Small Craft Advisory 894, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
529 AM AKST WED NOV 11 2015

.ANALYSIS AND UPPER LEVELS...
A DEEP LOW IS PUSHING EAST THROUGH THE SOUTHERN BERING AND IS
AIDED BY A 150 KT JET JUST TO THE SOUTH OF THE ALEUTIANS. THIS IS
RESULTING IN STRONG WINDS ON THE BACK SIDE OF THE LOW THAT CAN BE
SEEN IN A LARGE SWATH OF 50 TO 60 KT WINDS ON THE 08Z ASCAT PASS.
GUSTS FROM THIS STORM HAVE ALSO GUSTED TO 70 KT IN NIKOLSKI. FOR
THE SOUTHERN MAINLAND SHOWER ACTIVITY HAS DIMINISHED AHEAD OF THE
MAIN STORM AS WEAK RIDGING HAS MOVED IN. THE RIDGING HAS ALSO
HELPED IN FOG DEVELOPMENT IN THE SOUTHCENTRAL.

&&

.MODEL DISCUSSION...
THE MODELS IN THE SHORT TERM ARE IN GOOD AGREEMENT WITH LOW
PLACEMENT AND INTENSITY RESULTING IN HIGH CONFIDENCE WITH THE
BERING STORM AND ITS WINDS.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
FORECASTS ARE ON TRACK AS A POTENT STORM SYSTEM JUST NORTH OF
THE ALASKA PENINSULA CROSSES INTO THE WESTERN GULF LATER THIS
AFTERNOON AND THEN MOVES TO THE NORTHEAST GULF BY LATE THURSDAY.
WITH SUCH A STRONG AND RELATIVELY FAST MOVING SYSTEM EXPECT
RAPIDLY DETERIORATING CONDITIONS ACROSS THE GULF OF ALASKA...COOK
INLET...AND THE KENAI PENINSULA. HAVE INCREASED SNOW AMOUNTS OVER
THE EASTERN KENAI PENINSULA THIS AFTERNOON THROUGH TONIGHT.
DESPITE THE LOW LEVEL FLOW BACKING FROM THE EAST TO THE NORTH
(WHICH IS NOT GENERALLY FAVORABLE FOR HEAVY SNOW)...THE OVERALL
STRENGTH OF THE APPROACHING SYSTEM AND STRENGTH OF THE LOW LEVEL
FLOW WILL BE ENOUGH TO SPREAD SNOW WELL INLAND...INCLUDING ALONG
THE SEWARD HIGHWAY CORRIDOR. SOME GUSTY WINDS WILL ACCOMPANY THE
SNOW...BUT THE WINDIEST LOCATIONS (SUCH AS PORTAGE VALLEY) WILL
WARM TO NEAR OR JUST ABOVE FREEZING AND LIMIT THE AMOUNT OF
BLOWING SNOW. STILL...VISIBILITIES WILL BE REDUCED LESS THAN ONE
MILE AT TIMES IN THE HEAVIEST SNOW. PRECIPITATION ALONG THE GULF
COAST WILL QUICKLY COME TO AN END THURSDAY MORNING AS THE LOW
CENTER REACHES THE EASTERN GULF AND DRIER COLDER AIR STARTS TO
ADVECT SOUTHWARD.

