285
FXPQ50 PGUM 120800 CCA
AFDGUM
AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE TIYAN GU
600 PM CHST TUE AUG 12 2025
CORRECTED A TYPO IN MARIANAS SYNOPSIS.
MARIANAS SYNOPSIS
OVER GUAM, PARTLY CLOUDY SKIES REIGN WITH ISOLATED SHOWERS. OVER
CNMI, MOSTLY CLOUDY SKIES WITH SCATTERED SHOWERS DIMINISHING TO
ISOLATED. OVERALL THE WEATHER IS BECOMING MORE STABLE.
DISCUSSION
THE FAIRLY TAME WEATHER IS IN STORE FOR THE MARIANA. THE MAIN
CONCERNS ARE FOR ISLAND CONVECTION AND THE TUTT OVER HEAD. SHOWERS
TONIGHT ARE ANTICIPATED TO BE THE LOW TO MID RANGE FOR SCATTERED
WITH THE MOST SHOWERS OVER CNMI. OVER THE REST OF THE FORECAST
PERIOD, ISLAND HEATING IS ANTICIPATED TO PRODUCING ENOUGH UPWARD LIFT
TO IGNITE ISLAND CONVECTION. AS FOR THE TUTT MODELS DID NOT INDICATE
MUCH WEATHER FORCING TO TAKE PLACE, HOWEVER A PASSING TROUGH OR SOME
VERY CALM WIND DAYS COULD CHANGE THAT.
MARINE
LIGHT TO GENTLE WINDS ARE EXPECTED THROUGH THE WEEK. COMBINED SEAS
OF 3 TO 4 FEET WILL SLOWLY SUBSIDE, DROPPING TO BETWEEN 2 AND 3 FEET
TONIGHT. THE TRADE-WIND SWELL HAS CONTINUED TO SUBSIDE, ALLOWING THE
SURF TO FALL BY A FOOT. THIS HAS DROPPED THE RIP CURRENT RISK TO LOW
ALONG ALL REEFS. AN UPPER-LEVEL LOW WILL PRODUCE ISOLATED
THUNDERSTORMS THROUGH AT LEAST WEDNESDAY.
EASTERN MICRONESIA
THE MAIN "EYE'CATCHER" IS A CIRCULATION LOCATED NORTHEAST OF MAJURO
WHICH SHOWS A LOW-LEVEL CIRCULATION CENTER ON VISIBLE SATELLITE
IMAGERY AND SCATTEROMETER ANALYSIS. HOWEVER, THIS FEATURE IS IN A
HOSTILE ENVIRONMENT, AS 0-6KM WIND SHEAR IS NEAR 30 KNOTS. THUS, NO
STRENGTHENING OF THE CIRCULATION IS EXPECTED. THAT SAID, SHOWER AND
THUNDERSTORM POTENTIAL WILL INCREASE FOR PORTIONS OF THE RMI NEAR
KWAJALEIN, AS THE CENTER CONTINUES WESTWARD ALONG 10N IN THE COMING
DAYS.
FOR MAJURO, IT'S TOO FAR NORTH TO AMOUNT FOR ANYTHING THAN ISOLATED
SHOWERS OR THUNDERSTORMS. LATER IN THE WEEK, THE MODELS INDICATE
SOMEWHAT BETTER CONVERGENCE AND MOISTURE FOR KOSRAE AND POHNPEI, BUT
WE'RE SKEPTICAL OF THIS. FOR NOW, WE'LL HAVE LOW-END SCATTERED
SHOWER COVERAGE WITH 30 PERCENT PROBABILITIES WEDNESDAY NIGHT AT
KOSRAE, AND STARTING THURSDAY FOR POHNPEI.
OTHERWISE, WE'LL HAVE TO WAIT FOR ANY COMBINATION OF INCREASING
MOISTURE AND CONVERGENCE TOWARDS THE END OF THE WEEK TO HAVE A
POTENTIALLY BETTER POTENTIAL FOR RAINFALL AREA-WIDE. A PRONOUNCED
DISTURBANCE EAST OF THE DATE LINE NEAR 170W SHOULD ALSO MOVE INTO
MAJURO'S REGION TOWARDS THE LATTER HALF OF THE WEEK, HEADING WEST
INTO THE WEEKEND.
