110
FXPQ50 PGUM 261940
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
540 AM CHST FRI MAR 27 2026
MARIANAS UPDATE
MOSTLY CLOUDY SKIES AND SCATTERED SHOWERS ARE FOUND OVER THE MARIANAS
WATERS THIS MORNING. SINCE THE SHOWERS HAVE BEEN HANGING AROUND
LONGER THAN THE MODELS HAVE BEEN SAYING, WENT AHEAD AND PUT THEM IN
ALL DAY TODAY. THEY COULD THEN FADE TONIGHT AND COME BACK SATURDAY,
WHICH IS ALREADY IN THE FORECAST, SO THE ONLY CHANGE OF ANY SUBSTANCE
WAS TO EXTEND THE SCATTERED SHOWERS INTO THE AFTERNOON.
TROPICAL SYSTEMS
INVEST AREA 99W IS CENTERED LOOSELY AROUND 7N164E. IT IS MOVING
SLOWLY WESTWARD, WHICH HAS, FOR NOW AT LEAST, ALLOWED MAJURO TO
EMERGE FROM UNDER THE CLOUD DECK. THE LIKELIHOOD OF DEVELOPMENT IS
STILL VERY LOW, AND IT WOULD MOST LIKELY TAKE A FEW DAYS AT LEAST.
THE NATIONAL WEATHER SERVICE AND THE JOINT TYPHOON WARNING CENTER
WILL CONTINUE TO MONITOR 99W CAREFULLY FOR ANY CHANGES.
EASTERN MICRONESIA UPDATE
THE SHOWERS IN EASTERN MICRONESIA ASSOCIATED WITH INVEST AREA 99W
KEEP PULLING OFF TO THE WEST. THEREFORE CHANGED THE MAJURO FORECAST
TO PARTLY SUNNY WITH ISOLATED SHOWERS IN THE MORNING BECOMING
SCATTERED IN THE AFTERNOON, JUST IN CASE THEY DO START BUILDING UP
AGAIN. RAISED SHOWERS TO SCATTERED AT POHNPEI, AND LOWERED THEM TO
ISOLATED AT KOSRAE WHICH IS IN A DRY POCKET RIGHT NOW. EASTERN
MICRONESIA HAS JUST BEEN VERY CHANGEABLE LATELY.
WESTERN MICRONESIA UPDATE
WESTERN MICRONESIA IS PRETTY DRY AT THIS TIME. THIS WAS HANDLED WELL
IN THE FORECAST, SO NO CHANGES WERE NEEDED. KOROR AND YAP REMAIN DRY
THROUGH TUESDAY. CHUUK REMAINS DRY THROUGH MONDAY, THEN STARTS TO
MOISTEN ON TUESDAY. WINDS WILL BE MOSTLY 5 TO 10 KNOTS, WITH AN
OCCASIONAL 15 AT TIMES. SEAS WILL BE 3 TO 5 FEET.
PREV DISCUSSION
/ISSUED 1123 PM CHST THU MAR 26 2026/
MARIANAS SYNOPSIS...
A BROAD TROUGH IS PRODUCING A LARGE AREA OF SCATTERED SHOWERS ACROSS
THE REGION TODAY. ADDITIONALLY, LIGHT SOUTHERLY FLOW ACROSS GUAM WAS
ABLE TO GENERATE EXTRA ISLAND-EFFECT SHOWERS OVER THE NORTHERN HALF
OF GUAM EARLIER THIS AFTERNOON, BUT IN GENERAL, PERIODS OF SCATTERED
SHOWERS ARE EXPECTED TO CONTINUE OVER THE NEXT COUPLE DAYS. WINDS
ARE LIGHT TO MODERATE OUT OF THE SOUTH TO SOUTHEAST AND COMBINED SEAS
ARE AROUND 4 TO 5 FEET.
DISCUSSION...
