Small Craft Advisory 631, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
100 PM ADT SAT AUG 4 2007

.MODEL DISCUSSION...
MODELS IN GOOD AGREEMENT. EVEN THE NAM FOR A CHANGE. THE GLOBAL
MODELS EVEN OUT TO 120 HOURS ARE FAIRLY CLOSE...LENDING A DEGREE OF
CONFIDENCE TO THE FORECAST.

.ANALYSIS AND UPPER LEVELS...
UPPER LEVEL RIDGE OVER THE GULF OF ALASKA WITH A LOW IN THE EASTERN
BERING SEA. THE JET BETWEEN THESE FEATURES IS PUSHING SYSTEMS FROM
THE SOUTHWEST ACROSS SOUTHERN ALASKA. STRONG WINDS ALOFT ARE VERY
EVIDENT ON WATER VAPOR IMAGERY...WITH THE CORE OF STRONGEST WINDS
CROSSING DUTCH HARBOR AND MCGRATH. TROPICAL/ EXTRA-TROPICAL
INTERACTIONS ARE NOT STRONG...SO RAINFALL EXPECTED TO BE WITHIN THE
BOUNDS OF WHAT IS EXPECTED THIS TIME OF YEAR.

.SHORT TERM FORECAST...
THERE ARE TWO WEATHER SYSTEMS WITH THEIR ASSOCIATED PULSES OF
MOISTURE OVER THE AREA.

THE FIRST STRETCHES FROM ABOUT MCGRATH SOUTHEAST TO CORDOVA...
PRODUCING LIGHT TO MODERATE RAINFALL WITH EXTENSIVE COVERAGE. THIS
SYSTEM WILL MOVE EASTWARD TONIGHT...AND WEAKEN TOWARDS MORNING.

THE NEXT SYSTEM HAS MORE WIND BUT SIMILAR OR MAYBE SLIGHTLY LOWER
MOISTURE CONTENT THAN THE FIRST. IT STRETCHES FROM ABOUT DUTCH
HARBOR/COLD BAY NORTHEAST TO DILLINGHAM...THEN WRAPS BACK
NORTHWESTWARD TO THE SURFACE LOW CENTERED BETWEEN THE ISLANDS OF
NUNIVAK AND SAINT PAUL. THIS LOW WILL BLOSSOM INTO A DECENT RAIN
MAKER FROM THE ALASKA/ALEUTIAN RANGES NORTHWARD ON TONIGHT INTO
EARLY SUNDAY. RAINFALL WILL INCREASE IN SOUTH CENTRAL ALASKA BY LATE
MORNING AND CONTINUE INTO THE EVENING...FOR ANOTHER WET WEEKEND DAY
IN THE ANCHORAGE BOWL.

BY SUNDAY NIGHT THE UPPER LOW WILL BE OVER CENTRAL ALASKA...
SQUISHING THE NORTHERN END OF THE GULF RIDGE SOUTHWARD. THIS PUTS
SOUTHERN ALASKA IN CYCLONIC FLOW FOR A MORE SHOWERY REGIME ON
MONDAY.

.LONG TERM FORECAST...
AS THE LOW OVER ALASKA MOVES EAST THE GULF RIDGE RETROGRADES
SLIGHTLY...AND AN EXTENSION PUSHES UP ALONG THE WEST COAST OF
ALASKA AND THE EASTERN BERING SEA. THIS WILL GIVE A MORE
NORTHWESTERLY FLOW TO THE AREA...AND USHER IN A DRYER AND SUNNIER
REGIME. AFTER A (MAINLY DRY) SHORT WAVE CROSSES THE AREA ON
TUESDAY...WEDNESDAY THROUGH FRIDAY WILL SEE PARTLY TO MOSTLY SUNNY
SKIES OVER THE MAINLAND.

AS THE RIDGE BUILDS OVER THE EASTERN BERING SEA...A LARGE UPPER LOW
WILL DEVELOP OVER THE WESTERN BERING SEA. THIS LOW WILL SLOWLY CHIP
AWAY AT THE RIDGE...WITH WINDIER AND WETTER WEATHER WORKING EASTWARD
ACROSS THE ALEUTIANS DURING THE WEEK...THEN POSSIBLY INTO WESTERN
ALASKA SATURDAY...THOUGH THIS IS WHEN THE NUMERICAL MODELS BEGIN TO
DIVERGE.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM WARNING 176.
         GALE WARNING 155 165.
FIRE WEATHER...NONE.

LUDWIG AUG 07