEND.

&&

.LONG TERM FORECAST...

MODEL CONSISTENCY...BOTH RUN TO RUN AND BETWEEN MODELS...REMAINS A
PROBLEM. OVERNIGHT OPERATIONAL RUNS RAPIDLY LOST AGREEMENT,
ALTHOUGH THE MORNING RUNS OF THE GFS AND EC WERE MUCH
CLOSER...ESPECIALLY WITH THE LOWS AND FRONTAL SYSTEMS MOVING
ACROSS THE BERING. RELIED HEAVILY ON THE DECISION OF WPC TO BEGIN
WITH A 00Z EC MEAN AS A STARTING POINT. THE GRIDS REPRESENT A
BLEND OF THE WPC GUIDANCE...AND WITH WINDS ENHANCED WITH THE 00Z
EC. THE CONFIDENCE REMAINS FAIRLY LOW...BUT THERE IS SOME HOPE
THAT THE MODELS WILL COME INTO BETTER AGREEMENT IN THE NEXT DAY OR
SO.

THE SOLUTION INVOLVES TWO FRONTAL SYSTEM AFFECTING THE BERING AND
WESTERN AK OVER THE EXTENDED PERIOD. THE INITIAL FRONT...FROM A
BERING STRAIT LOW...MOVES INTO WESTERN AK AND THE EASTERN
ALEUTIANS MON AND DISSIPATES RAPIDLY ON TUE. THE SECOND LOW AND
FRONT AFFECT THE WESTERN BERING TUE NIGHT WITH THE FRONT REACHING
WESTERN AK THU BEFORE DISSIPATING INLAND BY FRI. YET ANOTHER FRONT
MOVES INTO THE WESTERN BERING ON FRI.

WHILE THIS IS HAPPENING THE REMNANTS OF TROPICAL STORM ANA MOVE
INTO SE AK LATER ON MON AND FORM AN ELONGATED TROUGH ALONG THE
NORTHEASTERN GULF COAST THAT PERSISTS THROUGH WED. HIGH PRESSURE
THEN BUILDS OVER THE GULF ON THU.

SHOWERS WILL PERSIST OVER THE BERING AND ALEUTIANS ON MON..AND
THEN RAIN AND SNOW ARE EXPECTED TUE NIGHT BEFORE CHANGING TO SNOW
SHOWERS WED AND THU. MORE RAIN AND SNOW IS EXPECTED FRI. SOME GALES
WILL ACCOMPANY THE FRONTS AS THEY TRANSIT THE BERING.

SOUTHWEST AK WILL HAVE RAIN AND SNOW SHOWERS MON...DRYING ON
TUE...RAIN AND SNOW WED INTO THU...AND SHOWERS LATER ON THU INTO
FRI.

SOUTHCENTRAL WILL BE GENERALLY DRY INLAND THROUGH FRI WITH
SHOWERS ASSOCIATED WITH THE TROUGH ALONG THE COAST TUE AND WED.

&&

AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...MARINE WEATHER STATEMENT 138 150.
         GALE 150.
FIRE WEATHER...NONE.

$$

RMC/DS OCT 14





000
FXAK68 PAFC 231322
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
522 AM AKDT THU OCT 23 2014

.ANALYSIS AND UPPER LEVELS...

PERSISTENT UPPER LEVEL TROUGHING OVER THE REGION IS BEGINNING TO
LOSE ITS GRIP OVER THE STATE AS A STOUT FRONT OVER THE WESTERN
BERING STRENGTHENS AN EASTERN BERING RIDGE...WITH THE ASSOCIATED
NORTH PACIFIC JET STREAM MOVING SOUTHEAST TOWARD THE WESTERN U.S.
COAST. THE EASTERN SIBERIA UPPER LOW COMPLEX DRIVING THE WARM
FRONT THROUGH THE BERING WILL SLOWLY MOVE EAST THROUGH THIS
WEEKEND...SHIFTING THE POLAR JET STREAM AND ASSOCIATED BAROCLINIC
ZONE FARTHER NORTH. THIS WILL DECOUPLE THE POLAR AND SUBTROPICAL
JETS...AND WILL USHER IN A FASTER ZONAL FLOW PATTERN.

&&

.MODEL DISCUSSION...

