287
FXPQ50 PGUM 171924
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
524 AM CHST TUE FEB 18 2025
MARIANAS UPDATE
A FIRE WEATHER WATCH REMAINS IN EFFECT THROUGH THURSDAY. NO
MEANINGFUL CHANGES TO THE FORECAST WERE NEEDED OVERNIGHT. THE
MARIANAS REMAIN PRETTY DRY. A LARGER NORTH SWELL MAY MAKE ITS
PRESENCE KNOWN LATER THIS WEEK.
EASTERN MICRONESIA UPDATE
JUST ISOLATED SHOWERS AT POHNPEI THROUGH WEDNESDAY NIGHT. REMOVED THE
THUNDERSTORMS FROM TODAY BASED ON THE COLDEST CLOUD TOPS OF -8C. THIS
FORECAST DOES STILL HAVE SCATTERED SHOWERS THURSDAY, AND SATURDAY
NIGHT THROUGH SUNDAY NIGHT. THAT WILL HAVE TO BE LOOKED AT THIS
AFTERNOON.
LITTLE CHANGE IN THE FORECAST FOR KOSRAE, JUST PARTLY CLOUDY WITH
ISOLATED SHOWERS.
FOR MAJURO, JUST REMOVED THE SHOWERS FROM TODAY AND TONIGHT, BASED ON
THE CLOUD TOPS OF 12C MOVED WEST OF THEM. THOSE TOPS ARE MOVING BACK
TOWARD MAJURO NOW, BUT IS THERE ANY RAIN WITH THEM?
GENTLE TO MODERATE TRADE WINDS WILL PREVAIL THROUGH WEDNESDAY, THEN
BECOME FRESH THROUGH THE WEEKEND. A SMALL CRAFT ADVISORY IS A
POSSIBILITY.
WESTERN MICRONESIA UPDATE
SCATTERED SHOWERS WILL AFFECT KOROR PALAU THROUGH WEDNESDAY NIGHT
THANKS TO A SERIES OF TROUGHS. STARTING THURSDAY THE SHOWERS SHOULD
DIMINISH IN COVERAGE TO ISOLATED, AND STAY THIS WAY THROUGH MONDAY.
YAP WILL HAVE SCATTERED SHOWERS TODAY, THEN ISOLATED SHOWERS THROUGH
MONDAY. AS A SHEAR LINE APPROACHES, WINDS WILL BUILD TO BREEZY
WEDNESDAY NIGHT AND WINDY THURSDAY NIGHT.
CHUUK WILL BE DRY TODAY, THEN ISOLATED SHOWERS TONIGHT THROUGH
SUNDAY. WINDS WILL BUILD TO BREEZY WEDNESDAY NIGHT, THEN WINDY
SATURDAY NIGHT AND SUNDAY. SUNDAY NIGHT AND MONDAY WILL HAVE
SCATTERED SHOWERS WITH A RETURN TO BREEZY CONDITIONS.
GENTLE TO MODERATE WINDS WILL FRESHEN THURSDAY ACROSS WESTERN
MICRONESIA, WITH GUSTS TO NEAR GALE FORCE POSSIBLE NEAR YAP. SEAS
COULD REACH 10 FEET AROUND THURSDAY, SO A SMALL CRAFT ADVISORY IS
FAIRLY LIKELY IN WESTERN MICRONESIA STARTING THURSDAY.
PREV DISCUSSION
/ISSUED 610 PM CHST MON FEB 17 2025/
MARIANAS SYNOPSIS...
THE REMNANTS OF A SHEAR LINE FRAGMENT ARE BRINGING PATCHY CLOUD COVER
AND ISOLATED SHOWERS ACROSS THE MARIANAS. SURFACE OBSERVATIONS AND
ALTIMETRY SHOW MOSTLY GENTLE TRADE WINDS WITH OCCASIONAL MODERATE TO
FRESH GUSTS.
DISCUSSION...
VERY DRY CONDITIONS WILL CONTINUE, WITH OCCASIONAL INCREASES IN
SHOWER COVERAGE AND MOISTURE RESULTING FROM SHEAR LINE REMNANTS
WORKING THEIR WAY SOUTH ACROSS THE AREA THROUGHOUT THE WEEK. TRADE
WINDS WILL BE MOSTLY GENTLE INTO WEDNESDAY DUE TO A RELAXED PRESSURE
GRADIENT ACROSS THE REGION. A TRADE-WIND SURGE WILL BEGIN TO SET UP
ON THURSDAY AS A STRONG SUBTROPICAL RIDGE BUILDS JUST NORTH OF THE
CNMI. THIS MAY LEAD TO SURF AND SMALL CRAFT CONCERNS BY THE END OF
THE WEEK.
MARINE...
LATEST BUOY AND ALTIMETRY DATA SHOW COMBINED SEAS OF 5 TO 7 FEET
ACROSS THE MARIANAS. LIGHT TO GENTLE WINDS ARE EXPECTED TONIGHT AND
TUESDAY WITH A TEMPORARY WEAKENING IN THE SUBTROPICAL RIDGE NORTH OF
THE MARIANAS. WINDS AND SEAS WILL INCREASE IN THE LATTER HALF OF THE
WEEK AS A STRONG SUBTROPICAL RIDGE SETS UP NORTH OF THE REGION,
PRODUCING A WIDESPREAD TRADE-WIND SURGE. SEAS COULD BECOME HAZARDOUS
TO SMALL CRAFT BY THE END OF THE WEEK. THERE WILL BE A MODERATE RISK
OF RIP CURRENTS FOR WEST, NORTH, AND EAST FACING REEFS THROUGH
TUESDAY NIGHT, BUT SURF AND SEAS LOOK TO CONTINUE DECREASING THROUGH
WEDNESDAY.
