Small Craft Advisory 195, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
436 PM AKST MON FEB 29 2016

.ANALYSIS AND UPPER LEVELS...
THE MAIN LOW IS A 965 MB LOW APPROACHING THE UNALASKA AREA WITH A
FRONT THROUGH THE EASTERN BERING SEA ACROSS THE ALASKA PENINSULA
SOUTHEAST ACROSS THE GULF OF ALASKA. A FRONTAL LOW HAS BEEN
FORMING NEAR 53N 143W. THE JET CROSSES THE FRONT NEAR 45N 140W AND
IS SUPPORTING A SURFACE LOW DEVELOPING AT THAT LOCATION. ANOTHER
LOW IS FORMING IN THE COLD AIR WRAPPING AROUND THE MAIN LOW NEAR
42N 149W. THE JET IS AIMED TOWARD HAIDA GWAII AND THIS SHOULD
RESULT IN LESS MOISTURE MOVING INTO THE NORTH GULF COAST AND
SOUTHERN MAINLAND OVERNIGHT TONIGHT.

&&

.MODEL DISCUSSION...
THE MODELS ARE IN POOR AGREEMENT WITH THE DETAILS OF THE NEXT
STORM TO APPROACH KODIAK ISLAND IN THE NEXT 24 HOURS THOUGH THEY
HAVE COME INTO BETTER AGREEMENT WITH THE LATEST MODEL RUNS. THE
OVERALL SYNOPTIC PATTERN IS HANDLED SIMILARLY BY ALL THE MODELS.
IT SEEMS THE EC AND CANADIAN ARE ALLOWING FAR MORE ENERGY TO
ADVECT INTO THE FRONTAL LOW NOW NEAR 50N 145W THAN THE NAM AND
GFS. THE PRESENCE OF THE LOW ALONG THE FRONT AT THE TRIPLE POINT
AND ANOTHER SOUTHWEST OF THAT WILL LIKELY SHUNT THE ENTRAINMENT OF
COLD AIR INTO THE FIRST MENTIONED FRONTAL LOW THUS WE FEEL THE NAM
AND GFS WILL LIKELY HAVE THE BETTER SOLUTION WITH REGARD TO AN
OPEN TROUGH MOVING ACROSS THE ALASKA PENINSULA AND KODIAK ISLAND
INSTEAD OF A STRONG CLOSED LOW. THE LATEST EC HAS BACKED OFF
CONSIDERABLY ON THE CLOSED LOW SOLUTION FOR TONIGHT. THIS SOLUTION
RESULTS IN VERY DIFFERENT WIND REGIMES ALONG THE NORTH GULF COAST
AND THROUGH SHELIKOF STRAIT THAN WHAT ONE WOULD EXPECT IF THE
OLDER RUN OF THE EC OR THE CANADIAN MODELS WERE TO VERIFY.

&&

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

STRONG LOW PRESSURE DEVELOPING ALONG A WELL-DEFINED FRONT WILL
BRING STORM-FORCE WINDS TO THE WESTERN GULF AND INSIDE WATERS FROM
THE BARREN ISLANDS REGION SOUTH THROUGH SHELIKOF STRAIT BY
MIDNIGHT...THEN AS IT QUICKLY MOVES INLAND OVER SOUTHWEST ALASKA
WINDS WILL QUICKLY DIMINISH THROUGH THE MORNING HOURS.

THE OTHER IMPACT BESIDES WINDS WILL BE THE POTENTIAL FOR SNOW
ACCUMULATIONS ON THE SOUTHERN KENAI PENINSULA. AS THE STRONG AND
WELL-DEFINED MID-LEVEL SYSTEM MOVES INLAND OVER SOUTHWEST ALASKA
OVERNIGHT...A PAIR OF WELL-DEFINED SURFACE AND MID-LEVEL FRONTS
WILL BECOME ORIENTED NEARLY PARALLEL TO THE MID-LEVEL FLOW FROM
THE CENTRAL GULF THROUGH LOWER COOK INLET. THESE FEATURES WILL
ALLOW FOR CROSS-BARRIER DOWNSLOPE FLOW TO GREATLY DIMINISH DURING
THE LATE MORNING HOURS (BETWEEN 6 AND 9 AM)...WITH SUFFICIENTLY
FAST AND RELATIVELY UNSTABLE MID-LEVEL FLOW THEN ABLE TO ADVECT
LIFT AND MOISTURE OVER THE SOUTHERN KENAI PENINSULA.

LOW-LEVEL THICKNESSES ARE PROJECTED TO CRASH WITH THE LOSS OF
CROSS-BARRIER 850-MB FLOW BETWEEN ABOUT 15Z AND 18Z TUESDAY
MORNING OVER THE SOUTHERN KENAI PENINSULA...ALLOWING FOR NUMEROUS
TO WIDESPREAD SNOW SHOWERS TO DEVELOP SOUTH OF CLAM GULCH THROUGH
THE DAY. SNOW LEVELS ARE LIKELY TO REACH SEA LEVEL BY EARLY OR
MID-AFTERNOON IN HOMER AND SELDOVIA...IF NOT SOONER.

