Small Craft Advisory 274, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
458 AM AKDT SAT MAR 28 2015

.ANALYSIS AND UPPER LEVELS...
THE OVERALL PATTERN REMAINS LARGELY UNCHANGED THIS MORNING AS A
BROAD LONGWAVE TROUGH CONTINUES TO DOMINATE THE NORTHERN PACIFIC
WITH AN EMBEDDED COMPLEX LOW CENTERED NEAR THE ALASKA PENINSULA.
NUMEROUS WAVES ROTATING AROUND THE PERIPHERY OF THIS LOW ARE THE
MAIN FEATURES IMPACTING THE WEATHER ACROSS THE REGION. RAIN
CONTINUES ALONG THE GULF COAST AS ONE OF THESE WAVES PUSHES INLAND
OVER SOUTHCENTRAL ALASKA...WITH LOCATIONS IN THE LEE OF THE
CHUGACH AND TALKEETNA MOUNTAINS STAYING MOSTLY DRY AS A RESULT OF
STRONG CROSS BARRIER FLOW. MEANWHILE...THE NEXT SYSTEM IS TAKING
AIM ON THE WESTERN GULF AS A DEEP LOW APPROXIMATELY 350 MILES
SOUTH OF KODIAK ISLAND BEGINS TO MOVE NORTHWARD. AN ASSOCIATED
FRONT IS ENTERING THE SOUTHERN GULF WELL AHEAD OF THE SURFACE
LOW...BRINGING RAIN AND GUSTY WINDS TO KODIAK ISLAND. AN UPPER
DISTURBANCE IS PUSHING WESTWARD THROUGH THE BERING...BRINGING RAIN
TO THE AKPEN/EASTERN ALEUTIANS AND AREAS OF BLOWING SNOW TO THE
PRIBILOF ISLANDS.

&&

.MODEL DISCUSSION...
MODELS REMAIN IN VERY GOOD SHORT TERM AGREEMENT AND HAVE CONVERGED
ON A SOLUTION FOR THE TRACK OF THE NEXT LOW SET TO IMPACT THE
GULF AS IT APPROACHES KODIAK ISLAND BY SUNDAY MORNING. MAINLY USED
THE GFS FOR THE MORNING FORECAST PACKAGE. ALSO UTILIZED THE
ENHANCED DETAIL OF THE CANADIAN (GEM) REGIONAL MODEL IN THE FIRST
36 HOURS OVER THE WESTERN HALF OF THE DOMAIN.

