Small Craft Advisory 847, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
451 PM AKDT MON OCT 26 2015

.ANALYSIS AND UPPER LEVELS...
EARLY THIS AFTERNOON WV SATELLITE IMAGERY IS SHOWING MID LEVEL
MOISTURE STREAMING INTO THE SOUTHERN MAINLAND BETWEEN AN UPPER LOW
SOUTH OF THE ALASKA PENINSULA AND A RIDGE ACROSS THE EASTERN
MAINLAND. TO THE WEST...A SECOND CLOSED LOW IS SPINNING SOUTH OF
THE KAMCHATKA PENINSULA. BOTH SYSTEMS ARE SPINNING IN PLACE AND
SLOWLY PUSHING A RIDGE OVER THE BERING TO THE NORTH. AT THE
SURFACE...RAIN IS DEVELOPING ALONG THE ALASKA PENINSULA WITH
LIGHTER RAIN ACROSS THE SOUTHWEST MAINLAND. RAIN ALSO CONTINUES TO
DEVELOP ACROSS A DEFORMATION ZONE ACROSS THE WESTERN BERING. WINDS
ARE GUSTY ALONG THE TWO SURFACE LOWS ASSOCIATED WITH THE TWO
AFOREMENTIONED UPPER LOW CENTERS. STRONG EASTERLY WINDS INCREASED
THIS MORNING ACROSS THE ALASKA PENINSULA AND BRISTOL BAY AND ARE
RAMPING UP ACROSS KODIAK ISLAND AND WESTERN GULF EARLY THIS
AFTERNOON. STRONG EAST WINDS ACROSS THE WESTERN BERING/ALEUTIANS
ARE BEGINNING A DOWNWARD TREND. THE REMNANTS OF TYPHOON CHAMPI IS
PASSING JUST SOUTH OF THE CENTRAL ALEUTIANS AS IT CONTINUES ON AN
EASTERN TRACK...HOWEVER THIS SYSTEM HAS WEAKENED AND CURRENTLY IS
LOW IMPACT.

&&

.MODEL DISCUSSION...
MODEL AGREEMENT IS GENERALLY GOOD WITH THE SYNOPTIC PATTERN THROUGH
WEDNESDAY AFTERNOON. THE ECMWF WAS FAVORED OVERALL FOR ITS
CONSISTENCY WITH THE TRACK AND STRENGTH ON THE TWO EVOLVING
SYSTEMS THROUGH WEDNESDAY. FOR LOCAL WIND ADJUSTMENTS THE USE OF
THE ECMWF WAS USED ALONG THE EASTERN FORECAST ZONES WITH THE
CANADIAN REGIONAL AND NAM USED ACROSS THE WEST.

