695
FXPQ50 PGUM 082058
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
658 AM CHST MON MAR 9 2026
MARIANAS UPDATE
A COMPLEX WEATHER PATTERN CONTINUES ACROSS THE REGION. SATELLITE AND
RADAR IMAGERY EARLY THIS MORNING SHOW SCATTERED SHOWERS ACROSS GUAM
COASTAL WATERS, WITH A LINE OF MODERATE TO DEEP CONVECTION SKIRTING
ALONG THE SOUTHERN TIP OF THE ISLAND. SHOWERS, WIND SPEED, AND
DIRECTION HAVE BEEN DIFFICULT TO NAIL DOWN IN THE FORECAST DUE TO
COMPLEX INTERACTIONS BETWEEN INVEST 95W TO THE SOUTHWEST, A SHEAR
LINE FRAGMENT OVER THE CNMI, THE ELONGATED TROUGH EXTENDING
NORTHEASTWARD THROUGH 95W AND ACROSS THE MARIANAS, AND THE WEAK,
SECONDARY CIRCULATION SPINNING UP WITHIN THE TROUGH NEARBY. WINDS
OVER GUAM AND ROTA HAVE BEEN GRADUALLY SHIFTING FROM SOUTHWEST TO
NORTHWEST SINCE LATE OVERNIGHT, AS THE SHEAR LINE BEGINS TO COME
DOWN AND A WEAK CIRCULATION DEVELOPS SOMEWHERE JUST EAST OF SAIPAN.
MEANWHILE, WINDS OVER SAIPAN AND TINIAN ARE MAINLY NORTH TO NORTH-
NORTHEAST, AND ARE EXPECTED TO INCREASE THROUGH THE DAY AS THE NEARBY
CIRCULATION PULLS AWAY. SO FAR, MOST OF THE SHOWER COVERAGE HAS
REMAINED WELL SOUTH TO SOUTHEAST OF THE ISLANDS, BUT MODELS INDICATE
A POSSIBILITY FOR PERIODS OF NUMEROUS LOCALLY HEAVY SHOWERS THROUGH
THE NEXT FEW DAYS, AS INVEST 95W GRADUALLY APPROACHES FROM THE
SOUTHWEST, AND THE SECONDARY CIRCULATION NEAR SAIPAN MOVES AWAY TO
THE NORTHEAST. THE FORECAST MAY CONTINUE TO SEE SIGNIFICANT
ADJUSTMENT OVER THE NEXT DAY OR SO AS THIS PATTERN EVOLVES. FOR THE
MARINE FORECAST, A SMALL CRAFT ADVISORY REMAINS IN EFFECT UNTIL
TUESDAY AFTERNOON AS COMBINED SEAS REMAIN AROUND 8 TO 10 FEET,
MAINLY FOR SAIPAN AND TINIAN WATERS. THERE WAS LITTLE ADJUSTMENT TO
OVERALL SEA HEIGHTS, BUT SECONDARY SWELLS WERE ADJUSTED IN THE
FORECAST, WITH A TERTIARY LONGER-PERIOD NORTH-NORTHEAST SWELL
INCLUDED STARTING TONIGHT.
TROPICAL SYSTEMS UPDATE
THE JOINT TYPHOON WARNING CENTER (JTWC)'S INVEST 95W REMAINS A
BROAD, ELONGATED DISTURBANCE, LOCATED NORTHEAST OF YAP NEAR 11.5N
139.5E AND EXTENDING NORTHEAST TOWARD THE MARIANAS. INVEST 95W IS
RATED "MEDIUM" FOR DEVELOPMENT, MEANING DEVELOPMENT INTO A
SIGNIFICANT TROPICAL CYCLONE (TROPICAL DEPRESSION) IS LOOKING MORE
LIKELY, BUT NOT WITHIN THE NEXT 24 HOURS. MODERATE TO DEEP CONVECTION
IS SPREAD ACROSS A BROAD AREA OVER YAP STATE TO THE SOUTH AND EAST OF
THE CIRCULATION CENTER WHERE CONVERGENCE IS STRONGEST, WITH THE
HEAVIEST SHOWERS SOUTH AND EAST OF MARIANAS COASTAL WATERS. MODEL
GUIDANCE CONTINUES TO DEPICTING A COMPLEX PATTERN IN WHICH A
SECONDARY CIRCULATION CENTER NEAR SAIPAN SPLITS OFF OF THE ELONGATED
TROUGH OVER THE NEXT DAY OR SO, MOVING EAST TO NORTHEASTWARD OVER THE
NEXT FEW DAYS. MEANWHILE, THE CENTER OF 95W NORTHEAST OF YAP LOOKS
TO VERY GRADUALLY SHIFT NORTHEAST AND STRENGTHEN THROUGH THE NEXT FEW
DAYS. THIS LOOKS TO BRING A FEW MORE ROUNDS OF HEAVY RAINFALL,
BREEZY WINDS, CHOPPY SEAS, AND STRONGER GUSTS ACROSS THE MARIANAS
THROUGH AT LEAST MIDWEEK, ESPECIALLY IN HEAVIER SHOWERS AND
THUNDERSTORMS.
