Small Craft Advisory 280, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 PM AKDT THU MAR 28 2013

.MODEL DISCUSSION...
MODELS HAVE ALL INITIALIZED FAIRLY WELL AND ARE IN GOOD AGREEMENT
THROUGH THE SHORT TERM. THERE ARE SOME POSITIONAL DIFFERENCES WITH
THE WEAK LOW IN THE GULF OF ALASKA FRIDAY THROUGH SATURDAY HOWEVER.
THE NAM IS THE PREFERRED MODEL AS IT BRINGS THE LOW INTO THE NORTHERN
GULF. FOR THE BERING SEA AND SOUTHWEST MAINLAND...THE GFS IS THE
PREFERRED MODEL OVERALL.

.ANALYSIS AND UPPER LEVELS...
TWO UPPER LOWS...ONE OVER FAR EASTERN RUSSIA AND ONE NEAR THE CENTRAL
ALEUTIANS...ARE BEING SEPARATED BY UPPER RIDGING PUSHING IN FROM THE
SOUTHWEST. ANOTHER UPPER LOW IS OVER NORTHEAST ALASKA AND NORTHWEST
CANADA...WHILE RIDGING IS IN PLACE OVER MUCH OF THE INTERIOR AND
SOUTH CENTRAL MAINLAND. AT THE SURFACE...A LARGE LOW CENTERED OVER
THE CENTRAL ALEUTIANS IS MOVING EASTWARD WITH A WARM FRONT MAKING ITS
WAY EASTWARD TOWARD THE GULF OF ALASKA. HIGH PRESSURE IS OVER THE
EASTERN GULF. SNOW CONTINUES OVER MUCH OF THE SOUTHWEST MAINLAND
TODAY AHEAD OF THE FRONT AS IT MOVES INLAND...AND SOME LIGHT
PRECIPITATION IS FALLING OVER THE GULF OF ALASKA AND GRADUALLY MOVING
TOWARD THE COASTAL COMMUNITIES.

.SHORT TERM FORECAST...
THE LOW AND ITS ASSOCIATED WARM FRONT WILL SLOWLY MOVE EASTWARD
THROUGH SATURDAY...WITH THE LOW CENTER REACHING THE KODIAK ISLAND
AREA BY SUNDAY MORNING. THE FRONT WILL SURGE EASTWARD AHEAD OF THE
LOW...SWINGING TOWARD THE GULF COAST TONIGHT AND FRIDAY. THIS FRONT
WILL NOT CONTINUE TO TRAVEL INLAND ALONG THE GULF COAST...THEREFORE
WHILE THOMPSON PASS WILL GET SOME SNOW AND SOME WIND...BLIZZARD
CONDITIONS ARE NOT EXPECTED. THE BEST CHANCE FOR SNOWFALL FOR THE
WESTERN KENAI PENINSULA...ANCHORAGE BOWL AND OTHER AREAS ON THE LEE
SIDE OF MOUNTAINS WILL BE AS THE FRONT MOVES THROUGH...WITH ANY
ACCUMULATION BEING LIGHT. THE HEAVIEST SNOWFALL WOULD BE ALONG THE
NORTH GULF COAST (WHERE PRECIPITATION TYPE IS SNOW).

SOUTHWEST MAINLAND AND BERING SEA/ALEUTIAN ISLANDS...
SNOW WILL GRADUALLY END TONIGHT ACROSS THE SOUTHWEST MAINLAND...WITH
THE EXCEPTION OF LOCATIONS EAST OF SLEETMUTE AND KING SALMON WHERE
SNOW WILL LINGER. THE LOW WILL CONTINUE EASTWARD AND BRING SHOWERS TO
THE ALEUTIANS AND ALASKA PENINSULA THROUGH THE WEEKEND.

.LONG TERM FORECAST...
SUNDAY AND BEYOND...THE REMNANTS OF THE LONGWAVE TROUGH WILL STILL BE
HANGING OVER SOUTHCENTRAL ALASKA...WITH AREAS OF SCATTERED SNOW
SHOWERS...MIXING WITH RAIN ALONG COASTAL AREAS. ONCE AGAIN...THE
GLOBAL MODELS ARE HAVING A DIFFICULT TIME HANDLING THE AMPLIFIED WAVE
PATTERN...WITH THE MAIN DISCREPANCIES REVOLVING AROUND THE POTENTIAL
FOR NUMEROUS CUTOFF LOWS AS THE EASTERN PACIFIC RIDGE BEGINS TO EXERT
A STRONGER INFLUENCE OVER MAINLAND ALASKA AND THE EASTERN BERING SEA.
RIGHT NOW...THERE IS HIGH CONFIDENCE THE UPPER LOW EXITS SOUTHERN
ALASKA BY LATE MONDAY...WITH HIGH PRESSURE LIKELY HOLDING STRONG OVER
MUCH OF MAINLAND ALASKA THROUGH MOST OF THE WEEK. ANY FRONTS WILL BE
WEAK AND LOW IMPACT...WITH THE MAIN STORM TRACK STAYING ACROSS THE
WESTERN BERING AND NORTH PACIFIC. TEMPERATURES WILL BE A BIGGER
CHALLENGE AS THE EXACT PLACEMENT OF THE BLOCK WILL DETERMINE WHETHER
OR NOT SOUTHERN ALASKA IS INFLUENCED BY NORTHERLY OFFSHORE FLOW AND
RETROGRADING EASTERLY WAVES...OR BY STABLE UPPER LEVEL HIGH PRESSURE.
HOWEVER...NO MAJOR COLD AIR ARCTIC OUTBREAKS SEEM EMINENT AT THIS
TIME AS THE MAIN COLD CENTERS DEVELOP OVER THE LOWER 48/CANADA AND
EASTERN ASIA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 120 125 129 130 172 175 176.
         HEAVY FREEZING SPRAY 179.
FIRE WEATHER...NONE.