&&

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

A FRONT THAT STRETCHES ACROSS THE SOUTHERN GULF OF ALASKA...IS
CURRENTLY BRINGING GUSTY WINDS AND HEAVY RAINS TO KODIAK ISLAND.
WIND GUSTS AND RAIN ARE EXPECTED TO CONTINUE INTO TUESDAY
AFTERNOON AS THE FRONT SLOWLY DRIFTS NORTHWARD. WINDS ARE EXPECTED
TO BE PARTICULARLY STRONG THROUGH LOCAL GAPS AND SHELIKOF STRAIT.
MEANWHILE...DRY CONDITIONS AND LIGHT WINDS ARE EXPECTED TO PERSIST
ACROSS MAINLAND ALASKA UNTIL TUESDAY EVENING AS THE FRONT IN THE
SOUTHERN GULF APPROACHES. BY WEDNESDAY MORNING...WIDESPREAD
SHOWERS ARE EXPECTED TO COVER MUCH OF SOUTHCENTRAL AS THE FRONTAL
SYSTEM LINGERS ALONG THE COAST AND SLOWLY DISSIPATES.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
SOUTHWEST ALASKA WILL GENERALLY REMAIN IN A WET AND WINDY PATTERN
THROUGH THE SHORT TERM AS CYCLONIC FLOW CONTINUES OVER THE REGION.
THE OCCLUDED FRONT ASSOCIATED WITH THE LOW SOUTH OF KODIAK WILL
STALL OVER THE SOUTHWEST COAST...KEEPING MOST OF THE PRECIPITATION
ALONG THE KUSKOKWIM AND BRISTOL BAY COASTLINES WITH A CHANCE OF
PRECIPITATION INLAND THROUGH WEDNESDAY. PRECIPITATION CHANCES
WILL BEGIN TO DIMINISH ON WEDNESDAY MORNING AS THE FRONT BEGINS TO
DISSIPATE. WITH RESPECT TO PRECIPITATION TYPE...TEMPERATURES WILL
REMAIN TOO WARM FOR SNOW OVER MOST OF THE AREA...ALTHOUGH
CONDITIONS WILL BE MORE FAVORABLE FOR A RAIN/SNOW MIX OVER THE
LOWER KUSKOKWIM VALLEY TONIGHT AND TUESDAY NIGHT. WINDS WILL
INCREASE TONIGHT ALONG THE COAST AS THE LOW MOVES NORTHWARD
TOWARDS KODIAK. EXPECT THE STRONGEST WINDS OVER THE COAST WITH THE
HIGHEST GUSTS ALONG THE ALASKA PENINSULA AND THE ALEUTIAN RANGE.
WINDS WILL CONTINUE TO BE ELEVATED THROUGH EARLY WEDNESDAY MORNING
AS A BROAD AND ELONGATED AREA OF LOW PRESSURE DEVELOPS ALONG THE
ALASKA PENINSULA ON WEDNESDAY.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
WINDS AND SEAS WILL REMAIN ELEVATED THROUGH MOST OF THE FORECAST
PERIOD FOR THE REGION AS BROAD CYCLONIC FLOW CONTINUES OVER THE
AREA AND HIGH PRESSURE DEVELOPS ALONG THE EASTERN RUSSIAN COAST.
WITH THIS SETUP...NORTHEASTERLY WINDS TO UPPER GALE FORCE ARE
EXPECTED TO DEVELOP TONIGHT OVER MOST OF THE BERING SEA AND
CONTINUE THROUGH WEDNESDAY. CONDITIONS WILL CONTINUE TO IMPROVE
FROM THE CENTRAL ALEUTIANS EASTWARD AS THE LOW SOUTH OF KODIAK
MOVES NORTHWARD AND EVENTUALLY BECOMES PART OF A LARGE ELONGATED
LOW CENTERED ALONG THE ALASKA PENINSULA BY WEDNESDAY. WAVE
HEIGHTS WILL CONTINUE TO INCREASE WITH THE LONG FETCH OVER THE
BERING SEA WHILE SLOWLY SUBSIDING ALONG THE ALASKA PENINSULA
COASTAL WATERS.

CONDITIONS WILL GENERALLY REMAIN WET FOR MOST OF THE REGION WITH
MOISTURE STREAMING AROUND THE BROAD UPPER LOW. PRECIPITATION WILL
BEGIN TO DIMINISH ON WEDNESDAY AS THE RIDGE OVER THE RUSSIAN COAST
WILL START TO PUSH EASTWARD.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
A SHOWERY REGIME WILL CONTINUE ACROSS MUCH OF THE REGION DURING
THE MIDDLE OF THE WEEK BENEATH AN ELONGATED UPPER TROUGH WITH
SEVERAL EMBEDDED LOWS SPANNING FROM THE MAINLAND TO THE WESTERN
ALEUTIANS. THIS TROUGH WILL BEGIN TO PUSH EASTWARD BY THURSDAY...
WITH DRIER CONDITIONS DEVELOPING ACROSS THE BERING AS HIGH
PRESSURE BUILDS IN FROM THE WEST.

ATTENTION THEN TURNS TO A SHARP ARCTIC TROUGH POISED TO DIG OVER
THE WESTERN MAINLAND LATE IN THE WEEK AND THEN PUSH ACROSS
SOUTHCENTRAL AK FRIDAY INTO SATURDAY. THIS WILL COINCIDE WITH A
NORTH PACIFIC SURFACE LOW MOVING INTO THE NORTHERN GULF...LEADING
TO THE POTENTIAL FOR SNOW AT LOWER ELEVATIONS OF SOUTHCENTRAL
INCLUDING THE ANCHORAGE BOWL AS COLDER AIR BEGINS TO MOVE INTO THE
REGION. CONFIDENCE IN THIS SCENARIO REMAINS LOW AT THIS TIME AS
MODELS CONTINUE TO STRUGGLE WITH FINER DETAILS...BUT THE OVERALL
SYNOPTIC AGREEMENT BETWEEN GFS AND EC GUIDANCE SUGGESTS THAT A
PERIOD OF COLDER TEMPERATURES AND GUSTY NORTH TO NORTHWEST WINDS
MAY BE IN STORE FOR THE WEEKEND. SNOW POTENTIAL WILL CONTINUE TO
BE CLOSELY MONITORED THROUGH THE REMAINDER OF THE WEEK.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...STORM 130 131 138
         GALE 119 120 132 136 137 139
              150 160 177 178 179 180 181 185 GALE 351 352
              411 412 413 414.

&&

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