FOR MORE INFORMATION ON INVEST 95W, PLEASE SEE THE BULLETIN ISSUED
BY THE JOINT TYPHOON WARNING CENTER UNDER WMO HEADER ABPW10 PGTW.
EASTERN MICRONESIA UPDATE
THE WEATHER PATTERN ACROSS EASTERN MICRONESIA CONTINUES TO BE
DOMINATED BY A SERIES OF TRADE-WIND TROUGHS, PROPAGATING WESTWARD
ACROSS THE REGION ALONG A BROAD INTERTROPICAL CONVERGENCE ZONE
(ITCZ)-LIKE BOUNDARY. A STRONGER TROUGH, SCATTERED TO NUMEROUS
SHOWERS, AND ISOLATED THUNDERSTORMS ARE LOCATED JUST EAST TO
SOUTHEAST OF KOSRAE. TROUGHS ARE ALSO SEEN JUST SOUTHWEST OF POHNPEI
AND SOUTH OF MAJURO. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE
EXPECTED ACROSS ALL THREE LOCATIONS THROUGH TONIGHT, SUPPORTED BY
DIVERGENT FLOW FAR ALOFT. WINDS ARE EXPECTED TO REMAIN LIGHT TO
MODERATE THROUGHOUT THE WEEK. A HIGH SURF ADVISORY REMAINS IN EFFECT
ALONG NORTH-FACING REEFS OF POHNPEI AND KOSRAE UNTIL 3 AM EARLY
MORNING TUESDAY, AS ELEVATED LONG-PERIOD NORTH-NORTHWEST SWELL MOVES
THROUGH THE REGION. ADDITIONALLY, A SMALL CRAFT ADVISORY HAS BEEN
ISSUED FOR POHNPEI AND KOSRAE UNTIL 3 PM THIS AFTERNOON, AS POHNPEI
BUOY DATA SHOWED SEAS INCREASING TO AROUND 10 FEET OVERNIGHT, WHICH,
TAKING LATEST MODEL GUIDANCE INTO ACCOUNT, SUPPORTED AN ISSUANCE FOR
KOSRAE AS WELL. SEAS ARE EXPECTED TO RELAX BELOW LEVELS HAZARDOUS TO
SMALL CRAFT THIS AFTERNOON.
WESTERN MICRONESIA UPDATE
AN UNSETTLED PATTERN CONTINUES ACROSS THE REGION, ASSOCIATED WITH THE
MESSY TROPICAL DISTURBANCE THAT IS INVEST 95W, ELONGATED
NORTHEASTWARD ALONG THE SOUTHERN PERIPHERY OF A SHEAR LINE. JTWC HAS
THE CENTER POSITIONED TO THE NORTHEAST OF YAP SOMEWHERE AROUND
11N139E, AND AN ELONGATED TROUGH EXTENDS NORTHEAST ACROSS PALAU,
YAP, THROUGH 95W, AND TOWARD THE MARIANAS. NUMEROUS TO WIDESPREAD
SHOWERS AND ISOLATED THUNDERSTORMS PERSIST ACROSS MUCH OF YAP STATE
WITHIN A REGION OF STRONG CONVERGENCE EAST TO SOUTHEAST OF 95W, BUT
FOR NOW, PALAU AND YAP REMAIN WITHIN A RELATIVELY DRIER PORTION OF
THE ELONGATED TROUGH, WITH PATCHY MODERATE TO DEEP CONVECTION ACROSS
THE AREA. PALAU CAN EXPECT AT LEAST SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS THROUGH THE NEXT FEW DAYS WITH LOCALLY HEAVY RAINFALL
POSSIBLE AT TIMES, WITH MOST OF THE SHOWERS BUILDING NEAR YAP, ALONG
INVEST 95W AND THE TRAILING CONVERGENCE TO ITS SOUTH AND SOUTHEAST.