&&

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

WITH THE LOW MOVING INTO THE GULF TODAY TAKING A SLIGHTLY MORE
WESTERLY PATH THAN IT LOOKED YESTERDAY IT WILL KEEP THE MAJORITY
OF SOUTHCENTRAL ALASKA IN WARM AND MOIST SOUTHEASTERLY FLOW. THERE
WILL BE A BIT OF RAINFALL OVER THE COASTAL MOUNTAINS WITH JUST
SOME ISOLATED RAIN SHOWERS REMAINING FOR THE LEEWARD SIDE OF THE
MOUNTAINS. SOME HIGHER ELEVATIONS SUCH AS TURNAGAIN PASS AND
THOMPSON PASS WILL SEE SOME SNOW MIXED IN DURING THE OVERNIGHT
HOURS BUT AREAS NEAR SEA LEVEL WILL PRETTY MUCH JUST EXPERIENCE
RAIN AS THE PRECIPITATION TYPE. THIS PATTERN WILL PERSIST THROUGH
THE WEEKEND.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
THE DOMINATE WEATHER FEATURE FOR THE NEXT 24 HOURS OVER SOUTHWEST
ALASKA WILL BE THE 973 MB LOW APPROACHING KODIAK WITH THE
ASSOCIATED FRONT MOVING INLAND TODAY. THIS SYSTEM WILL BRING
SCATTERED RAIN SHOWERS AND GUSTY WINDS MAINLY OVER THE WESTERN
CAPES AND ALASKA PENINSULA REGION OF BRISTOL BAY BEFORE
DISSIPATING TONIGHT. AS THE NORTHEASTERLY FLOW CONTINUES OVER THE
REGION...EXPECT A DRYING AND COOLING TREND THROUGH SUNDAY.
PRECIPITATION CHANCES WILL INCREASE SLIGHTLY LATE SUNDAY AS A
SECOND WEAK LOW THAT FORMS SOUTH OF COLD BAY MIGRATES EASTWARD TO
NEAR KODIAK.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
AT THE SURFACE...THE CENTRAL/EASTERN BERING SEA REMAINS FIRMLY
IN CYCLONIC FLOW FROM THE LOW APPROACHING KODIAK ISLAND THIS
MORNING WITH BRISK NORTHERLY WINDS FROM THE PRIBILOF ISLANDS
SOUTHWARD TO THE CENTRAL ALEUTIANS. PRECIPITATION...MAINLY
RAIN...WILL CONTINUE TODAY OVER MOST OF THE AREA WITH THE BEST
CHANCES FROM ATKA TO DUTCH HARBOR AS THE MARINE FLOW OFF THE
BERING COMBINED WITH A WEAKENING UPPER LEVEL LOW NORTH OF DUTCH
HARBOR MOVES SOUTHEASTWARD BEFORE DISSIPATING. TONIGHT INTO
SUNDAY...DRY NORTHERLY FLOW WILL MOVE OVER THE NORTHERN BERING
ENDING PRECIPITATION OVER THE PRIBILOF ISLANDS.

FURTHER WEST...A LOW AND ITS ASSOCIATED FRONT NEAR KAMCHATKA IS
FORECAST TO MOVE INTO THE WESTERN ALEUTIANS OVER THE NEXT 24
HOURS...BRINGING A SWATH OF PRECIPITATION INTO THE WESTERN
ALEUTIANS. PRECIPITATION IN THE WEST IS EXPECTED TO STAY MOSTLY
SNOW AS THERE IS NOT A SIGNIFICANT AMOUNT OF WARM AIR ADVECTION
INTO THE REGION WITH THIS SYSTEM.

&&

.LONG TERM FORECAST (MONDAY THROUGH FRIDAY)...

AN ACTIVE WEATHER PATTERN CONTINUES THROUGH NEXT FRIDAY AS A LONG
WAVE TROUGH REMAINS ACROSS THE EASTERN BERING AND GULF OF ALASKA.
PRECIPITATION WILL MAINLY STAY OVER AREA WATERS AND SURROUNDING
COASTS. ON MONDAY THE CLOSED LOW CENTER SOUTH OF KODIAK ISLAND
BEGINS TO MOVE SLOWLY EASTWARD AS ANOTHER LOW CENTER RACES ALONG
THE ALEUTIAN CHAIN. BY WEDNESDAY AFTERNOON...THE SURFACE LOW
ASSOCIATED WITH THIS NEXT STORM SYSTEM PASSES THE ALASKA
PENINSULA. AT THIS POINT THERE IS A BIT OF UNCERTAINTY WITH THE
TRACK OF THIS LOW BETWEEN THE OPERATIONAL MODELS...WITH A 400
MILE DIFFERENCE IN THE SURFACE PRESSURE CENTERS. THE ECMWF TRACKS
THIS SYSTEM JUST NORTH OF KODIAK ISLAND AND THE GFS TRACKS SOUTH
OF THE ISLAND. THE ECMWF WOULD BRING WARMER TEMPERATURES PUSHING A
FRONT INTO THE NORTHERN GULF AND THE GFS SOLUTION IS ON THE COOLER
SIDE WITH THE WARM FRONT SKIRTING THE SOUTHERN GULF.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALES 119 120 130 131 174.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...CB
SOUTHCENTRAL ALASKA...EZ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...RLF
LONG TERM...KH