FXPQ60 PGUM 250626
AFDPQ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
426 PM CHST WED MAR 25 2015
.SYNOPSIS...
A FEW SMALL SHOWERS ARE SEEN IN RADAR IMAGERY NEAR GUAM WITH MORE
SHOWERS SEEN EAST OF THE MARIANAS IN LATEST VISIBLE SATELLITE. A
WEAK CIRCULATION IS FOUND SOUTHEAST OF YAP NEAR 5N140E WHILE A
LARGER...MORE CONVECTIVELY ACTIVE...CIRCULATION IS FOUND NEAR
KOSRAE AND 5N164E.
&&
.DISCUSSION...
TWO SYSTEMS WILL DOMINATE THE WEATHER FOR THE NEXT WEEK. THE FIRST
WILL BE A WEAK SHEAR LINE FEATURE WHICH WILL CAUSE WINDS TO
INCREASE THURSDAY AND FRIDAY. CLOUDS WILL BEGIN TO INCREASE
THURSDAY NIGHT. FOR NOW...THURSDAY AND FRIDAY WILL BE THE WINDIEST
DAYS WITH WINDS EXPECTED TO BE BETWEEN 20 AND 25 MPH. WINDS WILL
DECREASE JUST SLIGHTLY FOR SATURDAY AND SATURDAY NIGHT. 
DECIDED TO INTRODUCE SCATTERED SHOWERS TO THE FORECAST FOR MONDAY
THROUGH TUESDAY DUE TO THE EXPECTED PASSAGE OF THE CIRCULATION
NOW NEAR KOSRAE. SEE THE TROPICAL SYSTEMS SECTION FOR MORE INFO ON
THIS DISTURBANCE. DRIER CONDITIONS ARE EXPECTED BY MIDDLE OF NEXT
WEEK.
&&
.MARINE...
FRESH TO STRONG WINDS ARE EXPECTED FOR THE NEXT COUPLE DAYS WITH
DAYTIME WINDS RANGING FROM 20 TO 25 KT THURSDAY AND FRIDAY. SEAS
WILL ALSO INCREASE FROM 5 TO 7 FT TONIGHT TO BETWEEN 8 AND 10 FT
BY SATURDAY...LIKELY REQUIRING SMALL CRAFT ADVISORIES. SURF WILL
ALSO INCREASE THE NEXT FEW DAYS WITH RISK OF RIP CURRENTS BECOMING
HIGH FRIDAY OR SATURDAY.
&&
.TROPICAL SYSTEMS...
MUCH UNCERTAINTY STILL EXISTS CONCERNING THE TRACK AND DEVELOPMENT
OF THE CIRCULATION NEAR KOSRAE...JTWC INVEST 98W. GFS AND NAVGEM
BOTH DEVELOP THE CIRCULATION MORE AGGRESSIVELY AND SEND IT FARTHER
NORTH THAN DOES THE ECMWF. NAVGEM MOVES IT SLOWER... SHOWING IT
PASSING OVER GUAM AROUND WEDNESDAY...WHILE GFS PASSES IT BY TO THE
SOUTHOF GUAM LATE MONDAY. ECMWF INDICATES A MUCH LESS ORGANIZED
SYSTEM PASSING FARTHER SOUTH OF GUAM...ALONG 10N...LATE SUNDAY.
FOR NOW...FORECAST MORE CLOSELY FOLLOWS THE GFS WITH THE
CIRCULATION PASSING BY JUST TO THE SOUTH OF GUAM SUNDAY THROUGH
TUESDAY. WIND FORECAST IS SOMEWHAT LOW CONFIDENCE AND WILL NEED TO
BE ADJUSTED IN THE COMING DAYS AS MODELS SHOW BETTER AGREEMENT.
&&
.EASTERN MICRONESIA...
ELEPHANT IN THE ROOM IS A VERY BROAD...DEVELOPING CIRCULATION
CENTERED VERY CLOSE TO KOSRAE. JTWC IS CURRENTLY CARRYING THIS
SYSTEM AS LOW INVEST AREA 98W. LATEST SCATTEROMETRY CARRIES WINDS
IN THE 15 TO 25 KNOT RANGE ON THE NORTH SIDE OF THE CIRCULATION
BETWEEN 7N AND 15N. BOTH MAJURO AND POHNPEI LIE CLOSE TO 7N...
WHICH WILL MAKE THE WIND FORECASTS FOR THESE LOCALES DIFFICULT.
