216
FXPQ50 PGUM 191955
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
555 AM CHST MON APR 20 2026
MARIANAS UPDATE
A DRY AND LIGHT WIND PATTERN EXTENDS OVER THE MARIANAS DUE TO THE
INFLUENCE OF A NEARBY RIDGE. WHILE LIGHT WINDS MAY SUPPORT A SLIGHT
INCREASE IN CLOUD COVER AND ISLAND SHOWERS DURING THE AFTERNOON,
DRIER AIR ALOFT WILL LIMIT AREAL COVERAGE AND DURATION. DRY WEATHER,
LIGHT WINDS, AND LITTLE CLOUD COVER WILL EXACERBATE THE HEAT ACROSS
THE MARIANAS, ESPECIALLY IF YOU ARE SPENDING A LOT OF TIME OUTSIDE OR
IN AN AREA EXPERIENCING POWER OUTAGES WHILE IN THE RECOVERY OF POST-
SINLAKU. KEEP HYDRATED AND TAKE SEVERAL BREAKS IN THE SHADE OR IN AN
AIR CONDITION AREA IF POSSIBLE TO LIMIT THE RISK OF HEAT ILLNESS, AND
MAKE SURE TO CHECK IN ON YOUR NEIGHBORS AND THOSE MOST AT RISK TO
SUFFER FROM THE HEAT. DRY WEATHER IS EXPECTED TO CONTINUE THROUGH THE
REST OF THE WEEK, THOUGH TRADE WINDS ARE EXPECTED TO INCREASE LATER
THIS WEEK AS A RIDGE OF HIGH PRESSURE BUILDS NORTH OF WAKE ISLAND,
AND INCREASING THE PRESSURE GRADIENT ACROSS THE REGION.
COMBINED SEAS HAVE DECREASED TO 5 TO 7 FEET TODAY AND ARE EXPECTED
TO DROP AN ADDITIONAL FOOT OR TWO AS DISTANT SWELLS CONTINUE TO
SUBSIDE. THIS HAS ALLOWED SURF ALONG NORTH FACING REEFS TO DROP
BELOW 9 FEET, ENDING THE HIGH SURF ADVISORY AND ALLOWING THE RISK OF
RIP CURRENTS TO DROP FROM HIGH TO MODERATE. MARINE CONDITIONS ARE
EXPECTED TO BE FAIRLY BENIGN BY THE MIDDLE OF THE WEEK.
EASTERN MICRONESIA UPDATE
SCATTERED TO NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS EXTEND
ACROSS MOST OF THE REGION AS PASSING TRADE-WIND TROUGHS INTERACT WITH
THE FRAGMENTED INTERTROPICAL CONVERGENCE ZONE (ITCZ). THE FORECAST
HAS CHANGED VERY LITTLE OVERNIGHT, WITH SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS PERSISTING AT ALL THE FORECAST SITES THROUGH
INTO TONIGHT, WITH SHOWER EXPECTED TO BECOME ISOLATED AT MAJURO
TUESDAY AS THE ITCZ CONTINUES TO WEAKEN AND TRADE-WIND TROUGH SHIFT
WESTWARD. MOSTLY GENTLE TO MODERATE EAST TO SOUTHEAST WINDS WILL
CONTINUE AT ALL THREE FORECAST SITES TODAY, WITH A BRIEF PERIOD OF
LIGHT TO GENTLE SOUTH TO SOUTHWEST WINDS TONIGHT AND TUESDAY. LIGHT
TO GENTLE EAST TO NORTHEAST WINDS ARE EXPECTED TO DEVELOP STARTING
LATE TUESDAY AND WILL INCREASE LATE THIS WEEK AS A RIDGE OF HIGH
PRESSURE BUILDS NORTH OF WAKE ISLAND.
COMBINED SEAS OF 4 TO 6 FEET WILL CONTINUE TO DIMINISH THIS WEEK,
EVENTUALLY DROPPING ANOTHER FOOT OR SO BY MIDWEEK. SEAS ARE EXPECTED
TO INCREASE LATE THIS WEEK AS A NORTHEAST SWELL BUILDS INTO THE
REGION.
