467
FXPQ50 PGUM 220215 AAA
AFDGUM
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TIYAN GU
1215 PM CHST SUN DEC 22 2024
MARIANAS UPDATE
EXTENDED SMALL CRAFT ADVISORY TO GUAM AND ROTA ONCE RITIDIAN BUOY
REVEALED HAZARDOUS SEAS OF 10 TO 11 FEET THIS MORNING. INCREASED
SURF HEIGHTS AS WELL TO REFLECT THIS LARGER IMPACT OF NORTH SWELL.
SURF OBSERVATIONS VERIFIED HAZARDOUS SURF ALONG NORTH-FACING REEFS,
BUT THE SURF OBSERVATION AT TUMON BAY ESTIMATED MODERATE SURF ALONG
WEST-FACING REEFS. EVEN SO, WENT AHEAD AND EXTENDED THE HIGH SURF
ADVISORY TO WEST FACING REEFS AND THE HIGH RISK OF RIP CURRENTS TO
WEST AND EAST FACING REEFS AS A PRECAUTION, SINCE RITIDIAN BUOY
SHOWED THE SWELL ENERGY COMING FROM THE NNW AND SAIPAN WOULD
REASONABLY SEE A RELATIVELY LARGER IMPACT OF NORTH SWELL.
PREV DISCUSSION
/ISSUED 439 AM CHST SUN DEC 22 2024/
MARIANAS UPDATE...
A HIGH SURF ADVISORY AND A HIGH RISK OF RIP CURRENTS HAS BEEN ISSUED
FOR NORTH FACING REEFS, AND A SMALL CRAFT ADVISORY HAS BEEN ISSUED
FOR TINIAN AND SAIPAN.
ONLY MINOR EDITS WERE NEEDED FOR THE FORECAST THIS MORNING. THE
MAIN CONCERN TONIGHT WAS THE INCOMING NORTH SWELL. ALTIMETRY PASS
WAS TO THE WEST OF THE MARIANAS ABOUT 300 NAUTICAL MILES SHOWS 8 TO
10 FEET. TANAPAG BUOY SHOWS 8 TO 9 FEET AND CLIMBING. MODELS,
HOWEVER, ARE A SUGGESTING A FOOT OR TWO LOWER THAN OBSERVATIONS. FOR
THESE REASON, A SMALL CRAFT ADVISORY FOR TINIAN AND SAIPAN. GUAM AND
ROTA'S SEAS WILL ALSO RISE, HOWEVER AT THIS TIME NOT EXPECTED TO
MEET THE 10 FOOT LEVEL TO WARRANT AN ADVISORY. ALL BOATERS IN THE
MARIANAS SHOULD EXERCISE CAUTION WHEN DEALING WITH THE SEAS.
EASTERN MICRONESIA UPDATE...
ONLY MINOR EDITS TO THE FORECAST THIS MORNING. THE DRIER TRADE-WIND
PATTERN HAS SETTLED INTO THE REGION, WITH MAINLY ISOLATED TRADE
SHOWERS EXPECTED. AN ITCZ EAST OF THE DATE LINE WILL CREEP WEST INTO
THE MARSHALL ISLANDS ON MONDAY, THEN INTO KOSRAE AND POHNPEI ON
TUESDAY, WITH SHOWERS AND THUNDERSTORM POTENTIAL INCREASING THROUGH
THE WEEK AS THE ITCZ BECOMES BETTER ORGANIZED.
THE TRADE SWELL HAS DIMINISHED JUST ENOUGH FOR THE HIGH SURF
ADVISORY TO BE DROPPED AT MAJURO, BUT REMAINS ELEVATED ENOUGH TO
MAINTAIN THE HIGH SURF ADVISORY FOR EAST REEFS OF KOSRAE INTO AT
LEAST TUESDAY. THE SMALL CRAFT ADVISORY WAS EXTENDED FOR MAJURO
THROUGH MONDAY AS COMBINED SEAS REMAIN HIGH. THE ELEVATED TRADE SWELL
AND LONG PERIOD NORTHERLY SWELLS, ALONG WITH FRESH TO AT TIMES
STRONG TRADE WINDS, WILL KEEP SEAS CHOPPY FOR MOST OF NEXT WEEK.
