Area Forecast Discussion
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000
FXPQ60 PGUM 202123
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
723 AM CHST SUN DEC 21 2014

.MARIANAS SYNOPSIS...EAST TRADE-WINDS AND A FEW SHOWERS PREVAILED
ACROSS THE MARIANAS TODAY. A FEW THUNDERSTORMS MOVED SOUTH OF GUAM
DURING THE MORNING.

&&

.DISCUSSION...
LITTLE CHANGE MADE TO FORECAST. THE HIGH PRESSURE AREA THAT
HELPED PRODUCE STRONG WINDS SATURDAY IS MOVING FURTHER AWAY.
WINDS SHOULD BE LESS TODAY THAN YESTERDAY AND SHOULD DECREASE
FURTHER MONDAY. THIS WILL BE A SHORT LULL AS WINDS ARE EXPECTED
TO AGAIN INCREASE TUESDAY AS ANOTHER HIGH PRESSURE AREA WILL MOVE
OFF ASIA. MODELS DEPICT A FEW TRADE-WIND DISTURBANCES PASSING
ACROSS THE LOCAL AREA THROUGH AT LEAST MONDAY NIGHT. EXPECT
PERIODS OF MOSTLY CLOUDY SKIES SHOWERS DURING THAT TIME.

AN AREA OF SHOWERS AND THUNDERSTORMS MOVED ACROSS THE COASTAL
WATERS SOUTH OF GUAM DURING THE MORNING. LIGHTNING WAS OBSERVED
DURING THE MORNING HOURS BEFORE SUNRISE. THIS AREA IS SMALL AND
EXPECT IT TO REMAIN SOUTH OF GUAM. ALSO BELIEVE THEY WILL PERSIST
ONLY THROUGH THE MORNING HOURS AND THEY WILL EITHER DIE OUT OR
MOVE OUT WEST OF THE LOCAL AREA.

&&

.MARINE...
AN EAST TRADE-WIND SWELL AND A NORTH SWELL WILL PERSIST THROUGH
THE FORECAST. RITIDIAN BUOY DATA INDICATES THE NORTH SWELL HAS
DECREASED AND IS EXPECTED TO CONTINUE TO DECREASE THROUGH THE
DAY. SURF WILL REMAIN HAZARDOUS ON NORTH FACING REEFS THROUGH THE
MORNING BEFORE FALLING BELOW HAZARDOUS LEVELS THIS AFTERNOON.

WINDS ARE STILL HIGH ENOUGH TO BE HAZARDOUS TO SMALL CRAFT AND
WILL REMAIN THAT WAY THROUGH THE DAY. WINDS SHOULD DECREASE
TONIGHT. EVEN THROUGH WINDS WILL DECREASE COMBINED SEAS WILL NOT.
EXPECT SEAS TO BE AT OR ABOVE SMALL CRAFT LEVELS THROUGH
WEDNESDAY. MODEL PROJECTIONS SHOW THAT SEAS WILL REMAIN ABOVE
SMALL CRAFT CRITERIA AFTER WEDNESDAY. MORE THAN LIKELY THE SMALL
CRAFT ADVISORY WILL BE EXTENDED PAST WEDNESDAY MORNING.

&&

.EASTERN MICRONESIA...
A LARGE DOME OF HIGH PRESSURE SLIDING EASTWARD FROM NORTH OF
MINAMI TORI SHIMA WILL CONTINUE TO CHANNEL FRESH TRADE WINDS
ACROSS THE REGION FOR THE NEXT FEW DAYS. A PERSISTENT UPPER-LEVEL
TROUGH IS ALSO ANTICIPATED TO LINGER ACROSS THE AREA NEAR 9N MOST
OF THIS WEEK. INCREASING TRADE CONVERGENCE IS GOING TO COUPLE
WITH MODEST DIVERGENT FLOW ALOFT TO TRIGGER ISOLATED
THUNDERSTORMS NEAR CHUUK... POHNPEI AND A FEW SHOWERS FOR KOSRAE
THRU TONIGHT. BY TONIGHT...THE CORE OF THE TRADES WILL PROVIDE
FAIR WEATHER FOR CHUUK AND POHNPEI. FARTHER EAST...A TRADE
DISTURBANCE IS SLOWLY PROGRESSING WESTWARD UNDERNEATH THE SAME
HIGH TOWARD THE MARSHALL ISLANDS THIS MORNING. THIS DISTURBANCE
WILL ALSO TAKE ADVANTAGE FROM THE PRESENCE OF THE UPPER TROUGH
AND SPARK OFF PERIODIC CONVECTION NEAR MAJURO BY LATER TONIGHT.
AS IT PUSHES FARTHER WESTWARD...UNSTABLE CONDITIONS WILL PROLONG
NEAR KOSRAE THRU TUESDAY AND REACH POHNPEI...CHUUK TOWARD
MIDWEEK. AFTER MIDWEEK...ANOTHER TRADE SURGE SHOULD BRING BACK A
DRIER REGIME FOR CHUUK...POHNPEI AND MAJURO. CONDITIONS NEAR
KOSRAE CAN REMAIN RELATIVELY WET AS THE TRADE CONVERGENCE ZONE
WILL BE NEARBY.

