High Wind Watch 8, NWS Anchorage, AK

267 
WWAK72 PAFC 230105
NPWALU

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE ANCHORAGE AK
405 PM AKST TUE DEC 22 2015

AKZ187-230215-
/O.CAN.PAFC.HW.A.0008.151223T1500Z-151224T0100Z/
CENTRAL ALEUTIANS-
INCLUDING THE CITY OF...ATKA AND ADAK
405 PM AKST TUE DEC 22 2015

...HIGH WIND WATCH IS CANCELLED...

THE NATIONAL WEATHER SERVICE IN ANCHORAGE HAS CANCELLED THE HIGH
WIND WATCH. 

WINDS DEVELOPING TONIGHT AROUND THE NORTH PACIFIC LOW ARE
EXPECTED TO STAY BELOW HIGH WIND CRITERIA.

$$

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
347 PM AKST MON DEC 21 2015

.ANALYSIS AND UPPER LEVELS...
FOG HAS BEEN THE PRIMARY WEATHER CONCERN ACROSS MUCH OF SOUTHERN
MAINLAND ALASKA THIS AFTERNOON. IN SOUTHCENTRAL IN AND AROUND
THE ANCHORAGE BOWL...AREAS OF LOCALLY DENSE FOG FORMED THIS
MORNING IN THE SATURATED LAYER THAT DEVELOPED UNDER A STRONG
SURFACE INVERSION. VERY LIGHT WINDS THROUGH THE LOWER HALF OF
THE ATMOSPHERE ALSO INHIBITED MIXING. A WEAK UPPER LEVEL WAVE
APPROACHED THE ANCHORAGE AREA MID-MORNING...CAUSING THE FOG TO
RAPIDLY DIMINISH AFTER SUNRISE. OVER SOUTHWEST ALASKA...WIDESPREAD
FOG INITIATED BY THE SAME PHENOMENA DESCRIBED ABOVE PERSISTS
ACROSS MOST INLAND AREAS FROM BETHEL EAST TO KOLIGANEK AND
SPARREVOHN. BETHELS 12Z SOUNDING THIS MORNING IS NEARLY IDENTICAL
TO ANCHORAGE...SHOWING A NEARLY SATURATED SURFACE INVERSION AND
NEARLY NON-EXISTENT WINDS NEAR THE GROUND. THE LARGER-SCALE
WEATHER MAPS SHOW SURFACE RIDGING ALONG THE KUSKOKWIM RIVER
WITH A COL OVER THE NORTHERN ALASKA PENINSULA...BOTH FEATURES
WHICH RESULT IN LITTLE WIND. THE LIGHT WINDS...NEARLY CLEAR
SKIES AWAY FROM THE COAST...AND AS MINIMAL A SOLAR INFLUENCE
AS IT GETS ALL CONTINUE TO FAVOR PERSISTENT LOCALLY DENSE FOG
OVER SOUTHWEST ALASKA.

OVER THE BERING...A STATIONARY FRONT/CONVERGENCE ZONE IS IN PLACE
STRETCHING FROM THE EASTERN BERING ACROSS THE NORTHERN BERING.
THE RELATIVE LOW PRESSURE IS SANDWICHED BETWEEN A STRONG SIBERIAN
POLAR HIGH AND A SUBTROPICAL HIGH OVER THE CENTRAL PACIFIC.
THUS...STRONG OPPOSING WINDS ON EITHER SIDE OF THE ZONE ARE
PREVENTING ANYTHING MORE THAN VERY SLOW MOVEMENT OF THE ASSOCIATED
PRECIPITATION. SOUTH OF THIS ZONE...RELATIVELY WARM LOW LEVEL AIR
IS UNDERNEATH A STRONG UPPER LEVEL LOW ASSOCIATED WITH COLD UPPER
LEVEL AIR. THE RESULT IS STRONG INSTABILITY AND "POPCORN" LOOKING
CUMULUS AND OCCASIONAL CUMULONIMBUS OVER A LARGE AREA OF THE
BERING AND NORTH PACIFIC...INCLUDING ALL OF THE ALEUTIANS.
DETECTED LIGHTNING STRIKES HAVE BEEN FEW AND FAR BETWEEN...BUT
ARE INDICATIVE OF THE LEVEL OF INSTABILITY IN THAT AREA.

