Small Craft Advisory 600, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM ADT SUN JUL 9 2006

.DISCUSSION...

ALOFT...A WEAK OMEGA BLOCK HAS FORMED ACROSS THE FORECAST AREA THOUGH
IT WILL BE A TRANSIENT FEATURE WITH WEAKENING LOW IN THE EASTERN GULF
OF ALASKA AND UPPER HIGH OVER CENTRAL ALASKA. DOMINANT FEATURE THIS
WEEK IS THE UNSEASONABLY STRONG UPPER LOW CURRENTLY ABOUT 200 NM
SOUTH OF ATKA ON THE ALEUTIAN CHAIN IN THE LONG WAVE TROUGH NEAR THE
DATELINE. CURRENT 5-WAVE LOOKS LIKE THE HEMISPHERE WILL TRANSFORM
FROM AN UNSTABLE 3 WAVE TO A STABLE 4 WAVE BY THE END OF THE WEEK
WITH THE LONG WAVE TROUGH REMAINING ANCHORED JUST EAST OF THE
DATELINE.

SURFACE...SURFACE LOW ASSOCIATED WITH THE DEEP UPPER LOW IN THE NORTH
CENTRAL PACIFIC APPEARS WELL INITIALIZED IN LOCATION AND DEPTH AS
WELL AS THE FRONTAL SYSTEM. FOG AND LOW STRATUS STILL FAIRLY
WIDESPREAD AS THE MARINE LAYER ERODING SLOWLY. HOWEVER, POTENTIAL
ENERGY ALONG A THERMAL RIDGE THAT STRETCHES FROM SOUTHWEST ALASKA TO
NEAR CANTWELL AND THEN SOUTHEAST TOWARD THE WRANGELLS WILL HELP IN
DISSIPATING THE INTERIOR STRATUS THIS AFTERNOON AND EVENING AS
CONVECTION TURNS THE ATMOSPHERE OVER.

MODELS...MODELS IN EXCELLENT AGREEMENT THROUGH 24 HOURS AT SURFACE
AND ALOFT. HOWEVER MAJOR DIFFERENCES WITH UPSTREAM LOW IN THE WESTERN
BERING. THIS IS A CLEAR CASE WHERE THE MODEL OF CHOICE IS THE GFS AS
THE NAM ALMOST CERTAINLY CONTAMINATED BY BOUNDARY RELATED ISSUES
THAT. HOWEVER BOTH MODELS TRACK FAIRLY WELL THROUGH 66 HOURS WITH
FEATURES EAST OF THE DATELINE. EASTERN DOMAIN USING NAM. WESTERN
DOMAIN USING NAM THROUGH 36 HOURS OR SO AND GFS BEYOND.

CONVECTION...SHOULD BE A REALLY GOOD CONVECTION AFTERNOON AND EVENING
EAST OF THE ALASKA RANGE.  STRONGEST LIKELY OVER THE TALKEETNAS.
STRATUS IN COOK INLET BEGAN SHOWING CUMULOFORM SIGNS BEFORE NOON AND
TOWERING CUMULUS WERE EVIDENT IN THE NORTHWEST COPPER RIVER BASIN.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALES 132 150 155 165 170 172.
FIRE WEATHER...NONE.

CAS JUL 06