Small Craft Advisory 926, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE ANCHORAGE AK
557 AM AKST SUN NOV 22 2015

CORRECTED ADVISORIES

.ANALYSIS AND UPPER LEVELS...
ZONAL FLOW RESIDES OVER THE REGION WITH SEVERAL DIFFERENT FEATURES
MOVING THROUGH. THE BIGGEST AND MOST IMPACTFUL TROUGH HAS BEEN
PUSHING IN OVER THE SOUTHWEST BRINGING SNOW SHOWERS TO THE AREA
BUT THERE IS NOT ENOUGH SUPPORT WITH IT TO SEE MUCH OF AN INCREASE
IN WINDS. THE NEXT BIG LOW IS APPROACHING THE WESTERN ALEUTIANS
FROM THE NORTH PACIFIC WITH ITS FRONT HAVING ALREADY TRACKED
ACROSS THE ISLANDS. THIS SYSTEM IS STILL DEEPENING AS IT HEADS
TOWARD THE BERING AND IS PULLING UP A FAIR AMOUNT OF WARM AIR
WITH IT.

&&

.MODEL DISCUSSION...
THE MODELS ARE IN GOOD AGREEMENT WITH THE POSITIONING OF THE MAJOR
FEATURES INTO TUESDAY BUT THERE ARE A COUPLE PROBLEMS WITH
INTENSITY AND TEMPERATURE. THE INTENSITY PROBLEM IS WITH THE LOW
TRACKING INTO THE BERING TODAY. THE GFS IS THE STRONGER SOLUTION
WITH THE OTHER MODELS ALL VARYING DEGREES WEAKER. WITH THE STRONG
SUPPORT IN THE UPPER LEVELS WITH A 150 KT JET THE STRONGER GFS
SOLUTION WAS PREFERRED. THE IMPACT OF THIS DIFFERENCE WILL SHOW IN
STRONGER WINDS AROUND THE LOW AS IT MOVES THROUGH THE BERING. THE
MOST RECENT SCATTEROMETER PASSES ALSO SHOW WINDS THAT MORE CLOSELY
RESEMBLE THE STRONGER SOLUTIONS. THE TEMPERATURE DIFFERENCES COME
INTO PLAY EARLY IN THE WEEK WITH TEMPERATURES ACROSS THE SOUTHERN
MAINLAND. THERE IS A FAIR AMOUNT OF VARIATION AMONGST THE MODELS
MAKING IT DIFFICULT TO DETERMINE HOW STRONG AND FAST THE WARM PUSH
WILL BE. THIS LOWERS CONFIDENCE IN THE TIMING OF THE SNOW EITHER
MIXING WITH OR TRANSITIONING TO RAIN FOR THE MORE SOUTHERN
LOCATIONS.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...

AN UPPER LEVEL DISTURBANCE WILL BRING ANOTHER QUICK ROUND OF SNOW
SHOWERS THIS AFTERNOON AND EVENING ACROSS THE ANCHORAGE
BOWL...MATANUSKA VALLEY AND SUSITNA VALLEY. DUE TO THE QUICK
PROGRESSION OF THE SYSTEM AND RELATIVELY WEEK FORCING...JUST A FEW
QUICK INCHES ARE EXPECTED ACROSS THE AREA.

