985
FXPQ50 PGUM 050803
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
603 PM CHST MON JAN 5 2026
MARIANAS SYNOPSIS
A SHEAR LINE EXTENDS ACROSS THE REGION AND IS PRODUCING CLOUDY
SKIES, NUMEROUS SHOWERS, AND FRESH TO STRONG WINDS ACROSS TINIAN AND
SAIPAN. SOUTH OF THIS FEATURE, GENTLE TO MODERATE WINDS AND ISOLATED
TO SCATTERED SHOWERS CONTINUE FOR GUAM AND ROTA. NORTH TO NORTHWEST
SWELL IS MOVING THROUGH THE REGION, RITIDIAN BUOY SHOWS HAZARDOUS SEAS
PEAKING AT AROUND 11 FEET THIS AFTERNOON.
DISCUSSION
THE SHEAR LINE IS EXPECTED TO SHIFT SOUTHWARD AND WEAKEN SLIGHTLY AS
IT APPROACHES GUAM AND ROTA OVERNIGHT AND TUESDAY. NUMEROUS SHOWERS
NEAR TINIAN AND SAIPAN TONIGHT DECREASE TO SCATTERED TUESDAY.
SHOWERS ARE EXPECTED TO INCREASE TO HIGH-END SCATTERED (50%) LATE
TONIGHT FOR ROTA, AND GUAM MAY START TO SEE MORE OF THE SHEAR LINE
AROUND MIDNIGHT, WITH SHOWERS INCREASING FROM ISOLATED TO SCATTERED.
BREEZY CONDITIONS CONTINUE FOR TINIAN AND SAIPAN TONIGHT, WITH
OBSERVATIONS SHOWING GUSTS NEAR 30 MPH. THE TIMING AND INTENSITY OF
INCOMING AND OUTGOING SHOWERS WAS A BIT OF A CHALLENGE BASED ON AN
OBSERVED WEAKENING TREND IN MODEL GUIDANCE, SO IF SATELLITE TRENDS
SUPPORT A BETTER LOOKING SHEAR LINE FEATURE OVERNIGHT, AN UPDATED
FORECAST TREND MAY BE NEEDED.
MARINE/SURF
FRESH TO STRONG NORTHEAST WINDS ARE EXPECTED THROUGH TONIGHT, DUE TO
THE NEARBY SHEAR LINE. NORTH TO NORTHWEST SWELL IS CURRENTLY MOVING
THROUGH THE REGION, WHICH BROUGHT A PEAK IN SEA HEIGHTS NEAR 11 FEET
EARLIER THIS AFTERNOON AND IS EXPECTED TO BEGIN SUBSIDING LATER
TONIGHT. A HIGH SURF ADVISORY ALONG NORTH-FACING REEFS AND A SMALL
CRAFT ADVISORY REMAINS IN EFFECT THROUGH LATE TONIGHT. A HIGH RISK OF
RIP CURRENTS STATEMENT IS IN EFFECT THROUGH LATE TONIGHT FOR NORTH-
FACING REEFS AND THROUGH TUESDAY AFTERNOON FOR EAST-FACING REEFS.
ADDITIONALLY, A MODERATE RISK OF RIP CURRENTS CONTINUES ALONG WEST-
FACING REEFS THROUGH TUESDAY AFTERNOON. AS THE SHEAR LINE WEAKENS
TUESDAY, WINDS BECOME MODERATE TO FRESH AND WIND-DRIVEN WAVES
DECREASE SLIGHTLY, WHICH MAY ALLOW FOR COMBINED SEAS TO SUBSIDE BELOW
HAZARDOUS LEVELS OF 10 FEET AS EARLY AS TUESDAY MORNING. THIS IS
DEPENDENT ON WHAT THE RITIDIAN BUOY SHOWS OVERNIGHT, IF SWELL DOES
NOT DECREASE AS FAST AS WHAT THE WAVE MODELS SUGGESTS, THE MARINE AND
SURF ADVISORIES MAY NEED TO BE EXTENDED. MODERATE TO FRESH EAST TO
NORTHEAST WINDS WILL THEN CONTINUE THROUGH LATE WEEK. COMBINED SEAS
GRADUALLY SUBSIDE TO 5 TO 7 FEET WEDNESDAY NIGHT, THEN INCREASE BACK
UP TO 7 TO 9 FEET SATURDAY WITH AN INCREASE IN NORTHEAST SWELL AND
WIND WAVES.
