748
FXPQ50 PGUM 222007
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
607 AM CHST TUE DEC 23 2025
MARIANAS UPDATE
RADAR AND SATELLITE IMAGERY SHOW SCATTERED SHOWERS ARE STILL PASSING
AROUND GUAM AND ROTA THIS MORNING, BUT THE HEAVIER SHOWERS AND
THUNDERSTORMS ARE CURRENTLY WELL WEST OF THE ISLANDS, FOLLOWING THE
TRADE-WIND TROUGH THAT PASSED NEAR GUAM YESTERDAY. ISOLATED
THUNDERSTORMS ARE STILL POSSIBLE NEAR GUAM AND SURROUNDING COASTAL
WATERS BUT THE RISK OF THUNDERSTORMS SHOULD DECREASE AS THE TROUGH
CONTINUES TO MOVE AWAY TO THE WEST. ALTIMETRY AND BUOY DATA SHOW
SEAS ARE AROUND 8 TO 10 FEET THIS MORNING, DRIVEN BY THE NORTHEAST
SWELL THAT IS ALSO SUPPORTING SURF UP TO 11 FEET ALONG NORTH FACING
REEFS AND A HIGH RISK OF RIP CURRENTS ALONG NORTH AND EAST REEFS.
THE ELEVATED NORTHEAST SWELL IS SLOWLY SUBSIDING AS THE SURGE IN THE
TRADE WINDS CONTINUES TO WEAKEN AS THE THE MID-LATITUDE HIGH
PRESSURE SYSTEM CONTINUES TO MOVE EASTWARD ACROSS THE PACIFIC. WHILE
SEAS MAY DROP BELOW 10 FEET AS EARLY AS THIS EVENING, SURF WILL BE
SLOWER TO SUBSIDE AND MAY NOT DROP BELOW 9 FEET ALONG NORTH AND EAST
FACING REEFS UNTIL WEDNESDAY MORNING, WHICH WOULD END THE HIGH SURF
AND HIGH RISK OF RIP CURRENTS. LOOKING TOWARDS CHRISTMAS, THE
POTENTIAL FOR SCATTERED SHOWER MAY LINGER INTO TONIGHT AND CHRISTMAS
EVE, BUT A MORE SEASONAL TRADE-WIND PATTERN IS EXPECTED ACROSS THE
MARIANAS. A COLD FRONT WILL BE PUSHING INTO THE PACIFIC OCEAN WILL
SLOWLY PUSH SOUTHEAST. DEPENDING HOW FAR SOUTH THE FRONT MOVES, THE
MARIANAS COULD SEE A SLIGHT INCREASE IN WINDS, SHOWERS, AND SEAS
LATE THIS WEEK OR EARLY NEXT WEEK.
EASTERN MICRONESIA UPDATE
AS THE TAIL-END OF A BROAD MID-LATITUDE LOW PRESSURE FRONTAL SYSTEM
PULLS AWAY FROM THE REGION, A CONVERGENT BOUNDARY EXTENDS THROUGH
THE NORTHERN RMI, NORTH OF KOSRAE, AND NEAR POHNPEI, AS IT MEETS A
BROAD SURFACE WEST OF CHUUK. A BAND OF WIDESPREAD, PATCHY CLOUDS AND
SHOWERS ARE FOUND ALONG THIS BOUNDARY, WITH CONVECTION DEEPENING
NORTH OF POHNPEI. KOSRAE IS SOUTH OF THE CONVECTION, BUT A PATCH BAND
OF SHOWERS HAS DEVELOPED WITHIN THE COASTAL WATERS OF MAJURO.
SHOWERS AROUND POHNPEI ARE EXPECTED TO DECREASE TO ISOLATE TONIGHT,
WITH ISOLATED TO SCATTERED SHOWERS ARE EXPECTED FARTHER EAST OVER
KOSRAE AND MAJURO THIS WEEK, THEN THE INTERTROPICAL CONVERGENCE ZONE
(ITCZ) LOOKS TO BUILD BACK IN OVER THE DATE LINE LATE WEEK.