NUMEROUS SHOWERS ARE EXPECTED TODAY, WITH A SLIGHT INCREASE TONIGHT.
CHUUK WILL SEE FAIRLY DRY CONDITIONS TODAY WITH LOW-END SCATTERED
SHOWERS (30 PERCENT CHANCE) IN THE FORECAST, BUILDING UP TO NUMEROUS
SHOWERS OVERNIGHT AS ANOTHER STRONG CONVERGENCE BOUNDARY SETS UP
NEARBY. THERE WAS LITTLE CHANGE IN THE MARINE FORECAST; ELEVATED
NORTHERLY SWELL CONTINUES TO PRODUCE HAZARDOUS SURF OF AT LEAST 9
FEET ALONG NORTH FACING REEFS OF PALAU, YAP, AND CHUUK. THE HIGH SURF
ADVISORY FOR CHUUK EXPIRES THIS AFTERNOON AS THE SWELL DIMINISHES
THERE, BUT REMAINS IN EFFECT FOR PALAU AND YAP UNTIL 5 AM WEDNESDAY.
PREV DISCUSSION
/ISSUED 736 PM CHST SUN MAR 8 2026/
MARIANAS SYNOPSIS...
SATELLITE IMAGERY SHOWS CLOUDY SKIES, WHILE RADAR SHOWS SCATTERED TO
NUMEROUS SHOWERS WITH MOST OF THE HEAVIER SHOWERS JUST OUTSIDE THE
COASTAL WATERS. IPAN BUOY DATA SHOWS SWELL OF 6 FEET AT 8 SECONDS,
HOWEVER THIS BUOY IS SHIELDED BY THE ISLAND OF GUAM FROM THE NORTH
AND NORTHEASTERN SWELLS.
A SMALL CRAFT ADVISORY, HIGH SURF ADVISORY, AND A HIGH RISK OF RIP
CURRENTS STATEMENT REMAIN IN EFFECT.
DISCUSSION...
SHOWERS HAVE BEEN SOMEWHAT LIGHT TODAY, THIS IS DUE TO THE NEAR MISS
OF THE HEAVIER SHOWERS. INVEST 95W REMAINS AS A BROAD DISORGANIZED
TROPICAL DISTURBANCE PRODUCING A TROUGH THAT EXTENDS INTO THE
WESTERN WATERS AND OVER THE NORTHERN CNMI. A SHEAR LINE REMAINS OVER
THE FAR NORTHERN CNMI. ALL THREE OF THESE FEATURES ARE PRODUCING A
DYNAMIC WET WEATHER PATTERN OVER THE MARIANAS. THIS WET WEATHER
PATTERN IS ANTICIPATED TO REMAIN THROUGH THE FIRST HALF OF THE WEEK.
THE LATTER HALF OF WEEK, MODELS SUGGEST A BIT OF A DRIER PERIOD MAY
BE IN STORE.
MARINE...
A BUSY MARINE PATTERN IS EXPECTED TO CONTINUE THROUGH THE NEXT
SEVERAL DAYS. A BRIEF DOWNWARD TREND IS EXPECTED TONIGHT, THEN
ANOTHER PULSE OF NORTH SWELL WILL RE-INVIGORATE THE SWELL UP TO
11 FEET, WINDS ARE EXPECTED TO BE GENTLE TO FRESH WITH PERIODS OF
STRONG THROUGH MUCH OF NEXT WEEK. SCATTERED SHOWERS, ISOLATED
THUNDERSTORMS, OCCASIONAL NEAR GALE TO GALE GUSTS AND SEAS
HAZARDOUS TO SMALL CRAFT ARE EXPECTED THROUGH THE NEXT FEW DAYS DUE
TO ELEVATED NORTH TO NORTHEAST SWELL, A TROPICAL DISTURBANCE
APPROACHING THE MARIANAS FROM THE SOUTHEAST, AND A SHEAR LINE OVER
THE CNMI.
