Small Craft Advisory 562, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM ADT FRI JUN 29 2007

.MODEL DISCUSSION...MODELS IN GOOD AGREEMENT TODAY. GFS WAS THE MODEL
OF CHOICE FOR THE AFTERNOON PACKAGES TO MAINTAIN CONTINUITY IN THE
DETAILS. GFS ITSELF IS HOLDING TOGETHER WELL WITH THE ENSEMBLE
REMAINING FAIRLY TIGHT THROUGH 84 HOURS.

.ANALYSIS AND UPPER LEVELS...AN UPPER LEVEL RIDGE REMAINS OVER THE
MAINLAND PART OF THE STATE TODAY. THIS RIDGE WILL RECEDE A LITTLE TO
THE NORTH THIS WEEKEND AS AN EASTERLY WAVE MOVES OVER THE COPPER
RIVER BASIN AND INTO SOUTHCENTRAL ALASKA. CONVECTIVE ACTIVITY LOOKS
FAVORABLE TODAY IN THE WESTERN COPPER RIVER BASIN AND SUSITNA VALLEY.
THE ATMOSPHERE BECOMES MORE STABLE OVER THE WEEKEND.

IN THE WEST AN UPPER LOW OVER THE NORTHERN BERING SEA WILL WEAKEN AND
MOVE SOUTH OF THE ALASKA PENINSULA BY SUNDAY AFTERNOON.

THE JET STREAM COMES OFF OF NORTHERN JAPAN AND THEN REACHES INTO THE
DUTCH HARBOR AREA BEFORE BENDING SOUTHEAST AND OUT OF THE AREA BY THE
TIME IT GETS TO COLD BAY. IT
IS VISIBLE ON THE IR SATELLITE RIDING OVER THE TOP OF THE LARGE RIDGE
IN THE NORTH CENTRAL PACIFIC. THE JET STREAM WILL FLATTEN OUT OVER
THE TOP OF THE RIDGE TONIGHT AND WEAKEN. IT WILL THEN INCREASE FROM
THE NORTH OVER THE CENTRAL ALEUTIAN ISLANDS EARLY NEXT WEEK AS THE
RIDGE PUSHES INTO THE WESTERN ALEUTIANS. THIS WILL ALSO HELP TO SPIN
UP A LOW IN THE NORTH PACIFIC AT THAT TIME...HOWEVER THIS LOW WILL
REMAIN WELL SOUTH OF THE FORECAST AREA UNTIL TUESDAY AT THE EARLIEST.

.SHORT TERM FORECAST...THE BIGGEST UNCERTAINTY IN THE SHORT TERM IN
IN RELATION TO THE EASTERLY WAVE IN THE COPPER RIVER BASIN. THE CLOUD
COVER ASSOCIATED WITH IT MAY KEEP THUNDERSTORMS FROM DEVELOPING THE
THE EASTERN PART OF THAT AREA TODAY BUT THE WESTERN PART IS GETTING A
BIT OF SOLAR HEATING SO THUNDERSTORMS SEEM MORE LIKELY THERE AS THE
WAVE PROPAGATES WESTWARD. IT ALSO HAS THE CHANCE OF BRINGING SOME
SHOWERS INTO THE SUSITNA VALLEY THROUGH KENAI PENINSULA OVER THE
WEEKEND.

.LONG TERM FORECAST...THE RIDGE IN THE NORTH CENTRAL PACIFIC WILL
BUILD INTO THE WESTERN BERING SEA LATE IN THE WEEKEND AND POKE INTO
SOUTHWEST ALASKA BY MONDAY. EASTERLY WAVES WILL BRING A CHANCE OF
PRECIPITATION OVER SOUTH CENTRAL ALASKA THROUGH THEN WEEKEND. CLOUDS
SHOULD DECREASE SOME EARLY NEXT WEEK AS THE UPPER LEVEL RIDGE
BUILDING IN THE BERING SEA MOVES OVER SOUTHWEST ALASKA. CONVECTION IS
POSSIBLE EARLY NEXT WEEK AS A THERMAL TROUGH MOVES INTO SOUTH CENTRAL
ALASKA AND THE ATMOSPHERE BECOMES MORE UNSTABLE.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.

JUN 07