328
FXPQ50 PGUM 052006
AFDGUM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
606 AM CHST MON APR 6 2026
MARIANAS UPDATE
PARTLY CLOUDY SKIES AND ISOLATED SHOWERS WILL DOMINATE THE MARIANAS
WATERS THE NEXT FEW DAYS. NO CHANGES WERE NEEDED AS EVERYTHING WAS
IN FINE SHAPE. RATHER DRY THE NEXT FEW DAYS, COULD BE BREEZY, THAT'S
MORE OF JUST A NUISANCE THOUGH SINCE FIRE WEATHER ISN'T PRIMED YET.
SO ALL EYES ARE TURNING TOWARD A DEVELOPING CIRCULATION IN EASTERN
MICRONESIA. IN THE EXTENDED FORECAST, ALL WILL DEPEND ON JUST HOW
CLOSELY IT APPROACHES THE MARIANAS, AND HOW INTENSE IT GETS.
MARINE
A TRADE-WIND SURGE HAS RAISED WINDS AND SEAS TODAY, AND THESE EFFECTS
COULD LAST UNTIL TOMORROW. A SMALL CRAFT ADVISORY REMAINS IN EFFECT
TO COVER THESE. CONDITIONS COULD SUBSIDE A BIT WEDNESDAY, THEN
DEPENDING ON WHAT THE DISTURBANCE DOES, THEY COULD RISE AGAIN FOR THE
WEEKEND.
EASTERN MICRONESIA UPDATE
RATHER SHOWERY IN EAST MICRONESIA. THIS WAS COVERED IN THE INHERITED
FORECAST FOR TODAY, SO JUST A FEW CHANGES. ADDED OCCASIONAL GUSTS TO
30 KNOTS AT MAJURO, BECAUSE THEY'VE BEEN HAPPENING, AND ARE NOW
HAPPENING AT KWAJALEIN ALSO. CHANGED STRAIGHT NUMEROUS SHOWERS AT
KOSRAE TO NUMEROUS SHOWERS DEVELOPING BY NOON, OR A DELAY OF A FEW
HOURS. ALSO EDITED THE HEADLINES FOR POHNPEI AND KOSRAE, SO INSTEAD
OF "ELEVATED SEAS AND SURF POSSIBLE" THEY NOW HAVE THE WORD "LIKELY",
SO IT'S BEEN RAMPED UP A NOTCH. A HIGH SURF ADVISORY WILL PROBABLY
GO OUT EITHER TODAY OR TONIGHT.
WESTERN MICRONESIA UPDATE
ADDED GUSTS TO 30 KNOTS FOR THE CHUUK FORECAST FOR TODAY, TONIGHT AND
TUESDAY. THIS SHOULD CARRY THEM THROUGH UNTIL THE CIRCULATION FROM
EASTERN MICRONESIA IS CLEARLY MOVING AWAY. CHUUK ALREADY HAD A SMALL
CRAFT ADVISORY IN EFFECT UNTIL WEDNESDAY, SO THIS WAS A FAIRLY MINOR
CHANGE.
PREV DISCUSSION
/ISSUED 623 PM CHST SUN APR 5 2026/
MARIANAS SYNOPSIS...
A DRY TRADE-WIND PATTERN CONTINUES ACROSS THE MARIANAS AS A TRADE-
WIND SURGE EXTENDS ALONG AND NORTH OF 10N FROM THE MARIANAS TO THE
DATE LINE. SATELLITE AND RADAR IMAGERY SHOWING SPOTTY SHOWERS MOVING
THROUGH THE FLOW THIS EVENING, LIMITED BY THE TRADE-WIND INVERSION
SEEN IN GUAM'S UPPER-AIR SOUNDING. OBSERVATIONS AT THE AIRPORTS ARE
REPORTING MODERATE TO FRESH WINDS AND SOME STRONG GUSTS ACROSS THE
ISLANDS. BUOY DATA AROUND GUAM AND SAIPAN ARE REPORTING SEAS AROUND
BETWEEN 6 AND 9 FEET, WHILE ALTIMETRY SHOWING SEAS ARE PUSHING UP TO
10 FEET JUST EAST OF THE MARIANAS.
DISCUSSION...
