Small Craft Advisory 434, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
205 PM AKDT SAT MAY 31 2014

ANALYSIS AND UPPER LEVELS...THE MAIN FEATURE IS THE LARGE UPPER
COLD CORE LOW NOW OVER THE KUSKOKWIM DELTA COAST WITH A TROUGH
EXTENDING EAST ACROSS SOUTH CENTRAL ALASKA. AT THE SURFACE THE
MAIN LOW PRESSURE SYSTEM IS OVER THE INTERIOR WITH A TROUGH TO
ANOTHER LOW INLAND OF THE SEWARD PENINSULA AND ANOTHER LOW OVER
THE NORTHERN COOK INLET REGION. A FRONT EXTENDS FROM THE COOK
INLET LOW ACROSS PRINCE WILLIAM SOUND TO THE COAST OF SOUTHEAST
ALASKA. THE FREEZING LEVELS WITH THIS SYSTEM HAVE DROPPED TO
AROUND 1500 FEET ACROSS THE SOUTH CENTRAL AREA RESULTING IN SNOW
OVER THE MOUNTAINS. PRESSURE RISES BEHIND THE FRONT THAT MOVED
ACROSS SOUTH CENTRAL ALASKA ARE PRODUCING STRONG GUSTY SOUTH WIND
UP COOK INLET INTO THE MATANUSKA AND SUSITNA VALLEYS AND ALONG
COOK INLET. A WEAK LOW IS SOUTH OF THE EASTERN ALEUTIANS THAT IS
MOVING EAST AS IT DISSIPATES. HIGH PRESSURE EXTENDS FROM THE NORTH
PACIFIC INTO THE CENTRAL BERING SEA BEHIND THE LOW PRESSURE SYSTEM
AND A FLAT RIDGE OF HIGH PRESSURE IS ACROSS THE GULF OF ALASKA.

MODEL DISCUSSION...
THE MODELS INITIALIZED WELL AND ARE IN GENERALLY GOOD AGREEMENT.
BY ABOUT SUN AFTERNOON THE NAM BECOMES A BIT OF AN OUTLIER AS IT
PLACES AN UPPER LOW FURTHER SOUTHWEST THAN THE GFS ECMWF UKMET AND
CANADIAN REGIONAL MODEL. AT THE SURFACE ALL THE MODELS AGREE ON A
TROUGH EXTENDING DOWN INTO COOK INLET SUNDAY. THE SURFACE AND
UPPER TROUGH DIGS SOUTH INTO THE GULF OF ALASKA THROUGH MON. THE
HIGH OVER THE BERING SEA MOVES ACROSS TO THE ALASKA PENINSULA SUN
NIGHT. THE CANADIAN REGIONAL AND ECMWF CONTINUE TO BE THE MOST
CONSISTENT AND BOTH HAVE REASONABLE SOLUTIONS...SO THEY ARE THE
PREFERRED MODELS ONCE AGAIN.

SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
AS THE FRONT AND LOW CONTINUE TO MOVE INLAND AND PRESSURES RISE
BEHIND THE FRONT STRONG GUSTY SOUTH WIND WILL CONTINUE INTO THE
EVENING HOURS ALONG COOK INLET INTO THE MATANUSKA AND SUSITNA
VALLEYS. HIGH PRESSURE BUILDING INTO THE GULF OF ALASKA COUPLED
WITH THE LOW OVER THE INTERIOR WILL ALSO KEEP THE STRONG SOUTH
WIND BLOWING ACROSS THE CHUGACH MOUNTAINS UP THE COPPER RIVER
VALLEY TONIGHT. A WEAK SURFACE LOW MOVES INTO THE KODIAK AREA
OVERNIGHT TONIGHT AND THIS SHOULD RELAX THE GRADIENT RESULTING IN
THE WIND DIMINISHING OVERNIGHT TONIGHT. SHOWERS WILL PERSIST
ACROSS THE SOUTH CENTRAL REGION IN THE RESIDUAL SOUTHWEST FLOW.
SNOW WILL LIKELY OCCUR AT THE HIGHER ELEVATIONS IN THESE SHOWERS
ABOVE 2000 FEET. THE TEMPERATURES WILL REMAIN BELOW NORMAL FOR A
FEW DAYS...BUT WILL RETURN TO NORMAL OR EVEN SLIGHTLY ABOVE NORMAL
BY THE MIDDLE TO LATTER PART OF THE WEEK.

SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...
THE BELOW NORMAL TEMPERATURES WILL PERSIST THROUGH SUNDAY ALLOWING
FOR SNOW ALONG THE ALASKA RANGE IN THE SHOWERY WEATHER ASSOCIATED
WITH THE SURFACE AND UPPER LEVEL LOW. THE TROUGH WILL PASS TO THE
NORTH AND EAST AND THE HIGH OVER THE BERING WILL BUILD IN FROM THE
WEST. THIS WILL REDUCE THE COVERAGE OF THE SHOWERS SIGNIFICANTLY
AND TEMPERATURES WILL RETURN TO NORMAL TO SLIGHTLY ABOVE NORMAL BY
MID WEEK.

THE HIGH PRESSURE OVER THE ALEUTIANS AND BERING SEA WILL RESULT IN
A CONTINUATION OF RELATIVELY BENIGN CONDITIONS. THE PRIBILOFS
COULD SEE SOME SHOWERS ON SUNDAY AS A SHORTWAVE TROUGH PASSES BY
THE NORTHERN HALF OF THE BERING SEA SUNDAY AFTERNOON AND EVENING.

LONG TERM FORECAST...
HIGH PRESSURE WILL BUILD OVER THE MAINLAND THROUGH THE WEEK
USHERING IN DRIER WARMER CONDITIONS. A LOW WILL COME UP OUT OF THE
NORTH PACIFIC TO SOUTH OF THE CENTRAL ALEUTIANS WED RESULTING IN
INCREASED EAST WIND AND A CHANCE FOR RAIN FROM THE ALASKA
PENINSULA WEST ACROSS THE ALEUTIANS THOUGH THE WIND WILL LIKELY
REMAIN BELOW GALE FORCE.

AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALES 139 140.
FIRE WEATHER...NONE.

MAY 14