102
FXPQ50 PGUM 220828
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
628 PM CHST SAT FEB 22 2025
MARIANAS SYNOPSIS
FRESH TO STRONG WINDS WITH NEAR GALE GUSTS PREVAIL ACROSS THE REGION.
SATELLITE IMAGERY INDICATES FRAGMENTS OF A SHEAR LINE MOVING OVER
GUAM AND ROTA. VARIOUS BUOYS INDICATE SEAS ARE BETWEEN 8 AND 11 FEET.
DISCUSSION
LINGERING FRAGMENTS OF A SHEAR LINE ARE EXPECTED TO BRING LOW-END
SCATTERED SHOWERS AND MOSTLY CLOUDY SKIES TO GUAM AND ROTA, WITH
LESSER SHOWERS EXPECTED AT TINIAN AND SAIPAN. IN ADDITION, WINDS WILL
REMAIN TO BE FRESH TO STRONG, WITH NEAR-GALE GUSTS AT TIMES DURING
THE DAYTIME HOURS ACROSS THE MARIANAS. WINDS ARE EXPECTED TO THEN
TAPER DOWN SLIGHTLY, BEFORE PICKING UP SIGNIFICANTLY ONCE AGAIN
AROUND MIDWEEK.
MARINE
COMBINED SEAS OF 8 TO 11 FEET ARE EXPECTED THROUGH LATE SUNDAY
NIGHT, BEFORE TAPERING DOWN THEREAFTER AS THE NORTHERLY SWELL BEGINS
TO WEAKEN. AS SUCH, A SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH
EARLY MONDAY MORNING. EVEN SO, A SMALL CRAFT ADVISORY IS LIKELY TO BE
RE-ISSUED AROUND MIDWEEK, AS ANOTHER MAJOR NORTHERLY SWELL AND
STRONGER TRADE SWELLS MAKE THEIR WAY ACROSS THE REGION. THE
AFOREMENTIONED WEAKENING NORTHERLY SWELL WILL ALLOW SURF CONDITIONS
TO FALL BELOW HAZARDOUS LEVELS, AND RIP CURRENT RISK TO DROP TO
MODERATE ALONG NORTH FACING REEFS BY LATE SUNDAY NIGHT.
FIRE WEATHER
NO RAINFALL WAS RECORDED YESTERDAY, ALLOWING THE KBDI TO RISE TO
656, WHICH REMAINS IN THE HIGH CATEGORY. A MOISTENING TREND WITH
HIGHER RELATIVE HUMIDITY VALUES AND AN INCREASED POTENTIAL FOR
SHOWERS IS EXPECTED THROUGH THE WEEKEND, WHICH COULD RESULT IN
REDUCED FIRE DANGER THREAT. AS SUCH, RED FLAG CRITERIA ARE NOT LIKELY
TO BE MET, SO THE FIRE WEATHER WATCH NO LONGER REMAINS IN EFFECT AT
THIS TIME. EVEN SO, ELEVATED WINDS AND DRIER VEGETATION ARE STILL
LIKELY TO PRODUCE A HIGHER FIRE THREAT IN THE SOUTHERN PORTIONS OF
GUAM OVER THE NEXT SEVERAL DAYS.
EASTERN MICRONESIA
THE WEATHER PATTERN ACROSS EASTERN MICRONESIA REMAINS FAIRLY
INACTIVE. A COUPLE OF TRADE-WIND TROUGHS, ONE BETWEEN KOSRAE AND
POHNPEI, THE OTHER BETWEEN MAJURO AND KOSRAE, ARE INTERACTING WITH
VERY WEAK TRADE-WIND CONVERGENCE TO BRING LOW-END SCATTERED SHOWERS
TO KOSRAE, WITH SCATTERED SHOWERS EXPECTED TO SPREAD INTO POHNPEI
DURING THE EVENING. THESE TROUGHS WILL MOVE OUT OF THE REGION AS THE
CONVERGENCE DISSIPATES BY SUNDAY AFTERNOON, RESULTING IN THE DRY
TRADE-WIND PATTERN, CURRENTLY OVER MAJURO, RETURNING TO BOTH
LOCATIONS. ANOTHER TROUGH IS EXPECTED TO MOVE THROUGH TO THE SOUTH OF
MAJURO EARLY NEXT WEEK. THIS TROUGH LOOKS TO BRING ANOTHER ROUND OF
INCREASED SHOWERS TO KOSRAE AND POHNPEI AROUND THE MIDDLE OF NEXT
WEEK. MAJURO LOOKS TO REMAIN DRY THROUGH OUT THE PERIOD, WITH ONLY A
FEW PASSING SHOWERS FOR THE NEXT WEEK.