A STRONG BUT VERY SEASONABLE OUTFLOW WIND EVENT WILL THEN SET UP
IN THE WAKE OF THIS STORM SYSTEM. THE SURFACE LOW WILL LINGER
OVER THE NORTHEASTERN GULF WHICH WILL MAINTAIN TIGHT PRESSURE
GRADIENTS WELL INTO THE WEEKEND. THEREFORE...EXPECT A LONG
DURATION WIND EVENT ALONG COASTAL LOCATIONS. MOST OF THE FORCING
FOR THE STRONG WINDS WILL BE IN THE LOW LEVELS (WITH TIGHT PRESSURE
GRADIENTS AND COLD ADVECTION). THE UPPER LEVELS ARE NOT VERY
SUPPORTIVE WITH GENERAL TROUGHINESS REMAINING IN PLACE AND A
COMPLETE LACK OF A STRONG ARCTIC JET. THIS WILL ENSURE WINDS
REMAIN BELOW WARNING LEVELS. MOST OF INTERIOR SOUTHCENTRAL WILL
SEE A LITTLE BIT OF WIND AS COLD ADVECTION FIRST KICKS IN...BUT
WILL THEN SETTLE INTO LIGHTER WINDS WITH A VERY COLD AIR MASS.
THIS WILL BRING THE COLDEST TEMPERATURES OF THE YEAR TO MUCH OF
SOUTHCENTRAL AS WE HEAD INTO THE WEEKEND (AND BEYOND).

&&

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

A DEEP LOW OVER THE SOUTHEASTERN BERING SEA WILL CROSS THE ALASKA
PENINSULA LATE THIS MORNING/EARLY THIS AFTERNOON AND PUSH INTO THE
GULF OF ALASKA. HIGH WINDS UPWARD TO 75 KNOTS HAVE ALREADY BEEN
REPORTED ON THE BACKSIDE OF THE LOW ASSOCIATED WITH A STINGER
(BANANA) JET. THE ALASKA PENINSULA WILL SEE THESE STRONGER GUSTS
BY MID MORNING AND THEY WILL RAPIDLY DIMINISH AS THE LOW TRANSLATES
INTO THE GULF OF ALASKA THIS AFTERNOON. A BRIEF PERIOD OF GUSTY
WINDS IS EXPECTED THROUGH LAKE CLARKE PASS THIS AFTERNOON AS THE
PRESSURE GRADIENT WILL BE FAVORABLY ORIENTED FOR JUST A SHORT
PERIOD OF TIME. THERE WILL BE A LITTLE ADVECTION OF WARM AIR ALONG
THE ALASKA PENINSULA SOUTH OF KING SALMON WHICH WILL KEEP RAIN
ACROSS THE ALASKA PENINSULA AS RAIN. COLDER AIR IS ALREADY
WRAPPING INTO THE LOW AS OBSERVED ON IR SATELLITE THIS MORNING...SO
AS THIS LOW SLIDES INTO THE GULF THIS AFTERNOON DECENT COLD AIR
ADVECTION SHOULD CHANGE THE PREDOMINANT PRECIPITATION TYPE TO
SNOW THIS EVENING. THE WEATHER IS MUCH QUIETER ACROSS THE
KUSKOKWIM DELTA AND LOWER KUSKOKWIM VALLEY AS A NEGATIVE VORTICITY
ANOMALY WILL CONTRIBUTE ENOUGH SUBSIDENCE THROUGH THE COLUMN TO
INHIBIT PRECIPITATION THROUGH THURSDAY. SKIES DID CLEAR OUT ACROSS
THESE LOCATIONS AND HAS LED TO PATCHY DENSE FOG. WITH CLOUDS
MOVING IN FROM THE SOUTH AND WINDS SHIFTING FROM THE SOUTHWEST TO
THE EAST THIS MORNING...THE FOG IS EXPECTED TO DISSIPATE BEFORE
SUNRISE.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...

