Area Forecast Discussion
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FXPQ60 PGUM 210820
AFDPQ

AREA FORECAST DISCUSSION...ADDED MICRONESIAN DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
605 PM CHST THU AUG 21 2014

.MARIANAS SYNOPSIS...
AN ELONGATED AND EXTREMELY WEAK SURFACE TROUGH IS EVIDENT ON
VISIBLE SATELLITE IMAGERY OVER THE MARIANAS. WINDS WERE LIGHT WNW
EARLIER ON GUAM AND ESE ON TINIAN AND SAIPAN...BUT WINDS HAVE
BECOME LIGHT AND VARIABLE IN THE LAST HOUR OR TWO. MEANWHILE...AN
UPPER-LEVEL LOW IS SEEN IN WATER VAPOR IMAGERY CENTERED AROUND
12N151E...MOVING WEST.

&&

.DISCUSSION...
MODELS SHOW THE WEAK CIRCULATION BREAKING DOWN OVERNIGHT INTO A WEAK
TROUGH ON FRIDAY...WHILE THE WESTWARD-MOVING UPPER LOW OPENS INTO A
TROUGH AS IT PASSES OVER THE ISLANDS ON FRIDAY. WITH ADEQUATE
MOISTURE STILL IN THE MID-LEVELS...THIS IS ENOUGH TO KEEP ISOLATED
THUNDERSTORMS IN THE FORECAST TONIGHT...AND HAVE EXTENDED THEM
THROUGH FRIDAY AS THE UPPER TROUGH MOVES BY AND ISLAND HEATING WITH
LIGHT WINDS PROVIDES AN EXTRA BOOST. THE REST OF THE FORECAST
REMAINS THE SAME AS PREVIOUS...PARTLY CLOUDY SKIES AND ISOLATED
SHOWERS--UNUSUALLY DRY FOR AUGUST.

&&

.EASTERN MICRONESIA...
A SURFACE TROUGH RUNNING FROM ABOUT 11N165E TO 1N154E IS WEAKENING
AS IT MOVES WESTWARD. THE MODELS INDICATE HIGH PRESSURE IS BUILDING
JUST EAST OF THE TROUGH FOR A SHORT WHILE UNTIL OTHER TROUGHS MOVE
IN AT INTERVALS BEHIND IT. TONIGHT AT MAJURO THERE IS A SURFACE
TROUGH JUST TO THE EAST FOLLOWED BY A CONVERGENCE ZONE. THE MODELS
SHOW THE CONVERGENCE ZONE AND WEAK TROUGHS AFFECTING MAJURO AFTER
TONIGHT. THIS EVENING KOSRAE IS ON THE TRAILING EDGE OF CLOUD COVER
AROUND THE WEAKENING TROUGH WITH A RIDGE TO THE EAST. THE MODELS
INDICATE THE RIDGE WILL AFFECT KOSRAE FRIDAY AND FRIDAY NIGHT...THEN
WEAK TROUGHS AND WEAK RIDGES WILL FOLLOW. POHNPEI IS EXPERIENCING
THE WEAKENED TROUGH THEN FOLLOWED BY ADDITIONAL WEAKENING FRIDAY
WITH RIDGING TO THE SOUTH.

&&

.WESTERN MICRONESIA...
NO MAJOR CHANGES TO THE INHERITED FORECAST FOR WESTERN MICRONESIA.
THE MONSOON TROUGH NORTH OF 10N CONTINUES TO BE THE PRIMARY WEATHER
INFLUENCE OVER THE REGION. MAINLY LIGHT WINDS ARE EXPECTED ACROSS
THE REGION. CHUUK IS ON THE EDGE OF CLOUD COVER WITH THUNDERSTORMS
NEARBY TO THE WEST. WHAT FOLLOWS AT CHUUK WILL BE WEATHER SIMILAR TO
POHNPEI. YAP IS IN AN AREA OF CONVERGENCE BETWEEN HIGH PRESSURE TO
THE SOUTH AND A CIRCULATION TO THE NORTHEAST. A RIDGING PATTERN IS
EXPECTED TO BE NEAR KOROR THROUGH THE WEEKEND.

&&

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

$$

MIDDLEBROOKE/DEVITA








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