LATEST ALTIMETRY AND BUOY DATA SHOW SEAS ARE STILL AROUND 4 TO 7
FEET AT KOSRAE, WHILE SEAS AT POHNPEI HAVE INCREASED TO 7 TO 9 FEET
SUGGESTING THE NORTH SWELL IS ARRIVING. FOR MAJURO, THERE HAS NOT
BEEN A NEW ALTIMETRY PASS IN THE PAST 12 HOURS, BUT DRIFTING BUOYS
SHOW SEAS ARE AROUND 8 TO 10 FEET NORTH OF KWAJALEIN, SO SEAS ARE
LIKELY SIMILAR TO POHNPEI, AROUND 7 TO 9 FEET. HAZARDOUS SURF IS
STILL EXPECTED ALONG NORTH REEFS OF POHNPEI AND KOSRAE THROUGH EARLY
WEDNESDAY MORNING DUE TO THE LONG-PERIOD NORTHERLY SWELL. AS PREVIOUS
FORECAST DISCUSSIONS HAVE STATED, DURATION OF LONG-PERIOD NORTHERLY
SWELL IN SUBSEQUENT MODEL RUNS WILL BE MONITORED TO SEE IF FURTHER
EXTENSIONS ARE NEEDED. CURRENT MODEL TRENDS SUPPORT SEAS NEAR POHNPEI
PEAKING AT 9 FEET TODAY, BUT THE BUOY AT POHNPEI WILL BE MONITOR TO
SEE IF SEAS WILL CLIMB EVEN HIGHER TO 10 FEET, REQUIRING A SMALL
CRAFT ADVISORY.
WESTERN MICRONESIA UPDATE
MUCH OF FAR WESTERN MICRONESIA REMAINS UNDER A RELATIVELY DRY TRADE-
WIND PATTERN, WITH SOME ISOLATED SHOWERS AROUND A BAND OF WEAK
TRADE-WIND CONVERGENCE JUST SOUTHEAST OF YAP. THE CIMSS LIGHTNINGCAST
SATELLITE PRODUCTS IS SHOWING A SLIGHT POTENTIAL FOR THUNDERSTORMS
WITH THE CONVERGENCE NEAR YAP, SO ADDED A SLIGHT CHANCE OF
THUNDERSTORMS TO YAP'S FORECAST FOR TODAY BUT LEFT SHOWERS ISOLATED.
MOST OF THE UNSETTLED WEATHER IN THE REGION IS STILL LOCATED NEAR CHUUK
LAGOON, BUT HAS SHIFTED NORTHWARD. NUMEROUS SHOWERS AND ISOLATED
THUNDERSTORMS ARE FOCUSED A BAND OF CONVERGENCE THAT EXTENDS INTO THE
REGION FROM EASTERN MICRONESIA, JUST NORTHEAST OF CHUUK COASTAL
WATERS. THE TROUGH THAT WAS NEAR CHUUK IS MOW MOVING INTO EASTER YAP
STATE, BUT CONVECTION HAS TRENDED DOWNWARD ALONG THE TROUGH
OVERNIGHT. MODEL GUIDANCE DEPICTS THE TRADE-CONVERGENCE SHIFTING
WESTWARD, FOLLOWING THE TROUGH AS LIFTING NORTHWEST OVER THE NEXT
DAY OR SO. THIS SHOULD BRING NUMEROUS LOCALLY HEAVY SHOWERS AND
ISOLATED THUNDERSTORMS TO CHUUK THIS AFTERNOON AND INTO THE EVENING
HOURS BEFORE TAPERING DOWN TO SCATTERED SHOWERS TONIGHT. THE TROUGH
WILL INCREASE SHOWERS FOR YAP AND PALAU AROUND THURSDAY THROUGH
SATURDAY AS IT TRANSITS WESTWARD THROUGH THE AREA, EXITING WEST OF
THE REGION AROUND SUNDAY.
LATEST ALTIMETRY DATA INDICATES COMBINED SEAS AROUND 6 TO 8 FEET
NEAR PALAU AND YAP. SEAS NEAR CHUUK ARE NOW PEAKING AROUND 10 FEET,
SO BASED ON THIS INFO, A SMALL CRAFT ADVISORY WAS ISSUED THROUGH THIS
AFTERNOON AS THE NORTHEAST SWELL IS EXPECTED TO SLOWLY SUBSIDE
STARTING THIS EVENING. THE ELEVATED NORTHEAST IS EXPECTED TO PEAK
TODAY, PRODUCING HAZARDOUS SURF UP TO 11 FEET FOR NORTH FACING REEFS
OF CHUUK. HIGH SURF ADVISORY IS IN EFFECT UNTIL 5 PM CHST THURSDAY,
WHEN THE NORTHEAST SWELL AND ASSOCIATED SURF ARE EXPECTED TO DIMINISH
BELOW HAZARDOUS LEVELS FOR CHUUK. FOR NOW, SEAS AND SURF LOOK TO
REMAIN BELOW HAZARDOUS LEVELS AT PALAU AND YAP, HOWEVER, A SLIGHT
INCREASE IN THE EXPECTED NORTHEAST SWELL COULD CHANGE THIS. GENTLE TO
MODERATE WINDS ARE EXPECTED AT CHUUK THROUGH THE WEEK. FOR YAP AND
PALAU, GENTLE TO MODERATE WINDS WILL BECOME LIGHT TO GENTLE AROUND
WEDNESDAY.
