Subject: Western Pacific: Synoptic Discussion For The Marianas

From: LDM Weather <[email-masked]>
Date: Tue, 28 Sep 2010 16:20:42 -0500

147 
FXPQ60 PGUM 282120
AFDPQ 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
720 AM CHST WED SEP 29 2010

.SYNOPSIS...
PGUA WSR-88D SHOWS ISOLATED SHOWERS IN THE MARIANAS WATERS WITH
SCATTERED SHOWERS TO THE SOUTHEAST MOVING IN. THESE ARE BEING
CAUSED BY THE COMBINATION OF LOW-LEVEL AND UPPER-LEVEL TROUGHS.

&&

.DISCUSSION...
TROUGH COMING IN NEARLY AS FORECAST. JUST TWEAKED THE FIRST 6
HOURS AS IT LOOKS LIKE IT MIGHT ARRIVE A LITTLE LATER THAN
PREVIOUSLY THOUGHT. OVERALL...FORECAST WAS IN GREAT SHAPE AND ONLY
THIS MINIMAL CHANGE WAS NECESSARY.

&&

.MARINE...
SWELL FROM FORMER TYPHOON MALAKAS SHOULD DIMINISH STARTING THIS
AFTERNOON. THIS WILL ALLOW THE HIGH SURF ADVISORY TO EXPIRE. SEA
HEIGHTS WERE NEVER HIGH ENOUGH TO REQUIRE A SMALL CRAFT ADVISORY.

&&

.EASTERN MICRONESIA...
FAIR WEATHER IS EXPECTED TO CONTINUE OVER CHUUK THRU THURSDAY 
EVENING...AND POHNPEI THRU TONIGHT AS DRIER GENTLE TRADE WINDS 
DOMINATE THE AREA. LATEST ASCAT IMAGERY INDICATES THE 
NEAR-EQUATORIAL TROUGH OVER THE MARSHALL ISLANDS EARLIER HAS
MOVED SOUTH OF MAJURO...AND TRANSFORMED INTO A SURFACE TROUGH. ITS
LEADING EDGE IS APPROACHING KOSRAE WITH SHOWERS ARRIVING BEFORE
NOON TODAY. WEAKER CONVERGENCE SOUTHEAST OF THE TROUGH AXIS WILL
MAINLY CREATE SOME CLOUDS AND A FEW SHOWERS FOR MAJURO INTO
THURSDAY. AS THE TROUGH KEEPS SLIDING WESTWARD...IT WILL ALSO
INCREASE THE CHANCE FOR SOME SHOWERS AT POHNPEI ON THURSDAY AND
CHUUK BY FRIDAY. AFTERWARD...WEAKER TRADES BEHIND THE TROUGH ARE
GOING TO PROMOTE ANOTHER ROUND OF DRY CONDITIONS FOR MAJURO AND
KOSRAE TOWARD THE WEEKEND...AND FOR POHNPEI AND CHUUK OVER THE
WEEKEND. HOWEVER...INCREASING TRADE CONVERGENCE FROM THE EAST
MIGHT START A WETTING TREND FOR THE MARSHALLS EARLY NEXT WEEK.

&&

.WESTERN MICRONESIA...
THE WEAK SURFACE CIRCULATION AND ITS ASSOCIATED TROUGH HAS DRIFTED 
NORTHWEST OF KOROR AND YAP THIS MORNING. AS A RESULT...CONVECTION
RELATED TO THIS FEATURE HAS ALSO SHIFTED NORTHWEST OF BOTH
LOCATIONS. NEVERTHELESS...WEAK CONVERGING WINDS SOUTH OF THIS
FEATURE CAN STILL TAKE ADVANTAGE OF UPPER-LEVEL DIVERGENCE TO
SPARK ISOLATED THUNDERSTORMS THRU THIS EVENING. THE NEXT POTENTIAL
WEATHER MAKER FOR WESTERN MICRONESIA WILL BE ANOTHER SURFACE
TROUGH PASSING SOUTH OF GUAM LATER THIS EVENING. AS IT CLOSES INTO
YAP ON THURSDAY...ANTICIPATE ANOTHER ROUND OF CONVECTIVE ACTIVITY
TO FIRE UP AGAIN. AT THIS POINT...THE BULK OF THE ACTION MIGHT
STAY JUST NORTH OF KOROR. IN THE WAKE OF THE PASSAGE OF THE SECOND
TROUGH...FAIR WEATHER CURRENTLY OVER EASTERN MICRONESIA SHOULD
FINALLY ARRIVE OVER THE WEEKEND. SURF OF AROUND 6 TO 7 FEET ALONG
NORTH FACING SHORES WILL GRADUALLY SUBSIDE TO BETWEEN 5 AND 6 FEET
BY THIS EVENING.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...HIGH SURF ADVISORY UNTIL NOON CHST TODAY FOR GUZ001>004.

MARIANAS WATERS...NONE.
&&

$$

STANKO/CHAN

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