097
FXPQ50 PGUM 070920
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
720 PM CHST SAT MAR 7 2026
MARIANAS SYNOPSIS
SATELLITE IMAGERY SHOWS CLOUDY SKIES, WHILE RADAR SHOWS SCATTERED TO
NUMEROUS SHOWERS WITH THE MOST SHOWERS OVER GUAM COASTAL WATERS.
IPAN BUOY DATA SHOWS SWELL OF 6 FEET AT 8 SECONDS, HOWEVER THIS BUOY
IS SHIELDED BY THE ISLAND OF GUAM FROM THE NORTH AND NORTHEASTERN
SWELLS.
A SMALL CRAFT ADVISORY, HIGH SURF ADVISORY, AND A HIGH RISK OF RIP
CURRENTS STATEMENT REMAIN IN EFFECT.
DISCUSSION
TODAY, WE HAD A RECORD AMOUNT OF RAIN FALL OF 1 INCH AT THE AFTERNOON
CLIMATE DATA GATHERING, THE PREVIOUS RECORD WAS 0.90 INCHES. MORE
RAIN IS EXPECTED OVER THE NEXT DAY OR TWO. THIS IS DUE TO THE
INTERACTION BETWEEN THREE FEATURES, A SHEAR LINE, INVEST 95W AND
A TROUGH EXTENDING FROM 95W. THIS INTERACTION IS EXPECTED TO BRING 4
TO 8 MORE INCHES OF RAINFALL TO THE REGION. WITH THE AMOUNT OF RAIN
THE ISLANDS HAVE HAD THIS PAST WEEK, MUDSLIDES ARE POSSIBLE. MODEL
GUIDANCE SUGGEST THAT THE MARIANAS MAY MOVE INTO A DRIER PATTERN ONCE
95W MOVES NORTHEAST OF ISLANDS.
MARINE
A BUSY MARINE PATTERN IS EXPECTED OVER THE NEXT SEVERAL DAYS.
MODERATE TO FRESH WINDS AND SEAS OF 8 TO 11 FEET ARE EXPECTED
TO GRADUALLY START DIMINISHING OVER THE REST OF THE WEEKEND, AND
POTENTIALLY FALL BELOW 10 FEET SUNDAY NIGHT BEFORE RISING TO 12
FEET EARLY NEXT WEEK. NUMEROUS TO WIDESPREAD SHOWERS, ISOLATED
THUNDERSTORMS, OCCASIONAL STRONG TO NEAR-GALE GUSTS AROUND HEAVY
SHOWERS AND SEAS HAZARDOUS TO SMALL CRAFT ARE EXPECTED THROUGH
SUNDAY DUE TO ELEVATED NORTH TO NORTHEAST SWELL, A TROPICAL
DISTURBANCE DEVELOPING IN YAP STATE, AND A SHEAR LINE APPROACHING
FROM THE NORTH.
HYDROLOGY
HEAVY RAINFALL FROM INVEST 95W INTERACTING WITH A SHEAR LINE WILL
MAINTAIN A THREAT OF FLASH FLOODING FOR THE MARIANAS THIS WEEKEND
AND INTO NEXT WEEK. THE RAIN IS EXPECTED TO CONTINUE THROUGH MONDAY
AFTERNOON. SEVERAL ROUNDS OF HEAVY TO VERY HEAVY RAINFALL WILL BE
POSSIBLE DURING THIS TIME FRAME. THIS COULD LEAD TO 4 TO 8 INCHES OF
ADDITIONAL RAINFALL ACROSS THE MARIANAS WITH LOCALLY HIGHER AMOUNTS
POSSIBLE. MUDSLIDE ARE ALSO POSSIBLE GIVEN THE AMOUNT OF SOIL
SATURATION.
GUIDANCE HAS HINTED AT A POTENTIAL STALL OF 95W. IF THIS OCCURS AND
IT DOES SO WITH 95W NEAR OR JUST WEST OF THE MARIANAS, THEN THE
RAINFALL FORECAST WILL SEE SIGNIFICANT CHANGES HEADING INTO NEXT WEEK
AS HEAVY RAINFALL WOULD CONTINUE FOR SEVERAL DAYS.
TROPICAL SYSTEMS
A BROAD, WEAK TROPICAL DISTURBANCE, INVEST 95W, REMAINS OVER YAP AND
WESTERN CHUUK STATES THIS EVENING. 95W IS CENTERED NEAR 9N141E. 95W
IS EXPECTED TO TURN TOWARD THE MARIANAS, AND AT CURRENT FORECAST
MOVEMENT, LOOKS TO MOVE PAST THE MARIANAS WITHIN THE NEXT COUPLE OF
DAYS. AS THE INVEST MOVES THROUGH, THE MARIANAS CAN EXPECT STRONG TO
NEAR-GALE GUSTS AND LOCALLY HEAVY RAINFALL. INVEST 95W IS CURRENTLY
RATED "MEDIUM", MEANING THAT DEVELOPMENT INTO A SIGNIFICANT TROPICAL
CYCLONE (TROPICAL DEPRESSION) IS MORE LIKELY, BUT EXPECTED TO OCCUR
BEYOND 24 HOURS. CONFIDENCE IN THE MOVEMENT AND DEVELOPMENT OF 95W
REMAINS LOW.
