572
FXPQ50 PGUM 311844
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
444 AM CHST SUN JUN 1 2025
MARIANAS UPDATE
ONLY MINOR EDITS WERE MADE WITH THIS FORECAST PACKAGE. SATELLITE AND
RADAR OBSERVATIONS SHOW PATCHY CLOUDS AND ISOLATED SHOWERS ACROSS
THE MARIANAS. HOWEVER, SCATTERED SHOWERS ARE SEEN SOUTHEAST OF
GUAM'S COASTAL WATERS.
MID-LEVEL WATER VAPOR IMAGERY SHOWS A STRENGTHENING TUTT CELL
LOCATED NEAR 20.30N, 153.00E. ISOLATED THUNDERSTORMS ARE DEVELOPING
ALONG THE WESTERN EDGE OF THIS TUTT CELL, WITH RECENT SCANS SHOWING
THESE THUNDERSTORMS BEGINNING TO DEVELOP ALONG THE EASTERN COASTAL
WATERS OF SAIPAN. MODEL GUIDANCE SUGGEST THAT THE TUTT WILL DIVE
SOUTHWARD TODAY BEFORE GETTING CAUGHT UP IN THE STEERING FLOW. THIS
WOULD KEEP MOST OF THE THUNDERSTORMS JUST EAST OF THE MARIANAS.
HOWEVER, THE TUTT IS STILL MOVING SOUTHWEST ON WATER VAPOR IMAGERY,
WHICH WOULD SHIFT THE FOCUS OF SHOWERS AND THUNDERSTORMS FURTHER
WEST. FOR NOW, HAVE KEPT THE MENTION FOR ISOLATED THUNDERSTORMS TO
CONTINUE THROUGH AT LEAST MONDAY.
NO CHANGES WERE MADE TO THE MARINE FORECAST. BENIGN SEA CONDITIONS
OF 3 TO 4 FEET WILL CONTINUE THROUGH THE FORESEEABLE FUTURE. THERE
WILL BE A MODERATE RISK OF RIP CURRENTS ALONG EAST FACING REEFS FOR
THE EXT FEW DAYS.
FIRE WEATHER UPDATE
0.09 INCHES OF RAIN FELL YESTERDAY AT THE GUAM INTERNATIONAL
AIRPORT, WHICH ALLOWED THE KBDI TO FALL TO 714. THIS IS IN THE HIGH
CATEGORY DUE TO WINDS REMAINING BELOW THE 20 MPH THRESHOLD. WINDS
SHOULD REMAIN BELOW THE RED FLAG WARNING CRITERIA THE NEXT FEW DAYS,
THOUGH RHS CONTINUE TO DROP TO AROUND 60 PERCENT. THERE WILL BE A FEW
CHANCES FOR SCATTERED SHOWERS THE NEXT COUPLE OF DAYS, BUT A
WIDESPREAD WETTING RAIN REMAINS UNLIKELY THROUGH THE EARLY WEEK
PERIOD. EVEN THOUGH RED FLAG WARNING CRITERIA IS NOT EXPECTED, THE
VERY DRY CONDITIONS ACROSS THE ISLAND WILL MAINTAIN A HIGH FIRE
DANGER.
EASTERN MICRONESIA UPDATE
AN INTERTROPICAL CONVERGENCE ZONE (ITCZ) CONTINUES TO STRETCH ACROSS
THE REGION. SOME UPPER-LEVEL DIFFLUENCE IS HELPING SUPPORT
CONVECTION WITH THE ITCZ, ESPECIALLY NEAR THE DATE LINE. THEN, ITCZ
SHOWERS BECOME MORE PATCHY, FOCUSING NEAR EMBEDDED TROUGHS PASSING
SOUTH OF MAJURO, OVER KOSRAE, AND SOUTH OF POHNPEI. SCATTERED
SHOWERS AND ISOLATED SHOWERS REMAIN NEAR POHNPEI AND KOSRAE THROUGH
TONIGHT AND SHOWERS ASSOCIATED WITH AN APPROACHING TROUGH ARE
EXPECTED TO CONTINUE BUILDING INTO MAJURO, WITH HIGH-END SCATTERED
SHOWERS EXPECTED BY THE AFTERNOON. THE ONLY CHANGES TO THE FORECAST
WERE TO ADD A SHORT PERIOD OF ISOLATED SHOWERS THIS MORNING NEAR
POHNPEI, INCREASING TO SCATTERED AROUND NOON AND TO ADD OCCASIONAL
GUSTS TO 25 KT NEAR MAJURO TODAY BASED ON MODELS SUGGESTING STRONGER
GUSTS WITH THE PASSING TROUGH.