HYDROLOGY...
HEAVY RAINFALL FROM INVEST 95W INTERACTING WITH A SHEAR LINE WILL
MAINTAIN A THREAT OF FLASH FLOODING FOR THE MARIANAS EARLY THIS WEEK.
THE RAIN IS EXPECTED TO CONTINUE THROUGH MONDAY AFTERNOON. SEVERAL
ROUNDS OF HEAVY TO VERY HEAVY RAINFALL WILL BE POSSIBLE DURING THIS
TIME FRAME. THIS COULD LEAD TO ADDITIONAL 4 TO 6 INCHES OF RAINFALL
ACROSS THE MARIANAS WITH LOCALLY HIGHER AMOUNTS POSSIBLE. MUDSLIDES
ARE ALSO POSSIBLE GIVEN THAT SOILS ARE ALREADY SATURATED.
GUIDANCE HAS HINTED AT A POTENTIAL STALL OF 95W. IF THIS OCCURS AND
IT DOES SO WITH 95W NEAR OR JUST WEST OF THE MARIANAS, THEN THE
RAINFALL FORECAST WILL SEE SIGNIFICANT CHANGES HEADING INTO NEXT WEEK
AS HEAVY RAINFALL WOULD CONTINUE FOR SEVERAL DAYS.
TROPICAL SYSTEMS...
THE POORLY ORGANIZED CENTER OF INVEST AREA 95W IS CENTERED NEAR 11N
140E, EAST-NORTHEAST OF YAP AND WEST-SOUTHWEST OF GUAM. 95W HAS BEEN
MOVING NORTHWARD OVER THE PAST 24 HOURS, AND IS EXPECTED TO TURN
TOWARD THE NORTHEAST, CROSSING THE MARIANAS THIS WEEK. UNCERTAINTY IS
HIGH BECAUSE SOME MODEL GUIDANCE HAS 95W STALLING NEAR OR JUST WEST
OF THE MARIANAS. THIS COULD EXTEND THE RAINY PATTERN SEEN THERE
RECENTLY. THE POTENTIAL FOR 95W TO DEVELOP INTO A TROPICAL CYCLONE
REMAINS MEDIUM, USUALLY INDICATING THAT DEVELOPMENT IS EXPECTED, JUST
NOT WITHIN THE NEXT 24 HOURS. FOR FURTHER INFORMATION ON 95W, REFER
TO THE SIGNIFICANT TROPICAL WEATHER ADVISORY FROM THE JOINT TYPHOON
WARNING CENTER UNDER WMO HEADER ABPW10 PGTW, AND THE TROPICAL
WEATHER DISCUSSION FROM THE GUAM NATIONAL WEATHER SERVICE OFFICE
UNDER WMO HEADER AXPQ20 PGUM.
EASTERN MICRONESIA...
THE MAIN WEATHER IMPACT CONTINUES TO BE A NORTH SWELL THAT'LL
MAINTAIN HIGH SURF CONCERNS FOR NORTH-FACING REEFS AT POHNPEI AND
KOSRAE THROUGH EARLY TUESDAY MORNING. ADDITIONALLY, SURF MAY BRIEFLY
BECOME ELEVATED FOR NORTH-FACING REEFS OF MAJURO MONDAY, BUT
CONFIDENCE IN IT REMAINING BELOW HAZARDOUS THRESHOLDS OF 12 FEET IS
FAIRLY HIGH. OTHERWISE, MAINLY LIGHT TO GENTLE TRADE WINDS MAY
BECOME GENTLE TO MODERATE FROM TIME TO TIME THROUGH TUESDAY, BEFORE
DECREASING FOR THE LATTER HALF OF THE WEEK.
PRECIPITATION WISE, A SERIES OF WEAK SURFACE TROUGHS WILL CONTINUE TO
CROSS THE REGION IN THE TRADE-WIND FLOW, PERHAPS INCREASING RAINFALL
POTENTIAL PERIODICALLY, BUT OVERALL WE DON'T SEE ANY BIG RAIN EVENTS
ON THE HORIZON.
