Area Forecast Discussion
Issued by NWS

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FXPQ60 PGUM 020838 AAA
AFDPQ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TIYAN GU
638 PM CHST TUE SEP 2 2014

.UPDATE...
RADAR AND SATELLITE SHOW MONSOONAL MCS BACK BUILDING FROM THE EAST
INTO ALL OF THE FORECAST ZONES. VAD WIND PROFILE SHOWS MCS IS
SUPPORTED BY DEEP MONSOONAL FLOW TO 30K FEET. WATER VAPOR LOOP
INDICATES BROAD HIGH PRESSURE OVERHEAD WHICH IS PROVIDING UPPER-
LEVEL DIVERGENCE. MODELS ARE NOT HANDLING THIS SYSTEM VERY WELL
BUT SIZE AND PAST HISTORY OF SUCH SYSTEMS SUGGESTS A 6 TO 12-HOUR
TIME FRAME...SO WILL INCREASE POPS 40 PERCENT UNTIL 18Z.

&&

.PREV DISCUSSION... /ISSUED 420 PM CHST TUE SEP 2 2014/

MARIANAS SYNOPSIS...
PGUA WSR-88D SHOWS A BAND OF SHOWERS IN THE ROTA CHANNEL AND
SCATTERED SHOWERS EAST OF THE MARIANAS WATERS. OTHERWISE...
ISOLATED SHOWERS AND THUNDERSTORMS ARE MOVING THROUGH THE MARIANAS
WATERS. THE VAD WIND PROFILE REVEALS WEST WINDS OF 10 TO 15 KNOTS
THROUGH THE LOWEST 20 THOUSAND FEET OF THE AIR.

DISCUSSION...
MONSOON TROUGH HAS BUILT INTO THE FORECAST ZONES AND SHOULD STAY
IN THE AREA THROUGH WEDNESDAY NIGHT. THE MONSOON TROUGH IS
CURRENTLY GENERATING ISOLATED SHOWERS AND THUNDERSTORMS WITHIN THE
MARIANAS WATERS. THERE IS AN AREA OF SCATTERED SHOWERS EAST OF THE
COASTAL WATERS THAT WILL NEED TO BE WATCHED. JUST TWEAKED THE SKY
COVER TO BE CLEARER THURSDAY THROUGH FRIDAY WHEN A RIDGE IS IN THE
AREA THEN A BIT CLOUDIER WHEN THE RIDGE MOVES OFF A BIT. THERE
WILL BE A SLIGHT INCREASE IN SEAS THURSDAY...NOT ENOUGH TO TRIGGER
ANY ADVISORIES THOUGH. ON FRIDAY SEAS ARE EXPECTED TO SUBSIDE BACK
TO CURRENT LEVELS THEN REMAIN THERE OVER THE WEEKEND.

EASTERN MICRONESIA...
ASCAT WIND ANALYSIS AND SATELLITE IMAGES SHOW CLOUDS AND SHOWERS
ASSOCIATED WITH A TRADE-WIND TROUGH ARE MOVING ACROSS KOSRAE STATE
THIS AFTERNOON. THE TROUGH WILL MOVE TOWARD POHNPEI TONIGHT. WEATHER
SHOULD BECOME DRIER AT KOSRAE AFTER WEDNESDAY...BUT THE TROUGH WILL
TAKE ANOTHER DAY OR TWO TO CLEAR THE POHNPEI AREA. MODELS INDICATE
THAT ANOTHER TROUGH MOVING ACROSS THE DATE LINE TODAY WILL MOVE
WEST-NORTHWEST ACROSS THE NORTHERN MARSHALL ISLANDS DURING THE NEXT
COUPLE OF DAYS AND IT COULD TRIGGER A FEW SHOWERS AND ISOLATED
THUNDERSTORMS AT MAJURO. OTHERWISE...MAINLY GENTLE NORTHEAST TO EAST
WINDS ARE EXPECTED ACROSS EASTERN MICRONESIA FOR THE COMING WEEKEND.

WESTERN MICRONESIA...
FAIR WEATHER PERSISTS AT CHUUK FOR THE NEAR TERM...BUT CHUUK WEATHER
COULD BECOME UNSTABLE TOWARD END OF THIS WEEK AS A TRADE-WIND TROUGH
ARRIVING FROM THE POHNPEI AREA COULD TRIGGER SHOWERS AND ISOLATED
THUNDERSTORMS BY ABOUT WEDNESDAY NIGHT.

SOUTHWEST MONSOON FLOW WILL DOMINATE WEATHER AT YAP AND KOROR DURING
THE NEXT COUPLE DAYS. IN THE LONGER TERM...WEATHER COULD BECOME MORE
CHANGEABLE SINCE GFS IN PARTICULAR INDICATES THE DISTURBANCE MOVING
FROM EASTERN MICRONESIA ACROSS CHUUK STATE IN THE COMING DAYS COULD
FURTHER DEVELOP AND MOVE TOWARD WESTERN PARTS OF MICRONESIA BY ABOUT
SATURDAY OR SUNDAY.

NO SURF ADVISORY HAS BEEN ISSUED...BUT THE SEA CONDITIONS AT YAP AND
PALAU WILL NEED TO BE MONITORED. LATEST WW3 GUIDANCE INDICATES THAT
SOUTHWEST WAVE COMPONENTS WILL BE SHORT-PERIOD AND BARELY INTO THE
RANGE OF A POSSIBLE SURF ADVISORY CRITERIA BY LATE ON WEDNESDAY OR
POSSIBLY WEDNESDAY NIGHT.

&&

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

$$

MCELROY/KLEESCHULTE





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