FOR MORE INFORMATION ON INVEST 95W, PLEASE SEE THE BULLETIN ISSUED
BY THE JOINT TYPHOON WARNING CENTER UNDER WMO HEADER ABPW10 PGTW.
EASTERN MICRONESIA
A SERIES OF TRADE-WIND TROUGHS CONTINUE TO DOMINATE THE PATTERN
ACROSS EASTERN MICRONESIA, WITH SATELLITE IMAGERY SHOWING SCATTERED
SHOWERS AT POHNPEI AND EXTENDING EASTWARD TO KOSRAE. THERE HAVE ALSO
BEEN A FEW SHORT-LIVED THUNDERSTORMS WITH SOME OF THE HEAVIER
SHOWERS, SO KEPT ISOLATED THUNDERSTORMS IN THE FORECAST FOR TONIGHT.
AT MAJURO, SHOWERS ARE ISOLATED BUT A WEAK TROUGH EAST OF MAJURO IS
SLOWLY DRIFTING WESTWARD AND IS EXPECTED TO SUPPORT SCATTERED SHOWERS
AT MAJURO LATE TONIGHT AND INTO SUNDAY. TRADE-WIND TROUGHS WILL
SUPPORT PERIODS OF SCATTERED SHOWERS, AND AT TIMES, ISOLATED
THUNDERSTORMS AS THEY PASS NEAR THE ISLANDS. THE GFS CONTINUES TO BE
THE PRIMARY MODEL BEING USED FOR GUIDANCE DUE TO HOW IT BETTER
DEPICTS THE UPWARD AND DOWNWARD TRENDS IN SHOWERS ASSOCIATED WITH THE
PASSAGE OF TROUGHS, SO CONTINUED TO USE IT FOR THE TIMING WHEN
SHOWERS WILL CHANGE BETWEEN ISOLATED AND SCATTERED AS TROUGHS PASS
NEAR THE ISLANDS
ALTIMETRY AND BUOY DATA CONTINUE TO SUPPORT THAT SEAS HAVE REMAINED
AROUND 6 TO 7 FEET, DRIVEN BY A LONG-PERIOD NORTH SWELL AND
BACKGROUND EASTERLY SWELL. SUNDAY, ANOTHER LONG-PERIOD NORTH SWELL,
WILL START TO MOVE INTO THE REGION. THIS WILL CAUSE SURF TO REACH
HAZARDOUS LEVELS OF 9 FEET ALONG NORTH FACING REEFS AT POHNPEI AND
KOSRAE BY SUNDAY AFTERNOON, AND WILL CAUSE SURF TO APPROACH HAZARDOUS
LEVELS OF 12 FEET AT MAJURO, BUT STILL UNCERTAIN IF SURF WILL
ACTUALLY REACH 12 FEET OR WILL MAX OUT AROUND 10 TO 11 FEET. IF SURF
DOES REACH 12 FEET AT MAJURO, MINOR COASTAL FLOODING MAY ALSO BE A
CONCERN FOR NORTHERLY EXPOSED SHORES THAT FACE THE OPEN OCEAN AND
INTO THE LAGOON. THIS SWELL WILL ALSO CAUSE SEAS TO BUILD TO AROUND 7
TO 8 FEET, POTENTIALLY HITTING 9 FEET DURING THE ONSET OF A NEW
NORTHERLY SWELL. SEAS AND SURF ARE EXPECTED TO SUBSIDE MONDAY NIGHT
AND TUESDAY AS NORTH SWELL BEGINS TO SUBSIDE.
WESTERN MICRONESIA
THE LATEST SATELLITE DATA SHOWS CLOUDY SKIES ACROSS YAP AND CHUUK
AND MOSTLY CLOUDY SKIES OVER PALAU. YAP AND PALAU ARE CURRENTLY
SEEING ISOLATED SHOWERS, WITH SCATTERED SHOWERS AT CHUUK. ALTIMETRY
SHOWS SEAS BETWEEN 6 AND 8 FEET NORTH OF PALAU, AT YAP, AND EAST OF
CHUUK, WITH 6 TO 7 FOOT SEAS WEST OF PALAU.