&&

.MODEL DISCUSSION...
THE MODELS REMAIN IN AGREEMENT ABOUT THE MOVEMENT AND INTENSITY
OF THE MAJOR FEATURES IMPACTING THE AOR. IN THE UPPER LEVELS...THE
PRIMARY PACIFIC JET STREAK REMAINS WELL SOUTH OF THE AREA...KEEPING
MOST OF THE STRONGER STORMS HEADING INTO THE PACIFIC NORTHWEST. A
DIGGING TROUGH OVER THE WESTERN BERING TUESDAY NIGHT HELPS AMPLIFY
A RIDGE OVER THE EASTERN BERING BY WEDNESDAY AFTERNOON...WITH SOME
MINOR DIFFERENCES IN THE INTENSITY OF THE JET STREAK THAT FORMS
DOWNSTREAM OF THE RIDGE OVER SOUTHWEST ALASKA. BIGGER DIFFERENCES
ARE ASSOCIATED WITH A STORM MOVING INTO THE WESTERN AND CENTRAL
ALEUTIANS WEDNESDAY MORNING...PRIMARILY AS A RESULT OF DIFFERENCES
IN STORM INTENSITY AND HOW FAVORABLE THE ATMOSPHERE BECOMES WITH
SUPPORTING A BROAD PRECIPITATION SHIELD. THE NAM WAS THE MODEL OF
CHOICE CONCERNING ALL OF THE ABOVE DIFFERENCES. THE NAMS HIGHER
RESOLUTION AND THE MIDDLE-OF-THE-ROAD SOLUTION WERE THE PRIMARY
FEATURES FAVORING IT OVER THE OTHER MODELS. CONFIDENCE IN THE
FORECAST IS HIGH CONSIDERING LOW MODEL SPREAD AND THE GENERALLY
QUIET WEATHER PATTERN.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THERE IS WEAK FLOW ALOFT AND LOOKING FOR ISOLATED PATCHY FOG TO
REDEVELOP FOR THE ANCHORAGE BOWL...MAT-SU VALLEYS AND THE UPPER
WESTERN KENAI PENINSULA TONIGHT. WHILE UPSTREAM THE UPPER LEVELS
HAVE A WEAK SHORTWAVE THAT WILL MOVE THROUGH THE SOUTHCENTRAL
REGION THROUGH TUESDAY MORNING. THIS WILL BRING ISOLATED SNOW
SHOWERS TO THE AOR AND AID IN MIXING OUT THE PATCHY FOG IN THE
REGION. BY TUESDAY NIGHT THE PRESSURE GRADIENTS WILL INCREASE
RESULTING IN GUSTY GAP WINDS DEVELOPING THROUGH WHITTIER...PORTAGE
AND OTHER FAVORED TERRAIN GAPS ALONG THE GULF COAST.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
THE PATTERN WILL BE DOMINATED BY LOW PRESSURE THROUGH MID WEEK
KEEPING LOW CLOUDS OR FOG ACROSS THE SOUTHWEST. THE WEAKENING
SURFACE TROUGH OVER THE SOUTHWEST TONIGHT WILL BE REPLACED BY A
LOW MOVING INLAND FROM THE EASTERN BERING INTO THE THE KUSKOKWIM
DELTA TUESDAY. THIS LOW MOVES A WEAK FRONT TO THE WEST COAST
EARLY TUESDAY AND CONTINUES AN EASTWARD TRACK TO THE ALASKA
RANGE. THE FRONTAL BOUNDARY WEAKENS QUICKLY AS IT MOVES INLAND
BRINGING LIGHT SNOW ACCUMULATIONS MAINLY ACROSS WESTERN AREAS
OF BRISTOL BAY...ELSEWHERE ONLY ISOLATED TO SCATTERED SNOW
ACTIVITY IS EXPECTED. THE LIGHT WIND PATTERN INCREASES OUT OF
THE NORTH TO WEST ON WEDNESDAY BEHIND THE EXITING SURFACE LOW.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
WESTERLY FLOW WILL CONTINUE THROUGH WEDNESDAY MORNING WITH
SCATTERED TO NUMEROUS SHOWERS ALONG A SLIGHTLY UNSTABLE AIR MASS.
THE NEXT STRONG FRONT DEVELOPS IN THE NORTH PACIFIC TUESDAY NIGHT
WHICH WILL INCREASE EASTERLY WINDS ACROSS THE WESTERN AND CENTRAL
ALEUTIANS INTO EARLY WEDNESDAY MORNING. THE LOW CENTER TRACKS
NEAR KISKA INTO THE SOUTHERN BERING WEDNESDAY MORNING BRINGING
A DIRECTIONAL WIND CHANGE WITH GUSTY WINDS SPREADING ACROSS THE
EASTERN ALEUTIANS TO THE NORTHERN BERING BY THE AFTERNOON.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
MODELS ARE COMING INTO SOMEWHAT BETTER AGREEMENT WITH RESPECT
TO THE MIDWEEK BERING STORM...HOWEVER THERE IS STILL SOME
DISAGREEMENT ABOUT HOW FAR NORTH THE SURFACE LOW WILL TRACK
WEDNESDAY NIGHT BEFORE IT STARTS EAST ON THURSDAY. WITH THE VERY
STRONG JET STREAM TO THE SOUTH AM STILL FAVORING THE MORE SOUTHERN
SOLUTIONS WHICH WHICH WOULD BRING THE LOW ROUGHLY 100 TO 150 NM
INTO THE BERING BEFORE IT GETS CAUGHT UP IN THE BROADER WESTERLY
FLOW AND SWINGS EAST.

