512
FXPQ50 PGUM 230846
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
646 PM CHST TUE DEC 23 2025
MARIANAS SYNOPSIS
THERE REMAINS A HIGH SURF ADVISORY AND A HIGH RISK OF RIP CURRENTS
STATEMENT IN EFFECT.
SATELLITE IMAGERY SHOWS MOSTLY CLOUDY TO CLOUDY SKIES, WHILE RADAR
IMAGERY SHOW SCATTERED SHOWERS OVER THE MARIANAS AND THEIR WATERS.
ALTIMETRY SHOWS COMBINED SEAS OF 8 TO 9 FEET AND BUOY DATA SHOWS SEA
HEIGHTS OF 7 TO 8 FEET.
DISCUSSION
ANOTHER WET AND GUSTY DAY TODAY. AS OF 4 PM CHST, 1.11 INCHES OF RAIN
HAS FALLEN SINCE MIDNIGHT. THESE SHOWERS ARE PRODUCED BY CONVERGENCE
ALONG THE BACKSIDE OF THE TROUGH THAT PASSED YESTERDAY WITH SUPPORT
FROM AN UPPER-LEVEL TROUGH. THIS MIXTURE OF FEATURES HAS BEEN
PRODUCING WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS JUST
WEST OUTSIDE THE COASTAL WATERS, WITH SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS BACK-BUILDING NEAR THE ISLANDS THIS EVENING. THESE
FEATURES ARE EXPECTED TO MAINTAIN SHOWERS NEARBY OVER THE NEXT DAY
OR SO, POTENTIALLY BRINGING WETTER CONDITIONS FOR CHRISTMAS EVE.
THEN, A RIDGE IS EXPECTED TO MOVE IN OVER THE MARIANAS FOR CHRISTMAS
DAY, BRINGING RELATIVELY DRIER WEATHER FOR THE REST OF THE WEEK.
MARINE/SURF...
THE SMALL CRAFT ADVISORY HAS EXPIRED. THE STRONG MID-LATITUDE HIGH
PRESSURE SYSTEM CONTINUES TO MOVE EASTWARD ACROSS THE PACIFIC AND
ALLOWING THE TRADE WINDS AND TRADE SWELL IN THE REGION TO DIMINISH.
SEAS OF 7 TO 9 FEET ARE EXPECTED TO SLOWLY SUBSIDE AS THE NORTHEAST
SWELL DECREASES. THIS DECREASE MAY BE SHORT LIVED AS ANOTHER
SIGNIFICANT PULSE OF NORTHEAST SWELL IS ANTICIPATED TO MOVE THROUGH
THE REGION LATER THIS WEEK. SURF AND RISK OF RIP CURRENTS ARE
EXPECTED TO FALL BELOW HAZARDOUS LEVELS AS EARLY AS WEDNESDAY
MORNING. THERE WILL BE A MODERATE RISK OF LIGHTNING THROUGH WEDNESDAY
FOR GUAM. NEAR THE END OF THE WEEK, ANOTHER PULSE OF NORTHEAST SWELL
IS ANTICIPATED TO MOVE THROUGH THE AREA. THIS MAY PRODUCE HIGHER
SURF.
EASTERN MICRONESIA
THE TAIL-END OF A BROAD MID-LATITUDE LOW PRESSURE FRONTAL SYSTEM
CONTINUES TO WEAKEN. A BAND OF PATCHY CLOUDS AND SHOWERS IS DRAPED
ACROSS THE NORTHERN RMI AND PASSES NORTH OF KOSRAE AND POHNPEI. CIMSS
MIMIC TPW PRODUCT SHOWS A RELATIVELY DRIER AIRMASS TO THE SOUTH OF
THE FEATURE, INDICATING PRECIPITABLE WATER AMOUNTS OF 1.20-1.60
INCHES OVER KOSRAE AND MAJURO. FAIRLY QUIET WEATHER IS EXPECTED OVER
THE NEXT FEW DAYS, THEN THE INTERTROPICAL CONVERGENCE ZONE (ITCZ)
LOOKS TO BUILD BACK IN OVER THE DATE LINE LATE WEEK, INCREASING
SHOWERS AT MAJURO BY FRIDAY AND AT KOSRAE OVER THE WEEKEND.
ALTIMETRY AND BUOY DATA SHOWED HAZARDOUS SEAS OF 8 TO 10 FEET TODAY.
POHNPEI BUOY STILL SHOWS ELEVATED SEAS THIS AFTERNOON, BUT IS
SLIGHTLY BELOW HAZARDOUS LEVELS, AT 8 TO 9 FEET. AS THIS PULSE OF
NORTHERLY SWELL GRADUALLY SUBSIDES TONIGHT AND WEDNESDAY, SEAS
DECREASE BACK DOWN TO 6 TO 8 FEET. THE HIGH SURF ADVISORY ALONG
NORTH-FACING REEFS WAS EXTENDED ANOTHER 12 HOURS, NOW EXPIRING
WEDNESDAY AFTERNOON. ANOTHER PULSE OF NORTHERLY SWELL ARRIVES LATE
WEEK AND OVER THE WEEKEND, POSSIBLY PUSHING SURF ALONG NORTH FACING
SURF AND COMBINED SEAS UP TO HAZARDOUS LEVELS ONCE AGAIN.