MEANWHILE...A DRAMATIC PATTERN CHANGE IS TAKING PLACE MONDAY INTO
TUESDAY AS A POTENT LOW MOVES TOWARDS THE KUSKOKWIM DELTA...AND
ITS ASSOCIATED FRONT BRINGS WIDESPREAD PRECIPITATION AND MUCH
WARMER TEMPERATURES TO SOUTHCENTRAL. PRECIPITATION WILL GENERALLY
BEGIN AS SNOW MONDAY AFTERNOON...BUT BEGIN TO CHANGE OVER TO RAIN
BEGINNING MONDAY EVENING INTO TUESDAY MORNING. DUE TO THE STRENGTH
OF THIS SYSTEM...DOWNSLOPING IS EXPECTED TO LIMIT RAIN AND
SNOWFALL ACROSS THE ANCHORAGE BOWL AND WESTERN KENAI. IN
CONTRAST...IN THE SUSITNA VALLEY...PERSISTENT UPSLOPE FLOW AND A
STEADY MOISTURE STREAM WILL SUPPORT HEAVY SNOW. SNOW AMOUNTS ARE
EXPECTED TO BE GREATEST TOWARDS THE PARK WHERE TEMPERATURES ARE
EXPECTED TO FAVOR SNOW THROUGH THE DURATION OF THE EVENT.
MEANWHILE...IN TALKEETNA AND SOUTH RAIN WILL BEGIN TO MIX IN
STARTING EARLY TUESDAY MORNING...LIMITING SNOW ACCUMULATIONS.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
SNOW WILL TAPER OFF FROM WEST TO EAST THROUGH THIS AFTERNOON
ACROSS THE SOUTHWEST MAINLAND AS AN UPPER DISTURBANCE AND
ASSOCIATED SURFACE LOW RAPIDLY MOVE OFF TO THE EAST. ATTENTION
THEN QUICKLY TURNS TO THE STRONG BERING FRONT WHICH WILL ARRIVE
ALONG THE COAST LATER TONIGHT...BRINGING BLOWING SNOW CONCERNS TO
PORTIONS OF THE KUSKOKWIM DELTA. THE MAIN LIMITING FACTOR FOR
BLOWING SNOW WILL BE WARM TEMPERATURES AS PRECIPITATION BEGINS AS
ALL SNOW BUT BEGINS TO CHANGE OVER TO RAIN FAIRLY QUICKLY ON
MONDAY MORNING IN DEEP SOUTHERLY FLOW BEHIND THE FRONT. THIS
RAPID WARMING SHOULD GENERALLY KEEP ANY AREAS OF BLOWING SNOW
VERY LOCALIZED AND SHORT LIVED. THEREFORE...THE BLIZZARD WATCH
FOR COASTAL PORTIONS OF THE KUSKOKWIM DELTA HAS BEEN CANCELLED
WITH ISSUANCE OF THE MORNING PACKAGE.

THE OTHER MAIN FORECAST CONCERN WITH THIS SYSTEM IS THE POTENTIAL
FOR HIGH SURF CONDITIONS FOR COASTAL COMMUNITIES ALONG THE
KUSKOKWIM DELTA...BEGINNING WITH THE HIGH TIDE CYCLE AROUND
MIDDAY MONDAY. CURRENT GUIDANCE SUGGESTS SEAS REACHING 2 TO 4 FEET
ABOVE MAX ASTRONOMICAL TIDE FOR SEVERAL CONSECUTIVE HIGH TIDE
CYCLES NORTH OF CAPE NEWENHAM. HAVE THEREFORE ISSUED A COASTAL
FLOOD ADVISORY FROM MONDAY MORNING THROUGH NOON TUESDAY TO COVER
THESE TIDE CYCLES.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
THE POWERFUL LOW APPROACHING THE WESTERN ALEUTIANS WILL REMAIN THE
DOMINANT FEATURE IN THE BERING OVER THE NEXT FEW DAYS AS THE STORM
FORCE FRONT MOVES GRADUALLY EASTWARD. THE FRONT WILL WEAKEN
SLIGHTLY BUT STILL MAINTAIN STRONG GALE FORCE WINDS AS IT CROSSES
THE EASTERN ALEUTIANS AND AKPEN THROUGH MONDAY. MEANWHILE...COLD
ADVECTION ON THE BACKSIDE OF THE LOW WILL PRODUCE ANOTHER ROUND
OF STORM FORCE WINDS ACROSS THE WESTERN BERING AND A SMALL AREA OF
HURRICANE FORCE WINDS EAST ACROSS THE UNPOPULATED PORTIONS OF THE
WESTERN ALEUTIANS EAST OF SHEMYA.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
ON TUESDAY THE FOCUS IN THE FORECAST WILL SHIFT FROM WEAKENING
BERING LOW TO THE FRONTAL SYSTEM IN THE WESTERN GULF. THERE
REMAINS VERY GOOD AGREEMENT THAT THIS WILL BRING WIDESPREAD RAIN
AND SNOW TO THE SOUTH MAINLAND...ALONG WITH STRONG WARM AIR
ADVECTION IN THE DEEP AND MOIST SOUTHERLY FLOW THAT WILL PERSIST
INTO MID WEEK. ENOUGH WARM AIR WILL SURGE NORTHWARD WITH THIS
FRONT TO CAUSE PRECIPITATION IN MOST AREAS TO SWITCH OVER TO
RAIN...WITH THE EXCEPTION OF THE NORTHERN SUSITNA VALLEY WHICH
WILL LIKELY REMAIN SNOW INTO WEDNESDAY. A VERY TIGHT PRESSURE
GRADIENT WILL ALSO SETUP ALONG THE KENAI AND CHUGACH MOUNTAINS
DURING THIS TIME...BRINGING STRONG GAP WINDS TO TURNAGAIN AND
KNIK ARM...AND GUSTY SOUTHEASTERLY WINDS INTO THE ANCHORAGE BOWL
ON TUESDAY. DOWNSLOPING FROM THESE WINDS WILL MOSTLY LIMIT
RAINFALL OVER THE ANCHORAGE BOWL AND MATANUSKA VALLEY TO SPOTTY
SHOWERS...WHILE THE GULF COAST WILL SEE LITTLE REPRIEVE FROM
STEADY RAIN AS STRONG UPSLOPE FLOW WILL PERSIST INTO WEDNESDAY.

