Small Craft Advisory 832, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM ADT WED SEP 13 2006

.DISCUSSION...

ANALYSIS...THE TRANSITION BETWEEN UPPER LEVEL LONGWAVE PATTERNS CONTINUES AS
THE ARCTIC VORTEX BELOW THE POLE THAT HAS GRAVITATED BETWEEN SIBERIA AND THE
NORTH COAST OF ALASKA GIVES WAY TO AMPLIFICATION OF THE WESTERLIES AND AN OMEGA
PATTERN OVER ALASKA AND THE YUKON.  A LARGE HIGH PRESSURE SYSTEM STRETCHING
FROM THE ARCTIC OCEAN SOUTH TO THE GULF OF ALASKA CONTINUES TO BUILD INTO
MAINLAND ALASKA.  AN UPPER TROUGH OVER EASTERN RUSSIA AND ANOTHER OVER WESTERN
CANADA ROUND OUT THE OMEGA PATTERN.

MAIN CHANGE TO THE FORECAST IS A TREND TOWARDS A DRIER END OF THE WEEK FOR
SOUTHCENTRAL ALASKA ALONG WITH STRONG SOUTHEAST WINDS IN THE TURNAGAIN ARM AREA
AHEAD OF AN APPROACHING SYSTEM.

MODEL ANALYSIS...IN THE SHORT TERM THE MODELS ARE FAIRLY CONSISTENT WITH MOVING
THE 985MB LOW NOW SITUATED WELL SOUTH OF THE ALEUTIANS NORTH TO THE BRISTOL BAY
AREA BY THURSDAY MIDDAY.  AFTER THIS POINT THOUGH THE MODELS HAVE VERY POOR RUN
TO RUN CONSISTENCY AND THUS HAVE LOW CONFIDENCE IN THE EXTENDED PERIOD FORECAST
AS THE NORTHERN GULF LOW STARTS TO IMPACT SOUTHCENTRAL WEATHER.  THE GFS BIAS
OF UNDERDOING THE NORTH GULF COAST RIDGE AHEAD OF THE APPROACHING FRONT SHOULD
TRANSLATE INTO MOST OF THE PRECIPITATION BEING CONFINDED TO KODIAK ISLAND AND
THE SOUTHERN KENAI PENINSULA THURSDAY EVENING AND FRIDAY...THE PRESSURE
GRADIENT WILL BE STRONG ENOUGH TO PRODUCE HIGH WINDS IN THE TYPICAL SOUTHEAST
FLOW SUSCEPTIBLE AREAS.

SHORT TERM FORECAST...ANOTHER SUNNY AND DRY DAY ON TAP FOR SOUTHCENTRAL ALASKA.
 FOG IS BEING REPORTED IN A FEW LOCALES ON THE KENAI PENINSULA AND IN A BROAD
REGION CENTERED AROUND THE Y-K DELTA AS THE CLEAR SKIES AND CALM WINDS ALLOW
FOR NEAR IDEAL RADIATIONAL COOLING.  THE DECOUPLED ATMOSPHERE WILL QUICKLY
REBOUND THIS MORNING ALLOWING TEMPERATURES TO AGAIN CLIMB TO THE LOWER 60S THIS
AFTERNOON FOR MUCH OF SOUTHERN MAINLAND ALASKA.  OUT WEST FOG AND STRATUS
DOMINATE MUCH OF THE ALEUTIANS AND THE PRIBLOFS AS WELL AS THE SOUTHERN WEST
COAST.  SOUTHWESTERLY WINDS ALONG THE WEST COAST AND AKPENN WILL GIVE WAY TO A
RAIN BY THIS EVENING IN ADVANCE OF THE APPROACHING LOW.

EXTENDED FORECAST...NOT HAVING MUCH CONFIDENCE IN ANY OF THE MODELS...HAVE
LEANED TOWARDS THE GFS SOLUTION GIVEN ITS RECENT PERFORMANCE...DESPITE ITS POOR
RUN TO RUN CONSISTENCY. THE LOW WILL BRING BACK CLOUDS AND WIND THIS WEEKEND
FOR SOUTHERN ALASKA.  OUT WEST THE NAM AND GFS ARE JUST BEGINNING TO PICK UP ON
A LOW RUNNING SOUTH OF THE ALEUTIANS LATER THIS WEEKEND AND HAVE NUDGED THE
FORECAST A LITTLE THAT WAY ACKNOWLEDGING THE STARK NWP DEVIATION FROM PREVIOUS
RUNS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...FLOOD ADVISORY 141
MARINE...GALE 130 132 138 150 155 160 165 170 185
FIRE WEATHER...NONE

SDM 06