WESTERN MICRONESIA UPDATE
SCATTERED SHOWER AND ISOLATED THUNDERSTORMS ARE MOVING INTO CHUUK
LAGOON THIS MORNING, ALONG A TRADE-WIND TROUGH ON THE LEADING EDGE OF
THE FRAGMENTING ITCZ. A SERIES OF TRADE-WIND TROUGHS WITHIN THE
FRAGMENTING ITCZ WILL SUPPORT PERIODS OF SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS ACROSS CHUUK THROUGH THE REST OF THE WEEK.
ACROSS PALAU AND YAP A LIGHT WIND AND DRY WEATHER PATTERN EXTENDS
ACROSS PALAU AND YAP, THOUGH LIGHT WINDS MAY SUPPORT ISLAND SHOWERS
THIS AFTERNOON DUE TO ISLAND HEATING, THOUGH DRIER AIR ALOFT WILL
LIMIT OVERALL AREAL COVERAGE AND DURATION OF SHOWERS. PALAU AND YAP
WILL LIKELY REMAIN IN THIS DRY PATTERN FOR MOST OF THE WEEK BEFORE A
TROUGH BEGINS TO MOVE INTO YAP AND PALAU AROUND FRIDAY.
NORTH-NORTHEAST SWELL FROM DISTANT TROPICAL STORM SINLAKU CONTINUES
TO MOVE ACROSS YAP AND PALAU, BRINGING ELEVATED SURF ALONG NORTH AND
EAST FACING REEFS OVER THE NEXT FEW DAYS. THE HIGH SURF ADVISORY AND
A COASTAL FLOOD STATEMENT FOR NORTH FACING REEFS OF YAP REMAIN IN
EFFECT THROUGH LATE TONIGHT. HAZARDOUS SURF OF 8 TO 10 FEET,
COMBINED WITH THE HIGHER HIGH TIDES FOLLOWING THE NEW MOON, MAY
PRODUCE MINOR COASTAL INUNDATION ALONG NORTHERN SHORELINES AT TIMES
OF HIGH TIDE. COMBINED SEAS OF 6 TO 8 FEET GRADUALLY SUBSIDE TO 3 TO
5 FEET TOWARDS THE MIDDLE OF NEXT WEEK AS NORTH TO NORTHEAST SWELLS
SUBSIDE.
PREV DISCUSSION
/ISSUED 549 PM CHST SUN APR 19 2026/
MARIANAS SYNOPSIS...
LIGHT TO GENTLE SOUTHERLIES PREVAIL ACROSS THE MARIANAS. SATELLITE
IMAGERY AND DOPPLER RADAR INDICATE FLATTENING OF THE LIGHT ISLAND
SHOWERS OVER GUAM AND SAIPAN. TANAPAG BUOY SHOWS SEAS ARE JUST BELOW
9 FEET.
DISCUSSION...
A RIDGE HAS SETTLED OVER THE MARIANAS AS TS SINLAKU (04W) EXITED NWS
GUAM'S AREA OF RESPONSIBILITY (AOR) TO THE NORTH-NORTHEAST PAST
MINAMITORISHIMA, ALLOWING LIGHT ISLAND SHOWERS TO FORMER ALONG THE
AXIS OF GUAM AND SAIPAN. WHILE SHOWERS WILL REMAIN MINIMAL OVERNIGHT
AS MOSTLY CLEAR SKIES DEVELOP, THERE IS A CHANCE FOR THE LIGHT HAZE
OBSERVED THE LAST FEW DAYS TO CONTINUE INTO THE NIGHT. LITTLE TO NO
SHOWERS AND CLOUD COVER THE NEXT FEW DAYS MAY EXACERBATE THE HEAT
ACROSS THE MARIANAS AS POWER OUTAGES CONTINUE TO PLAQUE MOST
RESIDENTS AS RECOVERY EFFORTS CONTINUE POST-SINLAKU. HYDRATION AND
DECREASED DAYTIME EXPOSURE TO THE SUN WILL HELP ALLEVIATE HEAT
EXHAUSTION RISKS, ESPECIALLY FOR THE MORE VULNERABLE POPULATIONS. A
GENTLE TO MODERATE TRADE-WIND PATTERN IS EXPECTED TO RETURN SOMETIME
IN THE SECOND HALF OF THE WEEK AS A SECOND HIGH-PRESSURE RIDGE MOVES
IN FOLLOWING A DISINTEGRATING SINLAKU WELL NORTH OF WAKE ISLAND.
