878
FXPQ50 PGUM 132019
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
619 AM CHST SAT MAR 14 2026
MARIANAS UPDATE
A BROAD TROUGH EXTENDING FROM AN ELONGATED CIRCULATION TO OUR
SOUTHWEST IS BRING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS TO
THE REGION THIS MORNING. AS THIS FEATURE CONTINUES TO MOVE EASTWARD,
LIGHT TO MODERATE SOUTHWEST TO WEST WINDS ARE EXPECTED TO SHIFT,
BECOMING MODERATE TO FRESH NORTHWESTERLIES THIS AFTERNOON, THEN
GENTLE TO FRESH NORTHEASTERLIES AROUND TUESDAY. A SHORT PERIOD OF
HEAVY SHOWERS AND THUNDERSTORMS MOVED THROUGH SOUTHWESTERN GUAM
COASTAL WATERS THIS MORNING, BUT FELL APART BEFORE REACHING THE
ISLAND. SCATTERED SHOWERS ARE STILL SEEN ACROSS THE REGION THIS
MORNING, BUT ARE EXPECTED TO DECREASE TO ISOLATED IN THE AFTERNOON.
A SMALL CRAFT ADVISORY AND A HIGH SURF ADVISORY REMAINS IN EFFECT,
SEE FULL DISCUSSION BELOW.
EASTERN MICRONESIA UPDATE
SATELLITE IMAGERY SHOWS SPOTTY LIGHT SHOWERS NEAR POHNPEI AND KOSRAE
AND NO MAJOR CHANGES WERE MADE TO THE FORECAST, WITH ISOLATED TO
SCATTERED SHOWERS NEAR MAJURO ASSOCIATED WITH AN AREA OF TRADE-WIND
CONVERGENCE ACROSS THE SOUTHERN MARSHALLS. NO MAJOR CHANGES WERE MADE
TO THE FORECAST.
NORTHEASTERLY SWELL EMANATING FROM A LARGE FETCH REGION NORTHWEST OF
A KONA LOW (WELL NORTHEAST OF THE REGION) IS REACHING MICRONESIA
WITH A HIGHER THAN AVERAGE WAVE PERIOD. POHNPEI SHOWS THE WAVE PERIOD
AROUND 16 SECONDS, HOWEVER SOME SWELL ENERGY WAS MEASURED TO BE
HIGHER, NEAR 18 SECONDS. HAZARDOUS SURF IS EXPECTED ALONG NORTH-
FACING REEFS OF POHNPEI AND NORTH- AND EAST-FACING REEFS OF KOSRAE.
THIS SWELL WOULD ALSO BRING ELEVATED SURF ALONG EAST-FACING REEFS OF
POHNPEI AND NORTH- AND EAST-FACING REEFS OF MAJURO. A HIGH SURF
ADVISORY REMAINS IN EFFECT FOR POHNPEI AND KOSRAE THROUGH TUESDAY
AFTERNOON, HOWEVER, THIS WILL LIKELY NEED TO BE EXTENDED AS A STRONG
LOW PRESSURE SYSTEM NEAR JAPAN CONTINUES TO MOVE EASTWARD AND IS ALSO
EXPECTED TO PRODUCE ANOTHER SET OF NORTHERLY SWELL FOR THE REGION.
WESTERN MICRONESIA UPDATE
STRONG WINDS ALOFT ARE HELPING SHEAR CLOUD TOPS FROM HEAVIER SHOWERS
AND THUNDERSTORMS SOUTHEAST OF YAP PROPER, BUT SATELLITE-DERIVED
PWATS (PRECIPITABLE WATER) SHOW RELATIVELY DRY AIR MOVING INTO YAP
AND PALAU. THE ONLY MINOR UPDATE WAS TO INCREASE CLOUD COVERAGE AND
ADD LOW-END SCATTERED SHOWERS THIS MORNING AT YAP, WITH CONDITIONS
CLEARING OUT THIS AFTERNOON. THE REST OF THE FORECAST REMAINS
UNCHANGED.
DUE TO STRONG WINDS AROUND A LOW PRESSURE SYSTEM NEAR JAPAN,
SIGNIFICANT NORTHERLY SWELL CONTINUES TO BUILD ACROSS PALAU AND YAP
OVER THE NEXT FEW DAYS, LIKELY BUILDING SURF ALONG NORTH-FACING REEFS
TO 12 FEET SUNDAY. LONG-PERIOD NORTHEASTERLY SWELL CONTINUES TO
PRODUCE HAZARDOUS SURF ALONG NORTH-FACING REEFS AT CHUUK, THEN AS THE
LOW PRESSURE SYSTEM MOVES EASTWARD, NORTH-NORTHWESTERLY SWELL BUILDS
INTO CHUUK NEXT WEEK. A HIGH SURF ADVISORY REMAINS IN EFFECT FOR
PALAU, YAP, AND CHUUK. ADDITIONALLY, A SMALL CRAFT ADVISORY REMAINS
IN EFFECT FOR YAP THROUGH TUESDAY AFTERNOON. SEE DISCUSSION BELOW
FOR MORE INFORMATION ON HAZARDOUS SEAS POTENTIAL AT PALAU.