EASTERN MICRONESIA
THE LATEST SATELLITE IMAGERY SHOWS A DRY PATTERN CURRENTLY IN PLACE
ACROSS EASTERN MICRONESIA. A FRONT THAT HAS PUSHED MUCH FARTHER SOUTH
THAN NORMAL CONTINUES TO PRODUCE NUMEROUS SHOWERS AND ISOLATED
THUNDERSTORMS EAST OF THE MARSHALLS. POHNPEI BUOY SHOWS SEAS BETWEEN
5 AND 6 FEET.
A DRY PATTERN WILL PREVAIL ACROSS THE REGION THROUGH TUESDAY. FOR
MAJURO, THE EXTREMELY WEAK FRONT TO THE EAST WILL PUSH EASTWARD AS
IT CONTINUES TO DISSIPATE. AS THIS OCCURS, IT WILL OPEN THE DOOR FOR
INCREASED MOISTURE TO MOVE INTO THE MARSHALLS. AS THE MOISTURE
INCREASES, A BAND OF TRADE-WIND CONVERGENCE IS EXPECTED TO DEVELOP
ACROSS THE REGION, REMAINING SOUTH OF KOSRAE AND POHNPEI.
ADDITIONALLY, WEAK TRADE-WIND TROUGHS ARE ALSO EXPECTED TO MOVE
THROUGH THE MARSHALLS. THIS COMBINATION IS EXPECTED TO BRING
SCATTERED SHOWERS TO MAJURO AS EARLY AS TUESDAY NIGHT. DUE TO THE
PROXIMITY OF A LINGERING UPPER-LEVEL LOW, ASSOCIATED DIVERGENCE WILL
RESULT IN ISOLATED THUNDERSTORMS TUESDAY NIGHT INTO WEDNESDAY. THEN,
AN UNSETTLED PATTERN LOOKS TO CONTINUE AT MAJURO INTO THE WEEKEND.
FOR KOSRAE AND POHNPEI, BOTH LOCATIONS LOOK TO REMAIN PRETTY DRY
THROUGH THE WEEK. BY THE WEEKEND, THE DRY PATTERN LOOKS TO BREAK DOWN
A BIT, ALLOWING INCREASED CONVECTION AS A TRADE-WIND TROUGH
APPROACHES THE REGION AND PULLS THE BAND OF CONVERGENCE FARTHER
NORTH.
LONG-PERIOD NORTH TO NORTHEAST SWELL AND NORTHEAST TRADE SWELL WILL
CONTINUE TO PRODUCE ELEVATED SURF ALONG NORTH AND EAST FACING REEFS.
HOWEVER, HAZARDOUS SURF CONDITIONS ARE NOT EXPECTED. COMBINED SEAS
OF 4 TO 6 FEET TONIGHT ARE EXPECTED TO BUILD BY MIDWEEK AS A LONG-
PERIOD NORTHWEST TO NORTH SWELL MOVES INTO THE REGION TUESDAY,
BECOMING THE DOMINANT SWELL FOR POHNPEI TUESDAY NIGHT AND FOR KOSRAE
WEDNESDAY. THIS INCREASE COULD RESULT IN HAZARDOUS SURF ALONG NORTH
FACING REEFS OF POHNPEI AND KOSRAE. WE WILL CONTINUE TO MONITOR
SUBSEQUENT WAVE MODEL DATA AND BUOY/ALTIMETRY DATA TO ASSESS ANY
POTENTIAL FOR HIGH SURF. LIGHT TO MODERATE WINDS NORTHEAST WINDS ARE
EXPECTED OVER THE NEXT COUPLE OF DAYS, WITH THE EXCEPTION OF LIGHT
TO GENTLE NORTH WIND TONIGHT AT KOSRAE. THE COASTAL FLOOD STATEMENT
REMAINS IN EFFECT FOR MAJURO THROUGH LATE MONDAY NIGHT FOR MINOR
INUNDATION ALONG NORTHERN AND EASTERN SHORELINES DURING TIMES OF HIGH
TIDE, DUE TO THE FULL MOON CYCLE.
WESTERN MICRONESIA
A DRY, GENTLE TO MODERATE TADE-WIND PATTERN EXTENDS ACROSS THE
REGION AS THE NEAR-EQUATOIRAL TROUGH AS SHIFTED SOUTHWARD AND WAY
FROM PALAU AND DRY AIR REMAINS WELL ESTABLISHED ACROSS THE REGION
ACCORDING THE THE BLENDED TOTAL PRECIPITABLE WATER (TPW) SATELLITE
PRODUCT. MODEL GUIDANCE KEEPS THIS DRY AIR IN PLACE THROUGH AT LEAST
THURSDAY SO THIS SHOULD SUPPORT DRY CONDITIONS ACROSS CHUUK, YAP AND
PALAU OVER THE NEXT COUPLE OF DAYS. HOWEVER, THERE IS THE SHEAR LINE
UP NEAR THE MARIANAS AND WHILE MODELS SHOW THIS FEATURE WEAKENING,
THE GFS AND ECMWF SHOW THIS AREA OF INCREASE CLOUD COVER SHIFTING
TOWARDS PALAU AND YAP AROUND THURSDAY AND FRIDAY, WHICH COULD LEAD A
SLIGHT INCREASE IN SHOWERS IF THIS FEATURE HOLDS TOGETHER. OTHERWISE,
MODELS SHOW WIND INCREASING TO MODERATE TO FRESH AROUND FRIDAY AND
SATURDAY AS A RIDGE OF HIGH PRESSURE BUILDS IN THE MID-LATITUDES.