MODELS ARE IN EXCELLENT AGREEMENT THROUGH SATURDAY BEFORE THEY
BEGIN TO RAPIDLY DIVERGE SUNDAY AND BEYOND. THE GLOBAL GUIDANCE
CONTINUES TO STRUGGLE WITH THE DEVELOPMENT OF A TROUGH OVER THE
BERING SEA...AND ITS INTERACTION WITH A SUBTROPICAL LOW (WHICH
ALSO INCLUDES THE REMNANTS OF FORMER TROPICAL STORM ANA). THE GFS
FAVORS A WEAKER INTERACTION WHILE THE ECMWF AND CANADIAN GDPS ARE
MORE AGGRESSIVE. THE FORMER SCENARIO WOULD RESULT IN RIDGING
BUILDING OVER THE STATE MONDAY THROUGH THURSDAY NEXT WEEK WHILE
THE ECMWF/CANADIAN GDPS WOULD FAVOR DEVELOPING PRECIPITATION AS
EARLY AS LATE MONDAY INTO TUESDAY ACROSS MUCH OF SOUTHERN ALASKA.
FOR THE TIME BEING...THE SHORT TERM FORECAST INTO THE WEEKEND IS
VERY HIGH CONFIDENCE...WITH LOW CONFIDENCE BEYOND THE WEEKEND. THE
GFS AND ECMWF WERE FAVORED IN THE SHORT TERM WITH A BLENDED WPC
APPROACH FOR THE EXTENDED.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...
ANOTHER QUIET DAY ACROSS SOUTHCENTRAL AS THE AREA HOLDS ON TO A
DRY OFFSHORE FLOW. RAIN AND SNOW SHOWERS ACROSS PARTS OF THE NORTH
GULF COAST INTO THOMPSON PASS WILL QUICKLY END THIS MORNING.
NORTHERLY GAP WINDS WILL CONTINUE THROUGH TODAY BEFORE
DIMINISHING. A FAST MOVING FRONT WILL MOVE INTO THE AREA THIS
EVENING AND FRIDAY...SPREADING CLOUDS AND RAIN AND SNOW SHOWERS
ACROSS THE REGION...ESPECIALLY OVER THE MOUNTAINS AND ACROSS THE
COPPER BASIN. INTERIOR LOCATIONS FROM ANCHORAGE WEST WILL ONLY SEE
A GLANCING BLOW AS THE ALASKA AND ALEUTIAN RANGES WILL DOWNSLOPE
MOST OF THE MOISTURE OUT. SNOW AND RAIN SHOWERS WILL LINGER OVER
THE COPPER BASIN AND NORTH GULF COAST INTO SATURDAY.

SOUTHWEST ALASKA...
A FAST MOVING FRONT WILL RAPIDLY TRACK FROM WEST TO EAST TODAY
THROUGH TONIGHT...SPREADING RAIN AND SNOW ACROSS THE REGION. LIGHT
ACCUMULATING SNOW WILL BE POSSIBLE...ESPECIALLY ACROSS THE
INTERIOR LOCATIONS WHERE COLD AIR WILL LINGER LONGER.
OTHERWISE...COASTAL LOCATIONS CAN EXPECT TO RAPIDLY CHANGE TO RAIN
WITH A BRIEF SHOT OF INITIAL SNOW. WESTERLY ONSHORE FLOW WILL
LINGER BEHIND THE FRONT...WITH EXTENSIVE CLOUD COVER PERSISTING
AFTER THE FRONT CLEARS.

BERING SEA/ALEUTIANS...
A FAST MOVING FRONT TRACKING ACROSS THE BERING WILL CLEAR THE
EASTERN BERING TONIGHT LEAVING LARGELY DRY CONDITIONS ACROSS MOST
OF THE ALEUTIANS AND BERING SEA HEADING INTO THE WEEKEND.

&&

.LONG TERM FORECAST...

MODELS CONTINUE TO STRUGGLE IN THE EXTENDED...AT LEAST PARTIALLY
DUE TO NO SATELLITE DATA BEING INGESTED. AGREED WITH WPC
ASSESSMENT THAT THE PREVIOUS FORECAST SHOULD ONLY BE MODIFIED
SLIGHTLY BY VARIOUS ENSEMBLE RUNS FOR NOW.

