574
FXPQ50 PGUM 200733
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
533 PM CHST THU FEB 20 2025
MARIANAS SYNOPSIS
LATEST SATELLITE IMAGERY IS SHOWING PARTLY CLOUDY SKIES AND SPOTTY
SHOWERS. NEARBY BUOYS AND ALTIMETRY PASSES ARE INDICATING SEAS OF 6
TO 8 FEET. WINDS ARE MODERATE TO FRESH WITH STRONG GUSTS.
DISCUSSION
A WEAKENING FRONTAL BOUNDARY DIPPING SOUTH WILL BRING LOW-END
SCATTERED SHOWERS TO TINIAN AND SAIPAN LATE TONIGHT INTO TOMORROW
MORNING, BEFORE WASHING OUT BY TOMORROW AFTERNOON. CONVERGENT FLOW
ALONG A SHEAR LINE SOUTHEAST OF THE MARIANAS WILL DRIFT NORTHWEST
INTO GUAM AND ROTA AND BRING SCATTERED SHOWERS LATE TOMORROW NIGHT
INTO THE WEEKEND, BUT LIKELY STAYING SOUTH OF TINIAN AND SAIPAN. FOR
NEXT WEEK, MAINLY ISOLATED SHOWERS EXPECTED WITH BRIEF PERIODS OF
LOW-END SCATTERED SHOWERS POSSIBLE WITH PASSING TRADE DISTURBANCES.
GUSTY WINDS ARE EXPECTED OVER THE COMING DAYS. THIS, ALONG WITH THE
DRY CONDITIONS, WILL RESULT IN FIRE WEATHER CONCERNS AND A RED FLAG
WARNING IS IN EFFECT THROUGH FRIDAY AFTERNOON. MORE INFORMATION CAN
BE FOUND BELOW IN THE FIRE WEATHER SECTION.
MARINE/SURF
MODERATE TO FRESH WINDS AND COMBINED SEAS 6 TO 8 FEET THIS AFTERNOON
WILL INCREASE AND BECOME HAZARDOUS TO SMALL CRAFT BY TOMORROW
MORNING, LIKELY CONTINUING THROUGH THE WEEKEND. SEAS LOOK TO BECOME
8 TO 10 FEET AS A LONGER PERIOD NORTHERLY SWELL ARRIVES AND THE TRADE
SWELL INCREASES. WINDS WILL ALSO BECOME MODERATE WITH STRONG TO
NEAR-GALE GUSTS AS A STRONG SUBTROPICAL RIDGE SETS UP TO THE NORTH
AND MULTIPLE SHEAR LINES PASS THROUGH THE MARIANAS.
A MODERATE RISK OF RIP CURRENTS WILL CONTINUE ALONG WEST, NORTH AND
EAST FACING REEFS THROUGH SATURDAY AS LONGER PERIOD NORTHERLY SWELL
AND ELEVATED TRADE SWELL CONTINUE. SURF AND RIP RISK COULD BECOME
HIGH BY LATE WEEKEND ALONG NORTH AND ESPECIALLY EAST FACING REEFS AS
THE TRADE SWELL CONTINUES TO BUILD.
FIRE WEATHER
A FEW SHOWERS BROUGHT 0.15 INCHES OF RAIN YESTERDAY, WHICH
ALLOWED FOR THE KBDI TO RISE TO 646. RELATIVE HUMIDITY AND FUEL
MOISTURE ARE EXPECTED TO BE LOW THROUGH TOMORROW, ALONG WITH LITTLE
TO NO RAIN. A POSSIBLE MOISTENING TREND WITH AN INCREASED POTENTIAL
FOR SHOWERS POSSIBLE OVER THE WEEKEND. WINDS ALSO LOOK TO BE A BIT
HIGHER THROUGH TOMORROW. A RED FLAG WARNING HAS BEEN ISSUED UNTIL 6PM
FRIDAY AS VERY DRY CONDITIONS AND GUSTY WINDS WILL RESULT IN A HIGH
FIRE START AND SPREAD THREAT. A FIRE WEATHER WATCH IS IN EFFECT FROM
FRIDAY EVENING THROUGH SUNDAY AFTERNOON.
