262
FXPQ50 PGUM 250853
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
653 PM CHST WED FEB 25 2026
MARIANAS SYNOPSIS
SATELLITE AND RADAR IMAGERY SHOW SCATTERED SHOWERS ACROSS GUAM AND
ROTA AND ISOLATED SHOWERS ACROSS TINIAN AND SAIPAN. ALTIMETRY AND
BUOY DATA SHOW COMBINED SEAS BETWEEN 12 AND 15 FEET ACROSS THE
MARIANAS.
DISCUSSION
SHOWER ACTIVITY HAS DECREASED THROUGHOUT TODAY, BUT SATELLITE DOES
SHOW ONE MORE BAND OF SHOWERS LOCATED OVER ROTA THAT HAS SOME
ISOLATED SHOWERS IMPACTING ROTA AND THE NORTHERN COASTAL WATERS OF
GUAM. DRY CONDITIONS LOOK TO RETURN TONIGHT AND WILL PERSIST THROUGH
SATURDAY NIGHT. ANOTHER SHEAR LINE IS EXPECTED TO MAKE ITS WAY INTO
THE REGION LATE THIS WEEKEND. THIS WILL BRING A CHANCE FOR SHOWERS
TO THE MARIANAS SUNDAY AND SUNDAY NIGHT. WINDY CONDITIONS ARE
EXPECTED ACROSS SAIPAN AND TINIAN ON THURSDAY AS THE TRADE-WIND
REGIME REMAINS IN PLACE. THE WIND ADVISORY WAS EXTENDED UNTIL
THURSDAY EVENING.
MARINE
HAZARDOUS SEAS, DANGEROUS SURF, AND DEADLY RIP CURRENTS CONTINUE
ACROSS THE MARIANAS. THERE IS A GALE WARNING FOR SAIPAN AND TINIAN
FOR FREQUENT GUSTS OF 35 KNOTS IN PLACE UNTIL 7 PM THIS EVENING,
WHEN WE SHOULD SEE GUSTS BECOME OCCASIONAL INTO THE NIGHT. A
HAZARDOUS SEAS WARNING REMAINS IN EFFECT FOR GUAM AND ROTA AND WILL
GO INTO EFFECT AT 7 PM FOR TINIAN AND SAIPAN UNTIL 5 PM THURSDAY.
IPAN BUOY HAS GENERALLY BE BETWEEN 12 TO 14 FEET TODAY. DUE TO
BLOCKAGE FROM THE NORTHEAST PORTIONS OF GUAM, IPAN IS LIKELY NOT
FEELING THE FULL SEA-STATE. WITH THE ADDITION OF AN ALTIMETRY PAST
EAST OF THE MARIANAS SHOWING SEAS OF 15 TO 17 FEET, THIS WAS ENOUGH
DATA TO GO WITH A HAZARDOUS SEAS WARNING FOR GUAM COASTAL WATERS.
THE ECMWF SHOWS A BRIEF DECREASE IN SEA HEIGHT TONIGHT BUT THEN
SHOWS ANOTHER INCREASE EARLY THURSDAY MORNING. SEAS FINALLY LOOK TO
SUBSIDE DURING THE DAY TIME THURSDAY, WHICH SHOULD ALLOW FOR THE
HAZARDOUS SEAS WARNING TO BE DOWNGRADED TO A SMALL CRAFT ADVISORY.
DANGEROUS SURF IS EXPECTED TO CONTINUE THROUGH TONIGHT, BUT COULD
FALL TO HAZARDOUS LEVELS DURING THE DAY TOMORROW. HOWEVER, WIND WAVES
LOOK TO BE THE MAIN COMPONENT CONTRIBUTING TO A DECREASE IN SEAS
TOMORROW AND THE ECMWF KEEPS SWELLS ELEVATED ENOUGH THAT COULD KEEP
DANGEROUS SURF FOR EAST FACING REEFS UNTIL FRIDAY AFTERNOON.