A WEAKENING NEAR-EQUATORIAL TROUGH (NET) ALONG WITH A BROAD TROPICAL
DISTURBANCE, INVEST 95W, REMAIN THE ACTIVE WEATHER PRODUCERS ACROSS
WESTERN MICRONESIA. THE WESTERLY FLOW SOUTH OF THE NET, SOUTH OF
PALAU AND YAP, HAS DECREASED SIGNIFICANTLY SINCE LAST NIGHT. THIS
WILL HELP TO SLOW THE DEVELOPMENT OF 95W. BASED ON MODEL CONSENSUS,
IT LOOKS LIKELY THAT 95W WILL TRACK TOWARD THE MARIANAS OVER THE NEXT
24 TO 48 HOURS WHILE DEVELOPING VERY SLOWLY. ALTHOUGH YAP AND PALAU
ARE ONLY SEEING ISOLATED SHOWERS AT THIS TIME, CONVECTION LOOKS TO
INCREASE AT BOTH LOCATIONS THROUGH THE EVENING. PALAU CAN EXPECT
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS LATER THIS EVENING,
FOLLOWED BY A DRYING TREND THROUGH THE REMAINDER OF THE WEEKEND INTO
NEXT WEEK.
AT YAP, SHOWERS LOOK TO BECOME NUMEROUS LATER THIS EVENING,
CONTINUING THROUGH SUNDAY AFTERNOON. LOCALLY HEAVY SHOWERS ARE
POSSIBLE, WITH GUSTY WINDS IN HEAVIER SHOWERS. ALTHOUGH CONVECTION
LOOKS TO DECREASE A BIT SUNDAY NIGHT INTO THE BEGINNING NEXT WEEK,
YAP CAN STILL EXPECT TO SEE POPS (PROBABILITY OF PRECIPITATION) OF
20 TO 40 PERCENT THROUGH THE MIDDLE OF NEXT WEEK.
FOR CHUUK, SCATTERED SHOWERS LOOK TO INCREASE TO NUMEROUS SHOWERS
AND ISOLATED THUNDERSTORMS THIS EVENING AS BANDS OF CONVECTION AND
OUTFLOWS MOVE OVER WENO. LOCALLY HEAVY SHOWERS AND GUSTY WINDS WITH
HEAVIER SHOWERS ARE POSSIBLE AS WELL. SHOWERS WILL SLOWLY DECREASE
OVER THE NEXT FEW DAYS, WITH POPS DROPPING TO 20 PERCENT MONDAY
NIGHT THROUGH THE MIDDLE OF NEXT WEEK.
FOR THE MARINE FORECAST, LATEST ALTIMETRY SHOWS SEAS A BIT HIGHER
THAN GUIDANCE, SO THE NORTH SWELL WAS INCREASED A FOOT OVER GUIDANCE
FOR THE NEXT FEW DAYS. ALTIMETRY SHOWS SEAS OF 6 TO 8 FEET FOR YAP
AND PALAU AND 5 TO 7 FEET AT CHUUK, WITH THE NORTH SWELL EXPECTED TO
BUILD A BIT MORE OVER THE NEXT 24 TO 36 HOURS. THE NORTH SWELL IS
CURRENTLY HIGH ENOUGH TO PRODUCE HAZARDOUS SURF ALONG NORTH FACING
REEFS OF PALAU, YAP AND CHUUK. NORTH SWELL WILL BEGIN TO SUBSIDE
MONDAY AT CHUUK, WITH SURF FALLING BELOW HAZARDOUS LEVELS MONDAY
EVENING. FOR YAP AND PALAU, ANOTHER BUILDING NORTH SWELL LOOKS TO
MOVE INTO THE REGION EARLY NEXT WEEK, BRINGING SEAS OF 10 FEET TO
YAP AS EARLY AS MONDAY NIGHT. THIS WILL BE MONITORED OVER THE NEXT
24 HOURS AND IF IT CONTINUES TO LOOK LIKELY, A SMALL CRAFT ADVISORY
WILL BE NEEDED. SEAS LOOK TO MAINTAIN HAZARDOUS SURF AT PALAU, BUT
REMAIN BELOW THE 10 FOOT THRESHOLD FOR A SMALL CRAFT ADVISORY.
GUM WATCHES/WARNINGS/ADVISORIES
GU...HIGH RIP CURRENT RISK THROUGH MONDAY AFTERNOON FOR GUZ001.
HIGH SURF ADVISORY UNTIL 4 PM CHST MONDAY FOR GUZ001.
FLOOD WATCH THROUGH MONDAY AFTERNOON FOR GUZ001.
MP...HIGH RIP CURRENT RISK THROUGH MONDAY AFTERNOON FOR MPZ001>003.
HIGH SURF ADVISORY UNTIL 4 PM CHST MONDAY FOR MPZ001>003.
FLOOD WATCH THROUGH MONDAY AFTERNOON FOR MPZ001>003.
MARIANAS WATERS...SMALL CRAFT ADVISORY UNTIL 5 PM CHST SUNDAY FOR
PMZ151>154.
MARIANAS: BOWSHER
EAST MICRONESIA: SCHANK
WEST MICRONESIA: KLEESCHULTE
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