Small Craft Advisory 628, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
150 PM ADT WED JUL 19 2006

.DISCUSSION...
GFS AND NAM COMING UP WITH DIFFERENT SOLUTIONS FOR DEEPENING LOW IN
THE SOUTHWESTERN GULF. THIS HAS BEEN A COMMON THEME WITH ONE LOW
HOLDING BACK THE CENTER OF CIRCULATION FURTHER WEST WITH EVERY RUN.
THE MORE WESTERLY POSITION IS VERIFYING SO WILL CONTINUE TO BASE THE
FORECAST OFF OF THE WESTERLY TRACK WHICH IN THIS CASE IS THE GFS.

UPPER LEVELS...THE AFOREMENTIONED LOW ENTERING THE SOUTHWESTERN GULF
IS A MATURE LOW THIS AFTERNOON. A STRONG JET MAX IS FLOWING AROUND
THE EASTERN PERIPHERY OF THE LOW AND WILL BEGIN TO WEAKEN AS IT MOVES
FURTHER AWAY FROM THE CENTER OF CIRCULATION. THE LONG WAVE TROUGH
WILL REMAIN NEARLY STATIONARY THROUGH THE WEEKEND BEFORE THE EXTENDED
GFS TAKES THE TROUGH WEST TOWARD THE ALASKA PENINSULA. AN UPPER RIDGE
IS POSITIONED OVER THE WESTERN ALEUTIANS AND WILL SHIFT EASTWARD TO
THE EASTERN BERING SEA BY SATURDAY WITH ANOTHER TROUGH FOLLOWING
CLOSE BEHIND. INLAND...HIGH PRESSURE ALOFT WILL BRIDGE ACROSS THE
REGION FROM BOTH THE EAST AND WEST AND HELP SETUP A THERMAL TROUGH AT
THE SURFACE THROUGH THE WEEKEND.

SOUTHCENTRAL SURFACE...DEALING WITH TWO FRONTAL BOUNDARIES ACROSS OUR
FORECAST DOMAIN INCLUDING ONE ENCROACHING ON THE GULF OF ALASKA.
PLENTY OF GALES OVER THE COASTAL WATERS AHEAD OF THE BOUNDARY
INCLUDING SHELIKOF STRAIT. INLAND...SEEING SOME VERY PLEASANT WEATHER
TODAY WITH HIGH PRESSURE WELL AHEAD OF THE FRONT. ISOLATED SHOWERS
WILL BE LIMITED TO THE MOUNTAINS THIS AFTERNOON AND THEN BECOMING
MOSTLY CLEAR OVERNIGHT. AS THE FRONT APPROACHES THURSDAY EXPECT TO
SEE THE GAP WINDS INCREASE AND CLOUDS INVADING THE COPPER RIVER
BASIN...WESTERN KENAI...ANCHORAGE BOWL...AND MATSU VALLEY BY THURSDAY
AFTERNOON AND THEN SPREADING NORTH INTO THE SUSITNA VALLEY BY
THURSDAY EVENING. THE SURFACE LOW WILL DRIFT NORTH BUT STILL REMAIN
SOUTH OF KODIAK ISLAND THROUGH THE WEEKEND AS THE FRONT DISSIPATES
ACROSS SOUTHCENTRAL. WITH THE INCREASED MOISTURE FROM THE DISSIPATING
FRONT AND THERMAL SURFACE TROUGH INLAND...WILL SEE SOME ISOLATED
THUNDERSTORMS AS EARLY AS THURSDAY EVENING OVER THE COPPER RIVER
BASIN AND NORTHERN SUSITNA VALLEY...THEN DEVELOP AGAIN FRIDAY
AFTERNOON AND EVENING.

SOUTHWEST SURFACE...GAP WINDS AND ISOLATED SHOWERS LIMITED TO THE
MOUNTAINS THIS EVENING AND THEN CLEARING SKIES OVERNIGHT. PATCHY FOG
WILL DEVELOP ALONG THE COAST IN ZONE 161 AS MARINE LAYER MOVES
FURTHER INLAND. ELSEWHERE OFFSHORE FLOW AND SUFFICIENT LOW LEVEL
MIXING WILL KEEP FOG FROM DEVELOPING. FRONTAL BOUNDARY MOVING IN TO
SOUTHCENTRAL WILL HAVE A HARD TIME MOVING ACROSS THE ALASKA RANGE BUT
WILL SEE AN INCREASE IN MID AND UPPER LEVEL CLOUDS STREAMING
NORTHWARD ACROSS THE ALEUTIAN AND ALASKA RANGES. SURFACE THERMAL
TROUGH COUPLED WITH INCREASED MID LEVEL MOISTURE WILL BE ENOUGH TO
INITIATE ISOLATED THUNDERSTORMS OVER THE KUSKOKWIM VALLEY THURSDAY
AND FRIDAY AFTERNOON AND EARLY EVENING.

OUT WEST...RIDGE AXIS CURRENTLY LOCATED OVER THE CENTRAL ALEUTIANS
AND WILL SHIFT SLOWLY EAST TOWARD THE EASTERN ALEUTIANS BY FRIDAY. TO
THE EAST OF THE RIDGE IS SOME MODERATE COLD AIR ADVECTION WITH GUSTY
NORTHWESTERLY WINDS OVER THE EASTERN BERING SEA AND ACROSS THE ALASKA
PENINSULA. TO THE WEST IS A DEVELOPING FRONTAL BOUNDARY BRINGING MORE
GALES FRIDAY EVENING TO THE WESTERN ALEUTIANS COASTAL WATERS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 120 130 132 138 150 155
FIRE WEATHER...NONE

AB JUL 06