829
FXPQ50 PGUM 131825
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
425 AM CHST WED JAN 14 2026
MARIANAS UPDATE
THE MAIN UPDATE WAS TO CANCEL THE SMALL CRAFT ADVISORY FOR THE
COASTAL WATERS OF TINIAN AND SAIPAN, AS WAVES HAVE DROPPED BELOW 10
FEET. HOWEVER, A HIGH RISK OF RIP CURRENTS FOR OUR EAST-FACING REEFS
REMAINS IN EFFECT THROUGH THURSDAY AFTERNOON. A MOISTURE SURGE
CURRENTLY CROSSING THE AREAS WILL ALLOW US TO KEEP SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS IN THE FORECAST, AS MODEL CROSS SECTIONS
AND MIMIC WATER VAPOR IMAGERY SUPPORT THIS POTENTIAL.
HOWEVER, CONVECTIVE COVERAGE HAS BEEN LESS THAN STELLAR. WE THOUGHT
ABOUT DECREASING CONVECTIVE COVERAGE/RAINFALL POTENTIAL, BUT OPTED TO
LET THE DAY SHIFT GET ANOTHER LOOK AT IT. A LATE MORNING UPDATE TO
ACCOUNT FOR THIS REMAINS POSSIBLE.
EASTERN MICRONESIA UPDATE
NO SIGNIFICANT CHANGES WERE NEEDED AS THE GOING FORECAST HAS THINGS
IN GOOD SHAPE.
WESTERN MICRONESIA UPDATE
INVEST 91W CONTINUES TO STRUGGLE WITH ITS ORGANIZATION, AND THE
LATEST RATING FROM THE JOINT TYPHOON WARNING CENTER CONTINUES TO
FURTHER SUGGEST DEVELOPMENT INTO A TROPICAL CYCLONE IS NOT
ANTICIPATED. THE CIRCULATION REMAINS SOMEWHAT BROAD AS WELL, AND
IT'S CURRENTLY CENTERED (ESTIMATED BASED ON SATELLITE) TO BE NEAR
7N131E. THE MIDNIGHT SCATTEROMETER HAND ANALYSIS WAS ALSO LESS THAN
IMPRESSIVE. STILL, IT IS BRINGING PERIODS OF LOCALLY HEAVY RAINFALL
AND GUSTY WINDS TO KOROR, NGULU, AND YAP, SO WE'LL KEEP AN EYE ON
THINGS. THE LLCC (LOW-LEVEL CIRCULATION CENTER) SHOULD BE OUT OF
GUAM'S AOR (AREA OF RESPONSIBILITY) IN THE NEXT 24 HOURS. AS THIS
OCCURS, RAINFALL INTENSITY AND COVERAGE WILL DECREASE BY LATE
TONIGHT. ADDITIONAL INFORMATION FOR YAP AND PALAU IS AVAILABLE IN A
SPECIAL WEATHER STATEMENT (SPSPQ2) UNDER WMO HEADER WWPQ82 PGUM.
WITH THAT SAID, THE FORECAST HAS THINGS WELL IN HAND. THUS, NO
UPDATES WERE NEEDED TO THE FORECAST.
PREV DISCUSSION
/ISSUED 616 PM CHST TUE JAN 13 2026/
MARIANAS SYNOPSIS...
MOSTLY CLOUDY SKIES WITH ISOLATED SHOWERS AND MODERATE TO
OCCASIONALLY FRESH TRADE WINDS PREVAIL ACROSS THE REGION. ALTIMETRY
SHOWS SEAS OF 10 TO 12 FEET NORTH AND EAST OF TINIAN AND SAIPAN.
DISCUSSION...
SATELLITE AND RADAR DATA SHOWS CONVECTION HAS DECREASED SIGNIFICANTLY
ACROSS THE MARIANAS THIS EVENING, THOUGH MOSTLY CLOUDY SKIES REMAIN
OVER THE ISLANDS. THIS IS EXPECTED TO CHANGE BY WEDNESDAY MORNING AS
INVEST 91W MOVES WEST-NORTHWEST AWAY FROM PALAU. THIS LOOKS TO PUSH A
BAND OF WEAK CONVERGENCE OVER THE MARIANAS THAT SHOULD INCREASE
SHOWERS AND THUNDERSTORMS THROUGH THURSDAY AFTERNOON. BY THURSDAY
NIGHT, A DRY TRADE-WIND PATTERN LOOKS TO MOVE BACK INTO THE REGION.
