727
FXPQ50 PGUM 251928
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
528 AM CHST FRI DEC 26 2025
MARIANAS UPDATE
THE INHERITED FORECAST FOR THE MARIANAS PAINTS A PICTURE OF ISOLATED
SHOWERS AND PARTLY CLOUDY SKIES. SATELLITE, MODELS AND RADAR ALL
AGREE, SO NO CHANGES WERE NEEDED. THE MARIANAS ARE PRETTY MUCH
BETWEEN FEATURES RIGHT NOW, SO WE'LL BE WATCHING FOR THE NEXT ONE.
THE RAIN DUMPS DID LOWER THE KBDI TO 0 YESTERDAY. IT'S NOW BEGINNING
THE LONG, SLOW REBOUND AS IT HITS 25 TODAY.
MARINE
A HIGH SURF ADVISORY WAS ISSUED THIS AFTERNOON. IT'S DEFINITELY LESS
ROBUST THAN THE PREVIOUS EVENT. THE BUOYS HAVE MADE IT OVER 7 FEET,
BUT THEY PROBABLY WON'T GO MUCH HIGHER. SWELL AND PERIOD CALCULATIONS
FROM THE 9 BAND PLOT AT RITIDIAN BUOY SHOW SURF IS LIKELY JUST 6 TO 8
FEET, BUT COULD BE JUST EKING OUT 7 TO 9. MAINTAINED THE ADVISORY AS
A MINIMAL EVENT.
EASTERN MICRONESIA UPDATE
AN OLD SHEAR LINE WINDS ITS WAY THROUGH EASTERN MICRONESIA, PASSING
NORTH OF MAJURO AND NEAR KWAJALEIN, KOSRAE, POHNPEI AND LATER CHUUK
AND YAP. THE PORTIONS NEAR POHNPEI AND KOSRAE WERE LOOKING
PARTICULARLY ROBUST TONIGHT ON SATELLITE, SO UPGRADED THEM TO 30 POPS
WITH SCATTERED SHOWERS, AS OPPOSED TO 20 AND ISOLATED. OTHERWISE THE
FORECAST WAS IN GREAT SHAPE AND NEEDED NO CHANGES.
WESTERN MICRONESIA UPDATE
THE INHERITED WESTERN MICRONESIA FORECAST PAINTS A BUSY PICTURE NEAR
KOROR, PALAU AND ESPECIALLY YAP; AND SATELLITE SHOWS THAT IT IS SO.
WINDS AND WAVES ARE NOT A MAJOR CONCERN HERE AT THIS TIME, SO NO
CHANGES WERE NEEDED. THE CONVECTION NEAR YAP IS LIKELY THE RESULT OF
INTERACTION BETWEEN THE TRADE-WIND TROUGH AND THE TERMINUS OF THE
SHEAR LINE.
PREV DISCUSSION
/ISSUED 637 PM CHST THU DEC 25 2025/
MARIANAS SYNOPSIS...
SATELLITE IMAGERY SHOWS PARTLY CLOUDY SKIES, WHILE RADAR IMAGERY
SHOWS A FEW ISOLATED SHOWERS OVER THE MARIANAS AND COASTAL WATERS.
ALTIMETRY SHOWS COMBINED SEAS OF 6 TO 9 FEET AND BUOY DATA SHOWS SEA
HEIGHTS OF 6 TO 7 FEET.
DISCUSSION...
A LARGE POCKET OF DRIER AIR AND A RIDGE HAS MOVED INTO THE REGION.
THIS WILL CAUSE A MORE STABLE AIR MASS OVER THE ISLANDS AND BRING
PLEASANT WEATHER THROUGH THE NEXT SEVERAL DAYS.
MARINE/SURF...
THE IS WHERE THE MAIN FORECAST CONCERNS ARE. THE NORTHEAST SWELL IS
EXPECTED TO RISE SLIGHTLY STARTING FRIDAY, BY ABOUT A FOOT. THIS IS
EXPECTED TO REMAIN BELOW THE 10 FOOT THRESHOLD OF A SMALL CRAFT
ADVISORY, HOWEVER, THIS WILL INCREASE THE SURF ALONG NORTH FACING
REEFS AND INCREASE THE RISK OF RIP CURRENTS TO HIGH ALONG NORTH AND
EAST FACING REEFS. THIS INCREASE IN SWELL IS ANTICIPATED TO LAST
OVER THE WEEKEND AND THEN THE SWELL IS ANTICIPATED TO DIMINISH TO
BELOW BELOW 9 FEET THROUGH THE MIDDLE OF NEXT WEEK.