MARINE...
COMBINED SEAS OF 7 TO 9 FEET ARE EXPECTED TO DECREASE BY SEVERAL FEET
OVER THE NEXT SEVERAL DAYS AS VARIOUS DISTANT SWELLS WEAKEN
CONSIDERABLY. AS SUCH, SEAS ARE NO LONGER EXPECTED TO BE HAZARDOUS TO
SMALL CRAFT BEGINNING TONIGHT, SO A SMALL CRAFT ADVISORY WAS ALLOWED
TO BE EXPIRED. EVEN SO, SEAS WILL REMAIN CHOPPY OVERNIGHT AS WEAKER
PULSES FROM DISTANT SINLAKU CONTINUE TO MAKE THEIR WAY ACROSS THE
REGION. AS SINLAKU CONTINUES TO MOVE AWAY TO THE NORTH-NORTHEAST,
THE PRIMARY SWELL HAS SHIFTED TO THE NORTH AND DECREASED, ALLOWING
SURF TO FALL BELOW HAZARDOUS LEVELS ALONG WEST AND SOUTH FACING REEFS
WHILE REMAINING HAZARDOUS ALONG NORTH FACING REEFS OVERNIGHT. AS
SUCH, SURF IS EXPECTED TO REMAIN BELOW HAZARDOUS LEVELS ALONG SOUTH
AND WEST FACING REEFS BEGINNING TONIGHT, AS WELL AS THE RIP CURRENT
RISK DROPPING TO MODERATE ALONG SAID REEFS. HAZARDOUS SURF AND A HIGH
RIP CURRENT RISK WILL REMAIN ALONG NORTH FACING REEFS OF THE
MARIANAS OVERNIGHT. SURF IS LIKELY TO FURTHER DECREASE ALONG ALL
REEFS THE NEXT SEVERAL DAYS, ALLOWING THE RIP CURRENT RISK TO DROP
FURTHER ALONG ALL REEFS AND SURF TO DROP BELOW HAZARDOUS LEVELS ALONG
NORTH FACING REEFS MONDAY.
EASTERN MICRONESIA...
A TRADE-WIND TROUGH IS CURRENTLY INTERACTING WITH THE FRAGMENTED ITCZ
ACROSS PORTIONS OF EASTERN MICRONESIA THIS AFTERNOON. NUMEROUS
SHOWERS AND ISOLATED THUNDERSTORMS ARE OBSERVED CENTERED ROUGHLY
AROUND KOSRAE AND THIS WILL CONTINUE THROUGH THE EVENING HOURS.
CONDITIONS SHOULD IMPROVE TO SCATTERED SHOWERS AFTER MIDNIGHT AS THE
TRADE-WIND TROUGH PROPAGATES WESTWARD AND WEAKENS. THOUGH, THE
ISOLATED THUNDERSTORM THREAT WILL PERSIST OVERNIGHT. SCATTERED
SHOWERS, ALONG WITH ISOLATED THUNDERSTORMS, CAN BE EXPECTED AT
POHNPEI OVERNIGHT AS THE WEAKENING TROUGH APPROACHES. ANOTHER TRADE-
WIND TROUGH EAST OF THE MARSHALL ISLANDS WILL BRING SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS TO EASTERN MICRONESIA OVER THE NEXT
COUPLE OF DAYS AS IT PROPAGATES WESTWARD AND INTERACTS WITH THE
WEAKENING ITCZ FRAGMENTS, FIRST AT MAJURO, THEN KOSRAE, AND
POTENTIALLY POHNPEI. MOSTLY SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS WILL PERSIST AT ALL THE FORECAST SITES THROUGH EARLY
THIS WEEK WITH A FEW PERIODS OF ONLY ISOLATED SHOWERS POSSIBLE.
MOSTLY GENTLE TO MODERATE EAST TO SOUTHEAST WINDS WILL CONTINUE AT
ALL THREE FORECAST SITES THROUGH MOST OF MONDAY, WITH A BRIEF PERIOD
OF LIGHT TO GENTLE SOUTH TO SOUTHWEST WINDS MONDAY NIGHT AND TUESDAY.