THIS FAIRLY SEASONAL TRADE-WIND PATTERN IS EXPECTED THROUGH AT LEAST
THE MIDDLE OF THE WEEK AS THE TRADE-WIND INVERSION, AS SEEN IN
GUAM'S UPPER AIR SOUNDING AROUND 860 MB, WILL HELP LIMIT SHOWER
DEVELOPMENT EVEN IF TRADE-WIND TROUGHS PASS THROUGH THE FLOW AND
INTO THE MARIANAS. A TRADE-WIND SURGE EXTEND OVER THE MARIANAS,
CREATED BY THE PRESSURE GRADIENT BETWEEN AN AREA OF HIGH PRESSURE
SHIFTING EASTWARD ACROSS THE NORTHERN PACIFIC AND THE NEAR-EQUATORIAL
TROUGH (NET) WELL SOUTH OF THE MARIANAS. THIS PRODUCED BREEZY
CONDITIONS AROUND 25 MPH TODAY, AND WHILE WINDS SHOULD SUBSIDE
SLIGHTLY OVERNIGHT AS AN INVERSION SETS UP OVER THE ISLANDS, WINDS
WILL REBUILD AFTER SUNRISE MONDAY. WINDS ARE EXPECTED TO SUBSIDE
SLIGHTLY TUESDAY AND WEDNESDAY AS THE TRADE-WIND SURGE WEAKENS AND
THE AREA OF STRONGER WINDS SHIFTS EASTWARD. LONG-RANGE GUIDANCE
CONTINUES TO SUPPORT A BROAD TROPICAL DISTURBANCE DEVELOPING IN
EASTERN MICRONESIA THAT WILL SLOWLY SHIFT WESTWARD INTO CENTRAL
MICRONESIA BEFORE POTENTIALLY LIFTING NORTHWARD AND CLOSER TO THE
MARIANAS LATE THIS WEEK OR EARLY NEXT WEEK. THIS TREND HAS BEEN IN
THE MODELS FOR A FEW DAYS SUGGESTING THE OVERALL ENVIRONMENT IS
SUPPORTIVE OF A CIRCULATION DEVELOPING WITHIN THE NET, BUT SO FAR NO
DISTINCT CIRCULATION IS VISIBLE ON SATELLITE IMAGERY. EASTERN
MICRONESIA WILL BE MONITORED CLOSELY TO SEE IF A CIRCULATION BEGINS
TO BECOME ESTABLISHED OVER THE NEXT FEW DAYS AS THE GFS AND ECMWF
SUGGEST. IF ONE DOES, THEN THE POTENTIAL FOR SHOWERS, THUNDERSTORMS,
AND SOME GUSTY WINDS AROUND THE MARIANAS WILL INCREASE LATE THIS
WEEK, BUT FOR NOW UNCERTAINTY REMAINS ELEVATED FOR THE FORECAST
BEYOND WEDNESDAY.
MARINE...
MODERATE TO STRONG NORTHEAST TO EAST WINDS AND COMBINED SEAS OF 7
TO 10 FEET WILL CONTINUE THROUGH TUESDAY, DUE THE CURRENT AFFECTS
OF THE TRADE-WIND SURGE AND THEN THE ARRIVAL OF NORTHERLY SWELL
MONDAY. THIS WILL ALSO CONTINUE THE HIGH RISK OF RIP CURRENTS ALONG
EAST FACING REEFS THROUGH AT LEAST TUESDAY, WITH ELEVATED SURF ALONG
NORTH FACING REEFS. WINDS AND SEAS ARE THEN EXPECTED TO DECREASE
SLIGHTLY AROUND MIDWEEK AS THE TRADE-WIND SURGE AND NORTHERLY SWELL
SUBSIDE SLIGHTLY, ALLOWING THE SMALL CRAFT ADVISORY TO EXPIRE. THE
HIGH RISK OF RIP CURRENTS MAY CONTINUE BEYOND TUESDAY, AS THE
ELEVATED EASTERLY SWELL MAY NOT SUBSIDE AS QUICKLY, IF THE TRADE-
WIND SURGE CONTINUES AROUND THE MARSHALL ISLANDS. LONG-RANGE MODELS
CONTINUE TO SUGGEST THAT A CIRCULATION WILL DEVELOP IN EASTERN
MICRONESIA AND START TO MOVE TOWARDS THE MARIANAS LATER IN THE WEEK.
THERE IS CURRENTLY NO DISCERNIBLE CIRCULATION WITHIN THE NET, SO
UNCERTAINTY BEYOND WEDNESDAY IS ELEVATED, BUT THE OVERALL PATTERN IS
SUPPORTIVE OF A CIRCULATION. IF A CIRCULATION DOES DEVELOP AND START
TO MOVE TOWARDS THE MARIANAS LATE THIS WEEK, THIS WOULD CAUSE WINDS
AND SEAS TO REBUILD FRIDAY AND BRING CONDITIONS BACK TO HAZARDOUS
LEVELS TO SMALL CRAFT THIS WEEKEND, WHILE HELPING TO PROLONG THE HIGH
RISK OF RIP CURRENTS ALONG EAST FACING REEFS.