EASTERN MICRONESIA...
LATEST SATELLITE DATA SHOWS PARTLY CLOUDY SKIES WITH ISOLATED
SHOWERS ACROSS THE REGION. POHNPEI BUOY AND ALTIMETRY SHOW SEAS OF 7
TO 8 FEET, MOSTLY NORTH SWELL, AT POHNPEI. ALTIMETRY SHOWS SEAS OF 5
TO 6 FEET AT KOSRAE AND 4 TO 5 FEET FOR MAJURO.
A WEAKENING SHEAR LINE FRAGMENT IS SEEN OVER THE REGION. THIS FEATURE
IS ONLY GENERATING PARTLY CLOUDY SKIES AND SPOTTY SHOWERS ACROSS THE
REGION. MODEL GUIDANCE FAVORS A MUCH DRIER PATTERN ACROSS EASTERN
MICRONESIA THROUGH SATURDAY. LATER IN THE WEEKEND, MODELS SHOW THE
DEVELOPMENT OF A WEAK INTER-TROPICAL CONVERGENCE ZONE (ITCZ) OVER
THE REGION. THIS FEATURE, ALONG WITH WEAK TRADE-WIND TROUGHS MOVING
THROUGH THE REGION, WILL PRODUCE PERIODS OF INCREASED CONVECTION
THROUGH THE BEGINNING OF NEXT WEEK, ESPECIALLY AT KOSRAE.
BUILDING SEAS ACROSS POHNPEI RESULTED IN THE ISSUANCE OF A HIGH SURF
ADVISORY FOR NORTH FACING REEFS. LATEST POHNPEI BUOY OBSERVATIONS
SHOW SEAS OF NEAR 8 FEET, COMPRISED MOSTLY OF A LONG-PERIOD NORTH
SWELL. THIS LOOKS TO CONTINUE THROUGH SATURDAY NIGHT, WITH THE NORTH
SWELL SUBSIDING ENOUGH FOR SURF TO FALL BELOW HAZARDOUS LEVELS FOR
SUNDAY ON. OTHERWISE, NO BIG CHANGES TO THE PRECIOUS MARINE FORECAST.
WESTERN MICRONESIA...
A MORE UNSETTLED REGIME IS TAKING SHAPE ACROSS FAR WESTERN
MICRONESIA. THE PATCHY REMNANTS OF AN OLD SHEARLINE ARE DRAPED
LOOSELY OVER THE AREA JUST SOUTH OF CHUUK, EXTENDING WEST-
NORTHWESTWARD TO JUST NORTHEAST OF YAP PROPER, WHERE THEY MEET A
BROAD, WEAK TRADE-WIND TROUGH. THIS TROUGH EXTENDS SOUTHWARD ACROSS
YAP, CURVING SOUTHWEST PAST THE MAJOR ISLANDS OF PALAU, BEFORE
EXTENDING FURTHER SOUTH INTO A WEAK BUFFER CIRCULATION NEAR EQ134E.
SATELLITE LATE THIS AFTERNOON SHOWS AREAS OF MODERATE PATCHY
CONVECTION LOOSELY FOCUSED ALONG THIS TROUGH AXIS, JUST EAST OF YAP
PROPER, AND JUST EAST TO SOUTHEAST OF PALAU. A BROADER LINE OF
CONVECTION IS SEEN FURTHER EAST ALONG THE BACKSIDE OF THE TROUGH,
ORIENTED FROM NORTH TO SOUTH ACROSS WESTERN YAP STATE ALONG AN AREA
OF TRADE-WIND CONVERGENCE.