BUOY DATA SHOWS COMBINED SEAS OF 4 TO 6 FEET ACROSS POHNPEI AND
KOSRAE AND UP TO 8 FEET EAST OF MAJURO. SCATTEROMETRY DATA INDICATES
GENTLE TO MODERATE TRADES NEAR POHNPEI AND KOSRAE AND MODERATE TO
FRESH TRADES NEAR AND EAST OF MAJURO.
WESTERN MICRONESIA UPDATE
SATELLITE IMAGERY SHOWS MODERATE TO DEEP CONVECTION ASSOCIATED WITH A
BROAD TROUGH SITUATED OVER FAR WESTERN MICRONESIA. THE BULK OF
CONVECTION IS PRIMARILY SOUTH OF KOROR, ACROSS THE FAR SOUTHERN
ISLANDS OF PALAU, BUT MOSTLY CLOUDY SKIES AND SCATTERED SHOWERS
CONTINUE ACROSS THE MAIN ISLANDS OF PALAU AND PARTS OF YAP STATE.
ONLY MINOR CHANGES TO YAP'S FORECAST TO HAVE SCATTERED SHOWERS EARLY
THIS MORNING TREND DOWN TO ISOLATED AROUND NOON. A MINOR TROUGH EAST
OF CHUUK IS GENERATING A SMALL AREA OF SHOWERS. THIS MAY BRING EXTRA
SHOWERS NEAR EASTERN WATERS, BUT MODELS TRENDS SHOW THESE SHOWERS
WEAKENING AS IT PASSES THROUGH CHUUK LAGOON.
BUOY DATA SHOWS COMBINED SEAS 2 TO 4 FEET NEAR YAP AND PALAU AND 4
TO 6 FEET NEAR CHUUK. SCATTEROMETRY DATA SHOWS LIGHT TO GENTLE EAST-
SOUTHEASTERLY WINDS NEAR YAP AND PALAU AND GENTLE TO MODERATE
EASTERLY TRADE WINDS NEAR CHUUK.
PREV DISCUSSION
/ISSUED 526 PM CHST SAT MAY 31 2025/
MARIANAS SYNOPSIS...
GENTLE TO MODERATE TRADES PREVAIL. SATELLITE IMAGERY AND DOPPLER
RADAR INDICATE A FEW LINES OF SHOWERS ENTERING GUAM'S NORTHEASTERN
WATERS. THE BUOYS INDICATE SEAS ARE 4 TO 5 FEET.
DISCUSSION...
A COMBINATION OF A LINGERING TUTT CELL OVERHEAD, SOUTHEASTERLIES WITH
INCREASING MOISTURE COLUMNS, AND A BUILDING RIDGE TO THE NORTHWEST,
ARE ALLOWING ISOLATED TO LOW-END SCATTERED SHOWERS AND SOME
THUNDERSTORMS TO MOVE IN ACROSS THE MARIANAS FOR MUCH OF THE FIRST
HALF OF NEXT WEEK. SHOWERS WILL BEGIN TO INCREASE MORESO STARTING
THURSDAY, AS A CONVERGENCE ZONE BUILDS ACROSS THE REGION INTO NEXT
WEEKEND.
MARINE...