THE CURRENT SOLUTION BRINGS A WEAK TROUGH INTO THE NORTHEAST GULF
OF AK LATE SUN THAT PERSISTS INTO MIDWEEK WITH SPOTTY
PRECIPITATION AT BEST FOR MOST OF SOUTHCENTRAL AND THE GULF COAST.

A FRONT FROM A LOW OVER EASTERN RUSSIA WILL MOVE ACROSS THE BERING
ON TUE...AND A SECOND LOW OVER THE NORTHERN BERING WILL BRING A
SECOND FRONT TO THE WESTERN AK COAST ON THU. TIMING AND STRENGTH
OF BOTH OF THESE SYSTEMS IS STILL UNCERTAIN...BUT SMALL CRAFT TO
GALES ARE POSSIBLE ALONG WITH RAIN MIXING WITH SNOW THROUGH THE
MIDDLE OF NEXT WEEK.

SOUTHWEST AK WILL BE DRY UNTIL RAIN AND SNOW SHOWERS ARRIVE WITH
THE INITIAL FRONT TUE AND THE SECOND FRONT THU.

-DS

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...MARINE WEATHER STATEMENT 138 150.
         GALE 150.
FIRE WEATHER...NONE.

&&

$$

AHSENMACHER OCT 14





000
FXAK68 PAFC 222143
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
143 PM AKDT WED OCT 22 2014

.ANALYSIS AND UPPER LEVELS...

500MB...A BROAD LOW COMPLEX WITH SEVERAL CENTERS WERE EVIDENT
OVER THE GULF AND NE PACIFIC. A HIGH AMPLITUDE RIDGE WAS PRESENT
OVER THE EASTERN BERING SEA WITH A TROUGH JUST EAST OF THE
KAMCHATKA PENINSULA. THE GULF LOW COMPLEX WILL CONTINUE TO SLOWLY
WEAKEN AND DRIFT SE THROUGH FRI. A TROUGH MOVING ACROSS EASTERN
RUSSIA/BERING SEA FLATTENS THE RIDGE AND SHOVES IT EAST AS IT
MOVES OVER THE CENTRAL MAINLAND FRI MORNING. AS A RESULT...NEARLY
ZONAL WESTERLY FLOW SETS UP OVER THE THE BERING SEA. THIS WILL
ALLOW UPPER WAVES AND ASSOCIATED FRONTAL TROUGHS TO PROGRESS
EASTWARD ACROSS THE BERING AND BRING UNSETTLED WEATHER TO THE
REGION.

NEAR SURFACE...THE MAIN LOW CENTER OVER THE GULF CONTINUES TO MOVE
WSW AND SLOWLY WEAKEN. ITS ASSOCIATED FRONTAL BOUNDARY OVER THE
NORTHERN GULF PRODUCED SOME SHOWERS ON ITS LEADING EDGE. WITH THE
EXCEPTION OF STRATUS AND FOG OVER THE COPPER RIVER
BASIN...SOUTHCENTRAL WAS RELATIVELY CLEAR. OUTFLOW WINDS WERE
EVIDENT ALONG THE NORTH GULF COAST WITH BRISK WINDS ACROSS THE
MARINE ZONES. OUT WEST...COLD NORTHERLY FLOW CONTINUED OVER THE
EASTERN BERING AND WESTERN AK PEN AND STREAMED SOUTH INTO THE
NORTH PACIFIC. A FRONTAL TROUGH MOVING OVER THE WESTERN BERING
SEA SET UP BRISK SOUTHERLY FLOW OVER THE WESTERN ALEUTIANS.