PREV DISCUSSION
/ISSUED 817 PM CHST FRI MAR 13 2026/
MARIANAS SYNOPSIS...
CLOUDY SKIES WITH SCATTERED SHOWERS AND GENTLE TO MODERATE WINDS
PREVAIL ACROSS THE REGION. ALTIMETRY SHOWS SEAS OF 8 TO 11 FEET OVER
THE WESTERN WATERS, WITH HIGHER SEAS NORTH OF 10N.
DISCUSSION...
CONVECTION IS WINDING DOWN OVER THE MARIANAS, WITH LOW-END (30
PERCENT PROBABILITIES) THROUGH TONIGHT, WITH A DRIER PATTERN MOVING
IN SATURDAY MORNING. THEN, A MORE NORMAL DRY PATTERN LOOKS TO
PERSIST THROUGH THE END OF NEXT WEEK.
MARINE/SURF...
THE MARINE FORECAST IS NOW THE PRIMARY CONCERN ACROSS THE MARIANAS. A
LARGE NORTHEAST SWELL IS MOVING THROUGH THE MARIANAS COASTAL WATERS.
THIS SWELL COMBINED WITH A SECONDARY NORTH SWELL, TERTIARY SOUTHWEST
SWELL AND WIND WAVES WILL MAINTAIN SEAS HAZARDOUS TO SMALL CRAFT
OPERATIONS THROUGH THE NEXT SEVERAL DAYS. ALTIMETRY SHOWS SEAS OF 8
TO 11 FEET OVER THE WESTERN WATERS, WITH HIGHER SEAS NORTH OF 10N.
THE HIGHER SEAS LOOK TO MOVE SOUTH INTO THE MARIANAS OVER THE
WEEKEND. FARTHER NORTH, A STRONG MID-LATITUDE LOW PRESSURE SYSTEM
SOUTH OF JAPAN WILL MOVE EAST, WITH STRONG WINDS BEHIND THE FRONT
PRODUCING A LARGE, LONG-PERIOD NORTHWEST TO NORTH SWELL. THIS SWELL
LOOKS TO MOVE INTO THE WATERS OVER THE WEEKEND INTO THE BEGINNING OF
NEXT WEEK, WITH SEAS OF 12 FEET EXPECTED MONDAY. THIS LONG-PERIOD
SWELL COULD BRING DANGEROUS SURF TO NORTH FACING REEFS SATURDAY NIGHT
OR SUNDAY AND SPREAD HAZARDOUS SURF CONDITIONS TO EAST FACING REEFS.
WITH A WEST COMPONENT TO THE SWELL ON MONDAY, HAZARDOUS SURF
CONDITIONS COULD DROP ALONG EAST FACING REEFS AND BECOME HAZARDOUS
ALONG WEST FACING REEFS SUNDAY NIGHT OR MONDAY. CURRENTLY, THE SMALL
CRAFT ADVISORY (SCA) IS SET TO EXPIRE EARLY MONDAY MORNING, BUT WILL
LIKELY NEED TO BE EXTENDED. THE DAY SHIFT ON SATURDAY WILL NEED TO
MONITOR THE SITUATION TO DETERMINE HOW LONG THE SCA NEEDS TO BE
EXTENDED. FOR THE HIGH SURF ADVISORY AND HIGH RIP CURRENT RISK, THE
DAY SHIFT WILL NEED TO EVALUATE THE SEAS TO DETERMINE F A HIGH SURF
WARNING IS NEEDED FOR NORTH FACING REEFS SATURDAY NIGHT INTO SUNDAY.
IF NOT, BOTH WILL NEED TO BE EXTENDED THROUGH MOST OF NEXT WEEK.
EASTERN MICRONESIA...
SURF'S UP, AS A NORTH TO NORTHEASTERLY SWELL HAS ARRIVED FROM A KONA
LOW. THIS SWELL ALSO HAS A WAVE PERIOD OF 13 TO 14 SECONDS, WHICH
EASILY PUTS POHNPEI AND KOSRAE AT HIGH SURF CRITERIA, WHILE ELEVATING
THINGS AT MAJURO. THESE CONCERNS ARE FOR NORTH FACING REEFS. THE
CURRENT MODEL GUIDANCE CARRIES THIS WELL INTO THE LATTER HALF OF NEXT
WEEK. HOWEVER, WE TRY NOT TO PUT OUT ADVISORIES FOR THAT LONG, AS
THINGS CAN CHANGE. FOR NOW, WE HOISTED THE HIGH SURF ADVISORY
THROUGH 3 AM TUESDAY. HOWEVER, AS WE APPROACH THIS TIME, IF CURRENT
MODEL TRENDS HOLD, WE'LL NEED TO EXTEND THIS.
