Area Forecast Discussion
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000
FXPQ60 PGUM 010634
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
434 PM CHST TUE SEP 1 2015

.SYNOPSIS...
RADAR AND SATELLITE SHOW ISOLATED SHOWERS AND THUNDERSTORMS
ACROSS THE AREA. A WEAK MONSOON TROUGH RUNS EAST-WEST JUST SOUTH
OF GUAM ALONG 12N-13N. A SURFACE TROUGH TO OUR EAST IS CAUSING
SHOWERS AND THUNDERSTORMS IN PATCHY AREAS BETWEEN 150E AND 160E.
VAD GRADIENT WINDS ARE LIGHT SOUTHEAST AND BUOYS RANGE FROM 3 FT
AT IPAN TO NEAR 6 FT AT TANAPAG.


&&

.DISCUSSION...
THE MONSOON TROUGH WILL BE NEARBY OR POSSIBLY MOVING FARTHER
NORTH OVER THE MARIANAS THIS WEEK. LIGHT SURFACE WINDS AND A MOIST
LOWER ATMOSPHERE WILL TRIGGER ISOLATED SHOWERS AND THUNDERSTORMS
ACROSS THE MARIANAS THROUGH FRIDAY...OTHERWISE MAINLY FAIR WEATHER
IS EXPECTED THROUGH THIS WEEKEND. GFS MODEL INDICATES A
SIGNIFICANT INCREASE IN ATMOSPHERIC MOISTURE COULD ARRIVE NEXT
WEEK.

&&

.MARINE...
REWORKED MARINE GRIDS TO INDICATE AN EAST SWELL WILL DEVELOP
LATER THIS WEEK AND EVENTUALLY BECOME THE PRIMARY SWELL...WHILE
THE NORTH SWELL GRADUALLY DIMINISHES. OTHERWISE...GENTLE TO
MODERATE MARINE CONDITIONS WILL CONTINUE. WIND GRIDS WERE
REFRESHED THROUGH DAY 5 WITH GFS40 01/00Z OUTPUT.

&&

.EASTERN MICRONESIA...
SCATTERED TO NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS
ASSOCIATED WITH A WEAK CIRCULATION EMBEDDED WITHIN THE MONSOON
TROUGH ARE OBSERVED IN VISIBLE SATELLITE IMAGERY PRIMARILY SOUTH
OF POHNPEI AND KOSRAE. LATEST SATELLITE IMAGES INDICATE SHOWER
ACTIVITY IS INCREASING OVER THE NORTHWESTERN COASTAL WATERS OF
KOSRAE. THUS...LEFT SCATTERED SHOWERS IN THE FORECAST FOR TONIGHT
AT KOSRAE. SHOWERS REMAIN MAINLY SOUTH OF POHNPEI BUT ARE EXPECTED
TO BEGIN FORMING FARTHER NORTH AS THE NIGHT PROGRESSES...LIKELY
BEING AN OVERNIGHT EVENT FOR POHNPEI WITH DRIER WEATHER EXPECTED
THERE BY WEDNESDAY AFTERNOON. INCREASED SHOWER ACTIVITY DID NOT
MATERIALIZE OVER MAJURO TODAY WITH RELATIVELY DRY CONDITIONS AND
MODERATE SOUTHWEST FLOW EXPECTED TO CONTINUE OVER MAJURO WATERS
TONIGHT. THE WEAK CIRCULATION CENTERED JUST WEST OF KWAJALEIN IS
NOT EXPECTED TO EVOLVE INTO A SIGNIFICANT DISTURBANCE AND IS
PROGGED TO WEAKEN WITHIN THE MONSOON TROUGH DURING THE NEXT COUPLE
OF DAYS.

&&

.WESTERN MICRONESIA...
QUIET WEATHER IS EXPECTED TO PERSIST OVER CHUUK AT LEAST THROUGH
TONIGHT WHILE SHOWER ACTIVITY REMAINS LARGELY TO THE EAST ACROSS
POHNPEI STATE. UNSETTLED WEATHER COULD MOVE BACK INTO THE AREA
FROM THE EAST AS LOW-LEVEL CONVERGENCE SOUTH OF THE MONSOON TROUGH
INCREASES OVER THE STATE. MODELS ARE STILL IN DISAGREEMENT IN THE
EXACT PLACEMENT AND TIMING OF MAJOR CONVECTIVE BURSTS SO
IMPORTANCE OF SHORT-TERM FORECASTING SHOULD BE EMPHASIZED. LOW-
LEVEL CONVERGENCE SOUTH OF THE MONSOON TROUGH CONTINUES TO
GENERATE SCATTERED SHOWERS ACROSS PALAU THIS AFTERNOON WHILE
SHOWERS HAVE SINCE DISSIPATED OVER YAP COASTAL WATERS. SHOWER
COVERAGE WILL GRADUALLY DECREASE OVER THE NEXT DAY OR SO OVER
KOROR BUT LARGE SCALE LOW- LEVEL CONVERGENCE AND SOME UPPER-LEVEL
FORCING WILL KEEP MOSTLY CLOUDY SKIES OVER THE REGION THROUGH THE
WEEKEND.

&&

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

$$

SIMPSON/WILLIAMS



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