A BROAD TROUGH PASSES THROUGH A WEAK DISTURBANCE WEST OF GUAM COASTAL
WATERS AND EXTENDS NORTHEASTWARD ACROSS THE CNMI. SATELLITE
OBSERVATIONS SHOW A LARGE AREA OF SHOWERS WITH THIS FEATURE,
EXTENDING ACROSS MUCH OF THE MARIANAS. THE NEARBY EMBEDDED
DISTURBANCE AND ATTENDANT TROUGH REMAINS FAIRLY STATIONARY OVER THE
NEXT FEW DAYS, KEEPING THE REGION UNDER LIGHT TO GENTLE WINDS WITH
PERIODS OF SCATTERED SHOWERS THROUGH AT LEAST SATURDAY, THEN THE
DISTURBANCE IS EXPECTED TO WEAKEN. ADDITIONALLY, LIGHT WINDS WILL
ALSO SUPPORT ISLAND-EFFECT SHOWERS DURING THE AFTERNOON OVER THE NEXT
FEW DAYS. AROUND SUNDAY, MODELS HINT AT WEAK SHEAR LINE FRAGMENT,
HOWEVER, THERE IS SOME UNCERTAINTY IF THIS WILL SET UP NEAR THE
ISLANDS OR BE FARTHER AWAY TO THE NORTHWEST. AFTER ALL THIS, A
RETURN TO A TYPICAL TRADE-WIND PATTERN IS EXPECTED NEXT WEEK AS
NEARBY FEATURES WEAKEN AND THE NEAR-EQUATORIAL TROUGH (NET) IN
WESTERN MICRONESIA SHIFTS SOUTHWARD.
MARINE/SURF...
BENIGN MARINE CONDITIONS ARE EXPECTED WITH LIGHT TO GENTLE WINDS
AND COMBINED SEAS OF 3 TO 5 FEET EXPECTED THROUGH SATURDAY NIGHT.
THEN, A PULSE OF NORTHERLY SWELL INCREASES SEAS BACK UP TO 4 TO 7
FEET EARLY NEXT WEEK. A MODERATE RISK OF RIP CURRENTS CONTINUES ALONG
NORTH AND EAST FACING REEFS FOR AT LEAST THE NEXT SEVERAL DAYS,
WHILE REMAINING LOW ALONG SOUTH AND WEST FACING REEFS. WITH THE
ARRIVAL OF NORTHERLY SWELL, AN INCREASE SURF ALONG NORTH-FACING
REEFS IS EXPECTED OVER THE WEEKEND, BUT SURF IS NOT EXPECTED TO REACH
HAZARDOUS LEVELS OF 9 FEET AT THIS TIME. REFRACTED SWELL ENERGY MAY
ALSO ADD A FOOT OR TWO TO SURF ALONG WEST-FACING REEFS, POSSIBLY
INCREASING THE RIP RISK TO MODERATE OVER THE WEEKEND OR EARLY NEXT
WEEK.
TROPICAL SYSTEMS...
A WEAK DISTURBANCE, INVEST 99W, IS CENTERED NEAR 8N165E, REMAINING
QUASI-STATIONARY AS IT MEANDERS AROUND THE WESTERN MARSHALL ISLANDS.
LATEST SATELLITE IMAGERY SHOWS EXTENSIVE CONVECTION WITH 99W FROM
KWAJALEIN AND AILINGLAPLAP EAST OVER MAJURO. MODEL GUIDANCE SHOWS
LITTLE TO NO CHANGE IN THE INTENSITY OF THE CIRCULATION OVER THE
NEXT FEW DAYS, HOWEVER, THEY DO MOSTLY AGREE THAT A VERY WET PATTERN
WILL BE IN PLACE ACROSS THE MARSHALLS WEST OF MAJURO AT LEAST
THROUGH THE BEGINNING OF NEXT WEEK. THERE IS A POTENTIAL FOR HEAVY
RAINFALL ACROSS THE REGION AS 99W DRIFTS AROUND THE MARSHALL ISLANDS
AND INTO KOSRAE STATE. THIS SYSTEM BEARS WATCHING OVER THE NEXT
SEVERAL DAYS AS IT IS OUT OF THE ORDINARY FOR THIS TYPE OF
DEVELOPMENT OVER THE MARSHALL ISLANDS. THE JOINT TYPHOON WARNING
CENTER (JTWC) AND THE NATIONAL WEATHER SERVICE WILL KEEP A CLOSE EYE
ON 99W OVER THE NEXT SEVERAL DAYS. THE INVEST IS ALREADY PRODUCING
SHOWERS OVER WOTJE AND UTIRIK, AND IF IT DRIFTS FARTHER NORTH, COULD
BRING ENOUGH RAINFALL TO END THE DROUGHT OVER BOTH LOCATIONS AND
NEARBY ISLANDS AND ATOLLS. RESIDENTS OF THE MARSHALL ISLANDS AND
KOSRAE SHOULD MONITOR FORECASTS FOR ANY CHANGES OR INDICATIONS OF
STRENGTHENING OF INVEST 99W.