PREV DISCUSSION
/ISSUED 657 PM CHST MON DEC 22 2025/
MARIANAS SYNOPSIS...
A SMALL CRAFT ADVISORY, A HIGH SURF ADVISORY AND A HIGH RISK OF RIP
CURRENTS STATEMENT REMAIN IN EFFECT.
SATELLITE IMAGERY SHOWS CLOUDY SKIES, WHILE RADAR SHOWS SCATTERED TO
NUMEROUS SHOWERS OVER THE REGION. ALTIMETRY SHOWS 9 TO 12 FEET TO THE
NORTHWEST OF THE MARIANAS AND BUOY DATA SHOWS SEA HEIGHTS AROUND 9 TO
10 FEET AT RITIDIAN POINT. AS OF 4 PM CHST, 1.41 INCHES OF RAIN HAVE
FALLEN AT THE AIRPORT.
DISCUSSION...
WET AND GUSTY CONDITIONS PREVAILED TODAY, DUE TO A ROBUST TRADE-WIND
TROUGH ALONG THE EDGE OF A FRAGMENTED SHEAR LINE AND TRADE-WIND SURGE
JUST TO THE EAST OF THE MARIANAS. TOGETHER, THESE FEATURES COMBINED
TO PRODUCE NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS OVER GUAM
TODAY. THE SURFACE TROUGH WILL CONTINUE TO MOVE WESTWARD AND AWAY
FROM THE AREA TONIGHT, WHILE THE TRADE-WIND SURGE DIMINISHES IN
STRENGTH AND AREAL COVERAGE JUST EAST OF THE ISLANDS, WHICH SHOULD
ALLOW FOR A BRIEF PERIOD OF RELATIVELY DRIER WEATHER TOMORROW.
FOR GUAM AND ROTA, A FEW ROUNDS OF SCATTERED SHOWERS ARE EXPECTED
THROUGH CHRISTMAS DAY, MAINLY FROM PASSING TRADE-WIND TROUGHS AND
INCREASED TRADE-WIND CONVERGENCE, AS THE SUBTROPICAL RIDGE BUILDS
JUST NORTHEAST OF THE CNMI AND INCREASES THE PRESSURE GRADIENT
NEARBY. CURRENT MODEL GUIDANCE POINTS TO RELATIVELY DRIER WEATHER
TOWARD THE END OF THE WEEK, BUT STILL HINTS AT THE POSSIBILITY OF
SOME SHEARLINE FRAGMENT-INDUCED SHOWERS AROUND FRIDAY AND SATURDAY.
MARINE/SURF...
THIS IS WHERE THE MAIN CONCERNS ARE AT. SEAS ARE EXPECTED TO REMAIN
ELEVATED AND MAY EXCEED 11 FEET AT TIMES OVER THE NEXT DAY OR SO.
WINDS HAVE DIMINISHED TO MODERATE TO FRESH. SURF ALONG NORTH FACING
REEFS REMAINS ELEVATED AND MAY REACH UP TO 12 FEET AT TIMES TONIGHT
AND EARLY TUESDAY. SURF ALONG EAST FACING REEFS HAS FALLEN BELOW THE
12 FOOT THRESHOLD FOR HAZARDOUS SURF CONDITIONS, AND THE HIGH SURF
ADVISORY HAS BEEN DROPPED FOR EAST REEFS. THE HIGH SURF ADVISORY FOR
NORTH FACING REEFS, AND THE HIGH RIP CURRENT RISK FOR NORTH AND EAST
FACING REEFS WERE EXTENDED THROUGH EARLY WEDNESDAY MORNING. THE SMALL
CRAFT ADVISORY WAS EXTENDED THROUGH TUESDAY AFTERNOON, AFTER WHICH
COMBINED SEAS ARE EXPECTED TO DIMINISH TO 7 TO 9 FEET OVER COASTAL
WATERS, BELOW LEVELS HAZARDOUS TO SMALL CRAFT. REGARDLESS, WHETHER
YOU ARE A BOATER, SURFER OR BEACH GOER, THE SEAS AND SURF ARE NOT
EXPECTED TO BE KIND FOR THE NEXT FEW DAYS. SEAS LOOK TO INCREASE ONCE
MORE IN THE LATTER HALF OF THE WEEK AS ANOTHER SIGNIFICANT NORTH TO
NORTHEAST SWELL ENTERS THE AREA, AND WILL BE MONITORED CLOSELY FOR
THE ISSUANCE OF ADDITIONAL SEA AND SURF HAZARDS.