EASTERN MICRONESIA
A DRY TRADE-WIND PATTERN CONTINUES ACROSS THE REGION. A COUPLE OF
WEAK TRADE-WIND TROUGHS THAT ARE EXPECTED TO MOVE THROUGH THE REGION
WILL BRING PERIODS OF INCREASED CONVECTION TO THE FORECAST POINTS.
THE FIRST OF THESE TROUGHS, CURRENTLY EAST OF MAJURO, IS EXPECTED TO
BRING LOW-END SCATTERED SHOWERS TO THE ATOLL FRIDAY MORNING. THE
TROUGH LOOKS TO MOVE INTO KOSRAE FRIDAY NIGHT AND POHNPEI SATURDAY
NIGHT. THE NEXT TROUGH IS JUST EAST OF THE DATE LINE AND IS EXPECTED
TO MOVE THROUGH RIGHT ON THE HEEL OF THE FIRST TROUGH, MAINTAINING
SCATTERED SHOWERS AN ADDITIONAL 12 HOURS AT ALL THREE LOCATIONS.
OTHERWISE, A TRADE-WIND SURGE IS EXPECTED TO DEVELOP ACROSS THE
REGION AS A HIGH PRESSURE SYSTEM MOVES EAST FROM THE CHINA COAST.
THIS WILL BRING BREEZY CONDITIONS TO REGION OVER THE WEEKEND.
THE LONG-PERIOD NORTH SWELL WILL SUBSIDE OVERNIGHT, ALLOWING SURF TO
FALL BELOW HAZARDOUS LEVELS. THIS MAY BE BRIEF AS ANOTHER NORTHERLY
SWELL IS EXPECTED TO MOVE INTO THE AREA OVER THE WEEKEND. THIS SWELL,
COMBINED WITH A BUILDING TRADE-WIND SWELL, IS EXPECTED TO BRING
HIGHER SEAS TO THE REGION, WITH SEAS REACHING AS HIGH AS 10 FEET OVER
THE WEEKEND. A SMALL CRAFT ADVISORY IS EXPECTED AS EARLY AS SATURDAY
FOR POHNPEI, SATURDAY NIGHT FOR MAJURO AND SUNDAY FOR KOSRAE. THIS
WOULD RESULT IN HAZARDOUS SURF ALONG NORTH FACING REEFS FOR KOSRAE
AND POHNPEI. DUE TO A BUILDING TRADE SWELL, KOSRAE COULD ALSO SEE
HAZARDOUS SURF ALONG EAST FACING REEFS.
WESTERN MICRONESIA
A NEAR EQUATORIAL TROUGH (NET) LINGERS WELL SOUTH OF PALAU AND
CHUUK, WHILE A TRADE-WIND SURGE IS DEVELOPING THE THE NORTHWEST OF
PALAU AND NEAR YAP AS AN AREA OF HIGH PRESSURE MOVES OFF OF MAINLAND
ASIA AND TOWARDS JAPAN AND STRENGTHENS THE PRESSURE GRADIENT ACROSS
THE REGION. BESIDES FOR SOME QUICK MOVING TRADE SHOWERS MOVING
THROUGH, PALAU AND CHUUK ARE IN AN FAIRLY DRY TRADE WIND PATTERN AT
THE MOMENT AS THE SHOWERS ASSOCIATED WITH THE NET REMAIN NEAR THE
EQUATOR. FOR YAP PROPER, SCATTERED SHOWERS HAVE STARTED TO DEVELOP
THIS AFTERNOON AROUND 10N, DUE TO CONVERGENCE ALONG THE SOUTHERN EDGE
OF THE DEVELOPING TRADE-WIND SURGE. AS THE AREA OF HIGH PRESSURE
MOVES EASTWARD ACROSS THE PACIFIC, THE TRADE-WIND SURGE FOLLOW,
BRINGING BREEZY CONDITIONS TO YAP TONIGHT AND TO PALAU FRIDAY, WHILE
WINDS ARE NOT EXPECTED TO BECOME BREEZY AT CHUUK UNTIL LATE THIS
WEEKEND. THIS TRADE-WIND SURGE WILL ALSO HELP TO MIX DRIER AIR NORTH
OF THE REGION INTO PALAU, YAP AND CHUUK OVER THE NEXT FEW DAYS,
WHICH WILL HELP TO LIMIT THE POTENTIAL FOR GUSTY WINDS AND SHOWERS
ACROSS THE REGION, THOUGH PASSING TRADE-WIND TROUGHS MAY BRING SOME
BRIEF PERIODS OF GUSTS AND SHOWERS TO ANY ISLAND THEY PASS NEARBY. A
SIMILAR PATTERN MAY DEVELOP AGAIN NEXT WEEK AS A COLD FRONT/SHEAR
LINE DROPS SOUTH TOWARDS THE MARIANAS AND WINDS INCREASE NEAR THE
PHILIPPINES AHEAD OF THE FRONTAL SYSTEM AS ANOTHER AREA OF HIGH
PRESSURE PUSHES OFF OF MAINLAND ASIA.
