316
FXPQ50 PGUM 040717
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
517 PM CHST SAT APR 4 2026
MARIANAS SYNOPSIS
A SEASONAL TRADE-WIND PATTERN EXTENDS ACROSS THE MARIANAS WITH
SATELLITE AND RADAR IMAGERY SHOWING SPOTTY SHOWERS MOVING THROUGH THE
FLOW THIS EVENING. OBSERVATIONS ARE REPORTING MODERATE TO FRESH
WINDS ACROSS THE ISLANDS. BUOY DATA AROUND GUAM AND SAIPAN ARE
REPORTING SEAS AROUND 5 TO 6 FEET, WHILE ALTIMETRY SHOWING SEAS ARE
PUSHING CLOSER TO 6 TO 8 FEET EAST OF THE MARIANAS. EXPECTING SEAS AND
WINDS TO BUILD SUNDAY AND MONDAY AS A TRADE-WIND SURGE STRENGTHENS
NEAR AND EAST OF THE MARIANAS.
DISCUSSION
THIS FAIRLY SEASONAL TRADE-WIND PATTERN IS EXPECTED THROUGH AT LEAST
THE MIDDLE OF WEEK. MODEL GUIDANCE SUGGEST A COUPLE OF WEAK TROUGHS
MAY PASS THROUGH THE MARIANAS SUNDAY NIGHT AND WEDNESDAY, BUT NOT
EXPECTING MUCH OF AN INCREASE IN THE POTENTIAL OF SHOWERS AT THIS
TIME. MODEL GUIDANCE DOES SUPPORT A TRADE-WIND SURGE STRENGTHENING
SUNDAY AND MONDAY, NEAR AND EAST OF THE MARIANAS AS A RIDGE OF HIGH
PRESSURE BUILDS TO THE NORTH OF THE REGION AND SLOWLY SHIFTS EASTWARD
ACROSS THE PACIFIC, PRODUCING BREEZY CONDITIONS AROUND 25 MPH DURING
THE DAYTIME HOURS OF SUNDAY AND MONDAY. WINDS ARE THEN EXPECTED TO
SUBSIDE SLIGHTLY TUESDAY AND WEDNESDAY AS THE TRADE-WIND SURGE
WEAKENS AND THE AREA OF STRONGER WINDS SHIFTS EASTWARD. LONG-RANGE
GUIDANCE SHOWS A BROAD TROPICAL DISTURBANCE IN EASTERN MICRONESIA
WILL SLOWLY SHIFT WESTWARD INTO CENTRAL MICRONESIA BEFORE POTENTIALLY
LIFTING NORTHWARD AND CLOSER TO THE MARIANAS NEXT WEEKEND OR EARLY
NEXT WEEK. THIS COULD INCREASE THE POTENTIAL FOR SHOWERS,
THUNDERSTORMS, AND SOME GUSTY WINDS AROUND THE MARIANAS, BUT THIS IS
STILL AT LEAST 7 TO 10 DAYS OUT SO UNCERTAINTY IN THE FORECAST
REMAINS FAIRLY HIGH AT THIS TIME.
MARINE
MODERATE TO FRESH NORTHEAST WINDS AND COMBINED SEAS OF 6 TO 8 FEET
WILL CONTINUE TONIGHT AND THEN INCREASE SUNDAY AS THE TRADE WIND
SURGE BUILDS ACROSS THE MARIANAS. THE INCREASE IN THE TRADE-WIND
SWELL AND WIND WAVES WILL ALSO BUILD SEAS TO 6 TO 9 FEET THROUGH
SUNDAY NIGHT WHILE WINDS ARE EXPECTED TO INCREASE TO AROUND 22 KT,
SUPPORTING HAZARDOUS CONDITIONS TO SMALL CRAFT, SO A SMALL CRAFT
ADVISORY WAS ISSUED, STARTING SUNDAY MORNING. THEN, A NORTHERLY SWELL
LOOKS TO ARRIVE MONDAY, WHEN SEAS ARE ANTICIPATED TO REACH 8 TO 10
FEET, PROLONGING HAZARDOUS CONDITIONS TO SMALL CRAFT THROUGH TUESDAY.