MAINLY LIGHT TO GENTLE WINDS WITH SEAS OF 3 TO 5 FEET AT KOSRAE ARE
EXPECTED AT KOSRAE. FOR POHNPEI, LIGHT TO GENTLE WINDS MAY BRIEFLY
BECOME MODERATE FROM TIME TO TIME, AND SEAS OF 3 TO 5 FEET MAY
INCREASE A FOOT AS WE HEAD TOWARDS THE WEEKEND.
WESTERN MICRONESIA
WESTERN MICRONESIA HAS A TRADE-WIND TROUGH IN THE EASTERN PORTIONS
AND A RIDGE CREATING SURFACE CONVERGENCE IN THE WESTERN PORTIONS.
ASCAT SHOWS WINDS LESS THAN 15 KNOTS ACROSS THE AREA, AND THOSE 10 TO
15 KNOT BARBS ARE JUST IN A SMALL AREA SOUTH OF KOROR. SO 10 KNOTS OR
LESS IS THE RULE FOR ALL THE MAJOR ISLANDS TONIGHT, AND AS WE SHALL
SEE, ALSO IN THE COMING DAYS. AS A RESULT, SEAS ARE NOT ALL THAT HIGH
EITHER, JUST A BIT CHANGEABLE IN DIRECTION AT PALAU, WHICH IS ON THE
BORDER BETWEEN THE TRADE SWELL AND THE MONSOON SWELL. THE MAIN
FORECAST CHALLENGE HAS JUST BEEN TRYING TO TIME SHOWERS.
FOR CHUUK, ISOLATED SHOWERS WILL CONTINUE THROUGH WEDNESDAY, THEN A
WEAK TROUGH COULD BRING THEM UP TO SCATTERED WEDNESDAY NIGHT. SHOWERS
WILL THEN BE ISOLATED AGAIN THURSDAY THROUGH FRIDAY, THEN ARE LIKELY
TO START BUILDING FOR THE WEEKEND BACK TO SCATTERED LEVELS. WINDS
WILL BE CAPPED AT 10 KNOTS THROUGH FRIDAY, THEN COULD TOUCH 15 KNOTS
OVER THE WEEKEND. SEAS OF 3 TO 4 FEET COULD BUILD TO BETWEEN 3 AND 5
FEET OVER THE WEEKEND.
A TROUGH TO THE NORTHWEST OF A RIDGE IS PROMOTING SCATTERED SHOWERS
OVER YAP TONIGHT. THIS TROUGH WILL RETREAT TO THE NORTHWEST AS THE
RIDGE MOVES IN, MAKING THE SHOWERS ISOLATED WEDNESDAY THROUGH
THURSDAY NIGHT. DISTURBANCES WILL THEN MAKE SCATTERED SHOWERS FOR
FRIDAY AND SUNDAY, WITH A SHORT BREAK ON SATURDAY. WINDS WILL BE
CAPPED AT 10 KNOTS, AND SEAS WILL BE 3 FEET FOR THE ENTIRE PERIOD.
FOR KOROR, PALAU, A TROUGH NORTHWEST OF THE RIDGE THAT'S MOVING IN
WILL CAUSE SCATTERED SHOWERS TONIGHT. WINDS CONVERGING INTO THE RIDGE
WILL CONTINUE TO CAUSE SCATTERED SHOWERS WEDNESDAY NIGHT, WITH SHORT
BREAKS WEDNESDAY AND THURSDAY. A PASSING DISTURBANCE WILL CAUSE
SCATTERED SHOWERS THURSDAY NIGHT AND FRIDAY, THEN AFTER A SHORT BREAK
ON SATURDAY, ANOTHER DISTURBANCE WILL BRING MORE SCATTERED SHOWERS ON
SUNDAY. WINDS WILL BE CAPPED AT 5 KNOTS THROUGH FRIDAY, THEN 10
KNOTS FOR THE WEEKEND. SEAS WILL BE 2 FEET TONIGHT, THEN AROUND 3
FEET WEDNESDAY THROUGH SATURDAY, THEN DIMINISH BACK TO 2 FEET FOR
SUNDAY.
GUM WATCHES/WARNINGS/ADVISORIES
GU...NONE.
MP...NONE.
MARIANAS WATERS...NONE.
MARIANAS: BOWSHER
EAST MICRONESIA: DOLL
WEST MICRONESIA: STANKO
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