INCREASING PRESSURE GRADIENT DUE TO A TRANSITING MID-LATITUDE HIGH
PRESSURE SYSTEM WILL RESULT IN MOSTLY MODERATE TO FRESH TRADE WINDS,
WITH STRONG GUSTS, OVER THE NEXT COUPLE OF DAYS. KOSRAE IS EXPECTED
TO SEE A BRIEF PERIOD OF FRESH TO STRONG WINDS WITH NEAR-GALE GUSTS
SUNDAY NIGHT. ALONG WITH THE WINDS, A BUILDING NORTH SWELL COMBINED
WITH TRADE-WIND SWELL AND WIND WAVES WILL RESULT IN COMBINED SEAS
REACHING AS HIGH AS 11 FEET FOR POHNPEI AND KOSRAE, AND 10 FEET FOR
MAJURO. THESE HIGHER SEAS ARE EXPECTED TO REACH POHNPEI LATER THIS
EVENING, AND SHOULD REACH KOSRAE AND MAJURO SUNDAY MORNING. THE NORTH
SWELL WILL BE HIGH ENOUGH TO PRODUCE HAZARDOUS SURF ALONG NORTH
FACING REEFS OF BOTH POHNPEI AND KOSRAE. LATER NEXT WEEK, BUILDING
TRADE SWELL IS EXPECTED TO REACH KOSRAE, BRINGING THE POSSIBILITY OF
HAZARDOUS SURF ALONG EAST FACING REEFS WITH IT.
ONE THING OF NOTE FOR MAJURO, ABNORMALLY HIGH TIDES ARE EXPECTED TO
ARRIVE THERE AROUND MIDWEEK. THE INCREASED TRADE SWELL COMBINED WITH
THE ABNORMALLY HIGH TIDES COULD RESULT IN INUNDATION OF AROUND 1 TO
2 FEET ALONG NORTH AND EAST FACING REEFS DURING HIGH TIDE. THIS WILL
BE MONITORED OVER THE NEXT DAY OR SO TO DETERMINE IF ANY ADVISORIES
OR HEADLINES ARE WARRANTED.
WESTERN MICRONESIA
CHUUK REMAINS IN A DRY TRADE-WIND PATTERN WITH SATELLITE IMAGERY
SHOWING JUST A FEW SPOTTY SHOWERS MOVING THROUGH THE FLOW. THIS DRY
PATTERN IS EXPECTED TO CONTINUE THROUGH WEDNESDAY, THEN A TROUGH
MOVING OUT OF EASTERN MICRONESIA WILL INCREASE SHOWERS AND THE
POTENTIAL FOR THUNDERSTORMS FOR THE LATTER HALF OF THE UPCOMING
WEEK. WINDS ARE EXPECTED TO INCREASE SUNDAY THROUGH MONDAY AS THE
PRESSURE GRADIENT INCREASES DUE TO A MID-LATITUDE HIGH PRESSURE
SYSTEM MOVING ACROSS THE PACIFIC. THIS WILL CREATE BREEZY CONDITIONS
WHILE ALSO MAKE SEAS CHOPPY. SINCE ALTIMETRY SHOWS SEAS AROUND 10 TO
11 FEET JUST NORTH OF CHUUK AND WINDS ARE EXPECTED TO BECOME 20 TO
25 KT BY SUNDAY NIGHT, A SMALL CRAFT ADVISORY WAS ISSUED STARTING
SUNDAY MORNING THROUGH MONDAY AFTERNOON. A FLOATING BUOY NORTHWEST OF
CHUUK ALSO SHOWS A LONG-PERIOD NORTH-NORTHEAST SWELL MOVING INTO THE
REGION, AND COMBINING WITH THE INCREASING NORTHEAST SWELL. THIS WILL
CAUSE SURF TO BUILD TO AROUND 9 FEET ALONG NORTH FACING REEFS
TONIGHT, SO A HIGH SURF ADVISORY IS IN EFFECT TONIGHT THROUGH MONDAY
AFTERNOON. BY MONDAY NIGHT WINDS AND THE NORTH TO NORTHEAST SWELL
WILL DECREASE ALLOWING SEAS AND SURF TO DROP BELOW HAZARDOUS LEVELS.