MODEL GUIDANCE CONSENSUS SUGGESTS 98W WILL TRACK SLOWLY
NORTHWESTWARD...THEN TOWARD THE WEST-NORTHWEST. BASED ON THIS
FORECAST WILL KEEP WIND SPEEDS CONSERVATIVE FOR ALL 3 FORECAST
LOCALES. GFS SEEMS TO INITIALIZE THE CIRCULATION THE BEST...SO
WILL FAVOR THIS MODEL...WHICH PROGS THE CENTER OF 98W PASSING
CLOSE TO POHNPEI ON THURSDAY NIGHT. CONSIDERED NUMEROUS COVERAGE
WITH LOCALLY HEAVY WORDING FOR BOTH POHNPEI AND KOSRAE SHORT TERM
FORECASTS...BUT BELIEVE STRONG WIND SHEAR OVER 98W WILL LIMIT
SHOWER COVERAGE TO SCATTERED AND REDUCE THAT CHANCES FOR HEAVY
RAINFALL. LONG TERM PATTERN FOR EASTERN MICRONESIA REMAINS
UNSETTLED AS MODELS CALL FOR ANOTHER TROPICAL DISTURBANCE TO
DEVELOP OVER THE MARSHALLS EARLY NEXT WEEK VIA ROSSBY WAVE TRAIN
DEVELOPMENT DOWNSTREAM FROM 98W.
FORECAST TRACK AND SLOW DEVELOPMENT OF 98W...AS WELL AS THE
CURRENT ORIENTATION OF THE WIND FIELD OF THIS SYSTEM...SUGGESTS
THE WORST OF THE SEAS AND SURF ASSOCIATED WITH 98W WILL REMAIN TO
THE NORTH OF ALL 3 FORECAST LOCALES. DO NOT ANTICIPATE ADVISORY
CONDITIONS AT THIS POINT...BUT IF 98W WERE TO DEVELOP MORE RAPIDLY
AND TAKE A TRACK FARTHER TO THE SOUTH...WINDS AND SEAS HAZARDOUS
TO SMALL CRAFT...AS WELL AS HIGH SURF...MAY BE POSSIBLE ON/NEAR
POHNPEI IN A DAY OR TWO.
&&
.WESTERN MICRONESIA...
LOOSELY ORGANIZED CONVECTION ASSOCIATED WITH A WEAK CIRCULATION
CENTERED SOUTHEAST OF YAP NEAR 5N140E. LOOSELY ORGANIZED
CONVECTION ASSOCIATED WITH THIS SYSTEM LIES MAINLY EAST OF KOROR
AND SOUTH OF YAP. CONVECTION NEAR CHUUK WAS TAPERING OFF IN
RESPONSE TO SUBSIDENCE ON THE WEST SIDE OF 98W.
FOR CHUUK...HAVE REDUCED SHORT TERM WINDS DUE TO THE LIGHT WIND 
FIELD SEEN ON THE SOUTH SIDE OF 98W IN THE LATEST SCATTEROMETRY. 
OTHERWISE...HAVE ASSUMED TRACK OF 98W WILL TAKE IT NORTH OF CHUUK ON 
SATURDAY. HAVE ASSUMED SOME MODEST DEVELOPMENT AS IT DOES SO. 
HEAVIEST WEATHER ASSOCIATED WITH 98W SHOULD PASS NORTH OF 
CHUUK...BUT SWELL FROM 98W COULD BRING HIGH SURF TO CHUUK AS EARLY 
AS SATURDAY NIGHT.
FOR KOROR AND YAP...TRADE-WIND CONVECTION NORTH OF THE NEAR-
EQUATORIAL TROUGH WILL HOLD ON THROUGH SUNDAY OVER YAP...THEN 
SUBSIDENT REGION ON THE SOUTHWEST SIDE OF 98W SHOULD ARRIVE 
OVERHEAD. WEATHER ASSOCIATED WITH 98W SHOULD PASS NORTH OF BOTH 
KOROR AND YAP...BUT IF 98W TRACKS FARTHER SOUTH THAN FORECAST...
POPS...CLOUD COVER AND WINDS WILL NEED TO BE INCREASED...
ESPECIALLY FOR YAP.
NORTHEAST SWELL BEHIND A COLD FRONT CURRENTLY MOVING SOUTHWARD OVER 
THE PHILIPPINE SEA WILL CLIP KOROR ON THURSDAY...BUT LATEST 
ALTIMETRY AND SCATTEROMETRY SUGGESTS LARGEST SWELL IN THE FETCH 
GENERATION REGION NORTH OF THE FRONT WILL BE DIRECTED TO THE NORTH OF 
KOROR AND YAP. SWELL FROM 98W COULD AFFECT YAP AS EARLY AS MONDAY 
NIGHT AND KOROR AS EARLY AS TUESDAY NIGHT...STAY TUNED.
&&
.GUM WATCHES/WARNINGS/ADVISORIES...
GU...NONE.
MARIANAS WATERS...NONE.
&&
$$
W. AYDLETT/MCELROY