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000
FXPQ60 PGUM 010717
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
515 PM CHST WED JUL 1 2015

.SYNOPSIS...
TROPICAL STORM CHAN-HOM (09W) IS LOCATED ABOUT 800 MILES EAST-
SOUTHEAST OF GUAM AT ABOUT 11N157E. CHAN-HOM IS INTENSIFYING AND
SLOWLY MOVING TOWARDS THE MARIANAS. FARTHER SOUTH...AN ACTIVE
MONSOON TROUGH RUNS ACROSS MICRONESIA WITH THREE ADDITIONAL INVEST
AREAS...94W WHICH IS LOCATED SOUTHEAST OF GUAM NEAR 9N149E...96W
NORTHWEST OF KOROR NEAR 13N131E AND 97W SOUTHEAST OF MAJURO NEAR
6N175E. STRONG WESTERLY WINDS AND SEAS HAVE BEEN REPORTED BY MANY OF
THE ISLANDS WITHIN MICRONESIA FROM THE REPUBLIC OF PALAU TO EAST OF
THE MARSHALLS. OTHERWISE...FAIR WEATHER PREVAILS ACROSS THE MARIANAS
TODAY. TANAPAG/SAIPAN BUOY IS BACK IN SERVICE AND SHOWS COMBINED
SEAS NEAR 4 FEET FROM THE NORTHEAST.

&&

.DISCUSSION...
TROPICAL STORM CHAN-HOM IS A REAL THREAT TO MOVE ACROSS THE MARIANAS
REGION AS A STRONG TROPICAL STORM OR TYPHOON BY SATURDAY OR EARLY
SUNDAY AND WILL BE TRACKED CLOSELY IN THE COMING DAYS. WATCHES AND
WARNINGS MAY BE NEEDED FOR THE MARIANA ISLANDS BY TOMORROW/THURSDAY.
AS CHAN-HOM APPROACHES THE MARIANAS...EXPECT DAMAGING WINDS AND
PERIODS OF HEAVY RAIN BEGINNING AS EARLY AS FRIDAY EVENING AND
POSSIBLY LASTING THROUGH THE WEEKEND.

&&

.MARINE...
MARINE CONDITIONS WILL DETERIORATE QUICKLY BEGINNING AS EARLY AS
FRIDAY AFTERNOON. WATCHES...WARNINGS AND ADVISORIES FOR WINDS AND
SEAS WILL LIKELY BE NEEDED BY LATE THURSDAY OR FRIDAY. COMBINED SEAS
ARE FORECAST TO BUILD TO 8 TO 12 FEET ON FRIDAY AND 15 TO 20 FEET BY
SATURDAY AND THEN PERSIST THROUGH MONDAY. FOR NOW...MODERATE TRADE-
WIND CONDITIONS WILL CONTINUE TONIGHT AND THURSDAY.

&&

.TROPICAL...
TROPICAL STORM CHAN-HOM EAST OF THE MARIANAS IS FORECAST TO MOVE
OVER THE MARIANAS AS EARLY AS SATURDAY MORNING. THIS WILL BRING IN
HEAVY WIND AND RAIN INTO THE AREA BY FRIDAY EVENING.  AS CHAN-HOM
CONSOLIDATES FURTHER OVER THE NEXT DAY OR TWO THE TIMING OF EVENTS
WILL BE BETTER UNDERSTOOD. HOWEVER FOR NOW...POSITIONING AND
INTENSITY HAVE BEEN SOMEWHAT UNCERTAIN AS CHAN-HOM IS STILL
INTERACTING WITH THE MONSOON TROUGH TO ITS SOUTH AND WITH ANOTHER
CIRCULATION JUST NORTHWEST OF CHUUK...THIS HAS CREATED A DEGREE OF
UNCERTAINTY IN BOTH THE TIMING OF THE ARRIVAL OF THE STRONG WINDS
AND RAIN AND ALSO THE EXACT PATH. RECENT COMPUTER MODELS HAVE
VARIED SOLUTIONS FROM MOVING THE TC AS A TYPHOON JUST SOUTH OF GUAM
ON SATURDAY MORNING TO RECURVING AS A TROPICAL STORM EAST OF THE
MARIANAS...NEVER ACTUALLY REACHING THE ISLANDS. THE CURRENT FORECAST
FOLLOWS THE LATEST JTWC WARNING FROM WEDNESDAY NOON AND TRACKS CHAN-
NOM ACROSS THE GUAM SOUTHERN COASTAL WATERS...WHILE THE PREVIOUS
JTWC TRACKS WERE CLOSER TO ROTA AREA. IN ANY CASE...THUNDERSTORMS
AND GUSTY WINDS ARE LIKELY TO BEGIN AS EARLY AS FRIDAY AND LAST THE
WEEKEND FOR THE FOUR MAIN ISLANDS.

