Small Craft Advisory 701, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
300 PM ADT THU AUG 30 2007

.MODEL DISCUSSION...MODELS BEGIN IN GOOD AGREEMENT BUT BEGIN TO
SIGNIFICANTLY DIVERGE AS TIME GOES ON. THE BIGGEST PLACE THIS IS
EVIDENT IS WITH THE LOW MOVING INTO THE WESTERN ALEUTIANS SATURDAY
EVENING. IN SHORT THE GFS HAS A TWO LOW SOLUTION WHILE THE NAM
CONSOLIDATES THE ENERGY INTO ONE LOW IN BETWEEN THE GFS LOW POSITIONS.
THE NAM IS NOTORIOUS FOR HAVING DIFFICULTY RESOLVING STORMS COMING
INTO THE AREA FROM THE FAR WEST AND IT IS ALSO AT THE END OF THE MODEL
RUN. THE GFS IS PROBABLY A BETTER SOLUTION AS IT IS STILL REASONABLY
STABLE ON THE MODEL ENSEMBLE AND HAS NOT DIFFERED MUCH IN THE BIG
PICTURE OVER THE LAST FEW MODEL RUNS.

.ANALYSIS AND UPPER LEVELS...A THERMAL TROUGH EXTENDS FROM THE
NORTHERN COPPER RIVER BASIN ACROSS THE MAT-SU AREA AND INTO THE
KUSKOKWIM VALLEY. THIS TROUGH COMBINED WITH WEAK UPPER LEVEL
DISTURBANCES ROTATING AROUND A LOW IN THE SOUTHEAST GULF OF ALASKA
WILL HELP TO BRING AFTERNOON AND EVENING CONVECTION TODAY AND
TOMORROW. TODAY WILL BE THE MORE ACTIVE DAY WITH THE ATMOSPHERE A
LITTLE MORE STABLE FRIDAY. THE FACT THAT THERE ARE UPPER LEVEL
DYNAMICS IN PLAY MAY CAUSE THE SHOWERS TO PERSIST THROUGH A GOOD PART
OF THE NIGHT SIMILAR TO WHAT OCCURRED THIS MORNING.
THE UPPER LEVEL JET IS WELL SOUTH OF MOST OF THE FORECAST AREA. THE
PLACE IT IS CLOSE IS IN THE WESTERN ALEUTIANS WHERE IT JUST SKIRTS
SOUTH OF THEM AND THEN HEADS SOUTHEAST. THIS JET WILL BE PUSHED
FARTHER SOUTH BY THE WEEKEND AS A COLD UPPER LEVEL TROUGH DESCENDS OUT
OF EASTERN RUSSIA AND MOVES INTO THE BERING SEA.

.SHORT TERM FORECAST...THIS AFTERNOON AND EVENING LOOK TO PRODUCE SOME
CONVECTION IN THE MATANUSKA AND SUSITNA VALLEYS AS WELL AS THE
KUSKOKWIM VALLEY. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE
EXPECTED. FRIDAY REMAINS MODERATELY UNSTABLE AS WELL WITH SHOWER
DEVELOPMENT LIKELY. THERE IS JUST A SLIGHT CHANCE OF THUNDERSTORMS IN
JUST THE SUSITNA VALLEY FRIDAY AFTERNOON AND EVENING WITH NONE
EXPECTED ANYWHERE IN THE FORECAST AREA AFTER THAT.
SHOWERS ARE LIKELY IN THE BRISTOL BAY AREA AND KUSKOKWIM DELTA THIS
AFTERNOON AND EVENING.

.LONG TERM FORECAST...THE LOW THAT IS MOVING INTO THE BERING SEA THIS
WEEKEND WILL INTERACT WILL PUSH THE JET STREAM SOUTH BUT ALSO BECOME
THE FOCUS FOR A RAPIDLY DEVELOPING LOW EARLY NEXT WEEK AS IT DOES.
THIS LOW SHOULD START TO REALLY DEEPEN SUNDAY NIGHT SOUTH OF THE
ALASKA PENINSULA AND THEN MOVE OVER THE ALASKA PENINSULA THROUGH
TUESDAY BEFORE BEGINNING TO WEAKEN AND MOVE TO THE NORTH GULF COAST
AFTER THAT. THIS WILL BRING VERY DEEP MOISTURE TO THE SOUTHWEST ALASKA
COASTAL AREAS AS WELL AS THE ALASKA PENINSULA AND GULF COAST.

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

AUG 07