Small Craft Advisory 548, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
155 PM AKDT FRI JUL 18 2014

.ANALYSIS AND UPPER LEVELS...
THERE IS AN UPPER LEVEL LOW OFF THE NORTHWEST ALASKA COAST. THERE
ARE TWO SHORT-WAVE TROUGHS ASSOCIATED WITH THIS LOW THAT WILL
AFFECT SOUTHERN ALASKA. THE FIRST EXTENDS SOUTH ACROSS THE WEST
COAST OF ALASKA THEN BENDS WEST OVER THE SOUTHERN BERING
SEA...JUST NORTH OF AND PARALLEL TO THE ALEUTIANS. THE OTHER
SHORT-WAVE IS FORMING OVER THE CHUKCHI SEA. THERE IS A RIDGE OVER
SOUTH CENTRAL ALASKA AHEAD OF THE FIRST TROUGH. THERE IS A LARGE
UPPER RIDGE OVER THE WESTERN BERING SEA.

&&

.MODEL DISCUSSION...
THE NUMERICAL MODELS ARE IN GOOD AGREEMENT THROUGH 84 HOURS. EVEN
THE NAM AGREES WELL WITH THE OTHER MODELS THROUGH 60 HOURS...THEN
BEGINS TO DIVERGE OVER THE ALEUTIANS/BERING SEA AFTER THAT.
FORECAST CONFIDENCE IS ABOVE NORMAL FOR THE AFTERNOON PACKAGE.

&&

.SHORT TERM FORECAST...

FOR SOUTH CENTRAL ALASKA...A PATTERN CHANGE IS IN STORE FOR THE
WEEKEND. THE UPPER LOW NORTH OF ALASKA WILL PUSH THE POLAR JET
SOUTHEAST OVER SOUTHERN ALASKA. THE FIRST FRONT ASSOCIATED WITH
THE TROUGH CURRENTLY OVER WESTERN ALASKA WILL BRING RAIN INTO THE
COOK INLET AREA LATE TONIGHT INTO SATURDAY...PUSHING THROUGH
PRINCE WILLIAM SOUND AND THE COPPER RIVER BASIN LATER IN THE DAY.
THE NEXT SYSTEM (CURRENTLY OVER THE CHUKCHI SEA) WILL RACE
SOUTHEAST AND WILL BRING MORE RAIN INTO WESTERN PORTIONS OF SOUTH
CENTRAL SATURDAY EVENING AND ACROSS THE AREA THROUGH SUNDAY. LATER
SUNDAY AND SUNDAY NIGHT THE BERING RIDGE WILL PUSH INTO SOUTHERN
ALASKA...USHERING IN A DRY MONDAY.

FOR SOUTHWEST ALASKA...THE FIRST SYSTEM WILL PUSH THROUGH THE AREA
TONIGHT. A BRIEF BREAK EARLY SATURDAY WILL GIVE WAY TO THE NEXT
SYSTEM SATURDAY AFTERNOON AND SATURDAY NIGHT. THE RIDGE WILL BUILD
OVER THE AREA ON SUNDAY AND CONTINUE TO PROTECT THE AREA THROUGH
MONDAY.

FOR THE BERING SEA/ALEUTIANS...HIGH PRESSURE OVER THE WESTERN
BERING SEA WILL PUSH INTO THE CENTRAL BERING SEA SATURDAY
NIGHT...INTO THE EASTERN BERING SUNDAY AND THEN INTO SOUTHWEST
ALASKA ON MONDAY. THE FRONT JUST NORTH OF THE ALEUTIANS WILL
CONTINUE TO WEAKEN WHILE PUSHING THROUGH THE ALEUTIANS/ALASKA
PENINSULA THROUGH EARLY SATURDAY MORNING. THE POLAR JET WILL PUSH
A COUPLE OF FRONTS ACROSS THE NORTHERN BERING THROUGH MONDAY WHICH
WILL BRING PERIODIC WESTERLY/SOUTHWESTERLY WINDS TO THAT AREA. ON
SUNDAY A LOW TO THE SOUTH OF THE ALEUTIANS WILL MOVE NORTH AND
MOVE INTO THE BERING SEA ON MONDAY...PUSHING INTO THE AREA VACATED
BY THE DEPARTING RIDGE.

&&

.LONG TERM FORECAST...
THE WARMING AND DRYING TREND IN STORE FOR EARLY NEXT WEEK WILL BE
SHORT LIVED AS UPPER LEVEL RIDGING GIVES WAY TO A SERIES OF
UPPER LOWS THAT WILL APPROACH THE ALASKAN MAINLAND FROM THE WEST
BEGINNING ON TUESDAY AS A BROAD UPPER LEVEL TROUGH SETS UP OVER
THE ARCTIC. THIS WILL LEAD TO GENERALLY CLOUDY CONDITIONS WITH A
CHANCE OF RAIN THROUGH MUCH OF NEXT WEEK AS TEMPERATURES MODERATE
TO AROUND OR PERHAPS SLIGHTLY BELOW NORMAL. MEANWHILE...A STOUT
UPPER LEVEL RIDGE WILL BEGIN TO BUILD OVER THE FAR WESTERN BERING
BY LATE TUESDAY AND DRIFT SLOWLY EASTWARD THROUGH THE END OF NEXT
WEEK. MODELS ARE SUGGESTING THAT THIS RIDGE MAY BEGIN TO INFLUENCE
THE MAINLAND BY LATE IN THE WEEK WITH WARMER AND DRIER
CONDITIONS...ALTHOUGH FORECAST CONFIDENCE IN THIS SCENARIO REMAINS
RELATIVELY LOW AT THIS TIME.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING 120 181 185.
FIRE WEATHER...NONE.

&&

LUDWIG/CB JUL 14