Small Craft Advisory 620, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
400 PM AKDT THU AUG 14 2008

.MODEL DISCUSSION...
MODELS IN GOOD AGREEMENT THROUGH 60 HOURS. DIFFICULTIES ARISE AFTER
72 HOURS REGARDING THE STRENGTH AND TRACK OF LOW MOVING INTO THE
SOUTHWESTERN GULF AT THAT TIME PERIOD. GFS PREFERRED MODEL BUT DUE TO
UNCERTAINTY WILL MAKE ONLY MODEST CHANGES TO THE FORECAST BEYOND
SUNDAY MORNING.

.ANALYSIS...
UPPER LEVEL LOW CENTERED OVER THE NORTHERN BERING SEA IS DOMINATE
FEATURE THIS MORNING. UPPER TROUGH EXTENDS FROM LOW CENTER ACROSS
SOUTHWESTERN ALASKA AND NORTHERN GULF OF ALASKA. AT THE SURFACE...
THE 1000 MB LOW JUST NORTHWEST OF SAINT PAUL WILL DISSIPATE NEAR
NUNIVAK ISLAND SAT AFTERNOON. A 1005 MB LOW IN THE NORTHERN GULF OF
ALASKA WILL DISSIPATE NEAR NINILCHIK FRI MORNING. WEAK HIGH PRESSURE
BUILDS OVER THE GULF AND SOUTHERN MAINLAND FRIDAY EVENING. LASTLY A
1000 MB LOW WILL DEVELOP OVER THE WESTERN ALEUTIANS SAT AFTERNOON.

.FORECAST...
NUMEROUS SMALL SHORTWAVES ARE ROTATING AROUND THE MAIN LOW PRODUCING
PERIODS OF SHOWERS ACROSS BOTH SOUTHCENTRAL AND SOUTHWESTERN ALASKA.
ALSO ENOUGH INSTABILITY FOR POTENTIAL THUNDERSTORMS THIS AFTERNOON
AND EVENING IN THE KUSKOKWIM VALLEY AND NORTHERN SUSITNA VALLEY.
HOWEVER VERY STABLE OVER THE BERING SEA...AREAS OF IFR STRATUS AND
FOG LIKELY TO PERSIST THROUGH AT LEAST TOMORROW MORNING.

.EXTENDED...
CLEARING SKIES OVER MAINLAND ALASKA BEGINNING SATURDAY WITH THE
ARRIVAL OF HIGH PRESSURE. THERMAL TROUGH LIKELY TO DEVELOP INLAND SO
CONVECTION WILL CONTINUE TO BE AN ISSUE FOR THE KUSKOKWIM AND
NORTHERN SUSITNA VALLEYS. STRATUS AND FOG TO PERSIST IN THE EASTERN
BERING.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...ASHFALL ADVISORY FOR 185
MARINE...ASHFALL ADVISORY FOR 170
         GALE 176
FIRE WEATHER...NONE.

ASB AUG 08