&&

.MODEL DISCUSSION...
THE NUMERICAL MODELS ARE IN GENERALLY GOOD AGREEMENT IN THE SHORT
TERM. TIMING OF THE FIRST FRONTAL TROUGH CROSSING THE BERING SEA
TONIGHT AND THU IS SIMILAR ON ALL THE MODELS. SOME TIMING ISSUES
ARISE WITH THE NEXT COUPLE OF FRONTS WHICH TYPICALLY OCCURS UNDER
STRONG ZONAL FLOW IN THE UPPER LEVELS.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...
QUIET WEATHER WILL PREVAIL ACROSS MOST OF SOUTHCENTRAL ALASKA AS
DRY OFFSHORE FLOW PERSISTS THROUGH TONIGHT. THE LACK OF A STRONG
PUSH OF DRY AIR INTO THE COPPER BASIN WILL LIKELY KEEP SOME DEGREE
OF LOW LEVEL CLOUDS AND PATCHY FOG IN THE BASIN...BUT MOST OTHER
LOCATIONS WILL STAY DRY AND LARGELY CLEAR. SOME RAIN SHOWERS
WILL IMPACT THE NORTH GULF COAST AND PRINCE WILLIAM SOUND THIS
EVENING AND TONIGHT. A FRONT MOVING IN FROM THE WEST WILL SPREAD
CLOUDS WITH A CHANCE OF SNOW INLAND FRI AND SAT WITH A MIX
ELSEWHERE. AT THIS TIME...IT LOOKS AS THOUGH MOST OF THE
PRECIPITATION WITH THIS FEATURE WILL FALL WEST OF THE ALASKA
RANGE. OUTFLOW WINDS WILL DIMINISH ACROSS THE NORTH GULF
OVERNIGHT... THOUGH THE EASTERN KENAI AND WESTERN COASTAL MARINE
AREAS WILL CONTINUE TO SEE BRISK W TO NW WINDS.

SOUTHWEST ALASKA...
LARGELY QUIET WEATHER WILL PREVAIL AS THE PRESSURE GRADIENT
BECOMES OFFSHORE/OUTFLOW ACROSS THE REGION. NORTHERLY WINDS WILL
BECOME GUSTY TODAY...ESPECIALLY ACROSS THE BRISTOL BAY COAST AND
THROUGH GAPS IN THE ALASKA RANGE. A FRONT WILL PROGRESS WEST TO
EAST THURSDAY MORNING THROUGH FRIDAY MORNING...BRINGING RAIN AND
SNOW TO THE COASTS AND MEASURABLE SNOW TO THE KUSKOKWIM VALLEY.
THERE IS ALSO A POSSIBILITY OF POCKETS OF LIGHT FREEZING RAIN IN
THE INTERIOR BRISTOL BAY ZONE LATER THU.

BERING SEA/ALEUTIANS...
NORTHERLY WINDS AND SHOWERS WILL RAPIDLY DIMINISH TODAY AS WEAK
HIGH PRESSURE BUILDS IN OVER THE CENTRAL AND EASTERN BERING. A
FAST MOVING FRONT WILL TRACK INTO THE WESTERN ALEUTIANS AND WILL
SPREAD TO THE EASTERN BERING BY THURSDAY NIGHT.

&&

.LONG TERM FORECAST...

MODELS CONTINUE TO STRUGGLE IN THE EXTENDED...AT LEAST PARTIALLY
DUE TO NO SATELLITE DATA BEING INGESTED. AGREED WITH WPC
ASSESSMENT THAT THE PREVIOUS FORECAST SHOULD ONLY BE MODIFIED
SLIGHTLY BY VARIOUS ENSEMBLE RUNS FOR NOW.

THE CURRENT SOLUTION BRINGS A WEAK TROUGH INTO THE NORTHEAST GULF
OF AK LATE SUN THAT PERSISTS INTO MIDWEEK WITH SPOTTY
PRECIPITATION AT BEST FOR MOST OF SOUTHCENTRAL AND THE GULF COAST.

A FRONT FROM A LOW OVER EASTERN RUSSIA WILL MOVE ACROSS THE BERING
ON TUE...AND A SECOND LOW OVER THE NORTHERN BERING WILL BRING A
SECOND FRONT TO THE WESTERN AK COAST ON THU. TIMING AND STRENGTH
OF BOTH OF THESE SYSTEMS IS STILL UNCERTAIN...BUT SMALL CRAFT TO
GALES ARE POSSIBLE ALONG WITH RAIN MIXING WITH SNOW THROUGH THE
MIDDLE OF NEXT WEEK.

SOUTHWEST AK WILL BE DRY UNTIL RAIN AND SNOW SHOWERS ARRIVE WITH
THE INITIAL FRONT TUE AND THE SECOND FRONT THU.

&&

AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 150 155 170 172 185.
FIRE WEATHER...NONE.

&&

$$

RMC/DS OCT 14





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