THE INCREASE IN THE EAST-NORTHEAST TRADE WINDS AND SWELL THROUGH THE
REST OF THE WEEKEND AND THE ARRIVAL OF NORTHERLY SWELL ON MONDAY ARE
EXPECTED TO BUILD SURF ALONG EAST AND NORTH FACING REEFS, INCREASING
THE RIP CURRENT RISK TO HIGH FOR EAST-FACING REEFS STARTING SUNDAY
AND THROUGH AT LEAST TUESDAY. WINDS AND SEAS ARE THEN EXPECTED TO
SUBSIDE SLIGHTLY AROUND MIDWEEK AS THE TRADE-WIND SURGE WEAKENS. THE
LONG-RANGE FORECAST IS MORE UNCERTAIN DUE TO THE POTENTIAL THAT A
BROAD TROPICAL DISTURBANCE WILL MOVE OUT OF EASTERN MICRONESIA AND
INTO CENTRAL MICRONESIA AROUND MIDWEEK, AND THEN POTENTIALLY LIFTING
NORTHWARD NEXT WEEKEND. IF THIS BROAD DISTURBANCE BECOMES MORE
ORGANIZED, THIS COULD STRENGTHEN THE TRADE WINDS EAST OF THE MARIANAS
AND REBUILD. THIS COULD PROLONG THE HIGH RISK OF RIP CURRENTS ALONG
EAST-FACING REEFS BEYOND TUESDAY, AND MAY EVEN CAUSE SEAS TO BUILD
BACK UP TO HAZARDOUS LEVELS OF 10 FEET FOR SMALL CRAFT.
EASTERN MICRONESIA
A DEEPENING IN ITCZ CONVECTION AS IT INTERACTS WITH THE NEAR-
EQUATORIAL TROUGH (NET) AND EMBEDDED NET DISTURBANCE DOWNSTREAM, IS
EXPECTED TO BRING PERIODS OF INTENSE SHOWERS, THUNDERSTORMS AND
STRONG TO NEAR GALE-FORCE GUSTS TO MAJURO, KOSRAE AND POHNPEI THE
NEXT FEW DAYS. SHOWERS AND WINDS WILL CONTINUE TO BUILD INTO MAJURO
THROUGH TONIGHT, FOLLOWED BY KOSRAE AND THEN POHNPEI COMING INTO
EARLY NEXT WEEK AS THE NET DISTURBANCE MOVING TO THE NORTHWEST AND
COLLIDING WITH THE LEADING EDGE OF THE ITCZ. CONDITIONS WILL IMPROVE
CONSIDERABLY ACROSS THE REGION BY THE MIDDLE OF NEXT WEEK AS THE
AFOREMENTIONED DISTURBANCE CONTINUES ITS TREK TOWARD CENTRAL
MICRONESIA NEXT WEEK.
COMBINED SEAS OF 6 TO 8 FEET ARE EXPECTED TO INCREASE CONSIDERABLY
OVER THE NEXT FEW DAYS AS ANOTHER PULSE IN NORTHEASTERLY SWELL MAKES
ITS WAY ACROSS THE REGION, POTENTIALLY INTRODUCING SEA CONDITIONS
HAZARDOUS TO SMALL CRAFT IN POHNPEI COASTAL WATERS AS EARLY AS SUNDAY
NIGHT. IF THE SWELL TRENDS CONTINUE, THERE IS A CHANCE THAT SURF MAY
ALSO BRIEFLY BECOME HAZARDOUS ALONG NORTH FACING REEFS OF POHNPEI
AND KOSRAE BY EARLY NEXT WEEK. AS SUCH, THE GENERAL PUBLIC MUST
CONTINUE TO MONITOR THE FORECASTS FOR ANY CHANGES OVER THE COMING
DAYS.