LITTLE CHANGE IN THE MARINE FORECAST. COMBINED SEAS OF 4 TO 6 FEET
WILL TAPER DOWN A FOOT SUNDAY, STAYING AS SUCH THROUGH AT LEAST
MIDWEEK. A MODERATE RISK OF RIP CURRENTS IS EXPECTED ALONG EAST
FACING REEFS THROUGH AT LEAST THE FIRST HALF OF NEXT WEEK.
FIRE WEATHER...
ONLY A TRACE OF RAIN HAS FALLEN AT THE AIRPORT SINCE MIDNIGHT. MORE
SHOWERS ARE SEEN UPSTREAM AND HEADING FOR GUAM, BUT THEY ARE NOT
EXPECTED TO BRING A WETTING RAIN TONIGHT. AS SUCH, THE KBDI MAY
EITHER STAY AROUND THE SAME OR DROP SLIGHTLY, WHICH IS CURRENTLY AT
720. THERE WILL BE A FEW CHANCES FOR SCATTERED SHOWERS THE NEXT FEW
DAYS, BUT A WIDESPREAD WETTING RAIN REMAINS UNLIKELY THE NEXT FEW
DAYS. IN ADDITION, THE ALREADY STRESSED FOLIAGE, ESPECIALLY IN THE
SOUTHERN PORTIONS OF GUAM, STILL CONTINUE TO POSE A HIGH FIRE DANGER,
BUT RED FLAG CONDITIONS ARE NOT EXPECTED TO BE MET.
EASTERN MICRONESIA...
AN INTER-TROPICAL CONVERGENCE ZONE (ITCZ) CONTINUES TO STRENGTHEN
ACROSS EASTERN MICRONESIA. THE ITCZ STRETCHES WEST, CURRENTLY SOUTH
OF MAJURO, INTO KOSRAE. THIS FEATURE IS GENERATING SCATTERED SHOWERS
AND AN OCCASIONAL THUNDERSTORM OVER KOSRAE. THERE IS A TRADE-WIND
TROUGH THAT IS STILL CROSSING THE DATE LINE THAT LOOKS TO MOVE TOWARD
MAJURO AS IT PROGRESSES, DRAGGING THE ITCZ A LITTLE FARTHER NORTH.
THIS WILL BRING INCREASING CONVECTION TO MAJURO BY SUNDAY MORNING.
FOR POHNPEI, ANOTHER TRADE-WIND TROUGH IS CURRENTLY MOVING THROUGH
THE STATE, PRODUCING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
THERE THIS AFTERNOON. THESE SHOWERS LOOK TO MOVE OUT THIS AFTERNOON.
HOWEVER, CONVECTION ALONG THE WESTERN END OF THE ITCZ LOOKS TO MOVE
INTO POHNPEI DURING THE AFTERNOON HOURS. LATEST MODEL GUIDANCE
INDICATES THAT AN OVERALL WET, UNSETTLED PATTERN WILL REMAIN OVER THE
REGION THROUGH THE MIDDLE OF NEXT WEEK AS THE DEVELOPING ITCZ
REMAINS ACTIVE. THERE WILL BE PERIODS OF INCREASED CONVECTION AS WEAK
TRADE-WIND TROUGHS TRAVERSE ACROSS THE AREA AND INTERACT WITH THE
ITCZ. MAJURO SHOULD SEE A DRIER TREND AROUND WEDNESDAY NEXT WEEK AS
THE ITCZ DRIFTS BACK TO THE SOUTH. THIS DRIER PATTERN ALSO LOOKS TO
MOVE INTO POHNPEI SATURDAY AS THE ITCZ ALSO RETREATS SOUTH AND
WEAKENS OVER THE STATE. KOSRAE, HOWEVER, LOOKS TO REMAIN IN A WET
PATTERN FOR A BIT LONGER AS THE ITCZ REMAINS OVER THE ISLAND AS IT
WEAKENS AND EVENTUALLY DISSIPATES.