HURRICANE FORCE WIND GUSTS HAVE BEEN OBSERVED ACROSS THE CENTRAL
ALEUTIANS AND WILL CONTINUE TO IMPACT THE AREA THROUGH EARLY THIS
AFTERNOON. OBSERVATIONS AT NIKOLSKI HAS BEEN OF GREAT HELP THIS
MORNING IN GAUGING THE WIND SPEED AS WELL AS MINIMUM PRESSURE OF
THE LOW WHEN COMPARING IT TO THE MOST RECENT MODEL DATA. PRESSURE
IS RISING RAPIDLY BEHIND THE LOW CENTER AS OBSERVED AT NIKOLSKI
WHICH HAS ADDED A BIT OF AN ISALLOBARIC COMPONENT TO THE WINDS.
THE COLD AIR ADVECTION IS STILL A TAD DELAYED AS COLDER AIR IS
JUST NOW WRAPPING INTO THE LOW. THE COLD AIR WILL COINCIDE WITH
THE ISALLOBARIC COMPONENT AS THE LOW SHIFTS EASTWARD WITH DUTCH
HARBOR AND THE ALASKA PENINSULA WEST OF THE SHUMAGIN ISLANDS
OBSERVE THE STRONGEST WINDS. AS THE LOW PUSHES ACROSS THE ALASKA
PENINSULA THIS AFTERNOON...WINDS WILL RAPIDLY DIMINISH BUT GUSTY
NORTHWEST WIND ARE EXPECTED TO LINGER ACROSS THE EASTERN BERING
SEA AND EASTERN ALEUTIANS THROUGH TONIGHT. FOLLOWING THE DEPARTURE
OF THIS IMPRESSIVE LOW...NORTHWEST FLOW ALOFT WILL USHER IN NUMEROUS
UPPER LEVEL DISTURBANCES WHICH WILL AID IN THE DEVELOPMENT OF
ADDITIONAL SNOW SHOWERS. LOOKING TOWARD THE PRIBILOF ISLANDS...A
HEAVY WET SNOW WILL CONTINUE THROUGH LATE THIS MORNING WHILE BEING
COUPLED WITH GUST UP TO 55 KNOTS. WINDS WILL QUICKLY DIMINISH
THROUGH THE MORNING HOURS AND PRECIPITATION WILL BECOMING MORE
SHOWERY IN NATURE AS THE LOW PUSHES EASTWARD. VISIBILITIES REDUCED
TO 1 MILE AT TIMES WILL BE POSSIBLE AS HEAVY SNOW MIXES WITH THE
STRONGER WINDS.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
MODELS SEEM TO BE IN FAIR AGREEMENT WITH KEEPING THE BERING SEA
AND ALEUTIAN CHAIN UNDER A PROGRESSIVE FLOW PATTERN THROUGH THE
BEGINNING OF THE WEEKEND...BRINGING A SYSTEM OFF THE KAMCHATKA
PENINSULA AND INTO THE NORTHERN BERING SEA BY FRIDAY NIGHT. AT
THIS POINT...MODELS BEGIN TO STRUGGLE WITH THE TRACK AND STRENGTH
OF THIS SYSTEM AS IT JOURNEYS THROUGH THE BERING OVER THE WEEKEND.
THE ECMWF IS SHOWING A SECONDARY LOW SPINNING OFF THE WESTERN
FLANK OF THIS SYSTEM AND DIVING DOWN OVER THE EASTERN ALEUTIANS
OVERNIGHT SATURDAY. HOWEVER...THE GFS IS MUCH SLOWER AT BRINGING
THIS SYSTEM OVER THE EASTERN ALEUTIANS AND TRACKS THE ANCHOR LOW
OVER THE SOUTHWEST MAINLAND. GIVEN THE DIFFERENCES BETWEEN THE
CURRENT MODEL SOLUTIONS...FORECAST CONFIDENCE WILL REMAIN LOW
REGARDING THE TIMING AND STRENGTH OF THE WINDS AND PRECIPITATION
MAKING IT INTO THE CENTRAL/EASTERN ALEUTIANS OVER THE WEEKEND.
HOWEVER...WHAT WE CAN TAKE AWAY FROM THIS IS THAT COLD AND GUSTY
NORTHERLY WINDS ALONG WITH SHOWERY CONDITIONS WILL MAKE IT BACK
INTO THIS REGION OVER THE WEEKEND. BY SUNDAY EVENING A HIGH
PRESSURE RIDGE WILL BEGIN TO BUILD INTO THE WESTERN ALEUTIANS AND
THE LOWER WESTERN BERING SEA.