THE NEXT SIGNIFICANT POINT OF UNCERTAINTY CONCERNS THE FATE OF THE
NEXT ITERATION OF THIS LOW IN THE FRIDAY AND SATURDAY TIME PERIOD.
THE GFS BRINGS THE LOW INTO BRISTOL BAY WHICH CONTINUES TO SEEM
WELL TOO FAR NORTH. IN THE EC...A NORTH PACIFIC TROUGH SWINGING
AROUND THE SOUTH SIDE OF THE LARGE UPPER LOW SPINS UP INTO ANOTHER
STRONG SURFACE LOW WHICH LIFTS NORTH TO THE WESTERN TIP OF THE
ALASKA PENINSULA LATE THURSDAY NIGHT/EARLY FRIDAY MORNING. THE
CANADIAN MODEL HANGS ON TO THE BERING LOW AS THE MAIN SURFACE
FEATURE BUT TAKES IT MORE ON A SLIGHTLY MORE SOUTHERLY TREK EAST.
ADDITIONALLY IT LIFTS THE FEATURE UP OUT OF THE NORTH PACIFIC
FASTER AND AS MORE OF A TRIPLE POINT RATHER THAN CLOSED LOW. RIGHT
NOW I AM TENDING TO FAVOR THE EC SOLUTION AS THE MORE SOUTHERLY
SURFACE LOW (RELATIVE TO THE GFS TRACK) IS MORE CONSISTENT WITH
THE UPPER LEVEL JET LOCATION AND STRENGTH. ALSO WITH ALL THE ENERGY
AND COLD AIR ASSOCIATED WITH THE TROUGH SWINGING THROUGH THE NORTH
PACIFIC ON THURSDAY AM FAVORING THE IDEA OF THE WAVE RAPIDLY
DEVELOPING INTO A CLOSED LOW THURSDAY NIGHT.

IMPACT WISE...THE SOLUTION WITH THE STRONG SURFACE LOW SWINGING
ACROSS THE TIP OF THE ALASKA PENINSULA WILL BRING RATHER WINDY
CONDITIONS TO THAT AREA...SOUTHWEST ALASKA AND KODIAK ISLAND
THURSDAY NIGHT AND FRIDAY AS WELL AS SUSTAINING THE NORTHERLY
OUTFLOW GAP WINDS IN SOUTHCENTRAL ALASKA. THE MORE SOUTHERLY
POSITION OF THE LOW CENTER HOWEVER WILL LIMIT THE HEAVIER
PRECIPITATION TO COASTAL AREAS. A CONTINUED ACTIVE STORM TRACK
WILL BRING ADDITIONAL STRONG LOWS ACROSS THE ALEUTIANS AND INTO
THE BERING THROUGH EARLY NEXT WEEK...HOWEVER FURTHER EAST THEY
WILL TEND TO DROP SOUTH CROSSING THE GULF CLOSER TO 50N ONLY
MINIMALLY IMPACTING SOUTHERN SOUTHCENTRAL ALASKA.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING 132 150 155 165 176 177 178 185.
         HEAVY FREEZING SPRAY WARNING 129 180 181 185.

&&

SYNOPSIS AND MODEL DISCUSSION...EN
SOUTHCENTRAL ALASKA...PD
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...KH
LONG TERM...JR