LIGHT TO GENTLE EAST TO NORTHEAST WINDS ARE EXPECTED TO DEVELOP
STARTING LATE ON TUESDAY AND WILL INCREASE LATE THIS WEEK.
COMBINED SEAS OF 4 TO 6 FEET WILL CONTINUE TO DIMINISH THIS WEEK,
EVENTUALLY DROPPING ANOTHER FOOT OR SO BY MIDWEEK. SEAS ARE EXPECTED
TO INCREASE LATE THIS WEEK AS A NORTHEAST SWELL BUILDS INTO THE
REGION.
WESTERN MICRONESIA...
A VERY QUIET PATTERN PERSISTS ACROSS THE REGION, WITH SATELLITE
IMAGERY DEPICTING MOSTLY CLEAR CONDITIONS ACROSS MUCH OF WESTERN
MICRONESIA THIS AFTERNOON. DESPITE FAIRLY LOW PWATS, BRIEF ISLAND-
EFFECT SHOWERS DEVELOPED OVER THE MAJOR ISLANDS OF PALAU AND OVER YAP
PROPER EARLIER IN THE DAY, WITH THIS MORNING'S SCATTEROMETRY
INDICATING A VERY LIGHT WIND FIELD ACROSS THE ENTIRE REGION. CHUUK
REMAINS IN A QUIET RIDGING ENVIRONMENT BETWEEN WEAK TROUGHS CENTERED
JUST WEST OF POHNPEI AND SOUTHEAST OF THE MARIANAS.
LATEST MODEL GUIDANCE INDICATES HEAVY SHOWERS DEVELOPING EAST OF
CHUUK LATE TONIGHT AS CONVERGENCE INCREASES ALONG THE APPROACHING
TROUGH ON THE FAR WESTERN PERIPHERY OF THE ITCZ, LOCATED JUST EAST
OF THE COASTAL WATERS. THE ITCZ, OR ITCZ FRAGMENTS, LOOK TO
GRADUALLY PUSH WEST INTO CHUUK STATE OVER THE NEXT FEW DAYS AS
INDIVIDUAL EMBEDDED TROUGHS WAX AND WANE, MAINTAINING AT LEAST
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS FOR MUCH OF THE COMING
WEEK. THESE FEATURES WILL LEAD TO INCREASING SHOWER AND THUNDERSTORM
CHANCES TOWARD THE END OF THE WEEK FOR YAP AND PALAU AS WELL. IN THE
MEANTIME, A VERY DRY, QUIET PATTERN WILL CONTINUE ACROSS FAR WESTERN
MICRONESIA. TOMORROW AFTERNOON PRESENTS ANOTHER OPPORTUNITY FOR
ISLAND-EFFECT SHOWERS OVER YAP AND PALAU WITH THE CONTINUATION OF
VERY LIGHT WINDS, DESPITE OVERALL LIMITED ATMOSPHERIC MOISTURE.
NORTH-NORTHEAST SWELL FROM DISTANT TROPICAL STORM SINLAKU CONTINUES
TO MOVE ACROSS YAP AND PALAU, BRINGING ELEVATED SURF ALONG NORTH AND
EAST FACING REEFS OVER THE NEXT FEW DAYS. THE HIGH SURF ADVISORY AND
A COASTAL FLOOD STATEMENT WAS EXTENDED FOR NORTH FACING REEFS OF YAP
THROUGH LATE MONDAY NIGHT. HAZARDOUS SURF OF 8 TO 11 FEET, COMBINED
WITH THE HIGHER HIGH TIDES WITH THE NEW MOON CYCLE, MAY PRODUCE MINOR
COASTAL INUNDATION ALONG NORTHERN SHORELINES AT TIMES OF HIGH TIDE.
COMBINED SEAS OF 6 TO 8 FEET GRADUALLY SUBSIDE TO 3 TO 5 FEET
TOWARDS THE MIDDLE OF NEXT WEEK AS NORTH TO NORTHEAST SWELLS SUBSIDE.
GUM WATCHES/WARNINGS/ADVISORIES
GU...NONE.
MP...NONE.
MARIANAS WATERS...NONE.
MARIANAS/EAST AND WEST MICRONESIA UPDATE: SCHANK
MARIANAS: MONTVILA
EAST MICRONESIA: WHISNANT
WEST MICRONESIA: DECOU
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page