Area Forecast Discussion
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FXPQ60 PGUM 020657
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
457 PM CHST TUE JUN 2 2015

.SYNOPSIS...
THE CENTER OF A WEAK TROPICAL DISTURBANCE IS CENTERED SOUTH-
SOUTHWEST OF GUAM NEAR 8N144E. AN UPPER-LEVEL LOW IS CENTERED
NEAR 23N145E AND AN ATTENDANT TROUGH EXTENDS SOUTHWEST OF THE
LOW. THESE FEATURES ARE GENERATING SCATTERED SHOWERS AND
SOME THUNDERSTORMS EAST OF THE MARIANAS. SCATTEROMETER DATA SHOWS
MODERATE TO FRESH TRADE WINDS ACROSS THE REGION.

&&

.DISCUSSION...
AS THE UPPER-LEVEL TROUGH MOVES A BIT FARTHER WEST OF THE
MARIANAS...UPPER-LEVEL FLOW WILL BECOME MORE FAVORABLE FOR THE
DEVELOPMENT OF SHOWERS AND THUNDERSTORMS OVER THE MARIANAS
TONIGHT AND WEDNESDAY. IN ADDITION...MODELS SHOW THE TROPICAL
DISTURBANCE SOUTH-SOUTHWEST OF GUAM WILL SLOWLY MOVE NORTH-
NORTHWEST TO THE WEST OF THE MARIANAS BY THURSDAY. THE FAVORABLE
UPPER-LEVEL ENVIRONMENT IN CONJUNCTION WITH THE SURFACE
DISTURBANCE WILL CAUSE AN ACTIVE WEATHER PATTERN TO EMERGE
BEGINNING TONIGHT. SHOWERS JUST EAST OF THE MARIANAS COASTAL
WATERS WILL GRADUALLY MOVE WEST INTO THE AREA...WITH SCATTERED
SHOWER COVERAGE EXPECTED TO COMMENCE AROUND MIDNIGHT. MODEL
AGREEMENT HAS BEEN GOOD AS WELL AS RUN-TO-RUN CONSISTENCY IN
BRINGING SEVERAL INCHES OF RAINFALL THROUGH FRIDAY FOR THE
MARIANAS. SHORT TERM FORECASTS OVER THE NEXT COUPLE OF DAYS WILL
NEED TO BE ADJUSTED TO WORK AROUND CYCLES OF CONVECTION THAT ARE
LIKELY TO OCCUR. MODERATE TO OCCASIONALLY FRESH WINDS WILL LAST
THROUGH FRIDAY BEFORE DIMINISHING SLIGHTLY OVER THE WEEKEND.

&&

.EASTERN MICRONESIA...
SCATTERED SHOWERS HAVE AGAIN FLARED UP OVER POHNPEI WATERS THIS
AFTERNOON ASSOCIATED WITH THE WEAKENING NEAR-EQUATORIAL TROUGH.
LATEST MODEL RUN DID PICK UP ON THIS AND SHOW THE SHOWERS
DISSIPATING LATER THIS EVENING. A DRIER PATTERN IS IN PLACE OVER
KOSRAE AS WEAK RIDGING BUILDS INTO THE REGION. THIS PATTERN WILL
CONTINUE OVER KOSRAE THROUGH THE WEEKEND AND THE WEAK RIDGING WILL
SLOWLY BUILD WESTWARD OVER POHNPEI STATE...RESULTING IN DRIER
CONDITIONS AND DECREASING CLOUDINESS FOR THE WEEKEND. LOW-LEVEL
CONVERGENCE CONTINUES TO PRODUCE SCATTERED SHOWERS MAINLY TO THE
EAST OF MAJURO. THE CONVERGENCE IS SLOWLY WEAKENING AND THE SHOWERS
ARE BEGINNING TO DECREASE. EXPECT AN UNSETTLED PATTERN TO REMAIN
OVER MAJURO THROUGH WEDNESDAY...WITH A DRIER PATTERN LIKELY
WEDNESDAY AFTERNOON OR EVENING. ANOTHER WEAK SURFACE TROUGH IS
EXPECTED TO CROSS THE DATE LINE FOR THE WEEKEND AND COULD BRING
ANOTHER ROUND OF SHOWERS TO MAJURO. CHOSE TO MAINTAIN FORECAST FOR
MOSTLY CLOUDY CONDITIONS AND ONLY ISOLATED SHOWERS FOR NOW AS
SYSTEM LOOKS TO BE RELATIVELY WEAK ON LATEST GFS RUN.

&&

.WESTERN MICRONESIA...
WEAK RIDGING BUILDING IN TO CHUUK STATE IS HELPING TO DISSIPATE THE
SHOWERS OVER THE REGION. LATEST GFS RUN MAINTAINS A MOSTLY DRY BIAS
OVER THE STATE THROUGH THE REMAINDER OF THE WEEK AND INTO THE
WEEKEND. WITH THE RIDGING EXPECTED OVER THE REGION...THIS IS
POSSIBLE. HOWEVER...NEED TO KEEP AN EYE ON THE TROUGH AND WEAK
DISTURBANCE OVER THE AREA FOR POSSIBLE INCREASE IN SHOWERS LATER IN
THE WEEK. THE NEAR-EQUATORIAL TROUGH WILL REMAIN OVER PALAU AND YAP
STATE THROUGH WEDNESDAY...KEEPING UNSETTLED CONDITIONS OVER YAP
TONIGHT AND OVER KOROR THROUGH WEDNESDAY NIGHT. THE TROUGH IS
EXPECTED TO DRIFT NORTHWARD OVER THE NEXT FEW DAYS...USHERING IN A
BENIGN PATTERN OVER BOTH LOCATIONS THROUGH THE WEEKEND.

&&

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

$$

WILLIAMS/KLEESCHULTE



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