CONDITIONS COULD BECOME HAZARDOUS TO SMALL CRAFT, ESPECIALLY AT
MAJURO.
WESTERN MICRONESIA UPDATE...
ONLY MINOR EDITS TO THE FORECAST THIS MORNING. LOW-END SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS ARE POSSIBLE FOR YAP AND FOR
PALAU AS THE NEAR-EQUATORIAL TROUGHS SHIFTS SOUTHWEST AND TRADE
TROUGHS PASS THROUGH. A DRIER TRADE-WIND PATTERN WILL SETTLE OVER
YAP AROUND TUESDAY AS THE NET SHIFTS SOUTH, WITH MAINLY ISOLATED
SHOWERS EXPECTED. THE NET LOOKS TO LINGER NEAR PALAU, KEEPING SHOWERS
AND THUNDERSTORMS POTENTIAL SLIGHTLY HIGHER. OVER TOWARDS CHUUK, A
TRADE TROUGH PASSING THROUGH WILL BRING SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS FOR THE WEEKEND BEFORE THE DRIER TRADE-WIND
PATTERN PUSHES IN EARLY NEXT WEEK, WITH MAINLY ISOLATED TO LOW-END
TRADE SHOWERS EXPECTED. THE ITCZ WILL BUILD WEST AND BRING AN
INCREASING POTENTIAL FOR SHOWERS AND THUNDERSTORMS FOR THE LATTER
HALF OF NEXT WEEK.
WINDS TODAY WILL BE GENTLE TO MODERATE FOR PALAU, GENERALLY MODERATE
FOR YAP, AND MODERATE TO FRESH FOR CHUUK. WINDS WILL INCREASE NEXT
WEEK AS THE NET SETTLES SOUTH AND TRADE FLOW INCREASES ACROSS THE
REGION. ALSO, MIXED SWELL WAVES FROM ENE AND THE NORTH MAY CAUSE
CHOPPY SEAS AT TIMES, AND LONGER-PERIOD NORTH SWELL WILL ARRIVE FROM
STORMY WEATHER MUCH FARTHER NORTH, POSSIBLY RESULTING IN HIGH SURF.
CONDITIONS MAY BECOME HAZARDOUS TO SMALL CRAFT NEXT WEEK, ESPECIALLY
FOR CHUUK.
PREV DISCUSSION... /ISSUED 509 PM CHST SAT DEC 21 2024/
MARIANAS SYNOPSIS...
MODERATE TRADES AND ISOLATED SHOWERS PREVAIL ACROSS THE REGION THIS
AFTERNOON. BUOY AND ALTIMETRY DATA ESTIMATE SEAS AT 6 TO 8 FEET.
DISCUSSION...
LATEST MODEL GUIDANCE SHOWS PERIODIC UPTICKS IN SHOWERS THROUGH
SUNDAY NIGHT AS MINOR TROUGHS PASS THROUGH THE REGION. THEN, A
DRIER-TRADE PATTERN BEGINS TO TAKE HOLD EARLY NEXT WEEK. MODELS ARE
HINTING AT A SHEAR LINE EXTENDING ACROSS THE FAR NORTHERN MARIANA
ISLANDS AROUND WEDNESDAY, POSSIBLY MOVING AS FAR SOUTH AS SAIPAN,
BEFORE FALLING APART LATE WEEK. THIS IS STILL SEVERAL DAYS OUT AND
ENSEMBLE MODELS DO NOT GIVE ANY MORE THAN ISOLATED SHOWERS AT THIS
TIME, BUT WILL CONTINUE TO MONITOR SUBSEQUENT MODEL RUNS FOR ANY
CHANGES.
MARINE/SURF...