LATEST ALTIMETRY DATA AND COMPUTER GUIDANCE STRONGLY SUGGEST THE
COMBINATION OF NORTHWEST SWELL...BUILDING TRADE-WIND SWELL AND
WIND WAVES HAS CAUSED SEA HEIGHTS TO REACH HAZARDOUS LEVELS FOR
SMALL CRAFT OPERATION ACROSS CHUUK...POHNPEI STATES AND THE
MARSHALL ISLANDS THIS MORNING. THIS PHENOMENON WILL ALSO OCCUR
NEAR KOSRAE BY MONDAY EVENING AND THEN CONTINUE FOR ALL THE
LOCATIONS THRU MIDWEEK. INTER-ISLAND/ATOLL TRAVEL BY BOAT SHOULD
BE HALTED FOR THE NEXT SEVERAL DAYS.

LARGE EAST-NORTHEAST TRADE-WIND SWELL WILL ALSO CAUSE HAZARDOUS
SURF ON KOSRAE BY LATE THIS AFTERNOON...ACROSS THE MARSHALLS BY
MONDAY AND POSSIBLY FOR POHNPEI AND CHUUK BY TUESDAY. COINCIDED
WITH THE SPRING HIGH TIDE CYCLE THIS WEEK...COASTAL INUNDATION
ARE EXPECTED ON MAJURO AND NEARBY ATOLLS. RESIDENTS ON ALL THE
MENTIONED LOCATIONS NEED TO STAY ALERT ON THE LATEST ADVISORIES
ISSUED BY THE NATIONAL WEATHER SERVICE AND INSTRUCTIONS FROM
THEIR LOCAL EMERGENCY MANAGEMENT OFFICES.

&&

.WESTERN MICRONESIA...
REASONING FOR THE CHUUK FORECAST IS INCLUDED UNDER THE EASTERN
MICRONESIA SECTION ABOVE DUE TO A SIMILAR TRADE-WIND PATTERN.

THE LARGE DOME OF HIGH PRESSURE HAS DRIFTED FARTHER NORTHEAST OF
THE MARIANA ISLANDS. THIS WILL ALLOW TRADE WINDS ACROSS THE
REPUBLIC OF PALAU AND YAP STATE TO BECOME MODERATE AND VEER TO
THE EAST TODAY. AS THE RESULT...A FEW SURFACE IMPULSES EMBEDDED
WITHIN THE TRADE FLOW WILL PASS THRU THE AREA AND GENERATE
SPORADIC CONVECTION NEAR YAP AND KOROR FOR THE NEXT COUPLE DAYS.
BY TUESDAY...ANOTHER HIGH PRESSURE SYSTEM COMING OFF THE EAST
CHINA SEA WILL REINFORCE ANOTHER SURGE OF NORTHEASTERLY WINDS AND
USHER IN PLEASANT BUT BREEZY CONDITIONS. TOWARD THE END OF THIS
WEEK...A BETTER ORGANIZED TRADE DISTURBANCE CURRENTLY UPSTREAM
OVER EASTERN MICRONESIA CAN BRING BACK SHOWERY WEATHER TO BOTH
PLACES.

RESIDUAL NORTH SWELL HAS SUBSIDED ENOUGH ACROSS THE REPUBLIC OF
PALAU AND YAP STATE TO ALLOW SURF TO DROP BELOW HAZARDOUS LEVELS
THIS MORNING. HOWEVER...BUILDING TRADE-WIND SWELL AND WIND WAVES
WILL CAUSE SEAS TO REMAIN HAZARDOUS FOR SMALL CRAFT UNTIL THIS
AFTERNOON. THERE IS A CHANCE THAT SEAS COULD RISE BACK UP AGAIN
LATER THIS WEEK AS TRADE-WIND SWELL BUILDS HIGHER.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...HIGH SURF ADVISORY UNTIL NOON CHST TODAY FOR GUZ001>004.

MARIANAS WATERS...SMALL CRAFT ADVISORY UNTIL 6 AM CHST WEDNESDAY FOR PMZ151>154.

&&

$$

ZIOBRO/CHAN





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