ANOTHER ASPECT WITH THIS WELL-DEFINED RESIDUAL FRONT OVER THE
SOUTHERN KENAI PENINSULA IS THAT COOLER AIR FROM THE INTERIOR OF
THE STATE WILL BE DRAWN SOUTH. THIS WILL ALLOW FOR TEMPERATURES
OVER THE SOUTHERN INTERIOR TO BEGIN TO DIMINISH SOMEWHAT CLOSER TO
SEASONAL NORMALS BY MID-WEEK.

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
CROSS BARRIER FLOW AND EASTERLY WINDS WILL CONTINUE FOR THE
SOUTHWEST MAINLAND TONIGHT WITH GUSTY WINDS FOR THE GREATER
BRISTOL BAY AREA. A FEW SPRINKLES ARE POSSIBLE WITH CHANCES
INCREASING FOR SHOWERS DURING THE OVERNIGHT HOURS. A MUCH DRIER
PATTERN SETTLES IN TOMORROW EVENING WITH THE ONLY CHANCE FOR
PRECIPITATION BEING SCATTERED SNOW SHOWERS ALONG THE KUSKOKWIM
DELTA COAST AS WELL AS SOME SNOW SHOWERS IN THE PORT ALSWORTH
AREA LATE TUESDAY NIGHT. WEDNESDAY WILL SEE CLOUDS DIMINISH ALONG
WITH LIGHT NORTHERLY WINDS AND DRY CONDITIONS EVERYWHERE. ABOVE
NORMAL TEMPERATURES WILL CONTINUE.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
AN UPPER LEVEL LOW WILL SLOWLY TRAVERSE THE CENTRAL BERING SEA
TODAY AND WEAKEN TOMORROW. SHOWER COVERAGE WILL CONTINUE TO
DIMINISH THROUGH WEDNESDAY WHILE THE SYSTEM SLOWLY DRIFTS WESTWARD
TOWARD THE WESTERN ALEUTIANS. A WEAK FRONT MOVES INTO THE CENTRAL
BERING SEA ON WEDNESDAY FROM UNALASKA THROUGH THE PRIBILOFS.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7...THU THROUGH MON)...THE
PERIOD WILL START WITH HIGH PRESSURE OVER THE SOUTHERN MAINLAND
TRYING TO EXTEND OVER SOUTHWEST ALASKA. THIS WILL MAKE FOR CLEAR
SKIES AND DRY CONDITIONS FOR THESE AREAS...AT LEAST THROUGH EARLY
FRI. TEMPERATURES WILL ALSO RETURN TO MUCH MORE SEASONABLE WITH
THE SLIGHT REPRIEVE FROM THE WARM SOUTHERLY FLOW. OVER THE
WEST...A BROAD WEAKENING LOW WILL CONTINUE TO TRACK NORTH OF THE
ALEUTIAN CHAIN TOWARD THE WESTERN ALEUTIANS. EAST TO NORTHEAST
FLOW BEHIND IT WILL BRING DRYING CONDITIONS TO THE EASTERN
BERING. IT WILL LEAVE THE ONLY REAL POTENTIAL FOR PRECIPITATION
CONFINED TO AREAS WEST OF THE PRIBILOF ISLANDS. EVEN THIS
PRECIPITATION WILL BE LIGHT AT BEST.

HEADING TOWARD THE WEEKEND...THE BROAD AREA OF LOW PRESSURE
SOMEWHERE NEAR 50N 145W WILL SLOWLY DRIFT NORTH TOWARD THE GULF OF
ALASKA. THIS WILL ONCE AGAIN OPEN UP COASTAL AREAS TO INCREASING
EASTERLY WINDS AND BETTER CHANCES FOR PRECIPITATION. THE LONG-
RANGE MODELS AND THEIR ENSEMBLE MEANS DID TREND SLIGHTLY FARTHER
NORTH AND EAST WITH THE PRIMARY LOW CENTER. THIS MIGHT OPEN UP
THE POSSIBILITY OF SOME PRECIPITATION MAKING IT INTO SOUTH CENTRAL
SAT INTO SUN. HOWEVER...THE TRACK OF THE SYSTEMS FROM THE
SOUTHEAST DOES NOT FAVOR MUCH MOISTURE MAKING IT OVER THE CHUGACH
AND KENAI MOUNTAINS. OUT WEST...FLOW REORIENTS TO A MORE NORTHERLY
DIRECTION. THIS COULD MAKE FOR A SHORT PERIOD OF GALES OVER THE
NORTHERN BERING AND SHOULD LEAD TO AN INCREASE IN COLD AIR
ADVECTION SHOWERS...ESPECIALLY ON THE BERING SIDE OF THE CHAIN.
&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 119 120 150-170 179 180.
		 STORM 130-138.

&&

SYNOPSIS AND MODEL DISCUSSION...SAM
SOUTHCENTRAL ALASKA...CC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MTL
LONG TERM...MO