EASTERN MICRONESIA...
THE BIG STORY FOR EASTERN MICRONESIA IS INVEST 99W, DISCUSSED IN THE
TROPICAL SYSTEMS SECTION. THIS FEATURE HAS DEVELOPED OVER THE
WESTERN MARSHALL ISLANDS OVER THE LAST 24 HOURS AND IS DRIFTING
AROUND THE WESTERN MARSHALL ISLANDS. THIS FEATURE IS CREATING AN
UNSETTLED PATTERN ACROSS THE MARSHALLS FROM MAJURO WESTWARD, AS FAR
NORTH AS UTIRIK. LATEST MODEL GUIDANCE SHOWS MORE THAN 4 INCHES OF
RAINFALL OVER MAJURO AND KWAJALEIN THROUGH THE WEEKEND, WITH OVER 2
INCHES FOR WOTJE AND UTIRIK. BASED ON SATELLITE TRENDS AND MODEL
GUIDANCE, INCREASED SHOWER COVERAGE AT MAJURO TO WIDESPREAD FOR
TONIGHT AND TO NUMEROUS FOR FRIDAY AND FRIDAY NIGHT, ALONG WITH
ISOLATED THUNDERSTORMS. SHOWERS LOOK TO DECREASE SLIGHTLY FOR THE
WEEKEND, THOUGH PROBABILITIES LOOK TO REMAIN AROUND 50 PERCENT
THROUGH THE BEGINNING OF NEXT WEEK. JTWC AND THE NATIONAL WEATHER
SERVICE WILL MONITOR INVEST 99W CLOSELY OVER THE COMING DAYS FOR ANY
INDICATIONS OF STRENGTHENING OR CHANGES IN EXPECTATIONS. IF 99W
BECOMES MORE ORGANIZED, A SPECIAL WEATHER STATEMENT MAY BE ISSUED
FRIDAY AFTERNOON. FOR THE MARINE FORECAST, ONLY LIGHT TO GENTLE WINDS
ARE EXPECTED FOR THE NEXT FEW DAYS, WITH SEAS REMAINING BELOW 6
FEET.
FOR KOSRAE, A BAND OF SCATTERED TO NUMEROUS SHOWERS AND ISOLATED
THUNDERSTORMS IS MOVING INTO KOSRAE NOW, AND LOOKS TO INCREASE
THROUGH THE EVENING. THE ORIGINAL FORECAST HAD PROBABILITIES OF
AROUND 30 PERCENT, BUT AN UPDATE WAS ISSUED INCREASING COVERAGE TO
NUMEROUS LATER THIS EVENING. LOCALLY HEAVY SHOWERS ARE POSSIBLE WITH
THESE SHOWERS. THIS WILL USHER IN AN OVERALL UNSETTLED PATTERN THAT
WILL REMAIN OVER KOSRAE FOR THE NEXT SEVERAL DAYS, AS LONG AS INVEST
99W REMAINS OVER THE WESTERN MARSHALL ISLANDS.
FOR POHNPEI, MOSTLY CLEAR SKIES TONIGHT WITH ONLY SPOTTY LIGHT
SHOWERS WILL GIVE WAY TO INCREASING CLOUDS AND SHOWERS OVER THE NEXT
COUPLE OF DAYS AS A TRADE-WIND TROUGH APPROACHES FROM NORTH OF
KOSRAE. THIS TROUGH WILL HELP TO STRETCH A SURFACE TROUGH OVER THE
STATE FROM INVEST 99W, MAINTAINING A WETTER PATTERN OVER THE WEEKEND
AND INTO NEXT WEEK.
