Small Craft Advisory 181, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
1200 PM AKST TUE MAR 8 2011

.ANALYSIS AND UPPER LEVELS...A CLOSED UPPER LEVEL BLOCKING RIDGE
IS PARKED NEAR THE BERING STRAIT WITH CLOSED LOWS SOUTH OF THE
GULF AND OVER THE FAR NORTHWEST PACIFIC. WATER VAPOR IMAGERY
SHOWS A SHORT-WAVE MOVING ACROSS THE SOUTHERN MAINLAND AS IT
MAKES ITS WAY AROUND THE HIGH. THIS IS CONTRIBUTING TO SOME
LOCALIZED GUSTY WINDS...ESPECIALLY THROUGH MOUNTAIN GAPS IN
SOUTHCENTRAL WHERE THE PRESSURE GRADIENT IS RELATIVELY TIGHT
(SUCH AS THROUGH THE MATANUSKA VALLEY). ASIDE FROM THESE WINDS
CONDITIONS ACROSS MOST OF ALASKA ARE QUITE BENIGN. CONDITIONS ARE
HEADED DOWNHILL ALONG THE FAR WESTERN ALEUTIANS WITH A DEEP LOW
BOTTOMING OUT AROUND 965 MB SOUTH OF THE KAMCHATKA PENINSULA.
THE FRONTAL SYSTEM WITH THIS LOW IS HEADED NORTH AND EAST TOWARD
THE ALEUTIANS.

.MODEL DISCUSSION...THERE ARE SOME MINOR DIFFERENCES WITH TRACK
OF LOWS FROM THE NORTHWEST PACIFIC TO THE ALEUTIANS THE NEXT FEW
DAYS...BUT ALL SOLUTIONS ARE GROUPED IN THE SAME GENERAL VICINITY.
WILL TREND HEAVILY TOWARD THESE LATEST GROUPINGS...WHICH FOR SOME
MODELS ARE QUITE A BIT DIFFERENT THAN PREVIOUS RUNS.

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...GAP WINDS WILL DIMINISH A BIT THIS AFTERNOON
AND EVENING AS THE SHORT-WAVE MOVES SOUTH AND WEST OF THE AREAS AND
THE SURFACE PRESSURE GRADIENT LOOSENS. HOWEVER...ANOTHER SHORT-WAVE
WILL DROP ACROSS THE YUKON TONIGHT THEN ACROSS THE EASTERN COPPER
RIVER BASIN SOUTHWARD TO THE GULF ON WEDNESDAY. ARCTIC AIR WILL
ACCOMPANY THE UPPER WAVE RESULTING IN COLD ADVECTION ACROSS
SOUTHCENTRAL...STRONGEST FROM THE COPPER BASIN TO PRINCE WILLIAM
SOUND. THE PRESSURE GRADIENT WILL ALSO TIGHTEN AS A SURFACE HIGH
OVER THE ARCTIC MOVES SOUTHWARD TO INTERIOR ALASKA AND CANADA.
THIS WILL ALL CULMINATE IN AREAS OF STRONG WINDS ESPECIALLY THROUGH
THE MATANUSKA VALLEY AND FROM THOMPSON PASS DOWN INTO VALDEZ.
WINDS WILL THEN GRADUALLY DIMINISH AS WE HEAD TO THURSDAY. UNDER
THE INFLUENCE OF THE BLOCKING HIGH TO THE NORTH DRY CONDITIONS
WITH SEASONABLE TEMPERATURES WILL PERSIST ACROSS SOUTHCENTRAL
ALASKA.

SOUTHWEST ALASKA/EASTERN BERING SEA...UPPER HIGH WILL SHIFT
A LITTLE SOUTH AND EAST THE NEXT FEW DAYS INTO WESTERN
ALASKA...ENSURING MORE SUNNY DAYS WITH TEMPERATURES NEAR
TO SLIGHTLY BELOW NORMAL.

WESTERN BERING SEA/ALEUTIANS...A SERIES OF LOWS WILL DEVELOP OVER
THE NORTH PACIFIC ALONG THE UPPER JET SOUTH OF THE UPPER CENTER
NEAR THE KAMCHATKA PENINSULA. INITIALLY THESE LOWS WILL CURVE
NORTHWARD TOWARD THE ALEUTIANS...BUT OVER TIME THE TROUGH WILL
DIG EASTWARD AND STORMS WILL TAKE MORE OF AN EAST-WEST TRACK
SOUTH OF THE ALEUTIAN CHAIN. MOST OF THE AFFECTS OF THESE SYSTEMS
WILL BE CONFINED TO THE CENTRAL TO WESTERN BERING SEA AND ALEUTIANS
AS THE BLOCKING HIGH KEEPS SYSTEMS FROM MOVING INTO THE EASTERN
BERING.

.LONG TERM FORECAST...CONDITIONS WILL REMAIN VERY QUIET ACROSS MOST
OF ALASKA AS WE HEAD INTO EARLY NEXT WEEK. MEDIUM RANGE MODELS SHOW
THE BLOCKING RIDGE BEGINNING TO WEAKEN ABOUT THAT TIME...BUT STILL
HOLDING OFF ANY MAJOR PATTERN CHANGE. THE STORM TRACK WILL REMAIN
PRIMARILY OVER THE NORTH PACIFIC WITH THE ALEUTIANS RIGHT ALONG
THE PERIPHERY OF THESE SYSTEMS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE WARNING...127 132 172 175 176.
FIRE WEATHER...NONE.

SEB MAR 11