Small Craft Advisory 394, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
1151 AM AKDT SAT MAY 17 2014

.ANALYSIS AND UPPER LEVELS...A PATTERN CHANGE IS UNDERWAY WITH A
COUPLE OF SHORT-WAVES OVER THE NORTHERN BERING AND NORTHWEST
ALASKA PUSHING THE RIDGE OFF TO THE SOUTH. TODAY WILL BE THE
LAST IN A STRETCH OF VERY WARM DAYS ACROSS MOST OF SOUTHWEST AND
SOUTHCENTRAL ALASKA. MEANWHILE WIDESPREAD STRATUS AND AREAS OF
FOG DOMINATE THE BERING/ALEUTIANS/ALASKA PENINSULA UNDERNEATH THE
STRONG RIDGE ALOFT.

&&

.MODEL DISCUSSION...MODELS ARE IN VERY GOOD AGREEMENT OVER THE
NEXT FEW DAYS AND FORECAST CONFIDENCE IS ABOVE AVERAGE.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL AND SOUTHWEST ALASKA...THE FIRST UPPER LEVEL SHORT-
WAVE TO CROSS THE SOUTHERN MAINLAND THIS AFTERNOON THROUGH TONIGHT
WILL SERVE TO PUSH THE RIDGE OUT OF THE WAY. THE WAVE WILL COME
THROUGH WITH A FAIRLY LOW AMPLITUDE TRACKING QUICKLY FROM WEST TO
EAST...SO EXPECT MOST OF THE REGION TO REMAIN DRY WITH SOME MID TO
UPPER LEVEL CLOUDINESS. THE WAVE WILL AMPLIFY AS IT MOVES THROUGH
THE COPPER RIVER BASIN LATE TONIGHT AND EARLY SUNDAY SO DO EXPECT
INCREASING CHANCES OF SHOWERS THERE. THE BIGGER STORY WILL BE
COOLING TEMPERATURES AND INCREASING WINDS. THE STRONGEST WINDS
WITH THE FIRST WAVE WILL BE ACROSS BRISTOL BAY AND INTO THE
WESTERN GULF AND KODIAK ISLAND. DRY AND WINDY CONDITIONS WILL
BRING A RETURN TO CRITICAL FIRE WEATHER CONDITIONS...STARTING WITH
THE BRISTOL BAY AREA THIS AFTERNOON AND EVENING.

WITH THE RIDGE PUSHED OFF TO THE SOUTH AND WEST...THE NEXT UPPER
WAVE TRACKING OUT OF RUSSIA WILL REALLY AMPLIFY THE TROUGH OVER
MAINLAND ALASKA AS IT CROSSES SOUTHWEST ALASKA SUNDAY AND INTO THE
GULF SUNDAY NIGHT. THIS WILL PRODUCE STRONGER AND MORE WIDESPREAD
WINDS. MORE SIGNIFICANT COLD AIR ADVECTION WILL CONTINUE THE
DOWNWARD TREND IN TEMPERATURES RESULTING IN NOTABLY COOLER HIGH
TEMPERATURES ON MONDAY. WINDS WILL KEEP THE LOW LEVELS WELL MIXED
KEEPING TEMPERATURES WELL ABOVE FREEZING AT NIGHT. THE ONE
EXCEPTION WILL BE THE KUSKOKWIM DELTA AND KUSKOKWIM VALLEY WHERE
NIGHT-TIME LOWS WILL DIP TO FREEZING OR BELOW.

EVEN THOUGH TEMPERATURES WILL BE FALLING...THE AIR MOVING IN
BEHIND THESE WAVES WILL BE VERY DRY. THUS CRITICAL FIRE WEATHER
CONDITIONS WILL PERSIST...MOST NOTABLY IN BRISTOL BAY...THE
SUSITNA VALLEY...AND KODIAK ISLAND.

AS THE TROUGH BEGINS TO AMPLIFY SUNDAY A LOW WILL DEVELOP OVER THE
NORTHERN GULF. THIS WILL ADVECT MOISTURE NORTHWARD TOWARD THE
COPPER RIVER BASIN LEADING TO AREAS OF RAIN OVER EASTERN PRINCE
WILLIAM SOUND AND THE COPPER RIVER BASIN...ALTHOUGH WITH LOW
LEVELS REMAINING DRY INLAND THE BULK OF PRECIP WILL FALL ALONG THE
MOUNTAINS.

THE UPPER TROUGH AND GULF LOW WILL EXIT TO THE SOUTH AND EAST
MONDAY NIGHT AND TUESDAY WITH THE UPPER RIDGE NOSING BACK IN FROM
THE WEST. THIS WILL ALLOW WINDS TO DIMINISH ACROSS THE REGION
WHILE DRY CONDITIONS WILL PERSIST WITH NEAR NORMAL TEMPERATURES.

BERING SEA/ALEUTIANS/SOUTHERN ALASKA PENINSULA...THE RIDGE WILL
REMAIN FIRMLY ENTRENCHED OVER THE REGION. THUS EXPECT STRATUS AND
FOG TO PERSISTS MOST AREAS. THE ONE EXCEPTION IS ON THE SOUTH SIDE
OF THE ALASKA PENINSULA AND EASTERN ALEUTIANS. LOW LEVEL NORTHERLY
FLOW WILL KEEP ALL THE CLOUDS BANKED UP AGAINST THE MOUNTAINS ON
THE BERING SIDE.

&&

.LONG TERM FORECAST...THE RIDGING WHICH MOVES BACK OVER THE
SOUTHERN MAINLAND TUESDAY WILL BE VERY SHORT-LIVED. ANOTHER
SERIES OF SHORT-WAVES WILL DROP DOWN OUT OF THE ARCTIC BEGINNING
TUESDAY NIGHT...AMPLIFYING THE PATTERN EVEN MORE. THIS WILL
MAINTAIN MORE SEASONABLE TEMPERATURES (COOLER THAN THIS PAST
WEEK) ACROSS THE SOUTHERN MAINLAND THROUGH NEXT WEEKEND. ALTHOUGH
THERE IS SOME DIFFERENCE IN THE DETAILS OF FEATURES DROPPING
SOUTHWARD...ALL MEDIUM RANGE SOLUTIONS ARE KEYING ON A COLD UPPER
LOW DROPPING DOWN TO THE GULF. THIS WOULD PROVIDE ENOUGH
INSTABILITY TO PRODUCE SOME SHOWERS ACROSS SOUTHCENTRAL BEGINNING
THE MIDDLE OF NEXT WEEK. IF DYNAMIC FORCING IS STRONG ENOUGH THERE
MAY EVEN BE SOME AREAS OF PLAIN OLD RAIN...WHICH WOULD DEFINITELY
BE A CHANGE TO THE VERY DRY PATTERN WE HAVE BEEN IN THIS MONTH.
MEANWHILE...BENIGN WEATHER WILL PERSIST ACROSS THE BERING AND
ALEUTIANS UNDER A STRONG BLOCKING RIDGE.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING 130 131.
FIRE WEATHER...RED FLAG WARNING 141 145 161 171.
&&

SEB MAY 14