WESTERN MICRONESIA...
THE MAIN WEATHER FEATURES AFFECTING WESTERN MICRONESIA THIS WEEK ARE
A TRADE-WIND TROUGH APPROACHING CHUUK FROM EASTERN MICRONESIA AND THE
NEAR-EQUATORIAL TROUGH RUNNING FROM THE PHILIPPINE SEA TO NEAR KOROR
AND YAP AND THEN TOWARD THE MARIANAS.
CHUUK CAN EXPECT SCATTERED SHOWERS THROUGH THE PERIOD, WHICH EXTENDS
FROM TONIGHT THROUGH FRIDAY. WINDS WILL BE 10 TO 15 KNOTS TONIGHT,
DIMINISHING TO BETWEEN 5 AND 10 KNOTS THROUGH FRIDAY. SEAS OF 6 TO 8
FEET TONIGHT WILL DIMINISH TO BETWEEN 4 AND 6 FEET MONDAY NIGHT, THEN
STAY NEAR THESE LEVELS THROUGH FRIDAY. MARINE CONDITIONS WILL BE
BENIGN THROUGH THE PERIOD, HOWEVER THROUGH MONDAY, THIS IS JUST
SUFFICIENT TO REQUIRE A HIGH SURF ADVISORY FOR NORTH FACING REEFS.
YAP WILL FEATURE NUMEROUS SHOWERS THROUGH TUESDAY NIGHT, EXCEPT FOR
WIDESPREAD SHOWERS MONDAY NIGHT AND TUESDAY. SCATTERED SHOWERS WILL
FOLLOW WEDNESDAY THROUGH FRIDAY. WINDS WILL BE NORTHWEST TO NORTH
FROM 5 TO 10 KNOTS. SEAS WILL BE 7 TO 9 FEET THROUGH TUESDAY NIGHT,
THEN 6 TO 8 FEET THROUGH FRIDAY. THE SEAS WILL CAUSE CHALLENGING
MARINE CONDITIONS THROUGH AT LEAST TUESDAY NIGHT AS WELL AS REQUIRING
A HIGH SURF ADVISORY FOR NORTH FACING REEFS THROUGH AT LEAST
WEDNESDAY, WHICH WILL LIKELY BE EXTENDED.
KOROR, PALAU WILL RECEIVE SCATTERED SHOWERS THROUGH THURSDAY THEN
NUMEROUS SHOWERS ON FRIDAY. WINDS WILL BE NORTHWEST TO NORTH AT 5 TO
10 KNOTS THROUGH FRIDAY, WITH SOME 15 KNOT VALUES POSSIBLE FRIDAY.
SEAS WILL BE 6 TO 8 FEET THROUGH WEDNESDAY, THEN 5 TO 7 FEET THROUGH
THURSDAY. THIS WILL SUPPORT BENIGN MARINE CONDITIONS, BUT IS JUST
ENOUGH TO REQUIRE A HIGH SURF ADVISORY THROUGH WEDNESDAY ALONG NORTH
FACING REEFS.
GUM WATCHES/WARNINGS/ADVISORIES
GU...FLOOD WATCH UNTIL 4 PM CHST THIS AFTERNOON FOR GUZ001.
HIGH RIP CURRENT RISK THROUGH TUESDAY AFTERNOON FOR GUZ001.
HIGH SURF ADVISORY UNTIL 4 PM CHST TUESDAY FOR GUZ001.
MP...FLOOD WATCH UNTIL 4 PM CHST THIS AFTERNOON FOR MPZ001>003.
HIGH RIP CURRENT RISK THROUGH TUESDAY AFTERNOON FOR MPZ001>003.
HIGH SURF ADVISORY UNTIL 4 PM CHST TUESDAY FOR MPZ001>003.
MARIANAS WATERS...SMALL CRAFT ADVISORY UNTIL 4 PM CHST TUESDAY FOR PMZ151>154.
MARIANAS/EAST AND WEST MICRONESIA/TROPICAL SYSTEMS UPDATE: DECOU
MARIANAS: BOWSHER
EAST MICRONESIA: DOLL
WEST MICRONESIA: STANKO
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