332
FXPQ50 PGUM 200830
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
630 PM CHST FRI MAR 20 2026
MARIANAS SYNOPSIS
SATELLITE IMAGERY SHOWS PARTLY CLOUDY SKIES. RADAR IMAGERY SHOWS
ISOLATED SHOWERS OVER THE COASTAL WATERS. ALTIMETRY SHOWS COMBINED
SEAS OF 8 TO 9 FEET TO THE WEST OF THE ISLANDS, AND IPAN BUOY DATA
SHOWS 7 FEET AT 15 SECONDS. WINDS ARE 15 TO 20 MPH WITH OCCASIONAL
GUSTS TO 25 MPH.
THE HIGH SURF ADVISORY, AND HIGH RISK OF RIP CURRENTS STATEMENTS WERE
EXTENDED THROUGH SUNDAY AFTERNOON. THE SMALL CRAFT ADVISORY WAS
ALLOWED TO EXPIRE.
DISCUSSION
TODAY, 0.00 RAIN FELL AT THE AIRPORT. WINDS DID PICK UP A BIT, AS THE
PRESSURE GRADIENT OVER THE ISLANDS INCREASED SLIGHTLY. THIS ALLOWED
FOR OCCASIONAL GUSTS OF 25 KNOTS (30 MPH) AT THE AIRPORT. A DRY
PATTERN REMAINS OVER THE ISLANDS AND IS EXPECTED TO CONTINUE THROUGH
THE WEEKEND. A WETTER PATTERN IS POSSIBLE AGAIN NEAR THE MIDDLE OF
NEXT WEEK AS WEAK TROUGHING MOVES THROUGH TO THE SOUTH, THOUGH MODEL
GUIDANCE CURRENTLY SHOWS THIS CONVECTION REMAINING SOUTH OF GUAM
WATERS.
MARINE
BUILDING NORTHEAST TO EAST SWELL, REINFORCED BY DIMINISHING LONG-
PERIOD NORTH TO NORTHEAST SWELLS FROM DISTANT LOW PRESSURE SYSTEMS
WILL CONTINUE TO PRODUCE SEAS OF 7 TO 9 FEET OVER MARIANA'S
WATERS WITH PERIODS OF LOCALLY HIGHER SEAS POSSIBLE FOR
NORTHEASTERN TINIAN AND SAIPAN WATERS. WINDS ARE EXPECTED TO BE
MODERATE TO FRESH WITH OCCASIONAL STRONG GUSTS. SEAS MAY BUILD BACK
TO 10 FEET OR HIGHER AS EARLY AS SATURDAY NIGHT AS THE TRADE SWELL
CONTINUES TO BUILD. OVERALL, SEAS ARE ANTICIPATED TO HOVER AROUND THE
THRESHOLD FOR A SMALL CRAFT ADVISORY THROUGH THE MIDDLE OF NEXT
WEEK.
EASTERN MICRONESIA
WITH THE LOSS OF THE POHNPEI BUOY DATA, WE RELIED ON ALTIMETRY AND
MODEL FORECASTS, WHICH SHOWED HAZARDOUS SURF REDEVELOPING AT POHNPEI
AND KOSRAE THROUGH SUNDAY NIGHT. AS SUCH, HIGH SURF ADVISORIES WERE
HOISTED FOR BOTH LOCATIONS. ADDITIONALLY AT POHNPEI, SEAS WILL
AVERAGE NEAR 9 FEET, WHICH IS A FOOT BELOW SMALL CRAFT ADVISORY
CRITERIA. WITH THIS IN MIND, WE ADDED A HEADLINE FOR ELEVATED SEAS TO
GET THE WORD OUT.
AS FOR RAINFALL, POHNPEI AND KOSRAE WERE PRETTY STRAIGHT FORWARD DUE
TO A PAIR OF SURFACE TROUGHS NEARBY. EARLIER, CLOUD TOP TEMPERATURES
COOLED BELOW -80 DEGREES CELSIUS TO THE EAST-SOUTHEAST, INDICATIVE
OF HEAVY RAINFALL. THEY HAVE SINCE WARMED, BUT A REPEAT OF NOCTURNAL
COOLING COULD OCCUR DURING THE NOCTURNAL MAX, SO LOCALLY HEAVY
RAINFALL WORDING AFTER MIDNIGHT WAS ADDED. AT POHNPEI, A NEARBY
REMNANT SHEAR LINE MAY KEEP LOW-END SCATTERED SHOWER COVERAGE GOING
FOR ANOTHER 24 TO 48 HOURS. THEREAFTER, IT'LL DEPEND IF THE SHEAR
LINE CAN MAINTAIN CONTINUITY/SURFACE CONVERGENCE, AND IF IT RETREATS
EAST OR NOT.
