Small Craft Advisory 330, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
442 PM AKDT TUE APR 14 2015

.ANALYSIS AND UPPER LEVELS...
THERE IS A LARGE UPPER LEVEL LOW CENTERED JUST TO THE SOUTHEAST OF
KODIAK ISLAND. THE OCCLUDED FRONT WITH THIS LOW RUNS IN AN ARC
FROM KODIAK ISLAND AND THEN PARALLEL TO...AND JUST OFF...THE GULF
COAST. ON THE FORWARD (NORTH) SIDE OF THE FRONT THE AIR MASS IS
FAIRLY COLD AND MOST PRECIPITATION THAT IS FALLING IS IN THE FORM
OF SNOW AND IS CONFINED TO AREAS NEAR THE COAST. WARMER AIR IS
BEHIND (SOUTH) OF THE FRONT. WEAK HIGH PRESSURE IS OVER INLAND
SOUTHERN ALASKA AHEAD OF THIS FRONT. A SOMEWHAT FLAT RIDGE IS OVER
THE BERING SEA AND NORTH TO NORTHWEST FLOW AT MOST LEVELS DOMINATES
THE BERING SEA...ALEUTIAN ISLANDS...AND ALASKA PENINSULA.
&&

.MODEL DISCUSSION...
THE NUMERICAL MODELS ARE IN GOOD AGREEMENT THROUGH THE SHORT TERM
PORTION OF THE FORECAST. THERE ARE SOME MINOR DIFFERENCES ON THE
SURFACE LOW LOCATION AS IT REACHES THE GULF COAST WEDNESDAY
NIGHT...BUT THESE ARE EASY TO HANDLE. THERE IS SOME MODEL SPREAD
ON A LOW SOUTH OF THE ALEUTIANS WEDNESDAY NIGHT AND THURSDAY AS
WOULD BE EXPECTED.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
GUSTY WINDS ACROSS THE NORTH GULF COAST AND THROUGH THE MATANUSKA
VALLEY WILL PEAK THIS EVENING AND THEN GRADUALLY DIMINISH THROUGH
WEDNESDAY MORNING AS THE STRONG FRONT OVER THE GULF MOVES ASHORE
AND BEGINS TO WEAKEN. THIS FRONT WILL CONTINUE TO BRING WIDESPREAD
PRECIPITATION TO AREAS ALONG THE COAST THROUGH WEDNESDAY...WITH A
RAIN/SNOW MIX GRADUALLY CHANGING OVER TO ALL RAIN AS TEMPERATURES
WARM. THIS WILL KEEP ANY ACCUMULATIONS RELATIVELY MINIMAL WITH
THE EXCEPTION OF LOCALLY HIGHER AMOUNTS IN AND AROUND TURNAGAIN
PASS WHERE TEMPERATURES WILL HOVER AROUND FREEZING THROUGH
WEDNESDAY MORNING. MEANWHILE...PRECIPITATION CHANCES WILL
GRADUALLY INCREASE FOR INLAND LOCATIONS THROUGH WEDNESDAY NIGHT AS
CROSS BARRIER FLOW WEAKENS IN RESPONSE TO THE GULF LOW MOVING
CLOSER TO THE COAST. THE LOW WILL THEN PUSH INLAND OVER THE KENAI
PENINSULA ON THURSDAY AND SPREAD PRECIPITATION FROM THE ANCHORAGE
BOWL INTO THE MAT-SU REGION. PRECIPITATION MAY BEGIN AS SNOW
WEDNESDAY NIGHT AND THEN BECOME A MIX OF RAIN AND SNOW THURSDAY
MORNING BEFORE TRANSITIONING TO RAIN DURING THE AFTERNOON. THIS
WILL SERVE TO LIMIT ANY POTENTIAL FOR ACCUMULATING SNOW.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
THE STORM FORCE NORTH PACIFIC LOW POSITIONED JUST SOUTHEAST OF THE
SHUMAGIN ISLANDS WILL CONTINUE TO TRACK EASTWARD BEFORE BEING
LOCATED NEAR SEWARD BY THURSDAY MORNING. THIS WILL PRODUCE WRAP-
AROUND MOISTURE SPREADING INTO THE ALASKA PENINSULA AND THE