HYDROLOGY
THE SHEAR LINE EVENT BROUGHT 2 TO 4 INCHES OF RAIN TO THE CNMI OVER
THE PAST FEW DAYS AND 1 TO 3 INCHES OF RAIN TO GUAM THIS MORNING. A
FEW FLOOD ADVISORIES WERE ISSUED FOR ROTA AND GUAM THIS MORNING.
SATELLITE IMAGERY TODAY HAS SHOWN A PERSISTENT THUNDERSTORM COMPLEX
THAT FORMED SOUTH OF GUAM AND HAS REMAINED NEARLY STATIONARY FOR MUCH
OF TODAY. THESE THUNDERSTORMS, JUST 40 TO 80 MILES SOUTH OF GUAM,
LIKELY WOULD HAVE BROUGHT TORRENTIAL RAINFALL AND A NOTABLE FLASH
FLOOD THREAT HAD IT FORMED JUST A LITTLE FURTHER NORTH AND CLOSER TO
GUAM.
MORE-SEASONABLE DRIER CONDITIONS ARE EXPECTED ACROSS THE REGION
HEADING INTO THE WEEKEND. HOWEVER, WE ARE WATCHING ANOTHER SIGNAL
THAT WOULD FAVOR ABOVE-NORMAL RAINFALL FOR THE MARIANAS AS WE HEAD
INTO THE LATTER HALF OF NEXT WEEK AND FURTHER INTO MARCH.
EASTERN MICRONESIA
SATELLITE IMAGERY THIS AFTERNOON SHOWS ACTIVE WEATHER ACROSS MUCH OF
EASTERN MICRONESIA, WITH A SPEED CONVERGENCE ZONE ACROSS POHNPEI AND
A TRADE-WIND TROUGH SLOWLY APPROACHING THE MARSHALL ISLANDS. THE
TRADE-WIND TROUGH WILL INTERACT WITH A SHEAR LINE APPROACHING FROM
THE NORTH AND SCATTERED SHOWERS WILL CONTINUE FOR THE NEXT COUPLE OF
DAYS ACROSS THE MARSHALL ISLANDS, WITH THUNDERSTORM CHANCES ALSO
INCREASING LATER THIS WEEK AS THE TWO FEATURES INTERACT. SCATTERED
SHOWERS WILL MOSTLY PREVAIL AT KOSRAE AND POHNPEI FOR THE NEXT
COUPLE OF DAYS AS THE TROUGH AND SHEAR LINE FRAGMENT PROPAGATE
EASTWARD, THOUGH A BRIEF LULL IN ACTIVITY IS POSSIBLE TONIGHT AND
EARLY THURSDAY FOR KOSRAE DUE TO DRIER AIR FILTERING IN. MODEL
GUIDANCE DIVERGENCES QUITE A BIT ON RAIN CHANCES WITH EACH OF THE
GFS AND EURO ALTERNATING ON TIMING OF HIGH RAINFALL CHANCES DURING
THE EXTENDED FORECAST, SO HAVE GENERALLY WENT TOWARD A BLENDED
APPROACH AFTER DAY 3. STRONGER WINDS ASSOCIATED WITH THE SHEAR LINE
ARE EXPECTED TO REMAIN NORTH OF 10N, THOUGH PERIODS OF MODERATE TO
FRESH WINDS ARE EXPECTED.
THE POHNPEI BUOY PEAKED THIS MORNING JUST OVER 9 FEET AND HAVE
ADJUSTED SEAS UPWARD BY A FOOT OR TWO GOING FORWARD TO ACCOUNT FOR
THE NORTH SWELL COMING IN HIGHER THAN FORECAST. THE HIGH SURF
ADVISORY FOR THE NORTH FACING REEFS OF POHNPEI WAS EXTENDED THROUGH
EARLY SUNDAY AND HAVE ADDED A HIGH SURF ADVISORY FOR THE NORTH FACING
REEFS OF KOSRAE FOR THE SAME TIME PERIOD GIVEN THE NORTH SWELL
COMING IN HIGHER THAN EXPECTED. HAVE ALSO ADDED A SMALL CRAFT
ADVISORY FOR POHNPEI'S COASTAL WATERS AS SEAS SHOULD REACH AROUND 10
FEET ON THURSDAY AND CONTINUE THROUGH AT LEAST SATURDAY NIGHT.
