Small Craft Advisory 318, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
302 PM AKDT SUN APR 10 2016

.ANALYSIS AND UPPER LEVELS...
A SURFACE LOW OVER THE ALASKA PENINSULA IS ROTATING A FRONT
THROUGH THE SOUTHERN MAINLAND. ANOTHER LOW WELL SOUTH OF THE
EASTERN ALEUTIANS IS MOVING TOWARD THE SOUTHERN GULF OF ALASKA.
BETWEEN THESE TWO SYSTEMS IS A RIDGE OF HIGH PRESSURE BUILDING IN
ALONG THE NORTH GULF COAST BEHIND THE FRONT. THIS IS PRODUCING THE
PRESSURE RISES ACROSS THE REGION THAT ARE FUELING THE GUSTY GAP
WINDS ACROSS THE KENAI PENINSULA...TURNAGAIN ARM AND OUT OF THE
KNIK RIVER VALLEY. THE STRONGER WINDS ARE STARTING TO SHOW UP
ALONG THE COPPER RIVER AS GULKANA HAS PICKED UP SOUTH WINDS. IN
THE BERING SEA TWO WEAK LOWS AT THE SURFACE ARE ROTATING CLOUDS
AND SHOWERS ACROSS SOUTHWEST ALASKA AND THE EASTERN BERING SEA.

&&

.MODEL DISCUSSION...
THE MODELS CONTINUE TO DO A GOOD JOB AND ARE IN GOOD AGREEMENT IN
THE SHORT TO MEDIUM RANGE. THE MODELS INITIALIZED WELL WITH
RESPECT TO THE SURFACE AND UPPER LEVEL FEATURES. THE QPF IS IN
GREAT AGREEMENT BETWEEN ALL THE MODELS AND AS USUAL THE HIGH
RESOLUTION MODELS DO BETTER DEFINING THE DOWNSLOPE PRECIPITATION
SHADOWS ACROSS SOUTH CENTRAL ALASKA.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE DECAYING WEATHER FRONT CONTINUES TO MOVE INLAND WITH THE
PRESSURE GRADIENTS WEAKENING RESULTING IN THE GAP WINDS
DIMINISHING BY LATE EVENING. THE UPPER LEVELS HAVE A TROUGH
EXITING THE SOUTHCENTRAL REGION AFTER MIDNIGHT TONIGHT. THIS WILL
GIVE A SMALL WINDOW OF CLEARING SKIES OVER SOUTH CENTRAL...EXCEPT
FOR THE NORTHERN COASTAL COMMUNITIES SEEING THE BULK OF THE
PRECIPITATION THROUGH MONDAY MORNING. LOOK FOR THE CROSS-BARRIER
FLOW TO CONTINUE TO PRODUCE DRIER CONDITIONS IN THE ANCHORAGE
BOWL...MATANUSKA VALLEY AND THE WESTERN KENAI PENINSULA REGIONS
HEADING INTO MONDAY. THE NEXT SYNOPTIC FEATURE TO AFFECT THE AREA
WILL BE ASSOCIATED WITH A GALE FORCE LOW APPROACHING SOUTH OF
KODIAK ISLAND BY MONDAY AFTERNOON. THIS WILL BRING A SWATH OF RAIN
AND GUSTY EASTERLY WINDS OVER THE KODIAK ISLAND BY MONDAY NIGHT
BEFORE SPREADING NORTHWARD INTO THE THE SOUTHERN EASTERN KENAI
REGION HEADING INTO TUESDAY.

&&

.FIRE WEATHER...
THERE ARE NO SIGNIFICANT FIRE WEATHER CONCERNS OVER THE NEXT
COUPLE OF DAYS.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
COLD AIR ALOFT ASSOCIATED WITH A SHORTWAVE MOVING OVER THE
SOUTHWEST MAINLAND TODAY WILL ALLOW FOR SCATTERED CONVECTIVE RAIN
SHOWERS TO CONTINUE INTO THIS EVENING...ENDING QUICKLY FROM SOUTH
TO NORTH. IT IS STILL VERY EARLY IN THE CONVECTIVE SEASON
HOWEVER...AND WITH LITTLE CLEARING AHEAD OF THE SHORTWAVE LIMITING
SOLAR HEATING...NO THUNDER IS EXPECTED. SKIES WILL THEN PARTIALLY
CLEAR BEHIND THE SHORTWAVE TONIGHT...ALLOWING FOR THE POTENTIAL
FOR PATCHY FOG OVERNIGHT TONIGHT...ESPECIALLY FOR BRISTOL BAY...AS
LOW LEVEL MOISTURE AND WARMING 925 MB TEMPERATURES MOVE OVERHEAD.
WEAK RIDGING ON MONDAY WILL THEN KEEP SKIES PARTLY SUNNY WITH JUST
PASSING SHOWERS AND TEMPERATURES REMAINING ABOVE NORMAL. A FRONT
WILL THEN APPROACH THE AKPEN LATE MONDAY INTO TUESDAY...BRINGING
RAIN AND SOME GUSTY WINDS TO THE ESPECIALLY TO THE PACIFIC SIDE OF
THE AKPEN.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
THE PERSISTENT UPPER LEVEL TROUGH WILL REMAIN OVER THE CENTRAL
BERING INTO TUESDAY...THOUGH IT WILL WEAKEN AND NARROW IN PLACE AS
RIDGING UPSTREAM IMPINGES UPON IT BY MONDAY NIGHT AND TUESDAY.
THIS WILL KEEP CYCLONIC FLOW AND RAIN SHOWERS OVER THIS REGION.
OTHERWISE THE WEATHER WILL REMAIN RELATIVELY QUIET UNTIL A WEATHER
FRONT BEGINS TO APPROACH THE WESTERN ALEUTIANS FROM THE SOUTH
TUESDAY WITH GALE-FORCE WINDS AND A CHANCE OF WET SNOW AND SOME
RAIN.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
BEGINNING TUESDAY EVENING...THE REMNANTS OF A GULF OF ALASKA LOW
WILL BE SLOWLY MOVING EAST AND WEAKENING...LEAVING WEAK HIGH
PRESSURE OVER SOUTHERN ALASKA AND THE EASTERN BERING SEA. SHOWERS
WILL BE POSSIBLE OVER THE MOUNTAINS AND ACROSS INLAND LOCATIONS IN
THE AFTERNOON AS THE MID APRIL SUN RAMPS UP. OTHERWISE...RATHER
DRY AND QUIET WEATHER CONDITIONS WILL LAST INTO THURSDAY BEFORE
ANOTHER NORTH PACIFIC LOW SKIRTING THE ALEUTIAN CHAIN MOVES INTO
THE GULF OF ALASKA. WITH THE LOW TRACKS REMAINING SOUTH OF THE
MAINLAND...THIS WILL KEEP A MOSTLY CROSS-BARRIER COMPONENT TO THE
LOW LEVEL WINDS...WHICH MEANS PRECIPITATION WILL BE MOSTLY ALONG
THE GULF COAST WITH DRIER INLAND CONDITIONS. THIS WILL ALSO KEEP
TEMPERATURES ABOVE AVERAGE AS SPRING CONTINUES TO SURGE FORWARD AT
A RAPID PACE.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING 132 138 150.

&&

SYNOPSIS AND MODEL DISCUSSION...SA
SOUTHCENTRAL ALASKA...PD
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...CC
LONG TERM...JA