MARINE...
MODERATE TO FRESH TRADE WINDS WILL CONTINUE THROUGH MIDWEEK FOR
GUAM AND ROTA AND THROUGH THURSDAY NIGHT FOR TINIAN AND SAIPAN,
BECOMING GENTLE TO MODERATE FOR THE REST OF THE WEEK INTO THE
WEEKEND. ANOTHER PULSE OF NORTH SWELL, ALONG WITH WITH THE BUILDING
TRADE SWELL WILL BRIEFLY PUSH NORTHERN SAIPAN WATERS TO 10 FEET
TONIGHT, THAT COULD MOVE INTO NORTHWESTERN TINIAN WATERS AS WELL.
THEREFORE, A SMALL CRAFT ADVISORY WAS ISSUED FOR TONIGHT FOR TINIAN
AND SAIPAN WATERS. OTHERWISE, THE ELEVATED TRADE-WIND SWELL IS
EXPECTED TO MAINTAIN HAZARDOUS SURF ALONG EAST FACING THROUGH
THURSDAY AFTERNOON.
TROPICAL SYSTEMS...
A TROPICAL DISTURBANCE, INVEST 91W, IS EMBEDDED ALONG THE NEAR
EQUATORIAL TROUGH (NET), CENTERED NEAR 5N134E. NUMEROUS TO
WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS ARE FOUND OVER A BROAD
AREA SOUTHWEST THROUGH NORTHEAST OF THE SYSTEM. INVEST 91W IS
EXPECTED TO CONTINUE TO MOVE WNW OVER THE NEXT FEW DAYS AS IT SLOWLY
STRENGTHENS, POSSIBLY BECOMING A TROPICAL DEPRESSION NEAR 130E. THIS
PATH WILL TAKE INVEST 91W S OF PALAU LATER TONIGHT. CONVECTION IS
EXPECTED TO CONSOLIDATE AS 91W PROGRESSES. INVEST 91W WILL BE
MONITORED CLOSELY FOR ANY INDICATIONS OF MORE RAPID DEVELOPMENT AS IT
MOVES TO THE WEST-SOUTHWEST OF PALAU. ADDITIONAL INFORMATION FOR YAP
AND PALAU IS AVAILABLE IN A SPECIAL WEATHER STATEMENT (SPSPQ2) UNDER
WMO HEADER WWPQ82 PGUM.
EASTERN MICRONESIA...
MULTIPLE SURFACE TROUGHS EMBEDDED WITHIN A DEVELOPING ITCZ WILL
CONTINUE TO BRING PERIODS OF SHOWERS AND THUNDERSTORMS, AS WELL AS
ELEVATED WINDS, ACROSS MUCH OF EASTERN MICRONESIA THIS WEEK.
CONVECTION IS EXPECTED TO PEAK OVER POHNPEI AND KOSRAE TONIGHT, AS
THE LEADING EDGE OF A TRADE-WIND SURGE HELPS FUEL SOME OF THESE
PASSING TROUGHS. SHOWERS WILL TAPER DOWN SLIGHTLY BUT CONTINUE TO BE
ON-AND-OFF IN NATURE AT POHNPEI AND KOSRAE FOR MUCH OF THE WEEK,
EXCEPT FOR A BRIEF PERIOD OF DIFFUSIVE FORCING THAT WILL DRY OUT THE
WEATHER NEAR POHNPEI WEDNESDAY NIGHT AND THURSDAY. MOST OF THE
CONVECTION DEVELOPING WITHIN THE ITCZ IS EXPECTED TO REMAIN JUST
SOUTH OF MAJURO, OCCASIONALLY LIFTING TO BRING PERIODS OF HEAVIER
SHOWERS AND SOME THUNDERSTORMS, NOW TO PEAK AROUND WEDNESDAY NIGHT
AND THURSDAY AS WELL. AFTER, A GENERALLY WETTER PATTERN WILL ENSUE.
AS THESE SHOWERS CONTINUE AND THE ITCZ STRENGTHENS, WINDS MAY PRODUCE
SEAS HAZARDOUS TO SMALL CRAFT IN THE SECOND HALF OF THE WEEK,
ESPECIALLY IN POHNPEI AND MAJURO WATERS, BUT TIMING REMAINS HIGHLY
UNCERTAIN AT THIS TIME.