WESTERN MICRONESIA
SATELLITE IMAGERY THIS AFTERNOON SHOWS THE NEAR-EQUARTORIAL TROUGH
(NET) BLANKETED ACROSS MICRONESIA, ENTERING THE AREA AROUND 4N130E
AND EXTENDING TO THE EAST, WELL SOUTH OF THE PALAU, YAP, AND CHUUK,
AND ENDING IN A BROAD AND DISORGANIZED TROPICAL DISTURBANCE NORTHEAST
OF NAURU. DRIER WEATHER IS EXPECTED TO CONTINUE AT YAP AND PALAU
INTO EARLY NEXT WEEK WITH SHOWER CHANCES REMAINING ISOLATED. WET
WEATHER IS IN STORE FOR CHUUK, STARTING TONIGHT AS A TRADE-WIND SURGE
BRINGS INCREASING SHOWER AND THUNDERSTORM CHANCES. SCATTERED TO
NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS ARE EXPECTED INTO EARLY
NEXT WEEK AT CHUUK, WITH LOCALLY HEAVY RAINFALL AND GUSTY WINDS
POSSIBLE, PARTICULARLY WITH HEAVY SHOWERS AND STRONG THUNDERSTORMS.
MODERATE TO FRESH EAST TO NORTHEAST WINDS WILL PREVAIL AT ALL
FORECAST SITES INTO EARLY NEXT WEEK, WITH STRONG WINDS POSSIBLE AT
CHUUK ASSOCIATED WITH A TRADE-WIND SURGE THROUGH THE WEEKEND.
ATTENTION THEN TURNS TO LATE NEXT WEEK AS A TROPICAL DISTURBANCE IS
FORECAST TO IMPACT CENTRAL MICRONESIA.
A NORTHEAST SWELL WILL MOVE THROUGH THE WATERS STARTING THIS WEEKEND
AND SEAS WILL BUILD IN RESPONSE TO THE ARRIVING SWELL AND INCREASING
WIND ASSOCIATED WITH A TRADE-WIND SURGE. SEAS OF 3 TO 5 WILL
CONTINUE AT PALAU THROUGH SUNDAY AND INCREASE TO 4 TO 6 FEET STARTING
EARLY NEXT WEEK AS THE NORTHEAST SWELL MOVES THROUGH WESTERN
MICRONESIA. SEAS WILL BUILD TO AROUND 6 TO 7 FEET AT YAP STARTING
LATE SUNDAY AND WILL PERSIST THROUGH EARLY NEXT WEEK. COMBINED SEAS
WILL CONTINUE TO BUILD THROUGH THE WEEKEND AT CHUUK AND REACH
HAZARDOUS LEVELS TO SMALL CRAFT (10 FEET), STARTING LATE ON SUNDAY.
AS SUCH, HAVE ISSUED A SMALL CRAFT ADVISORY STARTING SUNDAY EVENING.
THE SURF FORECAST IS A LITTLE TRICKY FOR CHUUK AND WILL BE CONTINUED
TO BE MONITORED WITH ELEVATED SURF EXPECTED ALONG NORTH AND EAST
FACING REEFS OF CHUUK STARTING EARLY MONDAY. IT WILL NOT TAKE MUCH TO
INCREASE SURF TO HAZARDOUS LEVELS OF 9 FEET ALONG NORTH FACING
REEFS. WINDS AND SEAS WILL BEGIN TO SUBSIDE ON TUESDAY.
GUM WATCHES/WARNINGS/ADVISORIES
GU...HIGH RIP CURRENT RISK FROM SUNDAY MORNING THROUGH TUESDAY
AFTERNOON FOR GUZ001.
MP...HIGH RIP CURRENT RISK FROM SUNDAY MORNING THROUGH TUESDAY
AFTERNOON FOR MPZ001>003.
MARIANAS WATERS...SMALL CRAFT ADVISORY FROM 6 AM SUNDAY TO 5 PM CHST
TUESDAY FOR PMZ151>154.
MARIANAS: SCHANK
EAST MICRONESIA: MONTVILA
WEST MICRONESIA: WHISNANT
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