AS HAS BEEN THE CASE FOR THE LAST SEVERAL DAYS...THE FORECAST FOR
WEDNESDAY ONWARD HAS BEEN DIFFICULT. MODELS ARE BEGINNING TO
CONVERGE ON A SOLUTION FOR EX-TYPHOON IN-FA WITH A 965 TO 975 MB
LOW MOVING ALONG THE ALEUTIAN CHAIN THURSDAY THROUGH EARLY
SATURDAY. THE MODELS HAVE NOT SIGNIFICANTLY IMPROVED HOWEVER ON
THE HANDLING OF THE LOW THAT IS ABOUT 700 MILES NORTH OF OAHU
THIS AFTERNOON. AT LEAST PORTIONS OF THIS FEATURE...IN WHATEVER
FORM IT WILL TAKE...SHOULD MOVE NORTHWARD ALONG THE WESTERN SIDE
OF THE RIDGE AND INTO THE THE ALASKA PENINSULA TO KODIAK REGION IN
THE WEDNESDAY TO THURSDAY TIME FRAME...BUT EVEN THIS IS NOT
CERTAIN AS THE MODELS ARE INCONSISTENT WITH SURFACE FEATURES AS
WELL AS WHAT TO DO WITH THE ENERGY ASSOCIATED WITH THIS LOW. BOTH
THE EC AND THE GFS HINT THAT WHATEVER REMAINS OF THIS ENERGY WILL
LIKELY INTERACT WITH THE REMAINS IN-FA ON DAY 6-7. WITH THIS BEING
SAID...AGAIN WPC GUIDANCE WAS USED HEAVILY IN THE DAY 4-7 TIME
FRAME TO ACCOUNT FOR THE HIGH DEGREE OF UNCERTAINTY IN THESE TWO
FEATURES.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER WEATHER ADVISORY 141.
         COASTAL FLOOD ADVISORY 155
MARINE...HURRICANE FORCE 177 178.
         STORM 173 175 176 179 181 185.
         GALE 132 138 150 155 160 165 170 171 172 174 180

&&

SYNOPSIS AND MODEL DISCUSSION...DK
SOUTHCENTRAL ALASKA...EN
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...CB
LONG TERM...DEK/RF

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1001 AM AKST SUN NOV 22 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0958 AM     NON-TSTM WND GST ADAK STATION            51.84N 176.64W
11/22/2015  M75.00 MPH                          AK   AWOS

            PEAK GUST REPORTED AT 0756 HST

&&

LINGRAM