Small Craft Advisory 597, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTH CENTRAL AND SOUTHWEST ALASKA
200 PM ADT FRI JUL 20 2007

.MODEL DISCUSSION...
THE MODELS DIFFER SIGNIFICANTLY ON A DEVELOPING LOW SOUTH AND WEST OF
THE ALEUTIANS. THE GFS HAS BEEN CONSISTENT WHEREAS THE NAM SEEMS TO
HAVE INITIALIZATION AND BOUNDARY PROBLEMS OUT WEST. THE MODELS ARE IN
GENERAL AGREEMENT OVER MAINLAND ALASKA THROUGH 42 HOURS WITH THE NAM
SHOWING BETTER DETAIL. WE WENT WITH THE NAM IN THE SHORT RANGE EAST
OF 170W AND THE GFS BEYOND 42 HOURS AND FOR THE DEVELOPING LOW
SOUTHWEST OF THE ALEUTIANS.

.ANALYSIS AND UPPER LEVELS...
A CUTOFF UPPER LOW IS CENTERED OVER THE BERING STRAIT. A TROUGH
EXTENDS FROM THIS LOW OVER KODIAK ISLAND AND INTO THE GULF OF ALASKA.
THE BERING STRAIT LOW WILL MOVE SLOWLY SOUTH TO THE KUSKOKWIM DELTA
BY SAT NIGHT THEN REMAIN STATIONARY OVER THE DELTA INTO EARLY NEXT
WEEK.  WEAK AREAS OF HIGH PRESSURE ALOFT WILL REMAIN STATIONARY OVER
THE WESTERN BERING AND OVER THE ALASKA CANADA BORDER THROUGH THE
WEEKEND. A WEAK SURFACE THERMAL TROUGH COVERS THE CENTRAL INTERIOR.
A LARGE WEAK AREA OF LOW PRESSURE PERSISTS SOUTH OF THE GULF ALONG
50N.  A WEAK SURFACE LOW IS NEAR SAINT LAWRENCE ISLAND UNDER THE
UPPER LOW. A WEAK RIDGE OF HIGH PRESSURE EXTENDS ACROSS THE ALEUTIANS
TO THE ALASKA PENINSULA. A DEVELOPING LOW IS SOUTHWEST OF THE
ALEUTIANS.

.SHORT TERM FORECAST...

BERING SEA...HIGH PRESSURE WILL WEAKEN OVER THE BERING SEA THROUGH
THE WEEKEND.  WIDESPREAD STRATUS AND FOG WILL PERSIST OVER THE
BERING. SHOWERS WILL CONTINUE OVER THE EASTERN BERING NEAR THE UPPER
LOW INTO NEXT WEEK.

SOUTHWEST ALASKA...FORECAST WILL BE DOMINATED THROUGH MID WEEK BY THE
LOW DROPPING SOUTH FROM THE BERING STRAIT TONIGHT AND SAT. ZONES 155
AND 161 WILL SEE AN INCREASE IN SHOWERS SATURDAY AFTERNOON AND SUNDAY
MORNING AS STRONGEST SHORT WAVE ROTATES AROUND BASE OF UPPER LOW. THE
UPPER LOW WILL STALL OVER THE DELTA SUN THROUGH TUE AND CONTINUE
SHOWERS FOR MOST OF SOUTHWEST ALASKA.

SOUTH AND EAST OF THE AK RANGE...PARTLY CLOUDY SKIES WITH SUNNY
BREAKS ARE FORECAST FOR SOUTH CENTRAL.  A FEW SHOWERS AND ISOLATED
THUNDERSTORMS ARE EXPECTED OVER THE COPPER RIVER BASIN THE TALKEETNA
MOUNTAINS AND NEAR THE ALASKA RANGE OVER THE NORTHERN SUSITNA VALLEY
OVER THE WEEKEND AND INTO NEXT WEEK.

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

RHH JUL 07