378
FXPQ50 PGUM 261936
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
536 AM CHST MON APR 27 2026
MARIANAS UPDATE
SATELLITE AND RADAR OBSERVATIONS SHOW LOW-END SCATTERED SHOWERS
ACROSS GUAM AND ROTA THIS MORNING. ALTIMETRY AND BUOY DATA SHOW
COMBINED SEAS BETWEEN 5 FEET. THE ONLY CHANGE WITH THIS FORECAST WAS
TO REDUCE POPS FROM 40% TO 30% TODAY. SATELLITE IS NOT TOO IMPRESSIVE
WITH THE WEAK TROUGH THAT IS MOVING OVER THE MARIANAS AND SOME OF THE
LATEST GUIDANCE IS BACKING OFF ON RAINFALL. THERE STILL LOOKS TO BE A
CHANCE FOR A CONCENTRATED DOWNPOUR OVER PORTIONS OF THE ISLANDS AND
COASTAL WATERS TODAY AND TONIGHT.
NO CHANGES WERE MADE TO THE MARINE FORECAST. COMBINED SEAS OF 5 TO 7
FEET WILL RISE ANOTHER 1 TO 2 FEET OVER THE NEXT COUPLE OF DAYS. SEA
CONDITIONS LOOK TO REMAIN BELOW HAZARDOUS TO SMALL CRAFT, BUT COASTAL
CONDITIONS COULD PRODUCE A HIGH RISK OF RIP CURRENTS ALONG EAST
FACING REEFS AND HAZARDOUS SURF ALONG NORTH FACING REEFS LATER THIS
WEEK.
EASTERN MICRONESIA UPDATE
EASTERN MICRONESIA REMAINS VERY ACTIVE WITH WIDESPREAD SHOWERS AND
ISOLATED TO SCATTERED THUNDERSTORMS SEEN ACROSS THE REGION. THESE
SHOWERS AND THUNDERSTORMS ARE SOUTH OF POHNPEI AND MAJURO, BUT HAVE
BEEN IMPACTING KOSRAE OVERNIGHT. GUIDANCE SHOWS THIS PATTERN LIFTING
NORTHWARD AS A POTENTIAL DISTURBANCE BEGINS TO DEVELOP THIS WEEK.
MARINE CONDITIONS WILL GENERALLY BE BENIGN OUTSIDE OF SHOWERS AND
THUNDERSTORMS WITH COMBINED SEAS BETWEEN 4 AND 7 FEET, AND CHOPPY
WITHIN SHOWERS AND THUNDERSTORMS.
WESTERN MICRONESIA UPDATE
NO CHANGES WERE MADE WITH THIS FORECAST PACKAGE. A LULL IN SHOWERS
ACTIVITY IS ONGOING ACROSS WENO, YAP PROPER, AND PALAU. A COMPLEX OF
SHOWERS AND THUNDERSTORMS WERE SEEN ACROSS SOUTHEASTERN YAP STATE
THIS MORNING. A WEAK CIRCULATION IS ASSOCIATED WITH THIS CONVECTION.
THIS SYSTEM WILL MOVE TO THE WEST-NORTHWEST, BRINGING INCREASED
SHOWER ACTIVITY TODAY PALAU AND YAP.
COMBINED SEAS ARE BETWEEN 4 AND 7 FEET ACROSS THE REGION. LITTLE
CHANGE IN SEA STATE IS EXPECTED OVER THE NEXT FEW DAYS, BUT SHOWERS
AND THUNDERSTORMS COULD CAUSE LOCALLY CHOPPY SEAS THAT WOULD MAKE
TRAVEL BY BOAT DIFFICULT.
PREV DISCUSSION
/ISSUED 514 PM CHST SUN APR 26 2026/
MARIANAS SYNOPSIS...
MODERATE TO FRESH NORTHEASTERLIES PREVAIL ACROSS THE REGION, AS
SATELLITE IMAGERY INDICATES A BROAD TRADE-WIND TROUGH MAKING ITS WAY
TOWARD THE MARIANAS FROM THE EAST. BUOYS SHOW SEAS ARE ABOUT 5 FEET.
DISCUSSION...
THE TRADE-WIND TROUGH JUST UPSTREAM IS EXPECTED TO BRING MODERATE
SCATTERED SHOWERS TO THE AREA AFTER MIDNIGHT TONIGHT. AFTER, A
THUNDERSTORM OR TWO IS EXPECTED TO DEVELOP BEFORE MONDAY AFTERNOON
ONCE THE SHARPEST PART OF THE TROUGH MAKES IT ACROSS THE ISLANDS AND
INTERACTS WITH A MINOR UPPER LOW OVERHEAD. SHOWERS WILL THEN TAPER
DOWN BEFORE MIDWEEK AS WINDS INCREASE, WITH A WETTER TREND LIKELY TO
RETURN BY THE NEXT WEEKEND.
