Small Craft Advisory 501, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTH CENTRAL AND SOUTHWEST ALASKA
200 PM AKDT MON JUN 23 2008

.MODEL DISCUSSION...
THE MODELS ARE IN GENERAL SYNOPTIC SCALE AGREEMENT THROUGH WED. ALL
MAINTAIN THE SURFACE RIDGE ALONG THE NORTH GULF COAST AND CONSOLIDATE
AND DEEPEN A LOW OVER THE EASTERN ALEUTIANS.  THE GFS FORMS THE
ALEUTIAN LOW NORTH OF THE UKMET AND NAM ON TUE THEN THE NAM JOINS THE
GFS SOLUTION ON WED WITH A CENTER NEAR FALSE PASS.  THE DIFFERENCE IS
ONLY ABOUT 100NM BUT IT IS THE DIFFERENCE OF THE LOW BEING SOUTH OF
THE CHAIN OR OVER IT.  AFTER WED THE GFS MOVES THE LOW EAST TO THE
SOUTHWEST GULF. THE UKMET KEEPS THIS LOW SOUTH OF THE CHAIN THE ENTIRE
PERIOD.  THE PREVIOUS ECWF IS CLOSE TO THE GFS.  WE WENT WITH THE 12Z
GFS SOLUTION.

.ANALYSIS AND UPPER LEVELS...
THE UPPER AIR PATTERN WILL EVOLVE FROM AN EAST-WEST TROUGH EXTENDING
FROM THE WESTERN BERING TO THE GULF WITH MULTIPLE CENTERS TO ONE LARGE
CUTOFF UPPER LOW OVER THE EASTERN ALEUTIANS BY WED.  THIS UPPER LOW IS
FORECASTS TO WEAKEN AND MOVE TO THE NORTHERN GULF BY FRI AS ANOTHER
UPPER TROUGH DIGS OVER THE WESTERN BERING.

EASTERLY WAVES MOVING FROM THE LOWER YUKON TO SOUTHWEST ALASKA
CONTINUE TO MOVE ACROSS THE MAINLAND. ONE WAVE IS EXITING OVER
SOUTHWEST AK THIS EVENING WITH RAIN AND SHOWERS. ANOTHER EASTERLY WAVE
MOVED INTO THE COPPER RIVER BASIN TODAY AND IS EXPECTED TO MOVE OVER
THE SUSITNA VALLEY TUE BRINGING RAIN AND SHOWERS WITH IT.

A WEAK LOW OVER BRISTOL BAY WILL MOVE WEST AND MERGE WITH THE
DEEPENING LOW OVER THE CENTRAL ALEUTIANS TONIGHT.

A WEAK LOW OVER THE WESTERN ALEUTIANS WILL STRENGTHEN AND MOVE EAST TO
A CENTER NEAR DUTCH HARBOR BY WED MORNING.

.SHORT TERM FORECAST...
RAIN WILL SPREAD OVER THE COPPER RIVER VALLEY AND SUSITNA VALLEY
TONIGHT AND TUE.  RAIN IS EXPECTED TO MOVE OVER KODIAK ISLAND TONIGHT
THEN A BREAK TUE BEFORE MORE RAIN TUE NIGHT AND WED WITH THE NEXT
FRONT MOVING IN FROM THE SOUTHWEST.

SOUTHWEST MAINLAND...SHOWERS WILL END TONIGHT WITH FOR LIKELY TUE
MORNING AS SKIES CLEAR FROM THE EAST.

ALEUTIANS AND BERING...MORE OF THE SAME WITH LOW CLOUDS AND FOG ACROSS
THE AREA. LOCAL AREAS OF DENSE FOG ARE POSSIBLE ACROSS THE PRIBILOFS,
ALASKA PENINSULA, AND EASTERN BERING SEA. LIGHT RAIN WILL AFFECT
THE ALASKA PENINSULA AND PRIBILOFS THROUGH TUESDAY AS A TROUGH REMAINS
IN THE AREA.  THE NEXT LOW WILL SPREAD RAIN AND GALE TO SMALL CRAFT
WINDS EASTWARD REACHING NORTHERN BRISTOL BAY BY TUE NIGHT.

.LONG TERM FORECAST...
THE MAIN STORY THROUGH MID WEEK WILL BE THE SLOW MOVING LOW SOUTH OF
THE ALASKA PENINSULA THROUGH THU. THIS LOW WILL WEAKEN AND DISSIPATE
IN THE WESTERN GULF FRI AS A WEAK RIDGE BUILDS OVER THE GULF. THE NEXT
ALEUTIAN LOW IS FORECAST TO TAKE A MORE SOUTHERLY TRACK SOUTH OF 50N
AND SHOULD AID IN BUILDING THE GULF RIDGE OVER THE WEEKEND. A SUMMER
GULF RIDGE AND INTERIOR THERMAL TROUGH TRANSLATE TO CLOUDY COOL
ONSHORE FLOW FOR SOUTH CENTRAL OVER THE WEEKEND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 150 160
FIRE WEATHER...NONE.

RHH JUN 08