Small Craft Advisory 998, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
414 PM AKST SUN DEC 14 2014

.ANALYSIS AND UPPER LEVELS...
THE UPPER LOW AND ASSOCIATED SURFACE CENTER NEAR KODIAK ISLAND
ARE FINALLY LIFTING NORTH TOWARD THE KENAI PEN. THE SURFACE FRONT
WHICH APPROACHED THE NORTH GULF THIS MORNING MOVED INLAND LATE
THIS MORNING. STORM FORCE WINDS...EVIDENT IN ADVANCE OF THIS
FEATURE...HAVE WEAKENED. PRESSURE RISES ON THE BACKSIDE THOUGH
HAVE ENHANCED GAP FLOWS. PRECIPITATION ALONG THE COASTS AND
EASTERN KENAI WAS GENERALLY IN THE FORM OF RAIN WITH SNOW AT
HIGHER ELEVATIONS (THOMPSON PASS) AS WELL AS THE COPPER RIVER
BASIN. PRECIPITATION WAS MORE VARIED WEST OF THE CHUGACH AS WARM
AIR CONTINUED ABOVE A SHALLOW LAYER OF COLD AIR. THIS GAVE RISE TO
FREEZING RAIN ACROSS THE ANCHORAGE BOWL THIS MORNING WITH A
MIXTURE OF RAIN AND SNOW SHOWERS ELSEWHERE SOUTH OF THE SUSITNA VALLEY.
GAP WINDS MIXED THE AIR OVER THE MATANUSKA VALLEY ALLOWING SURFACE
TEMPS TO REMAIN ABOVE FREEZING...SO WHAT LITTLE PRECIPITATION THAT
DID FALL FELL AS RAIN OR A MIX.

.OUT WEST...
A STACKED 960S LOW WAS EVIDENT SOUTHEAST OF THE PRIBILOF. A
FAIRLY TIGHT PRESSURE GRADIENT ON THE BACKSIDE OF THIS CENTER AND
COLD ADVECTION (EVIDENCED BY OPEN CELL CU STREAMING ACROSS THE
ALEUTIANS) PRODUCED STRONG WESTERLY WINDS FROM THE CENTRAL
ALEUTIANS TO WESTERN AK PEN AND THE SOUTHEAST BERING SEA. A FEW
SHOWERS WERE OBSERVED ACROSS THE SW MAINLAND AND WIDESPREAD RAIN
AND SNOW SHOWERS ACROSS MUCH OF THE ALEUTIANS AND SOUTHERN BERING
SEA.

&&

.MODEL DISCUSSION (SHORT TERM)...
OUT WEST...MODEL CONFIDENCE IS FAIRLY HIGH WITH THE MOVEMENT OF
THE LOW CENTER SE OF THE PRIBILOF ISLANDS AS INITIALIZATIONS THIS
MORNING AND FORECAST TRACK ARE FAIRLY SIMILAR. WILL BE LEANING
TOWARD A NAM BLEND FOR THIS AFTERNOON'S PACKAGE.

IN THE EAST...MODELS STRUGGLED SOME IN THE HANDLING OF THE WIND
AND PRESSURE FIELDS ASSOCIATED WITH THE FRONT WHICH MADE LANDFALL
IN THE GULF THIS MORNING. THE GEM REGIONAL DID THE BEST JOB THOUGH
ON PICKING THE TIMING OF THE GAP WINDS AND DOWNSLOPE ACROSS THE
ANCHORAGE BOWL/TURNAGAIN ARM THIS MORNING. THE NAM WAS TOO FAST.
THE BEST BET FOR THE NEAR TERM WILL BE THE GEM REG/NAM...THEN A
TRANSITION INTO THE GFS/NAM BEYOND THE GEM END POINT. MODELS ARE
ALL NOW PICKING UP THE NEXT LOW THAT ROLLS INTO THE SOUTHERN GULF
ON MON MORNING.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE SOUTHCENTRAL AND THE GULF OF ALASKA WILL CONTINUE TO HAVE
SOUTH TO SOUTHEASTERLY WINDS THROUGH TUESDAY. THIS WILL PROVIDE
WARMER AIR INTO THE NORTHERN GULF COASTLINE...PRINCE WILLIAM
SOUND AND THE EASTERN KENAI PENINSULA THROUGH TUESDAY. THE SURFACE
OBSERVATIONS ARE REPORTING TEMPERATURES ALONG THE EASTERN KENAI
PENINSULA THROUGH THE NORTHERN GULF COASTLINE IN THE UPPER 30S TO
LOWER 40S. THE TEMPERATURES ARE NEAR FREEZING IN THE ANCHORAGE
BOWL...COMBINE THIS WITH THE WARM LAYER ALOFT WILL RESULT IN SOME
AREAS RECEIVING POCKETS OF LIGHT FREEZING RAIN OVERNIGHT. THE
PRESSURE GRADIENT WILL CONTINUE TO STRENGTHEN THROUGH TOMORROW
NIGHT WITH A FRONTAL BOUNDARY PUSHING THROUGH THE REGION TONIGHT
BEFORE A GALE FORCE LOW TRACKING INTO THE EASTERN GULF BY TUESDAY
MORNING. THE AFOREMENTIONED SYNOPTIC FEATURES WILL RESULT IN GUSTY
TURNAGAIN ARM WINDS THIS EVENING THROUGH MONDAY EVENING. THE
THOMPSON PASS REGION EASTWARD ALONG THE CHUGACH MOUNTAINS WILL SEE
THE MAJORITY OF SNOWFALL WITH THE COLDER TEMPERATURES REMAINING IN
PLACE THROUGH TUESDAY.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (SUNDAY NIGHT THROUGH TUESDAY)...