ALEUTIAN RANGE THROUGH THURSDAY. THE PRECIPITATION WILL BE IN THE
FORM OF SCATTERED SNOW SHOWERS WITH RAIN MIXING IN AT TIMES. THE
REST OF THE SOUTHWEST ALASKA REGION WILL HAVE NORTHERLY WINDS AND
COOLER TEMPERATURES RESULTING IN DRIER CONDITIONS WITH SOME
ISOLATED SNOW SHOWERS HEADING INTO THURSDAY. BY FRIDAY A WARM
FRONT WILL BE ENTERING THE EASTERN BERING SEA BRINGING WARMER
TEMPERATURES TO THE BRISTOL BAY REGION.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
THE EASTERN ALEUTIANS AND THE BRISTOL BAY REGIONS WILL HAVE
NORTHEASTERLY WINDS THROUGH TONIGHT. THE NORTH PACIFIC LOW
LOCATED SOUTH OF THE EASTERN ALEUTIANS WILL CONTINUE TO TRACK
EASTWARD AND BY WEDNESDAY BE LOCATED EAST OF KODIAK. THE WINDS
WILL SHIFT TO A NORTHERLY DIRECTION WITH THE COLDER TEMPERATURES
RESULTING IN WIDESPREAD AREAS OF SNOW SHOWERS OVER THE REGION. BY
TUESDAY EVENING A WEAK RIDGE WILL MOVE INTO THE WESTERN
ALEUTIANS. THIS WILL GIVING WAY TO ANOTHER STORM FORCE NORTH
PACIFIC LOW ENTERING THE WESTERN ALEUTIANS BY WEDNESDAY MORNING.
THIS SYSTEM WILL TRACK EASTWARD RUNNING PARALLEL TO THE ALEUTIANS
CHAIN BEFORE BEING LOCATED JUST SOUTH OF NIKOLSKI BY FRIDAY. THIS
WILL BRING WARMER TEMPERATURES OUT AHEAD OF THE SYSTEM TO THE
ALEUTIAN CHAIN AND WILL SPILL OVER INTO THE LOWER TO CENTRAL
BERING SEA. THE AFOREMENTIONED SYSTEM WILL BE ACCOMPANIED BY GALE
FORCE WINDS TO THE ALEUTIANS AND THE BERING SEA.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
A DEEP LOW SOUTH OF THE ALEUTIANS IS THE MAJOR FEATURE IN THE MID
TERM. FOR THE MOST PART THERE IS GOOD AGREEMENT WITH THE TRACK OF
THIS LOW NORTH INTO THE EASTERN BERING BUT THERE ARE SOME
DISCREPANCIES WITH THE TIMING. THE GEM IS THE FASTEST PROGRESSING
THE LOW ACROSS THE ALEUTIANS WHILE BOTH THE EC AND GFS ARE SLOWER.
THE ENSEMBLES ALSO FAVORED THE SLOWER SOLUTION SO THAT WAS THE
PREFERRED TRACK.

DESPITE SOME TIMING DIFFERENCES WITH THE MAIN LOW CENTER THE
MODELS ARE IN DECENT AGREEMENT WITH THE PROGRESSION OF ITS
ASSOCIATED FRONT. THE CONSENSUS IS THAT THE FRONT WILL MAKE IT TO
KODIAK ISLAND BY FRIDAY AFTERNOON AND TO THE NORTH GULF COAST
FRIDAY NIGHT. THIS WILL BE A WARMER SYSTEM WITH THE MAJORITY OF
THE PRECIPITATION EXPECTED TO BE RAIN. THROUGH THE WEEKEND THE LOW
WILL SLOWLY TRACK NORTH ALONG THE WEST COAST KEEPING SOUTHERLY
FLOW FOR THE GULF AND NORTHERLY FLOW OVER THE BERING.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 120 130 131 138 139 150 165 176 177 180.
         STORM 119.
         HEAVY FREEZING SPRAY 160 179 180.
FIRE WEATHER...RED FLAG WARING 111.

&&

SYNOPSIS AND MODEL DISCUSSION...BL
SOUTHCENTRAL ALASKA...CB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PD
LONG TERM...DK