THIS BUILDING OF THE WINDS MAY CREATE AN AREA OF SPEED CONVERGENCE
ACROSS THE REGION THAT COULD CAUSE THE POTENTIAL FOR SHOWERS TO
INCREASE ACROSS THE REGION THIS WEEKEND.
ALTIMETRY AND THE DRIFTING BUOY NEAR YAP SHOWS SEAS HAVE BUILT TO
AROUND 7 TO 8 FEET AS THE NORTH-NORTHWEST SWELL MOVED THROUGH THIS
MORNING. WITH THE PRIMARY SWELL DIRECTION EXPECTED TO BE COME MORE
NORTH AND THEN NORTH-NORTHEAST, SURF ALONG WEST FACING REEFS HAS
LIKELY DROPPED BELOW 9 FEET ALONG WEST FACING REEFS OF PALAU AND YAP
THIS AFTERNOON, BUT REMAIN AROUND 8 TO 10 FEET ALONG NORTH FACING
REEFS. BASED THE LATEST TIMING OF THE MODELS, AND ACCOUNTING FOR
MODELS USUALLY BEING TO QUICK WITH DROPPING THE NORTH SWELL, SURF IS
EXPECTED NOT EXPECTED TO DROP BELOW 9 FEET ALONG NORTH FACING REEFS
UNTIL TUESDAY AFTERNOON. THE NORTH-NORTHWEST SWELL IS EXPECTED TO
REACH CHUUK LAGOON TUESDAY MORNING. AS STATED YESTERDAY, THE MARIANAS
BUOYS WILL BE HELPFUL IN SEEING IF THE WAVES MODELS ARE UNDER
ESTIMATING THE INCOMING SWELL, AND IT LOOKS LIKE THE MODELS ARE UNDER
PREDICTING THE HEIGHT OF THE SWELL BY 1 TO 2 FEET BASED ON TODAY'S
OBSERVATIONS. BASED ON THIS INFORMATION A HIGH SURF ADVISORY WAS
ISSUED FOR WEST AND NORTH FACING REEFS OF CHUUK FROM 5AM TUESDAY TO
5AM WEDNESDAY. SEAS WILL LIKELY PEAK AT AROUND 8 FEET TUESDAY,
REMAINING BELOW THE HAZARDOUS THRESHOLD OF 10 FEET FOR SMALL CRAFT.
THE NORTH-NORTHWEST SWELL AT CHUUK IS EXPECTED TO START DECREASE
TUESDAY EVENING, BUT SURF IS NOT EXPECTED TO DROP BELOW 9 FEET UNTIL
WEDNESDAY MORNING. LOOKING TOWARDS THE WEEKEND, THE TRADE WINDS ARE
EXPECTED TO INCREASE TO MODERATE TO FRESH AS A RIDGE OF HIGH PRESSURE
BUILDS IN THE MID- LATITUDES. THIS INCREASE IN WINDS WILL BUILD THE
NORTHEAST TO EAST TRADE SWELL AND LOCAL WIND WAVES, INCREASING SEAS,
AND SURF ALONG EAST FACING REEFS.
GUM WATCHES/WARNINGS/ADVISORIES
GU...HIGH RIP CURRENT RISK THROUGH TUESDAY AFTERNOON FOR GUZ001.
HIGH SURF ADVISORY UNTIL 6 AM CHST TUESDAY FOR GUZ001.
MP...HIGH RIP CURRENT RISK THROUGH TUESDAY AFTERNOON FOR MPZ001>003.
HIGH SURF ADVISORY UNTIL 6 AM CHST TUESDAY FOR MPZ001>003.
MARIANAS WATERS...SMALL CRAFT ADVISORY UNTIL 6 AM CHST TUESDAY FOR
PMZ151>154.
MARIANAS: CRUZ
EAST MICRONESIA: KLEESCHULTE
WEST MICRONESIA: SCHANK
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