EASTERN MICRONESIA...
THE TAIL-END OF A BROAD MID-LATITUDE LOW PRESSURE FRONTAL SYSTEM
EXTENDS INTO THE REGION AT AROUND 12N180 AND TRANSITIONS INTO A
WEAKENING SHEAR LINE ACROSS THE NORTHERN MARSHALLS, PASSES NEAR
KOSRAE AND POHNPEI, THEN MEETS A BROAD SURFACE TROUGH IN SOUTHERN
CHUUK AND POHNPEI STATES. A BAND OF WIDESPREAD, PATCHY CLOUDS AND
SHOWERS ARE FOUND ALONG THIS BOUNDARY, WITH CONVECTION DEEPENING
SOUTHWEST OF POHNPEI, CLOSER TO THE AFOREMENTIONED TROUGH. KOSRAE AND
MAJURO ARE SLIGHTLY SOUTH OF THE CONVECTION, SO ONLY ISOLATED
SHOWERS ARE EXPECTED TONIGHT, WITH SHOWERS STARTING TO FILL IN NEAR
MAJURO AFTER MIDNIGHT. SCATTERED SHOWERS AND A SLIGHT CHANCE OF
THUNDERSTORMS ARE EXPECTED AT POHNPEI TONIGHT, BUT AS THE TROUGH
CONTINUES TO MOVE FARTHER WESTWARD AND THE SHEAR LINE CONTINUES TO
DISSIPATE, OVERALL SHOWERS DECREASE TO ISOLATED BY TUESDAY NIGHT.
ISOLATED TO SCATTERED SHOWERS ARE EXPECTED FARTHER EAST OVER KOSRAE
AND MAJURO THIS WEEK, THEN THE INTERTROPICAL CONVERGENCE ZONE (ITCZ)
LOOKS TO BUILD BACK IN OVER THE DATE LINE LATE WEEK.
LATEST ALTIMETRY AND BUOY DATA SHOW SEAS ARE 4 TO 7 FEET AT KOSRAE
AND 6 TO 8 FEET NEAR POHNPEI AND MAJURO. HAZARDOUS SURF IS STILL
EXPECTED ALONG NORTH REEFS OF POHNPEI AND KOSRAE, BUT HAVE EXTENDED
ANOTHER 12 HOURS TO BETTER ENCOMPASS THE INCOMING PULSE OF LONG-
PERIOD NORTHERLY SWELL, EXPECTED TO ARRIVE LATE TONIGHT AND EARLY
TUESDAY MORNING. OTHERWISE, RETAINED A SIMILAR UNCERTAINTY CONVEYED
IN THE PREVIOUS FORECAST DISCUSSION, TO MONITOR THE DURATION OF LONG-
PERIOD NORTHERLY SWELL IN SUBSEQUENT MODEL RUNS BEFORE DECIDING TO
EXTEND THE ADVISORY TOO FAR OUT. WITH THIS PULSE IN NORTHERLY SWELL,
SEAS NEAR POHNPEI ARE EXPECTED TO INCREASE TO 7 TO 9 FEET ON TUESDAY,
POSSIBLY NEARING HAZARDOUS LEVELS OF 10 FEET.
WESTERN MICRONESIA...