A HIGH SURF ADVISORY AND A HIGH RISK OF RIP CURRENTS WILL BE
EFFECT STARTING EARLY SUNDAY MORNING THROUGH MONDAY ALONG NORTH
FACING REEFS. ALTIMETRY SHOWS SEAS OF 6 TO 8 FEET AND IS EXPECTED TO
INCREASE BY 1 TO 2 FEET AS A LARGER NORTHERLY SWELL EMANATING FROM A
STRONG MID-LATITUDE STORM LOOKS TO ARRIVE EARLY SUNDAY MORNING. SEAS
ARE EXPECTED TO RISE TO 7 TO 9 FEET, POSSIBLY REACHING HAZARDOUS
LEVELS OF 10 FEET AT TIMES FOR TINIAN AND SAIPAN. DESPITE THERE NOT
BEING A SMALL CRAFT ADVISORY, MARINERS SHOULD EXERCISE CAUTION AND
EXPECT SEAS TO BE CHOPPY AT TIMES WITH COMPETING NORTH AND EAST
SWELL. SURF ALONG NORTH FACING REEFS IS EXPECTED TO QUICKLY INCREASE
OVERNIGHT TO 7 TO 10 FEET. REFRACTED WAVES WILL CAUSE ELEVATED SURF
ALONG WEST FACING REEFS AS WELL, AROUND 6 TO 8 FEET. WAVE MODELS SHOW
THE SWELL COMING FROM THE N TO ENE, BUT WILL RELY ON BUOYS AND SURF
OBSERVATIONS TO INDICATE ANY INCREASING CONCERNS FOR WESTERN SHORES
(IF ACTUAL DIRECTION IS MORE NW). AFTER THIS, CONDITIONS SUBSIDE
BELOW HAZARDOUS LEVELS MONDAY NIGHT AND TUESDAY. THEN, A BUSY MARINE
PATTERN MAY START TO TAKE SHAPE AGAIN AS ANOTHER STRONG MID-LATITUDE
SYSTEM IS EXPECTED TO DEVELOP OFF THE COAST OF JAPAN THIS WEEKEND,
GENERATING ANOTHER PULSE OF NORTH SWELL TO ARRIVE BY TUESDAY. A SHEAR
LINE MAY ALSO CONTRIBUTE LARGE NORTHEAST SWELL, POSSIBLY REACHING
SMALL CRAFT ADVISORY CRITERIA THURSDAY. WINDS WILL GENERALLY BE
MODERATE, BECOMING MODERATE TO FRESH TUESDAY.
EASTERN MICRONESIA...
A DRY TRADE-WIND PATTERN IS WELL IN PLACE ACROSS EASTERN MICRONESIA,
WITH ONLY SPOTTY TO ISOLATED SHOWERS EXPECTED FOR AT LEAST THE NEXT
COUPLE OF DAYS. LATEST MODEL GUIDANCE SHOWS A DEVELOPING INTER-
TROPICAL CONVERGENCE ZONE (ITCZ) TO THE EAST OF THE DATE LINE. THIS
FEATURE LOOKS TO PUSH WEST INTO THE MARSHALLS MONDAY AFTERNOON, THEN
SPREAD FARTHER WEST INTO KOSRAE AND POHNPEI TUESDAY. THIS FEATURE,
COMBINED WITH ANOTHER TRADE-WIND SURGE, LOOKS TO BRING INCREASED
CONVECTION TO THE REGION FOR THE REMAINDER OF NEXT WEEK.
LATEST ALTIMETRY DATA SHOWS A LARGE AREA OF COMBINED SEAS BETWEEN 9
AND 12 FEET EXTENDING EAST FROM MAJURO TO AROUND 160W. THESE
COMBINED SEAS WILL BE VERY SLOW TO SUBSIDE AND MAY FALL AROUND 9 FEET
TUESDAY MORNING. THEN, ANOTHER TRADE-WIND SURGE, ALONG WITH A
BUILDING NORTH SWELL, COULD RESULT IN SEAS REACHING AS HIGH AS 12
FEET AGAIN AROUND THE MIDDLE OF NEXT WEEK. THE TRADE SWELL WILL
REMAIN HIGH ENOUGH THROUGH THE NIGHT TO MAINTAIN HAZARDOUS SURF
CONDITIONS ALONG NORTH AND EAST FACING REEFS OF MAJURO. EAST SWELL OF
6 TO 7 FEET LOOKS TO CONTINUE AT KOSRAE, MAINTAINING HAZARDOUS SURF
CONDITIONS ALONG EAST FACING REEFS. WINDS LOOK TO REMAIN MODERATE TO
FRESH THROUGH THE COMING WEEK.