FIRE WEATHER...
BRIEF SHOWERS BROUGHT A TRACE OF RAINFALL TODAY BUT THERE HAS NOT
BEEN A WETTING RAIN IN SEVERAL DAYS, WHICH ALLOWED FOR THE KBDI TO
RISE TO 625. A WETTING RAIN OF 0.20 INCHES OR HIGHER IS NOT EXPECTED
OVER THE NEXT FEW DAYS. RELATIVE HUMIDITY VALUES MAY DROP JUST BELOW
60 PERCENT TOMORROW, BUT WINDS WILL CONTINUE TO DECREASE BELOW RED
FLAG WARNING CRITERIA, AND THE RED FLAG WARNING IS NO LONGER IN
EFFECT. A FIRE WEATHER WATCH CONTINUES FOR THIS EVENING THROUGH
THURSDAY AFTERNOON, AS VERY DRY CONDITIONS AND OCCASIONAL GUSTY
WINDS WILL MAINTAIN A HIGH FIRE THREAT. HOWEVER, FORECASTED RELATIVE
HUMIDITY VALUES AND WINDS ARE BOTH BELOW RED FLAG WARNING CRITERIA
DURING THIS PERIOD.
EASTERN MICRONESIA...
A BROAD TROUGH EXTENDS NORTHEASTWARD ACROSS KOSRAE TO BETWEEN UTRIK
AND RONGELAP. SATELLITE TRENDS SHOW SCATTERED SHOWERS ACROSS KOSRAE
BEGINNING TO FALL APART THIS AFTERNOON AND MODELS SHOW THIS FEATURE
WEAKENING AND SHIFTING NORTH, REDUCING SHOWERS TO ISOLATED OVER
KOSRAE TONIGHT. IN THE WAKE OF THE TROUGH, A SMALL AREA OF SHOWERS
MOVED THROUGH MAJURO TODAY, ALTHOUGH SHOWERS ARE EXPECTED TO TAPER
DOWN TONIGHT AS WELL. DRIER WEATHER PERSISTS NORTHWEST OF THIS
TROUGH, INCLUDING POHNPEI. OVER THE NEXT SEVERAL DAYS, MODELS SHOW A
SERIES OF WEAK TROUGHS PASSING THROUGH THE REGION, BUT OVERALL,
SHOWERS LOOK TO STAY ISOLATED THIS WEEK, WITH PERIODIC UPTICKS TO
SCATTERED COVERAGE.
A HIGH SURF ADVISORY WILL BE IN EFFECT FOR POHNPEI AND KOSRAE
STARTING TUESDAY MORNING THROUGH WEDNESDAY NIGHT. ANOTHER PULSE OF
LONG-PERIOD NORTHERLY SWELL IS EXPECTED TO QUICKLY INCREASE SURF TO
HAZARDOUS LEVELS ALONG NORTH FACING REEFS. BY LATE WEEK, SURF
DECREASES BACK DOWN TO 5 TO 8 FEET AS NORTH SWELL SUBSIDES. HOWEVER,
ANOTHER PULSE OF NORTH SWELL AND AN INCREASE IN EAST-NORTHEAST TRADE
SWELL MAY KEEP SURF ELEVATED ALONG NORTH FACING REEFS OVER THE
WEEKEND. BUOY AND ALTIMETRY DATA SHOW COMBINED SEAS OF 3 TO 5 FEET
NEAR POHNPEI AND KOSRAE, AND UP TO 7 FEET NEAR MAJURO. EXPECT SEAS
TO INCREASE TO BETWEEN 7 AND 9 FEET WITH THE ARRIVAL OF A LARGER
NORTH SWELL PULSE. GENTLE TO MODERATE EAST-NORTHEAST TRADES ARE
EXPECTED TO BECOME MODERATE TO FRESH IN THE LATTER HALF OF THE WEEK
AS HIGH PRESSURE BUILDS TO THE DISTANT NORTH, INCREASING THE PRESSURE
GRADIENT ACROSS THE REGION.
WESTERN MICRONESIA...
A BROAD SURFACE TROUGH MOVES ACROSS THE WESTERN PORTIONS OF
MICRONESIA, BRINGING PATCHY SHOWERS TO PALAU AND YAP THE NEXT SEVERAL
DAYS. AS ANOTHER HIGH PRESSURE CELL MOVES OFF THE COAST OF CHINA AND
THEN ACROSS JAPAN, A DRIER REGIME WILL RETURN ONCE AGAIN IN THE
SECOND HALF OF THE WEEK. CHUUK WILL NOT SEE A SIGNIFICANT CHANGE IN
WEATHER, WITH ONLY ISOLATED SHOWERS AND OCCASIONALLY BREEZY
CONDITIONS EXPECTED FOR MUCH OF THE WEEK.
COMBINED SEAS OF 5 TO 7 FEET ARE EXPECTED AT PALAU, YAP AND CHUUK FOR
AT LEAST THE NEXT SEVERAL DAYS, FOLLOWED BY ANOTHER ROUND OF A NORTH
SWELL PULSE MAKING ITS WAY ACROSS THE REGION, POSSIBLY INCREASING
SEAS BY ANOTHER 2 TO 4 FEET BEFORE THE NEXT WEEKEND.
GUM WATCHES/WARNINGS/ADVISORIES
GU...FIRE WEATHER WATCH THROUGH THURSDAY AFTERNOON FOR GUZ001.
MP...NONE.
MARIANAS WATERS...NONE.
MARIANAS: BOWSHER/STANKO
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