Small Craft Advisory 741, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM ADT THU SEP 15 2005

.DISCUSSION...
A STRONG 975 MB LOW IS SITTING DIRECTLY OVER ST MATTHEW ISLAND THIS
AFTERNOON. THIS LOW AND ITS WEATHER FRONT ARE RESPONSIBLE FOR MOST OF
THE WEATHER OVER THE STATE TODAY. THE MAIN FRONT IS STRETCHED OUT OF
THE LOW INTO THE KUSKOKWIM VALLEY AND THEN DOWN TOWARD COOK INLET AND
KODIAK ISLAND. THE TRIPLE POINT THAT HAS BEEN MENTIONED IN PREVIOUS
DISCUSSIONS CAN BE SEEN NEAR KODIAK AS AN INFLECTION POINT ALONG THE
FRONT. THIS TRIPLE POINT LOW APPEARS TO BE HEADING TOWARD THE SEWARD
AREA AND THEN WILL WEAKEN AS IT JUMPS THE KENAI MOUNTAINS AND GOES
INTO NORTHERN COOK INLET OVERNIGHT. AREAS IN SOUTH CENTRAL ALASKA
WILL SEE PRECIPITATION AND GUSTY WINDS UNTIL THIS POINT MOVES THROUGH
THE AREA.
THE MAIN FRONT HAS BEEN MOVING EASTWARD AT A RAPID PACE BUT THAT IS
EXPECTED TO SLOW AS IT RUNS INTO A RIDGE IN THE EASTERN GULF OF
ALASKA.
THE PARENT LOW OVER ST MATTHEW ISLAND IS IN NO HURRY TO MOVE AND WILL
SLOWLY WEAKEN AND MOVE TOWARD NORTON SOUND THIS WEEKEND.

IN THE UPPER LEVELS...THE JET STREAM IS READILY VISIBLE SOUTH OF THE
ALEUTIAN ISLANDS ON THE IR SATELLITE PICTURE. AT 250 MB THIS JET IS
PUSHING 150 KNOTS IN WIND SPEED AN WILL BE THE CATALYST FOR THE RAPID
DEVELOPMENT AND MOVEMENT OF THE NEXT LOW THAT WILL MOVE INTO THE
AREA. A 1000 MB LOW THAT IS SOUTH OF ATTU WILL DEVELOP ALONG THIS JET
AND MOVE SOUTHWEST OF DUTCH HARBOR FRIDAY AFTERNOON. THIS LOW WILL
JUST SLIGHTLY STRENGTHEN TO 997 MB FRIDAY BUT THEN RAPIDLY DEEPEN
AFTER THAT DROPPING ABOUT 15 MB BY SATURDAY MORNING AS IT MOVES INTO
THE WESTERN GULF OF ALASKA.

ANOTHER SITUATION TO WATCH IS THE STORM SURGE THAT IS BUILDING UP
AROUND THE ST MATTHEW ISLAND LOW. THE LARGEST SURGE IN THE ANCHORAGE
FORECAST AREA WILL BE AROUND HOOPER BAY. WE ARE EXPECTING ABOUT 2
FEET ABOVE SPRING TIDES WITH TONIGHTS HIGH TIDE. LARGER VALUES ARE
LIKELY IN NORTON SOUND WHERE THE SURGE MAY BE 4 FEET ABOVE SPRING
TIDES.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALES 120 130 132 179 180 185.
FIRE WEATHER...NONE.

EZ SEP 05