Small Craft Advisory 202, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
300 PM AKST SAT JAN 31 2009

.MODEL DISCUSSION...MODELS ARE DOING WELL WITH THE OVERALL PATTERN
THROUGH TUESDAY. THE BIGGEST ITEM TO WATCH IS THE LOW MOVING INTO THE
GULF OVERNIGHT THROUGH SUNDAY NIGHT. IT ELONGATES AS THE TRIPLE POINT
DEVELOPS AHEAD OF THE MAIN LOW AND THERE IS SOME DISAGREEMENT AS TO
HOW THIS WILL DEVELOP. THE GFS BRINGS THE MAIN LOW NEAR YAKUTAT
SUNDAY NIGHT AFTER WEAKENING THE TRIPLE TO A TROUGH ALONG THE NORTH
GULF COAST. THE NAM ECMWF AND UKMET ALL FAVOR SPLITTING THE ENERGY
WITH THE TRIPLE POINT REMAINING A DISTINCT LOW ALONG THE NORTH GULF
COAST. THIS NAM ECMWF UKMET SOLUTION LOOKS BETTER NOT ONLY DUE TO THE
AGREEMENT OF THREE MODELS BUT DUE TO THE IMPACT OF THE VERY COLD AIR
TO THE WEST. THIS PATTERN TENDS TO STRENGTHEN LOWS ALONG THE NORTH
GULF COAST AND DOWNPLAYING IT AS THE GFS DOES IS NOT AS LIKELY.

.ANALYSIS AND UPPER LEVELS...A COLD UPPER LEVEL TROUGH EXTENDING FROM
THE NORTHERN YUKON TERRITORY THROUGH THE EASTERN ALEUTIANS IS FORCING
THE JET STREAM SOUTH OF MOST OF THE AREA. THE 250 MB JET IS NORTHWEST
OVER THE WESTERN ALEUTIANS AND THEN CONTINUES UNTIL NEAR 35N 165W
WHEN IT TURNS SHARPLY TO THE SOUTHWEST AND THEN CLIPS THE SOUTHEAST
GULF. THE JET WILL AMPLIFY AS THE TROUGH REMAINS DEEPLY DUG TO THE
SOUTH AND THEN WILL FORM A CUT OFF LOW WELL SOUTH OF ALASKA ON
TUESDAY. THE SURFACE FEATURE ASSOCIATED WITH THIS UPPER LOW IS A LOW
SOUTH WEST OF KODIAK ISLANDS THAT WILL BE ELONGATING ALONG A TRIPLE
POINT AND MOVING INTO THE GULF OVERNIGHT.
FARTHER WEST THERE IS A STRONG LOW DEVELOPING SOUTH OF THE KAMCHATKA
PENINSULA THAT IS EXPECTED TO DEEPEN INTO THE 940S AS IT MOVES NEAR
THE SOUTHWESTERN BERING SEA MONDAY.

.SHORT TERM FORECAST...WITH THE MAJORITY OF THE WEATHER SYSTEMS SOUTH
OF THE AREA THE BIG CONCERN TURNS TO THE POSSIBILITY OF FOG AND LOW
STRATUS. THE BERING SEA IS MOSTLY COVERED WITH STRATUS THAT IS
PUSHING ONTO THE ALASKA PENINSULA AND ALEUTIANS ISLANDS BRINGING SOME
LIGHT SNOW TO THESE AREAS. THERE IS AN OPEN AREA NEAR ST PAUL ISLAND
DUE TO THE NEARBY ICE EDGE.
THE COOK INLET AREA MAY ALSO SEE SOME STRATUS OR FOG OVERNIGHT. THE
FOG THAT DEVELOPED SATURDAY MORNING WAS NOT ABLE TO GET A FIRM HOLD
AS IT PRECIPITATED OUT IN FLURRIES AND LIGHT SNOWFALL WHERE IT
DEVELOPED. THIS WILL PROBABLY CONTINUE OVERNIGHT.

.LONG TERM FORECAST...LONG TERM WILL SEE THE UPPER LEVEL TROUGH
RETROGRADE TO WESTERN ALASKA WHICH WILL CONTINUE TO BRING STORMS INTO
THE BERING SEA AND SOUTHWEST ALASKA. AS THE FRONTS ASSOCIATED WITH
THESE LOWS MOVE TOWARD KODIAK ISLAND THEY WILL MOST LIKELY DEVELOP
TRIPLE POINTS ALONG THEM WHICH WILL DIVERT MOST OF THE WARMER AIR
FROM PRINCE WILLIAM SOUND EASTWARD FROM THE MIDDLE TO LATER PARTS OF
NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 120 130 132 155 172 175
    STORM 176
    HEAVY FREEZING SPRAY 121 129 130 138 140 141 150 155 160 165 179
FIRE WEATHER...NONE.

JAN 09