EASTERN MICRONESIA...
THE GEFS CONTINUES TO TREND STRONGLY TOWARDS THE ECENS (EUROPEAN
ENSEMBLE) IN TERMS OF A POTENTIAL CIRCULATION DEVELOPING. THE GEFS
INDICATES A CIRCULATION SHOULD BE WEAKLY-DEVELOPED AND PRESENT RIGHT
NOW NEAR 2N168E (SOUTHEAST OF KOSRAE), AND THERE'S NOTHING THERE
ASIDE FROM A NEAR-EQUATORIAL TROUGH (NET) AXIS. THE GEFS THEN HAS A
WELL-DEVELOPED SIGNATURE OF A CIRCULATION SOUTHEAST OF KOSRAE AROUND
MIDNIGHT TONIGHT. THE ECENS CONTINUES TO SHOW A SLOWER DEVELOPED,
WITH A MORE SOUTH AND WEST TRACK COMPARED TO THE GEFS. WITH THAT
SAID, THE GEFS CONTINUES TO TREND TOWARDS THE ECENS, GIVING MORE
CREDENCE TO FOLLOWING THE ECENS WHEN CREATING THE FORECAST, WITH
SUPPORT FROM THE VISIBLE IMAGERY.
GIVEN THESE THOUGHTS, WE TRENDED SHOWER COVERAGE DOWN TO SCATTERED
FOR TONIGHT AT MAJURO, AS SATELLITE IMAGERY WITH STREAMLINE ANALYSIS
OVERLAID ATOP OF IT SUGGESTS THE BEST CONVERGENCE HAS MOVED OFF TO
YOUR WEST, WHILE ALSO REMOVING LOCALLY HEAVY WORDING AND GUSTY WINDS.
FOR POHNPEI AND KOSRAE, WE GENERALLY MAINTAINED THE GOING FORECAST OF
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS TONIGHT, AND RETAINED
LOCALLY HEAVY RAINFALL WORDING STARTING MONDAY. OVERALL, MAJURO WILL
SEE SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS, WHILE POHNPEI AND
KOSRAE COULD SEE PERIODS OF NUMEROUS TO WIDESPREAD SHOWERS, WITH
LOCALLY HEAVY RAINFALL AND ISOLATED THUNDERSTORMS MIXED IN, FOR A
VAST MAJORITY OF THE FORECAST THROUGH AT LEAST THE MIDDLE OF THE
WEEK. OF COURSE, THIS IS ALL HIGHLY CONDITIONAL ON A LOW-LEVEL
CIRCULATION AND A FAIRLY GOOD AMOUNT OF INTENSE CONVECTION DEVELOPING
IN THE NEXT 2 TO 4 DAYS (48 TO 96 HOURS). STAY TUNED!
AS FOR WINDS AND SEAS, MAINLY MODERATE TO FRESH WINDS WILL GRADUALLY
SUBSIDE INTO THE GENTLE TO MODERATE RANGE AT POHNPEI AND MAJURO
DURING THE NEXT 24 HOURS, THEN CONTINUING THROUGH MID WEEK. SEAS ALSO
CAME IN LOWER NEAR POHNPEI ON THE LATEST SATELLITE ESTIMATES
COMPARED TO THE GFS WAVE WATCH FORECASTS WHICH WERE A FOOT OR TWO
ABOVE WHAT ALTIMETRY SHOWED. POSITIONING AND ORIENTATION OF A TRADE-
WIND SURGE TO THE NORTH WOULD ALSO FAVOR LOCATIONS FROM CHUUK
WESTWARD FOR THE POTENTIAL HAZARDOUS SWELL. AS SUCH, TONED-DOWN THE
WORDING IN THE HEADLINES FOR POHNPEI AND KOSRAE WHILE EXTENDING THEM
THROUGH MID WEEK AS ANY DEVELOPING CIRCULATION COULD AT LEAST CAUSE
IN INCREASE IN WIND-FRIVEN WAVES WHICH COULD AUGMENT SEA AND SURF
HEIGHTS SUFFICIENTLY FOR HAZARDOUS CONDITIONS TO DEVELOP NEAR
"BORDERLINE THRESHOLDS". USING THIS APPROACH AND RE-EVALUATIONG
THINGS IN 24 HOURS SEEMED LIKE A PRUDENT MOVE AT THIS POINT.
WESTERN MICRONESIA...