COMBINED SEAS OF 5 TO 8 FEET NEAR POHNPEI AND KOSRAE, AND 6 TO 9
FEET NEAR MAJURO, ARE EXPECTED TO INCREASE ANOTHER FOOT OR TWO AS
EARLY AS WEDNESDAY NIGHT, AS VARIOUS NORTHERLY AND NORTHEASTERLY
SWELLS, IN ADDITION TO LOCALIZED WIND WAVES, STRENGTHEN AND INCREASE.
WESTERN MICRONESIA...
AS INVEST AREA 91W PASSES SOUTH OF KOROR TONIGHT, LOOK FOR WIDESPREAD
LOCALLY HEAVY SHOWERS, WHICH WILL TAPER DOWN TO SCATTERED TO NUMEROUS
THROUGH FRIDAY IN A CONVERGENT TAIL BEHIND 91W. WINDS WILL BE 5 TO 15
KNOTS THROUGH FRIDAY, THEN VARIABLE AT 5 KNOTS FOR THE WEEKEND. SEAS
WILL START AT 6 TO 8 FEET, THEN REMAIN FAIRLY STEADY THROUGH THURSDAY
NIGHT, THEN DIMINISH TO BETWEEN 3 AND 5 FEET FOR THE WEEKEND. THERE
COULD BE OCCASIONAL GUSTS TO 25 KNOTS WEDNESDAY NIGHT AND THURSDAY,
BUT BY FRIDAY BENIGN MARINE CONDITIONS WILL REIGN. THE RISK OF HEAVY
RAIN AND THEREFORE POSSIBLY MUDSLIDES WILL GRADUALLY DIMINISH AFTER
TONIGHT, THEN GO TO ESSENTIALLY ZERO BY FRIDAY. ANOTHER DISTURBANCE
COULD BE WINDING UP AT CHUUK THOUGH, SO CONTINUE TO MONITOR.
WIDESPREAD LOCALLY HEAVY SHOWERS WILL CONTINUE AT YAP THROUGH
WEDNESDAY, THEN SCATTERED TO NUMEROUS THROUGH THURSDAY NIGHT AND
FINALLY ISOLATED THROUGH THE REMAINDER OF THE FORECAST PERIOD
(THROUGH SUNDAY). 10 TO 20 KNOT WINDS TONIGHT WILL BECOME 10 TO 15 ON
WEDNESDAY, THEN GO 5 TO 10 ON THURSDAY NIGHT. SEAS WILL BE 6 TO 8
FEET THROUGH WEDNESDAY, THEN 5 TO 7 FEET THROUGH THURSDAY NIGHT, THEN
4 TO 5 FEET THROUGH SUNDAY. SO MARINE CONDITIONS WILL BE BENIGN AFTER
WEDNESDAY, BUT THAT NEW DISTURBANCE COULD CHANGE THINGS NEXT WEEK.
AT CHUUK, WINDS WILL BE A FAIRLY STEADY 10 TO 15 KNOTS FROM TONIGHT
THROUGH SUNDAY. SEA HEIGHTS OF 4 TO 6 FEET WILL GRADUALLY BUILD,
REACHING 6 TO 8 FEET BY SUNDAY. ISOLATED SHOWERS TONIGHT AND
WEDNESDAY WILL BECOME SCATTERED WEDNESDAY NIGHT. BY FRIDAY, THEY
MIGHT EVEN GO NUMEROUS OR WIDESPREAD IF THE NEW DISTURBANCE IS
DEVELOPING, BUT FOR NOW CAPPED THEM AT SCATTERED DUE TO UNCERTAINTY.
THIS WILL BE SOMETHING TO WATCH OVER THE NEXT DAY OR THREE.
GUM WATCHES/WARNINGS/ADVISORIES
GU...HIGH RIP CURRENT RISK THROUGH LATE THURSDAY NIGHT FOR GUZ001.
MP...HIGH RIP CURRENT RISK THROUGH LATE THURSDAY NIGHT FOR MPZ001>003.
MARIANAS WATERS...NONE.
MARIANAS/EAST AND WEST MICRONESIA/TROPICAL UPDATE: DOLL
MARIANAS: KLEESCHULTE
EAST MICRONESIA: MONTVILA
WEST MICRONESIA: STANKO
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