MUCH OF FAR WESTERN MICRONESIA REMAINS UNDER A RELATIVELY DRY TRADE-
WIND PATTERN, WITH ISOLATED TO SCATTERED SHOWERS LOOSELY FOCUSED
AROUND A SHALLOW TROUGH JUST WEST OF PALAU, AND A NORTHWEST-TO-
SOUTHEAST ORIENTED BAND OF WEAK TRADE-WIND CONVERGENCE JUST EAST OF
YAP. SHOWERS LOOK TO DECREASE NEAR PALAU OVERNIGHT AS THE TROUGH
MOVES AWAY, AND INCREASE SLIGHTLY NEAR YAP LATE OVERNIGHT AS A
ROBUST TRADE-WIND TROUGH, CURRENTLY LOCATED JUST WEST OF THE
MARIANAS, SHIFTS WESTWARD TOWARDS THE AREA WITH TRADE-WIND
CONVERGENCE INCREASING SLIGHTLY AHEAD OF IT. HOWEVER, MOST OF THE
UNSETTLED WEATHER IN THE REGION IS LOCATED MUCH FURTHER EAST, JUST
SOUTH OF CHUUK LAGOON. NUMEROUS TO WIDESPREAD SHOWERS AND ISOLATED
THUNDERSTORMS ARE FOCUSED ALONG A ROBUST TRADE-WIND TROUGH WHICH
EXTENDS SOUTHWEST FROM AROUND 7N154E, JUST SOUTHEAST OF CHUUK COASTAL
WATERS, INTO A BUFFER CIRCULATION CENTERED AROUND EQ145E. MODEL
GUIDANCE DEPICTS THIS TROUGH LIFTING NORTHWEST OVER THE NEXT DAY OR
SO, BRINGING NUMEROUS LOCALLY HEAVY SHOWERS AND ISOLATED
THUNDERSTORMS TO CHUUK ON TUESDAY, TAPERING DOWN TO SCATTERED
SHOWERS LATE TUESDAY NIGHT AS THE TROUGH SHIFTS WEST OF THE AREA.
THIS FEATURE WILL INCREASE SHOWERS FOR YAP AND PALAU AROUND THURSDAY
THROUGH SATURDAY AS IT TRANSITS WESTWARD THROUGH THE AREA, EXITING
WEST OF THE REGION AROUND SUNDAY.
LATEST ALTIMETRY DATA INDICATES COMBINED SEAS AROUND 5 TO 7 FEET NEAR
PALAU, AND 6 TO 8 FEET FOR YAP AND CHUUK. A BUILDING NORTHEAST TRADE
SWELL WILL MOVE INTO THE REGION THIS EVENING, AND IS EXPECTED TO
BRING HAZARDOUS SURF UP TO 10 FEET FOR NORTH FACING REEFS OF CHUUK,
POTENTIALLY INCREASING AS HIGH AS 11 FEET TUESDAY. A HIGH SURF
ADVISORY IS IN EFFECT UNTIL 5 PM CHST THURSDAY, WHEN THE NORTHEAST
SWELL AND ASSOCIATED SURF ARE EXPECTED TO DIMINISH BELOW HAZARDOUS
LEVELS FOR CHUUK. FOR NOW, SEAS AND SURF LOOK TO REMAIN BELOW
HAZARDOUS LEVELS AT PALAU AND YAP, HOWEVER, A SLIGHT INCREASE IN THE
EXPECTED NORTHEAST SWELL COULD CHANGE THIS. SEAS MAY STILL SEE AN
INCREASE UP TO AROUND 10 FEET FOR CHUUK FOR TUESDAY AND TUESDAY
NIGHT, BUT MODEL TRENDS HAVE BACKED OFF SLIGHTLY WITH THE 10-FOOT
SEAS REMAINING FURTHER NORTH, AND COMBINED SEAS ARE EXPECTED TO
INCREASE TO AROUND 7 TO 9 FEET OVER CHUUK COASTAL WATERS. GENTLE TO
MODERATE WINDS ARE EXPECTED AT CHUUK THROUGH THE WEEK. FOR YAP AND
PALAU, GENTLE TO MODERATE WINDS WILL BECOME LIGHT TO GENTLE BY
MIDWEEK.
GUM WATCHES/WARNINGS/ADVISORIES
GU...HIGH RIP CURRENT RISK THROUGH LATE TONIGHT FOR GUZ001.
HIGH SURF ADVISORY UNTIL 4 AM CHST WEDNESDAY FOR GUZ001.
MP...HIGH RIP CURRENT RISK THROUGH LATE TONIGHT FOR MPZ001>003.
HIGH SURF ADVISORY UNTIL 4 AM CHST WEDNESDAY FOR MPZ001>003.
MARIANAS WATERS...SMALL CRAFT ADVISORY UNTIL 6 PM CHST THIS EVENING FOR PMZ151>154.
MARIANAS/EAST AND WEST MICRONESIA UPDATE: SCHANK
MARIANAS: BOWSHER/DECOU
EAST MICRONESIA: CRUZ
WEST MICRONESIA: DECOU
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page