Small Craft Advisory 213, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AST WED FEB 28 2007

.DISCUSSION...

MODELS IN GENERALLY GOOD AGREEMENT BUT GFS PREFERRED WEST OF 160W
DUE TO ITS BETTER HANDLING OF LOW MOVING INTO WESTERN ALEUTIANS THIS
EVENING.

UPPER LEVEL PATTERN IS CHARACTERIZED BY A STRONG RIDGE POSITIONED
OVER THE NORTHERN AND EASTERN BERING SEA. THE RIDGE WEAKENS THROUGH
48 HOURS THEN REBUILDS BY 72 HOURS. OTHER NOTABLE FEATURES ALOFT
INCLUDE A TROF DIGGING INTO EASTERN INTERIOR AND YUKON TERRITORY. BY
48 HOURS THIS FEATURE IS PROGGED TO DEVELOP A CUT OFF LOW NEAR
YAKUTAT WHICH HOLDS THROUGH 72 HOURS AND BEYOND. ALSO BOTH GFS AND
UKMET RECOGNIZE A PERSISTENT CUT OFF LOW AT 500 MB JUST SOUTH OF THE
EASTERN ALEUTIANS AND A SECOND LOW ANCHORED OVER KAMCHATKA.

AT THE SURFACE...FORECAST PROBLEM OF THE DAY IS THE TIGHTENING
PRESSURE GRADIENT ALONG THE GULF COAST. HIGH PRESSURE OVER INTERIOR
ALASKA HOLDS THROUGH THE PERIOD. MEANWHILE COMPLEX LOW PRESSURE IN
THE GULF GRADUALLY STRENGTHENS. A WELL DEFINED 995 MB LOW IS
EXPECTED TO DEVELOP IN THE EASTERN GULF OF ALASKA THU AFTERNOON.
HOWEVER...MODELS CANT AGREE ON ITS EXACT LOCATION.

GUSTY WINDS THROUGH N-S CHANNELS SHOULD DEVELOP THIS MORNING. WIND
SPEEDS ARE EXPECTED TO REACH HWW CRITERIA AS EARLY AS THIS EVENING
IN AND NEAR VALDEZ. WIND CHILL ADVISORIES FOR THE SUSITNA VALLEY AND
COPPER RIVER BASIN GO INTO EFFECT LATE WEDNESDAY NIGHT.

OUT WEST...THE PRIMARY CONCERN WILL BE THE LOW MOVING INTO THE
WESTERN ALEUTIANS JUST WEST OF ADAK THIS EVENING. THE ASSOCIATED
OCCLUDED FRONT WILL PASS OVER THE CENTRAL AND EASTERN ALEUTIANS
TODAY AND REACH THE PRIBILOF ISLANDS AND ALASKA PENINSULA TONIGHT.
EXPECT GALE FORCE WINDS AND PERIODS OF MODERATE RAIN ALONG AND JUST
IN ADVANCE OF THE FRONT.

LOOKING BEYOND 72 HOURS...PERSISTENT HIGH PRESSURE BOTH ALOFT AND AT
SURFACE COUPLED WITH DROPPING THICKNESS VALUES OVER THE MAINLAND
WILL MAKE FOR AT LEAST ANOTHER WEEKS WORTH OF JANUARY LIKE
TEMPERATURES FOR SOUTHCENTRAL AND MAINLAND SOUTHWESTERN ALASKA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HWW 111 131 135
MARINE...GALES 120 121 125 130 138 140 141
               155 170 172 175 176 179 185
FIRE WEATHER...NONE.

ASB FEB 07