ALTIMETRY SHOWS SEAS AROUND 4 TO 5 FEET AT CHUUK THIS EVENING, WHILE
THE BUOY NEAR PALAU IS REPORTING SEAS AROUND 6 TO 7 FEET. ALTIMETRY
SHOWS SEAS INCREASING TO AROUND 7 TO 9 FEET AROUND YAP AND AROUND 10
FEET CLOSER TO THE PHILIPPINES, LIKELY DUE TO THE STRONGER WINDS OF
THE TRADE-WIND SURGE. EXPECTING SEAS TO CLIMB UP TO AROUND 10 FEET AT
YAP TONIGHT AND FRIDAY AS THE TRADE-WIND SURGE EXPANDS EASTWARD, SO A
SMALL CRAFT ADVISORY WAS ISSUED FOR YAP THROUGH FRIDAY AFTERNOON.
RIGHT NOW MODELS HAVE SEAS AND WINDS SLIGHTLY WEAKER AT PALAU FRIDAY,
SO HELD OFF ON AN ADVISORY FOR PALAU BUT MENTIONED SEAS WILL BE
CHOPPY FRIDAY AND FRIDAY NIGHT IN THE FORECAST WITH WINDS AROUND 20
KTS AND SEAS GETTING NEAR 9 FEET. AS THE TRADE-WIND SURGE CONTINUES
EASTWARD, SEAS WILL BUILD AT CHUUK LATER THIS WEEKEND, BUT THE
HIGHEST SEAS AND STRONGEST WINDS ARE EXPECTED TO BE AROUND OR NORTH
OF 10N, SO NOT EXPECTING HAZARDOUS MARINE CONDITIONS AT THIS TIME.
SINCE THE PRIMARY NORTHEAST SWELL WILL LIKELY BE WIND DRIVEN AND THE
LONGER PERIOD NORTH SWELL IS NOT EXPECTED TO BUILD MUCH OVER THE NEXT
FEW DAYS, SURF WILL BE ELEVATED ALONG NORTH AND EAST FACING REEFS,
BUT SHOULD REMAIN BELOW HIGH SURF CRITERIA OF 12 FEET ALONG EAST
REEFS AND 9 FEET ALONG NORTH REEFS THROUGH THE WEEKEND.
GUM WATCHES/WARNINGS/ADVISORIES
GU...RED FLAG WARNING UNTIL 6 PM CHST FRIDAY FOR GUZ001.
FIRE WEATHER WATCH FROM FRIDAY EVENING THROUGH SUNDAY AFTERNOON
FOR GUZ001.
MP...NONE.
MARIANAS WATERS...SMALL CRAFT ADVISORY FROM 6 AM FRIDAY TO 6 AM CHST
MONDAY FOR PMZ151>154.
MARIANAS: SLAGLE
EAST MICRONESIA: KLEESCHULTE
WEST MICRONESIA: SCHANK
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