MARINE...
COMBINED SEAS OF 5 TO 7 FEET WILL INCREASE A FOOT OR TWO AROUND
MIDWEEK AS A SECONDARY NORTHERLY SWELL ARRIVES TO THE AREA.
A MODERATE RISK OF RIP CURRENTS IS EXPECTED ALONG NORTH AND EAST
FACING REEFS OF THE MARIANAS FOR AT LEAST THE NEXT FEW DAYS.
A STRENGTHENING TRADE SWELL AND HIGHER WIND WAVES MAY PRODUCE A HIGH
RISK OF RIP CURRENTS ALONG EAST FACING REEFS BY THE MIDDLE OF THIS
WEEK.
EASTERN MICRONESIA...
LATEST SATELLITE IMAGERY SHOWS MOSTLY CLOUDY TO CLOUDY SKIES ACROSS
THE REGION WITH SCATTERED TO NUMEROUS SHOWERS AND ISOLATED
THUNDERSTORMS. ALTIMETRY SHOWS SEAS OF 5 TO 7 FEET ACROSS THE
REGION.
AN UNSETTLED WET PATTERN IS EXPECTED ACROSS EASTERN MICRONESIA FOR
THE NEXT SEVERAL DAYS. A DEVELOPING NEAR-EQUATORIAL TROUGH (NET) IS
SEEN FROM SOUTH OF POHNPEI AND KOSRAE TO WELL SOUTH OF KWAJALEIN.
THERE ARE A COUPLE OF WEAK CIRCULATIONS SEEN ALONG THE NET AS WELL.
TO THE SOUTH OF MAJURO, AN INTER-TROPICAL CONVERGENCE ZONE (ITCZ)
FRAGMENT IS ALSO EVIDENT. THESE FEATURES LOOK TO DOMINATE THE
PATTERN ACROSS EASTERN MICRONESIA FOR THE NEXT SEVERAL DAYS. A WEAK
TRADE-WIND TROUGH MOVING THROUGH THE MARSHALL ISLANDS NORTH OF THE
ITCZ IS INTERACTING WITH THE ITCZ TO GENERATE NUMEROUS SHOWERS AND
ISOLATED THUNDERSTORMS ACROSS THE MARSHALLS THIS AFTERNOON. AS THE
TROUGH SLOWLY MOVES WEST, IT LOOKS TO KEEP AN OVERALL UNSTABLE
PATTERN ACROSS MAJURO, WITH SCATTERED TO NUMEROUS SHOWERS EXPECTED
THROUGH THE MIDDLE OF THE WEEK. AROUND MIDWEEK, SHOWERS MAY DECREASE
A BIT, HOWEVER, IT LOOKS LIKELY THE WET PATTERN WILL CONTINUE, WITH
AT LEAST A 50 PERCENT CHANCE OF SHOWERS THROUGH THE END OF THE WEEK.
FOR KOSRAE AND POHNPEI, A WET PATTERN IS ALSO LIKELY THROUGH THE END
OF THE WEEK. THE NET LOOKS TO SLOWLY DEVELOP OVER THE NEXT FEW DAYS
AS THE WEAK CIRCULATIONS MEANDER AROUND THE REGION. MODEL GUIDANCE
DIFFERS GREATLY ON WHAT WILL HAPPEN OVER THE COMING DAYS, WITH THE
GEFS AND GFS WANTING TO DEVELOP A COUPLE OF CIRCULATIONS OVER THE
NEXT WEEK WHILE THE ECMWF DETERMINISTIC AND ENSEMBLE ARE A BIT MORE
WEAKER WITH THIS PATTERN. HOWEVER, BOTH ECMWF MODELS AND GEFS/GFS
SHOW A VERY WET PATTERN FROM TODAY THROUGH AT LEAST MIDWEEK.
UNFORTUNATELY, CONFIDENCE IS FAIRLY LOW ON WHAT COULD COME FROM THIS
PATTERN, SO DECIDED TO KEEP POPS (PROBABILITY OF PRECIPITATION) AT 50
TO 70 PERCENT THROUGH MIDWEEK. POPS COULD INCREASE OVER THE NEXT
COUPLE OF DAYS DEPENDING ON HOW THE OVERALL PATTERN DEVELOPS.