SEAS LOOK TO DECREASE FOR THE LATTER HALF OF THE WEEK, WITH LIGHT TO
GENTLE WINDS PREVAILING AREA-WIDE.
WESTERN MICRONESIA
LATEST SATELLITE DATA SHOWS PARTLY CLOUDY SKIES WITH SPOTTY LIGHT
SHOWERS ACROSS PALAU AND YAP PROPER. MOSTLY CLOUDY SKIES WITH
SCATTERED SHOWERS ARE SEEN OVER CHUUK. ALTIMETRY SHOWS SEAS OF
AROUND 8 FEET NEAR YAP.
NOT MUCH OF A CHANGE FROM THE PREVIOUS FORECAST. LATEST VISIBLE
SATELLITE AND ASCAT ANALYSIS SHOW A WEAK CIRCULATION TO THE SOUTHEAST
OF CHUUK. CONVERGENCE NORTH OF THIS CIRCULATION IS GENERATING
SCATTERED SHOWERS ACROSS WENO THIS EVENING. THE LATEST MODEL GUIDANCE
SHOWS THE CIRCULATION MOVING WEST OVER THE NEXT FEW DAYS. THIS
SHOULD ALLOW THE DRY PATTERN TO MOVE BACK OVER WENO FOR THE WEEKEND.
THIS DRIER PATTERN IS THEN EXPECTED TO REMAIN OVER CHUUK THROUGH THE
WEEKEND. EARLY NEXT WEEK, THE APPROACH OF A COUPLE OF WEAK TRADE-WIND
TROUGHS FROM EASTERN MICRONESIA LOOK TO BRING INCREASED SHOWERS AND
THE RISK OF THUNDERSTORMS TO WENO. BY MIDWEEK, DRIER CONDITIONS ARE
EXPECTED TO RETURN TO CHUUK.
FOR YAP AND PALAU, DRY CONDITIONS ARE EXPECTED TO CONTINUE OVER BOTH
LOCATIONS THROUGH THE WEEKEND. BY MONDAY, THE WEAK CIRCULATION
CURRENTLY SOUTHEAST OF WENO LOOKS TO APPROACH THE REGION, BRINGING
INCREASED CONVECTION TO THE AREA AS IT REINVIGORATES THE NEAR-
EQUATORIAL TROUGH (NET). THIS WILL PUSH THE NET A LITTLE FARTHER
NORTH BRINGING INCREASED CONVECTION TO BOTH LOCATIONS. AROUND THE
MIDDLE OF NEXT WEEK, THE FIRST OF THE TRADE-WIND TROUGHS MOVING
THROUGH CHUUK ARE EXPECTED TO APPROACH YAP, INCREASING THE
PROBABILITY OF SHOWERS TO AROUND 40 PERCENT. THIS WILL LIKELY AFFECT
PALAU A LITTLE LATER IN THE WEEK.
MARINE CONDITIONS ARE SLOWLY IMPROVING ACROSS THE REGION. LATEST
ALTIMETRY SHOWS THAT YAP SHOULD STILL BE SEEING HAZARDOUS SURF ALONG
NORTH FACING REEFS WITH WAVE MODEL GUIDANCE SHOWING A SLOW DECREASE
THROUGH SATURDAY AFTERNOON. THEN SURF SHOULD FALL BELOW HAZARDOUS
LEVELS. SEAS OF 6 TO 8 FEET AT YAP LOOK TO FALL TO BETWEEN 5 AND 7
FEET, WHILE SEAS OF 5 TO 7 FEET AT PALAU AND CHUUK LOOK TO DROP TO
AROUND 4 TO 6 FEET EARLY 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...SMALL CRAFT ADVISORY UNTIL 5 PM CHST THIS AFTERNOON
FOR PMZ151>154.
MARIANAS: BOWSHER
EAST MICRONESIA: DOLL
WEST MICRONESIA: KLEESCHULTE
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