FURTHER EAST...GUSTY OUTFLOW GAP WINDS WHICH WILL DEVELOP AROUND
THE NORTHERN GULF COAST IN THE WAKE OF A LOW TRACKING THROUGH THE
GULF EARLIER IN THE WEEK...WILL BEGIN TO DIMINISH AS THE LOW
STALLS OUT AND WEAKENS ALONG THE NORTHERN GULF COAST OVER THE
WEEKEND. THIS WILL KEEP MUCH OF THE SOUTHCENTRAL MAINLAND UNDER
DRIER AND COLDER CONDITIONS THROUGH THE BEGINNING OF NEXT
WEEK...WITH THE EXCEPTION OF THE COPPER RIVER BASIN SEEING SOME
MOISTURE WRAP AROUND THE SYSTEM AND BRINGS A FEW SNOW SHOWERS TO
THE AREA OVER THE WEEKEND.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WARNING 181 185.
MARINE...HURRICANE FORCE WIND WARNING 155 170 172
         STORM WARNING 119 120 130 131 139 150 165 171 174
         GALE WARNING 125 127 132 136 137 138 140 141 160 173
                      175 176 179 180.

&&

SYNOPSIS AND MODEL DISCUSSION...DK
SOUTHCENTRAL ALASKA...SEB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MMC
LONG TERM...TP

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1020 AM AKST WED NOV 11 2015

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

0823 AM     NON-TSTM WND GST UNALASKA                53.93N 166.51W
11/11/2015  M83.00 MPH                          AK   AWOS

            AIRPORT

0835 AM     NON-TSTM WND GST AKUTAN                  54.14N 165.79W
11/11/2015  M90.00 MPH                          AK   ASOS

            AIRPORT

0935 AM     NON-TSTM WND GST AKUTAN                  54.14N 165.79W
11/11/2015  M86.00 MPH                          AK   ASOS

            AIRPORT

&&

KUTZ

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1100 AM AKST WED NOV 11 2015

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

1045 AM     NON-TSTM WND DMG UNALASKA                53.93N 166.51W
11/11/2015                                      AK   LAW ENFORCEMENT

            ROOFS DAMAGED. STREETLIGHT POST AND SEVERAL TRAFFIC SIGNS
            BLOWN DOWN. DUMPSTERS AND CONEX CONTAINED ROLLED OVER OR
            MOVED. SEVERAL HOUSE AND ONE VEHICLE WITH GLASS DAMAGE.

1045 AM     NON-TSTM WND DMG AKUTAN                  54.14N 165.79W
11/11/2015                                      AK   EMERGENCY MNGR

            CONSTRUCTION MATERIALS AT A NEW FOUR PLEX BLOWN AWAY.
            VERY STRONG WINDS STILL OCCURRING.

&&

KUTZ

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE ANCHORAGE AK
158 PM AKST WED NOV 11 2015

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

0950 AM     NON-TSTM WND GST UNALASKA                53.93N 166.51W
11/11/2015  M75.00 MPH                          AK   AWOS

1015 AM     NON-TSTM WND GST AKUTAN                  54.14N 165.79W
11/11/2015  M81.00 MPH                          AK   ASOS

1045 AM     NON-TSTM WND DMG UNALASKA                53.93N 166.51W
11/11/2015                                      AK   LAW ENFORCEMENT

            ROOFS DAMAGED. STREETLIGHT POST AND SEVERAL TRAFFIC SIGNS
            BLOWN DOWN. DUMPSTERS AND CONEX CONTAINED ROLLED OVER OR
            MOVED. SEVERAL HOUSE AND ONE VEHICLE WITH GLASS DAMAGE.

1045 AM     NON-TSTM WND DMG AKUTAN                  54.14N 165.79W
11/11/2015                                      AK   EMERGENCY MNGR

            CONSTRUCTION MATERIALS AT A NEW FOUR PLEX BLOWN AWAY.
            VERY STRONG WINDS STILL OCCURRING.

&&

KUTZ