THE MAIN TWO FEATURES IN THE REGION CONTINUE TO BE THE NEAR
EQUATORIAL TROUGH (NET) AND THE TRADE-WIND SURGE. THE NET ENTERS THE
REGION NEAR 2N130E AND EXTENDS EASTWARD ACROSS THE SOUTHERN PORTION
WESTERN MICRONESIA WHERE IT CONTINUES INTO EASTERN MICRONESIA. SOUTH
THE NET AXIS, ISOLATED TO SCATTERED SHOWERS ARE SEEN ON SATELLITE
IMAGERY.
FOR PALAU AND YAP, A DRY TRADE-WIND PATTERN REMAINS OVER THE REGION.
ISOLATED SHOWERS ARE ANTICIPATED TO REMAIN THROUGH THE WEEK. WINDS
ARE EXPECTED TO BE AROUND 10 TO 15 KNOTS AROUND PALAU, THEN THESE
WINDS ARE ANTICIPATED TO BEGIN TO FALL AROUND MONDAY NIGHT. WINDS
AROUND YAP ARE EXPECTED TO BUILD UP TO 20 KTS THROUGH MONDAY. THEN,
THESE WINDS ARE ANTICIPATED TO FALL TO 5 TO 15 KTS BY AROUND
THURSDAY, AND CONTINUE TO FALL FRIDAY.
FOR CHUUK, SHOWERS ARE EXPECTED TO REMAIN IN THE FORECAST THIS WEEK.
THIS IS MAINLY DUE TO A FEW FACTORS: FIRST, THE INTERACTION OF THE
TRADE-WIND SURGE AND A TROUGH ARE PRODUCING A LINE OF SHOWERS AND
ELEVATED WINDS, AND FOR THE LATTER HALF OF THE WEEK, A POTENTIAL
CIRCULATION MAY MOVE NEARBY. THE TROUGH AXIS STARTS NEAR 9N148E AND
EXTEND SOUTHEASTWARD OVER CHUUK LAGOON AND EXITS THE REGION NEAR
6N155E BETWEEN CHUUK AND POHNPEI STATES. OVER THE FEW DAYS, THE
EASTER PORTION OF THE TROUGH IS EXPECTED TO BEND SOUTHWARD AS THE
WHOLE TROUGH MOVES WESTWARD. SHOWERS ALONG THIS TROUGH ARE EXPECTED
TO BE THE HEAVIEST SOUTH OF THE TROUGH AXIS. DEPENDING ON HOW THIS
TROUGH MOVES AND BENDS OVER THE NEXT FEW DAYS, SHOWERS AT THE LAGOON
MAY VARY. AROUND THE MIDDLE TO END OF NEXT WEEK, MODEL GUIDANCE
SUGGEST A CIRCULATION IS ANTICIPATED TO BUILD IN EASTERN MICRONESIA
AND NEAR THE REGION, THIS WOULD ALLOW FOR SHOWERS TO REMAIN IN THE
REGION THROUGH THE REST OF THE WEEK.
COMBINED SEAS VARY OVER THE REGION WITH THE LOWEST IN THE WEST AND
THE HIGHEST IN THE EAST. SEAS OVER THE REGION ARE BETWEEN 2 TO 4 FEET
TO THE WEST OF PALAU, SEAS NEAR YAP ARE 4 TO 6 FEET AND BUILD TO 8
TO 11 FEET NEAR CHUUK. AT CHUUK, A SMALL CRAFT ADVISORY (SCA) AND A
HIGH SURF ADVISORY (HSA) ALONG NORTH FACING REEFS ARE IN EFFECT.
SEAS FOR CHUUK ARE EXPECTED TO CREST AROUND TUESDAY AND MAY FALL
BELOW CRITERIA LEVELS OF 10 FEET FOR SCA AND 9 FEET FOR HSA AS EARLY
AS WEDNESDAY MORNING. SEAS ARE EXPECTED TO CONTINUE TO SUBSIDE FOR
THE REMAINDER OF THE WEEK.
GUM WATCHES/WARNINGS/ADVISORIES
GU...HIGH RIP CURRENT RISK THROUGH TUESDAY AFTERNOON FOR GUZ001.
MP...HIGH RIP CURRENT RISK THROUGH TUESDAY AFTERNOON FOR MPZ001>003.
MARIANAS WATERS...SMALL CRAFT ADVISORY UNTIL 5 PM CHST TUESDAY FOR
PMZ151>154.
MARIANAS/EAST AND WEST MICRONESIA UPDATE: STANKO
MARIANAS: SCHANK
EAST MICRONESIA: DOLL
WEST MICRONESIA: BOWSHER
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