A FRONT ALONG THE EASTERN BERING SLOWLY PUSHES INLAND OVERNIGHT.
GUSTY WINDS ACCOMPANY THE FRONTAL PASSAGE ALONG WITH
PRECIPITATION. TEMPERATURES REMAIN COLD ENOUGH TO KEEP
PRECIPITATION ALL SNOW EXCEPT FOR THE BRISTOL BAY AREA EAST OF
DILLINGHAM WHERE TEMPERATURES HAVE CLIMBED INTO THE MID 30S TO
LOWER 40S ALONG THE ALEUTIAN RANGE WITH THE FRONT THAT PUSHED
THROUGH ON SATURDAY. SCATTERED SHOWERS STAY IN THE FORECAST
THROUGH TUESDAY AS LOW PRESSURE SENDS WEAK WAVES ACROSS THE
SOUTHWEST...WITH PRECIPITATION CHANGING OVER TO ALL SNOW BY MONDAY
NIGHT AS COLDER AIR ADVECTS BACK INTO THE SOUTHWEST. WINDS ALONG
THE KUSKOKWIM DELTA AND ALONG THE COAST OF BRISTOL BAY GUST
THROUGH TUESDAY AS A SURFACE LOW KEEPS A TIGHT PRESSURE GRADIENT
ALONG THE EASTERN BERING.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS AND ALASKA PENINSULA (SUNDAY
NIGHT THROUGH TUESDAY)...

GUSTY WINDS ACROSS THE BERING/ALEUTIANS AND ALASKA PENINSULA
CONTINUE THROUGH MONDAY AND THEN TAPER OFF MONDAY NIGHT AS THE
SURFACE LOW MOVES NORTH OF THE ALASKA PENINSULA. THE EASTERN
ALEUTIANS AND ALASKA PENINSULA WILL SEE THE HIGHEST GUSTS WITH
THIS SYSTEM WITH STORM FORCE WINDS ACROSS THE SURROUNDING WATERS.
RAIN AND SNOW CONTINUE THROUGH THE BEGINNING OF THE WEEK AS FAST
MOVING SYSTEMS MOVE UP FROM THE NORTH PACIFIC.

&&

.LONG TERM FORECAST (WEDNESDAY THROUGH NEXT SUNDAY)...
A STACKED LOW PRESSURE SYSTEM WILL BE LOCATED JUST WEST OF NUNIVAK
ISLAND BY WEDNESDAY...KEEPING A SHOWERY REGIME OVER MUCH OF THE
REGION DURING THE MIDDLE OF THE WEEK WITH A BROAD UPPER TROUGH
ENCOMPASSING THE BERING AND DEEP SOUTHERLY FLOW OVER SOUTHCENTRAL
ALASKA WITH VARIOUS DISTURBANCES ROTATING NORTHWARD THROUGH THE
GULF. THE WET PATTERN WILL THEN CONTINUE INTO NEXT WEEKEND AS A
PAIR OF LOWS IMPACT THE REGION...WITH ONE LOW APPROACHING THE GULF
BY LATE IN THE WEEK AND ANOTHER SKIRTING THE ALEUTIAN CHAIN IN THE
SAME TIME FRAME. CONFIDENCE REMAINS LOW REGARDING THE SPECIFIC
DETAILS OF THESE FEATURES GIVEN A RELATIVELY LARGE AMOUNT OF MODEL
SPREAD...HOWEVER THE GENERAL SENSIBLE WEATHER IMPACTS WILL
RESEMBLE THOSE OF THE CURRENT PATTERN WITH SHOWERS ACROSS THE
BERING AND THE BULK OF THE PRECIPITATION OVER SOUTHCENTRAL AK
FOCUSED MAINLY ALONG THE GULF COAST.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALES...119 120 130 139 140 150 155 171-174 181 185
         STORMS...165 170
         HEAVY FREEZING SPRAY...181
FIRE WEATHER...NONE.

&&