Small Craft Advisory 627, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
100 PM AKDT SUN AUG 17 2008

.MODEL DISCUSSION...
NUMERICAL MODELS IN DECENT AGREEMENT THROUGH ABOUT 84 HOURS BEFORE
DIFFERENCES BEGIN TO BE SIGNIFICANT. AFTERNOON FORECAST PACKAGE
MAINLY BASED ON GFS...WITH A SPRINKLING OF NAM. AFTER 84 HOURS
CONFIDENCE NOT HIGH AND FORECASTS WERE NOT CHANGED MUCH.

.ANALYSIS AND UPPER LEVELS...
UPPER LOW CENTERED OVER THE EASTERN BERING SEA WITH A SAGGY
PROTUBERANCE INTO SOUTHERN ALASKA. WEAK UPPER RIDGE OVER THE
CENTRAL BERING CONNECTED NORTHWARD TO A MUCH STRONGER RIDGE NORTH
OF SIBERIA. THE JET STREAM SLICES THROUGH THE ALEUTIANS WITH A
SURFACE LOW FORMING IN THE LEFT EXIT REGION.

.SHORT TERM FORECAST...
THE SURFACE LOW FORMING SOUTH OF THE ALASKA PENINSULA WILL RAPIDLY
DEEPEN ON MONDAY WITH ALL MAJOR MODELS FORECASTING A CENTRAL
PRESSURE OF LESS THAN 980 MB. AS MENTIONED ABOVE THIS SYSTEM HAS
NICE JET SUPPORT AND STORM FORCE WINDS ARE LIKELY OVER THE WATERS
SOUTH OF ALASKA FROM ABOUT SAND POINT NORTHEASTWARD TO ABOUT KODIAK.
RAIN FROM THIS SYSTEM WILL POSSIBLY GET AS FAR NORTH AS THE EASTERN
KENAI PENINSULA WITH HEAVIER RAINFALL OVER KODIAK ISLAND.

OVER INTERIOR PORTIONS OF SOUTHERN ALASKA SHOWERS AND ISOLATED
THUNDERSTORMS EXPECTED THIS EVENING IN THE UNSTABLE AIR ASSOCIATED
WITH THE SAGGY TROUGH OVERHEAD. LESS ACTIVITY MONDAY WITH SOME
SUPPRESSION NORTH OF THE GULF LOW AND WARM AIR ADVECTION ALOFT.

.LONG TERM FORECAST...
UPPER LEVEL TROUGH SETTLES IN OVER ALASKA LATER IN THE WEEK FOR MORE
UNSETTLED WEATHER. EXACT PATTERN CONFIDENCE NOT SO GREAT...BUT
LIKELIHOOD OF CYCLONIC FLOW (THUS SHOWERY WEATHER) IS HIGH. HPC
GUIDANCE LOOKS GOOD AND FITS WELL WITH GOING FORECAST.

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

LUDWIG AUG 08