PALAU AND YAP ARE NEAR THE SHEAR LINE THAT EXTENDS SOUTH OF THE
MARIANAS ENDS SOUTH OF PALAU. CONVERGENCE ALONG THE SHEAR LINE
BROUGHT SOME SCATTERED SHOWERS TO PALAU EARLIER TODAY BUT IT LOOKS
LIKE MOST OF THESE SHOWERS HAVE PUSHED OFF TO THE WEST, LEAVING
ISOLATED SHOWERS AND MOSTLY CLOUDY SKIES. SHOWERS WERE ISOLATED AT
YAP FOR MOST OF THE DAY BUT HAVE STARTED TO INCREASE DURING THE
AFTERNOON, AND ARE EXPECTED TO CONTINUE THROUGH TONIGHT. MODELS HAVE
THE SHEAR LINE SLOWLY DRIFTING WEST-NORTHWEST THROUGH MONDAY, MOVING
THE POTENTIAL FOR SCATTERED SHOWERS WEST-NORTHWEST OF PALAU AND YAP
WHILE ALSO ALLOWING WINDS TO RELAX OVERNIGHT AND THROUGH SUNDAY
NIGHT. THEN A NEW SHEAR LINE WILL DROP INTO THE REGION AS A HIGH
PRESSURE SYSTEM MOVES OFF MAINLAND ASIA AND INCREASES THE PRESSURE
GRADIENT AND WINDS ACROSS YAP MONDAY AND PALAU MONDAY NIGHT. THIS
WILL BRING BACK BREEZY CONDITIONS AND THE POTENTIAL FOR SHOWERS.
SATELLITE ALTIMETRY AND BUOY DATA FROM PALAU SHOW SEAS ARE AROUND 7
TO 8 FEET THIS EVENING AROUND YAP AND PALAU. SEAS MAY DECREASE
SLIGHTLY SUNDAY, BUT AS WINDS INCREASE AROUND MONDAY SEAS WILL
REBUILD AND REACH UP TO 10 FEET, ALONG WITH WINDS AROUND 25 KNOTS,
CREATING HAZARDOUS CONDITIONS TO SMALL CRAFT. ALSO, THE NORTH-
NORTHEAST SWELL IS EXPECTED TO BUILD AROUND THAT TIME SO HAZARDOUS
SURF ALONG EAST AND ESPECIALLY NORTH FACING REEFS WILL BE POSSIBLE
THIS UPCOMING WEEK.
GUM WATCHES/WARNINGS/ADVISORIES
GU...HIGH RIP CURRENT RISK THROUGH LATE SUNDAY NIGHT FOR GUZ001.
HIGH SURF ADVISORY UNTIL 5 AM CHST MONDAY FOR GUZ001.
MP...HIGH RIP CURRENT RISK THROUGH LATE SUNDAY NIGHT FOR MPZ001>003.
HIGH SURF ADVISORY UNTIL 5 AM CHST MONDAY FOR MPZ001>003.
MARIANAS WATERS...SMALL CRAFT ADVISORY UNTIL 5 AM CHST MONDAY FOR
PMZ151>154.
MARIANAS: MONTVILA
EAST MICRONESIA: KLEESCHULTE
WEST MICRONESIA: SCHANK
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