BENIGN MARINE CONDITIONS WILL CONTINUE AT BOTH POHNPEI AND KOSRAE,
WITH MOSTLY LIGHT TO GENTLE WINDS AND SEAS OF 3 TO 5 FEET.
WESTERN MICRONESIA...
THE MAIN FEATURE IN THE REGIONS REMAINS THE NEAR EQUATORIAL TROUGH
(NET) WITH AN EMBEDDED CIRCULATION (WITH LITTLE CHANCE OF
DEVELOPMENT). THE NET ENTERS THE REGION NEAR 6N130E AND EXTENDS
NORTHEAST THROUGH THE DISTURBANCE NEAR 7N137E AND CONTINUES TO
EXTEND SOUTHEAST UNTIL IT EXITS WESTERN MICRONESIA NEAR
KAPINGAMARANGI. THE EMBEDDED DISTURBANCE IS LOCATED TO THE SOUTH-
SOUTHWEST OF NGULU ATOLL. OVER THE PAST FEW DAYS, THE EMBEDDED
CIRCULATION HAS DIMINISHED IN AREAL COVERAGE. THIS IS DUE TO THE
CIRCULATION ENTRAINING SOME DRIER AIR. SHOWERS IN THE IMMEDIATE AREAS
AROUND THE CIRCULATION ARE EXPECTED TO RANGE FROM SCATTERED TO
WIDESPREAD. LATEST MODEL GUIDANCE SUGGESTS THE EMBEDDED CIRCULATION
WILL GRADUALLY REPOSITION SOUTHEASTWARD OVER THE NEXT FEW DAYS.
FOR PALAU, A DRIER PATTERN IS ANTICIPATED, WITH ONE CAVEAT. THAT
CAVEAT IS HOW FAR WEST THE ABOVE EMBEDDED CIRCULATION MOVES BEFORE
REPOSITIONING AND IF IT GETS AN INJECTION OF MOISTURE. AT THIS TIME
THERE IS LOW CONFIDENCE THAT THIS CIRCULATION WILL BRING ANYTHING
MORE THAN SOME CLOUD COVER AND ISOLATED SHOWERS TO PALAU. LOOKING
INTO THE FUTURE, PALAU IS EXPECTED TO REMAIN IN A DRIER WEATHER
PATTERN THROUGH THE THE MIDDLE OF NEXT WEEK.
FOR YAP AND CHUUK, FAIRER WEATHER IS IN STORE FOR THESE REGIONS. A
FEW SHOWERS AND MAY LINGER AROUND FOR THE NEXT DAY OR TWO. WINDS ARE
EXPECTED TO BE LIGHT TO GENTLE AT YAP AND LIGHT AT CHUUK.
MARINE CONDITIONS ARE MOST ELEVATED NEAR THE DISTURBANCE NEAR NGULU
WITH COMBINED SEAS OF 4 TO 6 FEET. ALTIMETRY SHOWS COMBINED SEAS 3 TO
5 FEET FOR THE REST OF THE REGION. WINDS ARE EXPECTED TO BE LIGHT TO
GENTLE FOR MUCH OF THE DOMAIN, AND GENTLE TO MODERATE NEAR THE
DISTURBANCE. OVER THE WEEKEND AN INCREASE IN NORTHERLY SWELL MAY
ARRIVE IN THE REGION. THIS COULD BUILD SURF LEVELS ALONG NORTH FACING
REEFS TO AROUND 8 FEET.
GUM WATCHES/WARNINGS/ADVISORIES
GU...NONE.
MP...NONE.
MARIANAS WATERS...NONE.
MARIANAS/EAST AND WEST MICRONESIA/TROPICAL UPDATE: STANKO
MARIANAS: SPELLER/CRUZ
EAST MICRONESIA: KLEESCHULTE
WEST MICRONESIA: BOWSHER
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