WESTERN MICRONESIA
A FAIRLY DRY TRADE-WIND REGIME PREVAILS ACROSS FAR WESTERN
MICRONESIA, WITH SATELLITE THIS AFTERNOON SHOWING JUST ISOLATED
SHOWERS ACROSS MUCH OF THE REGION. A BROAD TRADE-WIND TROUGH,
CURRENTLY CENTERED JUST NORTHEAST OF YAP PROPER, IS EXPECTED TO
PROPAGATE WESTWARD ACROSS THE PHILIPPINE SEA OVER THE NEXT DAY OR SO,
WITH THE SOUTHERN EXTENT MOVING OVER YAP. MODEL GUIDANCE POINTS TO A
FAIRLY DRY PATTERN CONTINUING FOR YAP AS MOST OF THE SHOWERS AND
THUNDERSTORMS REMAIN FURTHER NORTH, WHERE UPPER-LEVEL SUPPORT IS
MORE FAVORABLE. SHOWERS INCREASE FROM WEDNESDAY NIGHT ONWARD AS A
SEPARATE TRADE-WIND TROUGH, MOVING WEST ACROSS YAP STATE, GRADUALLY
PROGRESSES THROUGH THE AREA. SHOWERS WILL REMAIN AT LEAST SCATTERED
FOR PALAU AND YAP THROUGH THE WEEKEND, POSSIBLY BECOMING NUMEROUS
FOR YAP AT TIMES TOWARD THE END OF THE WEEK.
FOR CHUUK, THE TRADE-WIND TROUGH THAT WAS EXPECTED TO BRING HEAVIER
SHOWERS THROUGH THE AREA IS MOVING AWAY WELL TO THE WEST OF COASTAL
WATERS, NOW CENTERED NEAR SATAWAL. DRIER CONDITIONS FOLLOW
IMMEDIATELY IN ITS WAKE, BUT AN UPTICK IN SHOWERS IS EXPECTED
OVERNIGHT DUE TO WEAKLY CONVERGENT TRADES BEHIND THE EXITING TROUGH,
AS THE NEXT TRADE-WIND TROUGH APPROACHES FROM THE EAST NEAR POHNPEI.
SCATTERED SHOWERS ARE EXPECTED THROUGH THE NEXT FEW DAYS AS WEAK
PASSING TROUGHS IN THE AREA INTERACT WITH THE REMNANTS OF A SHEARLINE
FRAGMENT NEARBY, WITH A PEAK AROUND THURSDAY. DRIER CONDITIONS LOOK
TO PREVAIL THIS WEEKEND, BEFORE A POSSIBLE TRADE-WIND DISTURBANCE
INCREASES SHOWERS EARLY NEXT WEEK.
SATELLITE ALTIMETRY FROM THIS MORNING CONTINUED TO SHOW ELEVATED
SEAS ACROSS THE REGION, WITH CHUUK LOCATED ROUGHLY ALONG AN AREA
OF 9 TO 10 FOOT COMBINED SEAS, AFTER THE NORTH-NORTHEAST SWELL
REACHED PEAK INTENSITY. SEAS ARE EXPECTED TO DIMINISH TO AROUND 6 TO
8 FEET THROUGH TONIGHT AS THE PULSE OF ELEVATED SWELL SUBSIDES,
REMAINING IN THIS RANGE FOR MUCH OF THE WEEK BEFORE ANOTHER PULSE OF
ELEVATED NORTH-NORTHEAST SWELL ENTERS THE REGION AROUND SATURDAY.
THE NEXT PULSE OF SWELL IS EXPECTED TO BE A BIT WEAKER OVER CHUUK
WATERS WITH MORE OF THE SWELL ENERGY FOCUSED FURTHER EAST, BUT WILL
BE CLOSELY MONITORED FOR POTENTIAL SURF AND SMALL CRAFT HAZARDS THIS
WEEKEND. THE HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 5 PM CHST
THURSDAY, WHEN THE NORTHEAST SWELL AND ASSOCIATED SURF ARE EXPECTED
TO DIMINISH BELOW HAZARDOUS LEVELS FOR CHUUK. FOR PALAU AND YAP,
ALTIMETRY REVEALS COMBINED SEAS AROUND 6 TO 8 FEET, AND SEAS AND SURF
LOOK TO REMAIN BELOW HAZARDOUS LEVELS, 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,
WINDS LOOK TO REMAIN MOSTLY LIGHT TO GENTLE.
GUM WATCHES/WARNINGS/ADVISORIES
GU...HIGH RIP CURRENT RISK UNTIL 4 AM CHST WEDNESDAY FOR GUZ001.
HIGH SURF ADVISORY UNTIL 4 AM CHST WEDNESDAY FOR GUZ001.
MP...HIGH RIP CURRENT RISK UNTIL 4 AM CHST WEDNESDAY 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: BOWSHER
EAST MICRONESIA: CRUZ
WEST MICRONESIA: DECOU
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