&&

.EASTERN MICRONESIA...
TROPICAL STORM CHAN-NOM IS OVER 300 MILES NORTHWEST OF POHNPEI AND
ABOUT 375 MILES NORTHEAST OF CHUUK AND MOVING TOWARD WEST-NORTHWEST.
CHAN-NOM SHOULD REMAIN WELL NORTH OF WENO CHUUK...BUT SOME OF THE
NORTHERN ISLANDS OF CHUUK STATE MAY BE SUBJECT TO HEAVY WEATHER
TONIGHT AND THURSDAY...MAINLY GUSTY SOUTHWEST WINDS AND HAZARDOUS
SEA CONDITIONS. ASCAT ANALYSIS SHOWS A VERY ACTIVE MONSOON TROUGH
RUNS SOUTHEASTWARD FROM CHAN-NOM TO A LOW-LEVEL CIRCULATION WHICH
IS SOUTHEAST OF MAJURO NEAR 6N175E...JTWC INVEST AREA 97W. SATELLITE
SHOWS EXTENSIVE CLOUDINESS AND EMBEDDED HEAVY SHOWERS SPREAD ACROSS
THE MARSHALL ISLANDS...WITH OTHER SHOWERS ACROSS KOSRAE STATE. MOST
OF THE HEAVIER SHOWERS HAVE MOVED AWAY FROM POHNPEI FOR THE TIME
BEING. THE CIRCULATION ASSOCIATED WITH INVEST 97W WILL NEED TO BE
WATCHED CLOSELY...AND MAJURO WAS HEADLINED FOR HEAVY RAINFALL
TONIGHT ALONG WITH HAZARDOUS SEA CONDITIONS AND COASTAL INUNDATION
FOR SOUTH AND WEST FACING SHORES.

HIGH SURF ADVISORIES REMAIN IN EFFECT FOR CHUUK...POHNPEI AND
KOSRAE. SURGING WESTERLY WINDS WILL CAUSE HAZARDOUS SURF AND SEA
CONDITIONS FOR MUCH OF MICRONESIA THIS WEEK INTO THE WEEKEND.

&&

.WESTERN MICRONESIA...
ASCAT ANALYSIS SHOWS THE ACTIVE MONSOON TROUGH RUNS EASTWARD FROM A
CIRCULATION NORTHWEST OF KOROR NEAR 13N131E TO ANOTHER CIRCULATION
NORTHWEST OF CHUUK AT 9N149E. LARGE AREAS OF SHOWERS AND A FEW
THUNDERSTORMS ARE ASSOCIATED WITH THESE CIRCULATIONS. SOUTHWEST TO
WEST MONSOON WINDS CONTINUE TO SURGE ACROSS MOST OF MICRONESIA WITH
SCATTERED SHOWERS AND A FEW THUNDERSTORMS AT TIMES DURING THE NEXT
SEVERAL DAYS AT LEAST. THIS MONSOON WEATHER PATTERN IS EXPECTED TO
PERSIST THROUGH WEEKEND AND INTO NEXT WEEK. THE MODELS STILL DIFFER
SIGNIFICANTLY ABOUT FUTURE DEVELOPMENTS WITHIN THE MONSOON TROUGH
AND THE DIFFERENT EMBEDDED CIRCULATIONS...AND THE SITUATION WILL
NEED TO BE  MONITORED CLOSELY IN THE COMING DAYS.

HIGH SURF ADVISORIES REMAIN IN EFFECT FOR YAP...KOROR AND CHUUK. SEA
CONDITIONS WILL BE HAZARDOUS FOR SMALL CRAFT AT TIMES ACROSS
WESTERN MICRONESIA THROUGH EARLY NEXT WEEK.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...NONE.
MARIANAS WATERS...NONE.
&&

$$

SIMPSON/EDSON



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