Area Forecast Discussion
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FXPQ60 PGUM 050820 AAA
AFDPQ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TIYAN GU
620 PM CHST SAT SEP 5 2015

UPDATED TO ADD MICRONESIA DISCUSSIONS

.SYNOPSIS...
RADAR SHOWS ISOLATED LIGHT SHOWERS ACROSS THE COVERAGE AREA...AND
SATELLITE SHOWS PARTLY CLOUDY SKIES ACROSS THE LOCAL REGION. ASCAT
ANALYSIS INDICATES A LOW-LEVEL CIRCULATION (INVEST AREA 92W) WELL
NORTHWEST OF SAIPAN NEAR 16.5N 141.5E DRIFTING AWAY TOWARD NORTHWEST
WITH SHOWERS AND THUNDERSTORMS WITHIN ABOUT 150 MILES OF ITS CENTER.
BUOYS RANGE FROM 3 TO 4 FT AND RITIDIAN BUOY SHOWS A SOUTHWEST WAVE
COMPONENT STARTING TO ARRIVE. VAD GRADIENT WINDS ARE SOUTHWEST 15 KT.

&&

.DISCUSSION...
THE MONSOON TROUGH HAS MOVED NORTHWARD TO JUST ABOVE SAIPAN AND
WEST TO SOUTHWEST SURFACE WINDS PREVAIL ACROSS THE FORECAST AREA.
ONLY ISOLATED SHOWERS AND THUNDERSTORMS ARE IN THE FORECAST AT
THIS TIME...BUT MODELS INDICATE THAT AN AREA OF SCATTERED SHOWERS
WILL DEVELOP JUST SOUTH OF GUAM BY MONDAY OR TUESDAY...MAINLY
BETWEEN 10N AND 13N. SOME PERIODS OF SCATTERED SHOWERS COULD YET
AFFECT OUR FORECAST ZONES DURING THE COMING WEEK.

&&

.MARINE...
CONTINUE PREVIOUS FORECAST TRENDS. SOUTHWEST SWELL AND WIND WAVES
WILL DEVELOP ACROSS THE AREA WHILE SIGNIFICANTLY LARGER AND LONGER
PERIOD SWELL MOVES OUR WAY FROM EAST-NORTHEAST THIS COMING WEEK.
THIS LONG PERIOD SWELL EMANATING FROM TYPHOON KILO MIGHT CAUSE SURF
ALONG EAST FACING REEFS TO BUILD TO HIGH SURF ADVISORY LEVELS BY
TUESDAY OR WEDNESDAY. ITS ALSO POSSIBLE THAT SEAS COULD BUILD TO
SMALL CRAFT ADVISORY LEVELS DURING THE MIDDLE OF NEXT WEEK.

&&

.EASTERN MICRONESIA...
SURFACE ANALYSIS SHOWS WEAK CIRCULATIONS ON THE MONSOON TROUGH...
ONE NORTHWEST OF MAJURO AND A SECOND NORTHEAST OF MAJURO NEAR
THE DATELINE. SHOWERS AND THUNDERSTORMS ARE EDGING WESTWARD TOWARD
POHNPEI AS THE FIRST CIRCULATION MOVES CLOSER TO POHNPEI. THE SECOND
CIRCULATION IS WELL NORTHEAST OF MAJURO AND STAYS WELL NORTH AS IT
MOVES WESTWARD. HOWEVER...THERE WILL BE ENOUGH INSTABILITY IN THE
AREA TO SUPPORT ISOLATED THUNDERSTORMS AT MAJURO THROUGH THE WEEKEND.
KOSRAE WILL REMAIN SOUTH OF MOST OF THE ACTIVITY ASSOCIATED WITH THE
MONSOON TROUGH AND THE CIRCULATIONS.

WAVE MODELS CONTINUE TO INDICATE INCREASING NORTH SWELL OVER THE
WEEKEND AND EARLY NEXT WEEK AS TY KILO DRIFTS BY NORTH OF WAKE
ISLAND. THE LARGEST IMPACT WILL BE THE FAR NORTHERN ATOLLS OF THE
MARSHALL ISLANDS THIS WEEKEND AND EARLY NEXT WEEK. THE NORTHERN
ATOLLS SHOULD REDUCE THE SIZE OF THE SWELL REACHING MAJURO.
POHNPEI AND CHUUK WILL SEE LONG PERIOD NORTH SWELL BUILDING EARLY
NEXT WEEK. MODELS SHOW SIMILAR TRENDS FOR KOSRAE...BUT OVERALL
SWELL IS EXPECTED TO BE SLIGHTLY SMALLER.

&&

.WESTERN MICRONESIA...
HAVE DECREASED THE SHOWER COVERAGE OVER YAP TONIGHT AS A WEAK
CIRCULATION PULLS THE MONSOON TROUGH NORTHWARD. MODELS INDICATE
THE MONSOON TROUGH WILL REESTABLISH ITSELF AGAIN FARTHER SOUTH
AS A DISTURBANCE WEST OF THE MARIANAS CONTINUES NORTHWEST. A DRIER
PATTERN HAS BECOME ESTABLISHED AT CHUUK BUT SHOWERS WILL BUILD
INTO THE AREA SUNDAY NIGHT AS THE FIRST CIRCULATION MENTIONED IN
THE EASTERN MICRONESIAN DISCUSSION SHIFTS TO THE WEST-NORTHWEST.

COMBINED SEAS ARE STILL EXPECTED TO INCREASE AT CHUUK NEXT WEEK...
SEE DISCUSSION IN EASTERN MICRONESIA FOR MORE DETAILS ON TIMING.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...NONE.
MARIANAS WATERS...NONE.
&&

$$

SIMPSON/DEVITA



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