Gale Warning 510, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AKDT SAT AUG 16 2008

.ANALYSIS AND UPPER LEVELS...
THE MAIN UPPER LEVEL FEATURE IS A LOW NEAR ST. MATTHEW ISLAND WITH A
TROUGH STRETCHING DOWN INTO THE CENTRAL GULF. THERE IS A WEAK SFC
REFLECTION IN THE BERING SEA...BUT NEGLIGIBLE IN THE GULF WHICH IS
DOMINATED BY HIGH PRESSURE.  A WEAK LOW WILL MOVE ALONG A
FRONTAL BOUNDARY DRAPED ALONG THE WESTERN ALEUTIANS...BECOMING THE
DOMINATE LOW SOUTH OF THE EASTERN ALEUTIANS ON SUNDAY.

.MODEL DISCUSSION...
MODELS IN DECENT AGREEMENT AND RUN-TO-RUN CONSISTENCY FOR AT LEAST
THE FIRST 48 HOURS. THEN THERE BEGINS TO BE DISAGREEMENT IN MORE
THAN ONE WAY. THE FIRST IS THE HANDLING OF THE EJECTION OF THE GULF
LOW...WHICH THE NAM WANTS TO EJECT 12 TO 24 HOURS FASTER THAN MOST
OF THE OTHER NUMERICAL MODELS. SECOND...THE LOW MOVING INTO THE
ALEUTIANS FROM THE WEST AND WHERE IT WILL GO. MODELS ARE TRENDING
FURTHER SOUTH WITH THE LOW MOVING ACROSS THE ISLAND CHAIN...OR MORE
LIKELY SOUTH OF IT AS ADVERTISED BY THE NAM AND ECMWF.

.SHORT TERM FORECAST...
THUNDERSTORMS EXPECTED AGAIN IN THE COPPER RIVER BASIN...ACROSS THE
SUSITNA VALLEY AND IN THE KUSKOKWIM VALLEY ALONG A WEAK THERMAL
TROUGH. AS EVIDENCE FROM THE PAST COUPLE OF DAYS...ANY BREAKS IN THE
CLOUDS WILL ALLOW ENOUGH HEATING GENERATE CONVECTION IN A FAIRLY
UNSTABLE ATMOSPHERE. THIS SHOULD CONTINUE THROUGH THE WEEKEND.

FURTHER WEST...A LOW THAT IS DRAPED ACROSS KODIAK ISLAND THROUGH
BETHEL IS BEING SHREDDED APART AS IT MAKES NO PROGRESS DUE TO THE
GULF RIDGE. THE NEXT LOW CURRENTLY SPINNING UP OVER THE ALEUTIANS
IS EXPECTED TO BE STRONGER AND WILL MAKE RAPID PROGRESS INTO THE
WESTERN GULF SUNDAY NIGHT.

.LONG TERM FORECAST...
THE LOW IN THE WESTERN GULF WILL BOMB OUT SOUTH OF KODIAK ISLAND
ON MONDAY...DROPPING TO ABOUT 978 MB IF YOU AVERAGE THE VARIOUS
MODEL PROJECTIONS. THIS SHOULD PRODUCE A PERIOD OF GALES IN THE
SURROUNDING WATERS. THE FURTHEST NORTHEAST THAT PRECIPITATION FROM
THIS LOW LOOKS TO GET WILL BE ABOUT AT KODIAK CITY.

SOUTHWEST AND SOUTH CENTRAL ALASKA WILL CONTINUE TO SEE SHOWERS
DURING THE FIRST HALF OF THE WEEK DUE TO THE SURFACE THERMAL LOW.
THE ACTIVITY SHOULD BE LIMITED IN THE ABSENCE OF MAJOR SYSTEMS AND A
WEAK RIDGE ALOFT.

BY LATER IN THE WEEK THE GFS AND ECMWF GLOBAL MODELS ARE STILL IN
DECENT AGREEMENT...BUT WITH SOME DETAIL DIFFERENCES. THEY INDICATE A
CONTINUATION OF THE BASIC PATTERN BUT WITH THE UPPER LOW HAVING A
STRONGER INFLUENCE ON INTERIOR SOUTHERN ALASKA...BUT THE MAIN JET
STREAM ACTION WILL STILL BE SOUTH OF THE AREA.

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

LUDWIG AUG 08