882
FXPQ60 PGUM 261059
AFDPQ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
859 PM CHST THU NOV 26 2009
SYNOPSIS
WINDS ASSOCIATED WITH SUPER TYPHOON NIDA HAVE CONTINUED
TO DIMINISH ACROSS THE MARIANA ISLANDS TODAY. AS A RESULT WE HAVE
CANCELLED THE SMALL CRAFT ADVISORY FOR STRONG WINDS AND REPLACED
IT WITH A SMALL CRAFT ADVISORY FOR SEAS GREATER THAN 10 FEET. SAT
IMAGERY SHOWS NIDA CHURNING OVER 300 MILES WEST OF THE MARIANAS...
WITH SHOWERS IN RAIN BANDS HEADED TOWARD THE ISLANDS. RADAR SHOWS
SCATTERED SHOWER ACTIVITY ALL ACROSS THE REGION. THE IPAN BOUY HAS
SEAS ONLY ABOUT 7 FT...THE RESULT OF SWELLS BEING BLOCKED BY GUAM.
DISCUSSION
PRIMARY FORECAST CONSIDERATION IN THE SHORT TERM IS
HOW HIGH THE SEAS AND SURF GENERATED BY THE TYPHOON WILL BE AND HOW
LONG THEY WILL CONTINUE AT HAZARDOUS LEVELS. FOR THIS WE USED WW3
GUIDANCE WITHOUT SEPARATING OUT WIND WAVES FROM UNDERLYING SWELL.
REASONING IS VERY INTENSE WINDS NEAR THE EYE OF AN INTENSE TYPHOON
ARE OFTEN POORLY RESOLVED BY THE WAVE MODELS...LEADING TO AN UNDER
FORECAST OF SEAS AND SURF NEARBY. EXPECT SWELLS TO REMAIN LARGE A
FEW MORE DAYS ESPECIALLY IF THE TYPHOON SLOWS CONSIDERABLY AS FCST
BY THE JMA. NEXT AREA OF CONCERN WILL BE A DEVELOPING DISTURBANCE
LOCATED AT LOW LATITUDE SOUTH OF KOSRAE NEAR 2N160E. ECMWF GFS AND
NOGAPS ALL MAINTAIN THIS AS A PROMINENT CIRCULATION THE NEXT COUPLE
OF DAYS AND SLOWLY INTENSIFY IT...WITH THE LOW PASSING CLOSE TO THE
MARIANAS THE MIDDLE OF NEXT WEEK AROUND WEDNESDAY WITH 25-30 KNOT
WINDS. SO INCREASED CLOUDS AND POPS A BIT TUE NIGHT THROUGH THU.
EASTERN MICRONESIA
A LOW-LEVEL CIRCULATION EMBEDDED ALONG THE MONSOON TROUGH IS
EXPECTED TO BRING SHOWERY CONDITIONS AND ISOLATED THUNDERSTORMS FOR
BOTH POHNPEI AND KOSRAE THRU FRIDAY NIGHT. MEANWHILE...A TRADE-WIND
DISTURBANCE IS AROUND MAJURO THROUGH TONIGHT. TRADE-WIND CONVERGENCE
TRAILING TO THE EAST OF 180 MAY AFFECT MAJURO BY SUNDAY .
TRADE-WIND SWELL WILL BEGIN TO CAUSE HIGHER SEAS AND SURF ALONG
NORTH AND EAST SHORES ON POHNPEI AND MAJURO BY FRIDAY MORNING...BUT
NO HIGH SURF ADVISORY IS EXPECTED AT THIS TIME.
WESTERN MICRONESIA
SUBSIDENCE TO THE SOUTHEAST OF SUPER TYPHOON NIDA IS BRINGING VERY
NICE WEATHER TO CHUUK TODAY INTO FRIDAY. AFTERWARD...THE MODELS
DISAGREE AND A WEAK CIRCULATION NOW AROUND POHNPEI APPEARS TO BE
FADING.
A MONSOON TAIL HAS DEVELOPED SOUTHWEST OF NIDA AND IS GIVING KOROR
SCATTERED SHOWERS TONIGHT AND THE MODELS INDICATE INCLEMENT WEATHER
FOR YAP AND PALAU THROUGH FRIDAY. SWELLS FROM BOTH NIDA AND THE
MONSOON WINDS ARE KEEPING HAZARDOUS SEAS AND SURF ACROSS PALAU AND
YAP INTO AT LEAST SATURDAY. THINGS SHOULD BEGIN TO IMPROVE BY EARLY
NEXT WEEK AS NIDA MOVES FARTHER NORTH OF THE AREA.
GUM WATCHES/WARNINGS/ADVISORIES
GU...HIGH SURF ADVISORY UNTIL 11 AM CHST SUNDAY FOR GUZ001>004.
MARIANAS WATERS...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 8
PM CHST SATURDAY FOR PMZ151>154.
MUNDELL/DEVITA
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