FOR THE MARINE CONDITIONS, COMBINED SEAS LOOK TO BE AROUND 3 TO 6
FEET FOR KOSRAE AND POHNPEI THROUGH THE END OF THE WEEK, WITH SEAS
INCREASING A BIT IN THE LATTER HALF OF THE WEEK AT MAJURO. GENTLE TO
MODERATE WINDS LOOK TO BECOME LIGHT TO GENTLE AROUND MIDWEEK.
WESTERN MICRONESIA...
AN UNSETTLED WEATHER PATTERN CONTINUES TO DEVELOP OVER CHUUK STATE.
VISIBLE SATELLITE THIS AFTERNOON SHOWS SCATTERED TO NUMEROUS SHOWERS
AND ISOLATED THUNDERSTORMS ACROSS THE REGION, FOCUSED ALONG THE NET
AXIS ACROSS SOUTHERN CHUUK AND SOUTHEASTERN YAP STATES, ROUGHLY
CONCENTRATED ALONG 2N. WITHIN THE NET, THE BEGINNINGS OF A WEAK,
LOPSIDED LOW-LEVEL CIRCULATION ARE TAKING SHAPE, CENTERED SOMEWHERE
AROUND 4N152E TO THE SOUTH OR SOUTH-SOUTHEAST OF WENO, CHUUK. A
BROAD TRADE-WIND TROUGH, CURRENTLY LOCATED JUST EAST OF MARIANAS
COASTAL WATERS, EXTENDS SOUTHWARD INTO THIS DISTURBANCE. MUCH DRIER
TRADE-WIND CONDITIONS PREVAIL FARTHER WEST OVER PALAU AND YAP
PROPER. AN EXTENSIVE, BUT SHALLOW LINE OF SHOWERS EXTENDS EAST-
SOUTHEAST ACROSS MUCH OF WESTERN MICRONESIA ALONG AN AREA OF TRADE-
WIND CONVERGENCE, NOW SWEEPING SOUTHWEST OVER THE MAJOR ISLANDS OF
PALAU.
THESE FEATURES WILL MAINTAIN SCATTERED SHOWERS FOR PALAU (30
PERCENT CHANCE) AND CHUUK (40 PERCENT CHANCE) THROUGH TONIGHT, WITH A
SLIGHT DECREASE IN SHOWER CHANCES EXPECTED ACROSS THE REGION THROUGH
MONDAY NIGHT AS THE WEAK DISTURBANCE (AND CONNECTED TRADE-WIND
TROUGH) SHIFT WESTWARD INTO FAR EASTERN YAP STATE. THEREAFTER,
SHOWERS WILL INCREASE FOR PALAU AND YAP THROUGH THE END OF THE WEEK
AS THE DISTURBANCE LURCHES SLOWLY WEST-NORTHWEST INTO THE AREA.
LATEST MODEL GUIDANCE DEPICTS A PEAK IN SHOWERS AROUND THURSDAY,
MAINLY FOR YAP ALONG THE FEATURE'S NORTHERN PERIPHERY WHERE IT
INTERACTS WITH THE INCOMING TRADE WINDS. CHUUK WILL LIKEWISE SEE AT
LEAST SCATTERED SHOWERS THROUGH THE LATTER HALF OF THE WEEK AS THE
OVERALL DISTURBANCE, AND TRAILING CONVERGENCE, SHIFT NORTHWARD, WHILE
THE NEXT DISTURBANCE BEGINS TO FORM TO THE EAST.
RECENT ALTIMETRY DATA INDICATES COMBINED SEAS AROUND 4 TO 6 FEET
ACROSS THE REGION. A PULSE OF NORTH-NORTHEAST SWELL IS MOVING
THROUGH FAR WESTERN MICRONESIA, AND MAY INCREASE SEAS BY AROUND A
FOOT FOR PALAU THROUGH TONIGHT. THE NORTHEAST TRADE SWELL THEN LOOKS
TO BUILD OVER THE NEXT FEW DAYS INTO NORTHERN CHUUK STATE, WHICH
WILL INCREASE SEAS BY A FOOT OR TWO THERE AND LEAD TO ELEVATED SURF
ALONG NORTH FACING REEFS AROUND TUESDAY.
GUM WATCHES/WARNINGS/ADVISORIES
GU...NONE.
MP...NONE.
MARIANAS WATERS...NONE.
MARIANAS/EAST AND WEST MICRONESIA UPDATE: WILLIAMS
MARIANAS: MONTVILA
EAST MICRONESIA: KLEESCHULTE
WEST MICRONESIA: DECOU
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