OTHERWISE, A DIFFUSE OUTFLOW BOUNDARY COMBINED WITH A DISSIPATING
ITCZ (LARGELY DISSOLVED) PROVIDED JUST ENOUGH SURFACE CONVERGENCE TO
SPARK SCATTERED SHOWERS AT MAJURO. AS SUCH, HAVE THAT IN THE FORECAST
THROUGH TOMORROW. POHNPEI AND KOSRAE WILL JUST SEE ISOLATED SHOWERS.
THEN, AS WE HEAD INTO THE FIRST PART OF NEXT WEEK, RAINFALL
POTENTIAL LOOKS TO INCREASE AREA-WIDE.
AS FOR MARINE CONDITIONS, ASIDE FROM THE ELEVATED SEAS (WHICH WILL
STAY BELOW SMALL CRAFT CRITERIA IN TERMS OF ANY ADVISORY), LIGHT TO
GENTLE WINDS WILL PREVAIL ACROSS THE REGION.
WESTERN MICRONESIA...
THE MAIN WEATHER FEATURE AFFECTING WESTERN MICRONESIA IS A TROUGH
EXTENDING SOUTHWESTWARD FROM THE REMNANT CIRCULATION OF TROPICAL
DEPRESSION NURI WHICH THEN JOINS WITH THE NEAR-EQUATORIAL TROUGH WELL
SOUTH OF KOROR, PALAU.
CHUUK WILL EXPERIENCE ISOLATED SHOWERS TONIGHT, SCATTERED SHOWERS
SATURDAY THROUGH TUESDAY, AND ISOLATED SHOWERS ON WEDNESDAY. WINDS
WILL BE 5 TO 10 KNOTS THROUGH SUNDAY, 10 TO 15 KNOTS SUNDAY AND
MONDAY, THEN 5 TO 10 KNOTS AGAIN TUESDAY AND WEDNESDAY. SEAS WILL BE
6 TO 8 FEET TONIGHT, 7 TO 9 FEET SATURDAY THROUGH TUESDAY, THEN BACK
TO BETWEEN 6 AND 8 FEET ON WEDNESDAY. THIS WILL LEAD TO CHALLENGING
MARINE CONDITIONS SATURDAY THROUGH TUESDAY, AND PERHAPS TONIGHT AND
WEDNESDAY ALSO, AND ALSO WILL REQUIRE A HIGH SURF ADVISORY, WHICH WAS
PUT OUT THIS EVENING.
YAP WILL RECEIVE ISOLATED SHOWERS THROUGH THE ENTIRE FORECAST PERIOD,
WITH THE POSSIBLE EXCEPTION OF SUNDAY NIGHT, WHEN THEY MIGHT HAVE NO
SHOWERS AT ALL. WINDS WILL BE 10 TO 20 KNOTS TONIGHT AND SATURDAY,
THEN 10 TO 15 KNOTS THROUGH WEDNESDAY. SEAS WILL BE 9 TO 12 FEET
THROUGH MONDAY, THEN DIMINISH TO BETWEEN 7 AND 10 FEET TUESDAY AND
WEDNESDAY. THIS WILL LEAD TO HAZARDOUS MARINE CONDITIONS THROUGH AT
LEAST TUESDAY, THEN EITHER CHALLENGING OR HAZARDOUS ON WEDNESDAY. A
HIGH SURF ADVISORY REMAINS IN EFFECT, AND A SMALL CRAFT ADVISORY IS
NOW IN EFFECT.
KOROR, PALAU WILL SEE ISOLATED SHOWERS THROUGH THE ENTIRE FORECAST
PERIOD. WINDS WILL BE 10 TO 15 KNOTS THROUGH SUNDAY NIGHT, WITH
OCCASIONAL GUSTS TO 25 KT POSSIBLE TONIGHT, THEN 5 TO 10 KNOTS MONDAY
THROUGH WEDNESDAY. SEAS WILL BE 7 TO 9 FEET THROUGH SATURDAY, THEN 8
TO 11 FEET THROUGH MONDAY, THEN 6 TO 9 FEET TUESDAY AND WEDNESDAY.
THIS WILL LEAD TO CHALLENGING MARINE CONDITIONS TONIGHT AND SATURDAY,
AS WELL AS TUESDAY AND WEDNESDAY, WITH HAZARDOUS MARINE CONDITIONS
SATURDAY NIGHT THROUGH MONDAY. A SMALL CRAFT ADVISORY WILL LIKELY BE
ISSUED SATURDAY, AND A HIGH SURF ADVISORY REMAINS IN EFFECT THROUGH
TUESDAY.
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.
MARIANAS WATERS...SMALL CRAFT ADVISORY UNTIL 5 AM CHST MONDAY FOR PMZ151>154.
MARIANAS/EAST AND WEST MICRONESIA UPDATE: CRUZ
MARIANAS: KLEESCHULTE
WEST MICRONESIA: STANKO
EAST MICRONESIA: DOLL
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