COMBINED SEAS OF 4 TO 6 FEET FOR POHNPEI AND KOSRAE WILL SLOWLY
SUBSIDE OVER THE NEXT FEW DAYS, DROPPING TO BETWEEN 3 AND 5 FEET
EARLY NEXT WEEK. FOR MAJURO, SEAS ARE SLIGHTLY HIGHER, CURRENTLY
BETWEEN 5 AND 7 FEET. SEAS LOOK TO SUBSIDE TO BETWEEN 3 AND 5 FEET
FOR MAJURO LATER NEXT WEEK. GENTLE TO MODERATE TRADE WINDS WILL
CONTINUE INTO THE COMING WEEK, POSSIBLY BECOMING LIGHT AROUND MIDWEEK
AT POHNPEI AND KOSRAE.
WESTERN MICRONESIA...
SATELLITE IMAGERY THIS AFTERNOON SHOWS SCATTERED SHOWERS OVER AND
JUST SOUTH OF PALAU, WITHIN AN AREA OF TRADE-WIND CONVERGENCE ALONG
THE NORTHERN PERIPHERY OF A BROAD SURFACE TROUGH. YAP SITS IN A
FAIRLY QUIET TRADE REGIME FOR THE TIME BEING, WITH ISOLATED SHOWERS
AND PARTLY CLOUDY SKIES ACROSS THE AREA. FURTHER SOUTHEAST OVER YAP
STATE, AN AREA OF WIDESPREAD SHOWERS AND CLOUDINESS IS SEEN,
ASSOCIATED WITH A BROAD SOUTH-SOUTHWEST TO NORTH-NORTHEAST ORIENTED
TROUGH CENTERED BETWEEN SOROL AND EAURIPIK. FURTHER EAST, MUCH OF
CHUUK STATE IS FAIRLY DRY THIS AFTERNOON, WITH JUST ISOLATED SHOWERS
AND A FEW REMNANT OUTFLOW BOUNDARIES SEEN NEAR CHUUK LAGOON FROM DEEP
CONVECTION TO THE NORTHEAST. TRADE WINDS ARE MOSTLY GENTLE ACROSS
YAP STATE AND THE REPUBLIC OF PALAU, AND GENTLE TO MODERATE OVER
CHUUK. DISORGANIZED TRADE-WIND CONVERGENCE AND THE APPROACH OF A
BROAD TRADE-WIND TROUGH WILL MAINTAIN SCATTERED SHOWERS NEAR PALAU
TONIGHT INTO EARLY NEXT WEEK, AND LEAD TO INCREASING SHOWERS FOR YAP
LATER TONIGHT. ALTHOUGH FAIRLY QUIET FOR NOW, CHUUK AND YAP CAN
EXPECT PATCHY SHOWERS FROM TIME TO TIME THROUGH EARLY NEXT WEEK, WITH
AN INCREASE IN SHOWER CHANCES AROUND THE MIDDLE OF NEXT WEEK.
SEVERAL WEAKER TRADE-WIND TROUGHS LOOK TO CROSS THE AREA OVER THE
NEXT FEW DAYS, BEFORE A MORE ROBUST DISTURBANCE OR TWO LOOK TO BUILD
OVER CHUUK AND EASTERN YAP STATE AROUND WEDNESDAY.
BENIGN MARINE CONDITIONS CONTINUE. COMBINED SEAS OF 2 TO 4 FEET NEAR
PALAU AND YAP ARE EXPECTED TO CONTINUE THROUGH AT LEAST THE FIRST
HALF OF THIS WEEK. COMBINED SEAS OF 4 TO 6 FEET NEAR CHUUK WILL
CONTINUE THROUGH THE WEEKEND, STARTING TO TAPER DOWN EARLY NEXT WEEK
AS THE PRIMARY SWELL WEAKENS.
GUM WATCHES/WARNINGS/ADVISORIES
GU...NONE.
MP...NONE.
MARIANAS WATERS...NONE.
MARIANAS UPDATE: WILLIAMS
EAST/WEST MICRONESIA UPDATE: CRUZ
MARIANAS: MONTVILA
EAST MICRONESIA: KLEESCHULTE
WEST MICRONESIA: DECOU
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