WESTERN MICRONESIA...
SATELLITE OBSERVATIONS SHOW SCATTERED SHOWERS APPROACHING WENO AND
YAP PROPER WITH ISOLATED SHOWERS NEAR PALAU. ALTIMETRY DATA SHOWS
COMBINED SEAS OF 3 TO 5 FEET NEAR PALAU AND 4 TO 6 FEET ACROSS YAP
AND CHUUK.
SCATTERED SHOWERS NEAR THE REMNANTS OF INVEST 97W PERSIST NORTHWEST
OF YAP WHILE SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE SEEN
ALONG A TROUGH IN YAP STATE TO THE EAST OF YAP PROPER. THESE SHOWERS
WILL IMPACT YAP LATER THIS EVENING AND MAY IMPACT PALAU LATER
TONIGHT. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE MOVING INTO
CHUUK ALONG A WEAK TRADE-WIND TROUGH. THE NEAR EQUATORIAL TROUGH
(NET) WILL MOVE INTO YAP STATE AND PALAU THIS WEEK, BRINGING ACTIVE
WEATHER. SCATTERED SHOWERS WILL BE POSSIBLE MONDAY AND MONDAY NIGHT
WITH THE ACTIVE PATTERN CONTINUING THROUGH THE WEEK FOR PALAU.
COMBINED SEAS WILL BUILD 1 TO 2 FEET OVER THE NEXT FEW DAYS ACROSS
WESTERN MICRONESIA WITH COMBINED SEAS OF 6 TO 8 FEET POSSIBLE FOR
YAP AND CHUUK AND 5 TO 7 FEET FOR PALAU. LATEST GUIDANCE SHOW
COMBINED SEAS REMAINING BELOW 10 FEET THIS WEEK ACROSS THE REGION AS
WELL AS WINDS PREDOMINATELY BETWEEN 10 AND 20 KNOTS. THIS WOULD KEEP
MARINE CONDITIONS BELOW HAZARDOUS LEVELS TO SMALL CRAFT. THAT SAID,
CHOPPY SEAS WILL REMAIN LIKELY THE NEXT SEVERAL DAYS WITH TWO STRONG
SWELLS INTERACTING FROM THE NORTH AND EAST. A HIGH SURF ADVISORY WAS
CONSIDERED FOR YAP ALONG NORTH FACING REEFS FOR THE SUNDAY THROUGH
MONDAY NIGHT PERIOD. HOWEVER, WITH GUIDANCE SUGGESTING THAT THE TWO
SWELLS WILL BE EAST AND NORTH WITH THE EAST SWELL BEING 080 DEGREES,
THE SWELLS THEMSELVES WERE TOO LOW TO SUPPORT A HIGH SURF ADVISORY.
IF OBSERVATIONS SHOW BOTH A NORTH SWELL AND A NORTHEAST SWELL CLOSER
TO 040 DEGREES, THEN A HIGH SURF ADVISORY WOULD LIKELY BE NEEDED.
MARINERS ACROSS PALAU, YAP, AND CHUUK SHOULD CONTINUE TO MONITOR
FORECASTS FOR POTENTIAL TRENDS TOWARDS HIGHER SEAS.
GUM WATCHES/WARNINGS/ADVISORIES
GU...HIGH RIP CURRENT RISK THROUGH MONDAY AFTERNOON FOR GUZ001.
HIGH SURF ADVISORY UNTIL 4 PM CHST MONDAY FOR GUZ001.
MP...HIGH RIP CURRENT RISK THROUGH MONDAY AFTERNOON FOR MPZ001>003.
HIGH SURF ADVISORY UNTIL 4 PM CHST MONDAY FOR MPZ001>003.
SMALL CRAFT ADVISORY UNTIL 4 PM CHST MONDAY FOR MPZ003.
MARIANAS WATERS...SMALL CRAFT ADVISORY UNTIL 4 PM CHST MONDAY FOR PMZ151>154.
MARIANAS UPDATE: CRUZ
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page