MEANWHILE, SEAS AT KOSRAE AND MAJURO WILL HOVER BETWEEN 6 AND 8 FEET
THROUGH THURSDAY, BEFORE INCREASING TO 7 TO 9 FEET BY THIS WEEKEND.
WESTERN MICRONESIA
WESTERN MICRONESIA WEATHER IS BEGIN AFFECTED BY TRADE-WIND
CONVERGENCE JUST EAST OF CHUUK, THE NEAR-EQUATORIAL TROUGH SOUTH OF
THE FORECAST ZONES, AND A VIGOROUS SHEAR LINE NORTH OF THE FORECAST
ZONES.
CHUUK WILL SEE NUMEROUS SHOWERS THROUGH THURSDAY, THEN SCATTERED
SHOWERS THROUGH MONDAY WITH THE EXCEPTION OF A POSSIBLE RETURN TO
NUMEROUS FRIDAY NIGHT. WINDS WILL BE EAST AT 10 TO 15 KNOTS THROUGH
SATURDAY, THEN DIMINISH TO BETWEEN 5 AND 10 KNOTS AS THE NET LIFTS
NORTHWARD TOWARD THEM. SEAS WILL BE 8 TO 10 FEET THROUGH FRIDAY
NIGHT, THEN 6 TO 8 FEET FOR THE WEEKEND, AND FINALLY 5 TO 7 FEET FOR
MONDAY. THIS WILL MAKE MARINE CONDITIONS HAZARDOUS THROUGH FRIDAY
NIGHT, CHALLENGING FOR THE WEEKEND AND PERHAPS FINALLY BECOMING
BENIGN FOR NEXT WEEK.
YAP WILL GET SCATTERED SHOWERS THROUGH MONDAY, WITH THE POSSIBLE
EXCEPTION OF A BRIEF PERIOD OF ISOLATED SHOWERS ON SATURDAY. WINDS
WILL BE NORTHEAST TO EAST AT 10 TO 15 KNOTS. SEAS WILL BE 7 TO 9 FEET
THROUGH FRIDAY NIGHT, 6 TO 8 FEET FOR THE WEEKEND, THEN 5 TO 7 FEET
FOR MONDAY. THIS WILL MAKE MARINE CONDITIONS CHALLENGING THROUGH THE
WEEKEND, AND PERHAPS FINALLY BECOMING BENIGN FOR NEXT WEEK.
KOROR, PALAU, WILL HAVE ISOLATED SHOWERS TONIGHT BECOMING SCATTERED
FOR THE REMAINDER OF THE FORECAST PERIOD, OR THROUGH MONDAY. WINDS
WILL BE NORTH TO NORTHEAST AT 5 TO 10 KNOTS THROUGH THE FORECAST
PERIOD. SEAS OF 4 TO 6 FEET WILL BUILD TO 5 TO 7 FEET TONIGHT, THEN
MAINTAIN THIS LEVEL THROUGH MONDAY. THIS WILL LEAVE MARINE CONDITIONS
BENIGN FOR KOROR, PALAU THROUGH THE PERIOD.
GUM WATCHES/WARNINGS/ADVISORIES
GU...HIGH SURF WARNING UNTIL 5 PM CHST FRIDAY FOR GUZ001.
MP...HIGH SURF WARNING UNTIL 5 PM CHST FRIDAY FOR MPZ001>003.
WIND ADVISORY UNTIL 7 PM CHST THURSDAY FOR MPZ002-003.
MARIANAS WATERS...HAZARDOUS SEAS WARNING UNTIL 5 PM CHST THURSDAY
FOR PMZ151>154.
MARIANAS: WILLIAMS
EAST: SCHANK/WHISNANT
WEST MICRONESIA: STANKO
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