THE PORTION OF THE TROUGH OVER YAP WILL GRADUALLY PUSH WESTWARD
THROUGH THE AREA, MAINTAINING SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS FOR PALAU AND YAP OVERNIGHT. SHOWERS LOOK TO BECOME
NUMEROUS FOR YAP BY LATE MORNING FRIDAY AS THE AREA OF CONVERGENCE
AND ASSOCIATED CONVECTION THEN MOVES OVERHEAD, WHILE SCATTERED
SHOWERS PERSIST FOR PALAU. ALTHOUGH SHOWERS MAY SEE A BRIEF LULL
AROUND PALAU AS THE STRONGER CONVERGENCE WILL STAY FURTHER NORTH,
THESE FEATURES WILL MAINTAIN A FAIRLY WET PATTERN FOR PALAU AND YAP
THROUGH THE WEEKEND AS THE ORIGINAL DISTURBANCE STALLS JUST WEST OF
THE REGION, AND ANOTHER TRADE-WIND TROUGH APPROACHES FROM THE EAST.
THE WET PATTERN LOOKS TO CONTINUE FOR PALAU THROUGH EARLY NEXT WEEK
AS A BUFFER CIRCULATION REMAINS ANCHORED TO THE SOUTH, AND PASSING
TRADE-WIND TROUGHS AND CONVERGENCE ARE SHUNTED FURTHER TO THE SOUTH
AND WEST. A NEAR-EQUATORIAL TROUGH (NET) LOOKS TO TAKE SHAPE AROUND
THE MIDDLE OF NEXT WEEK, BUILDING NORTHWARD INTO THE REGION. CHUUK
WILL SEE MAINLY DRIER TRADE-WIND CONDITIONS OVER THE NEXT WEEK, WITH
PERIODS OF SCATTERED SHOWERS AT TIMES FROM WEAK PASSING DISTURBANCES.
ALTIMETRY DATA SHOWS COMBINED SEAS AROUND 5 TO 7 FEET ACROSS THE
REGION. THE HIGH SURF ADVISORY FOR CHUUK WAS ALLOWED TO EXPIRE THIS
AFTERNOON AS THE PULSE OF ELEVATED NORTH-NORTHEAST SWELL HAS
DIMINISHED, ALLOWING SURF TO RELAX BELOW HAZARDOUS LEVELS OF 9 FEET
ALONG NORTH-FACING REEFS. HOWEVER, ANOTHER PULSE OF SIGNIFICANT
NORTH-NORTHEAST SWELL IS EXPECTED TO ENTER THE REGION AROUND FRIDAY
NIGHT, WITH MOST OF THE SWELL ENERGY FOCUSED NORTH AND EAST OF CHUUK.
THIS WILL LIKELY NECESSITATE THE ISSUANCE OF ANOTHER HIGH SURF
ADVISORY FOR NORTH REEFS BY THIS WEEKEND AS SURF INCREASES ONCE MORE.
ADDITIONALLY, WAVE MODELS INDICATE SEA HEIGHTS MAY INCREASE TO
AROUND 10 FEET OVER CHUUK WATERS THIS WEEKEND, WITH A PEAK
ANTICIPATED AROUND SATURDAY MORNING, AND A SMALL CRAFT ADVISORY MAY
BE NEEDED AS WELL. THIS WOULD LIKELY BE SHORT-LIVED, AS MODELS SHOW
SEAS QUICKLY FALLING BELOW HAZARDOUS LEVELS FOR SUNDAY. WINDS WILL BE
MODERATE TO FRESH FOR CHUUK TONIGHT, BECOMING GENTLE TO MODERATE
THROUGH THE REST OF THE FORECAST PERIOD WITH OCCASIONAL FRESH TO
STRONG GUSTS. PALAU AND YAP CAN EXPECT MOSTLY LIGHT TO MODERATE WINDS
OVER THE NEXT WEEK.
GUM WATCHES/WARNINGS/ADVISORIES
GU...HIGH RIP CURRENT RISK THROUGH SUNDAY AFTERNOON FOR GUZ001.
HIGH SURF ADVISORY UNTIL 4 PM CHST SUNDAY FOR GUZ001.
MP...HIGH RIP CURRENT RISK THROUGH SUNDAY AFTERNOON FOR MPZ001>003.
HIGH SURF ADVISORY UNTIL 4 PM CHST SUNDAY FOR MPZ001>003.
MARIANAS WATERS...NONE.
MARIANAS/EAST AND WEST MICRONESIA UPDATE: STANKO
MARIANAS: BOWSHER
EAST MICRONESIA: KLEESCHULTE
WEST MICRONESIA: DECOU
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