Area Forecast Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
000
FXPQ60 PGUM 041950
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
550 AM CHST SAT SEP 5 2015

.SYNOPSIS...
LATEST ASCAT ANALYSIS SHOWS THE MONSOON TROUGH SHIFTING NORTHWARD
THROUGH SAIPAN WATERS. THE TROPICAL DISTURBANCE THAT PASSED
THROUGH YESTERDAY HAS WEAKENED...LEAVING RELATIVELY QUIET WEATHER
OVER THE FORECAST ZONES IN ITS WAKE. SATELLITE SHOWS DEEP
CONVECTION OVER THE NORTHERN CNMI BUT ONLY CONVECTIVE DEBRIS OVER
THE FORECAST ZONES. RADAR INDICATES ONLY ISOLATED SHOWER COVERAGE
OVER THE FORECAST ZONES.

&&

.DISCUSSION...
LATEST FORECAST ISSUANCE CLOSELY FOLLOWS CONTINUITY BUT DID
PERFORM SOME GRID EDITS. REFRESHED WIND GRIDS DAYS 1 THROUGH 5
USING THE ECMWF...WHICH INITIALIZED BEST WITH THE LATEST ASCAT
ANALYSIS. ECMWF THEN KEEPS THE MONSOON TROUGH NORTH OF SAIPAN.
EXTENDED MENTION OF MOSTLY CLOUDY SKIES AND THUNDER THROUGH NEXT
THURSDAY AS MONSOONAL PATTERN STAYS IN PLACE AT LEAST THAT LONG.
GFS TIME-HEIGHT CROSS SECTION MAINTAINS DEEP MOISTURE OVER THE
FORECAST DOMAIN THROUGH DAY 7. KEPT SHOWER COVERAGE ISOLATED
THROUGH THE FORECAST PERIOD. MODELS ALL SUGGEST BAND OF DEEP
MONSOONAL CONVECTION WILL REMAIN CONFINED SOUTH OF GUAM. IF MODEL
AND SATELLITE TRENDS BRING THE MONSOONAL BAND NORTHWARD...
SCATTERED SHOWERS MAY NEED TO BE INTRODUCED INTO THE FORECAST...
BEGINNING WITH GUAM.

&&

.MARINE...
HAVE REWORKED MARINE SWELL GRIDS...ESPECIALLY FOR DAYS 3 THROUGH
7 TO MORE ACCURATELY DEPICT LONG PERIOD SWELL FROM KILO AND
SHORTER PERIOD MONSOONAL SWELL. OTHERWISE...OVERALL NARRATIVE
REMAINS UNCHANGED. STILL EXPECT MODERATE RIP CURRENT RISK UNTIL
MONDAY. LONG PERIOD SWELL EMANATING FROM TY KILO COULD CAUSE SURF
ON EAST FACING REEFS TO BUILD TO ADVISORY LEVELS BY MID WEEK. IT
APPEARS LESS LIKELY...BUT POSSIBLE...THAT SEAS COULD BUILD TO
ADVISORY LEVELS AS WELL DURING THE MIDDLE OF NEXT WEEK.

&&

.EASTERN MICRONESIA...
SURFACE ANALYSIS SHOWS A WEAK CIRCULATION CENTERED NORTHEAST OF
MAJURO NEAR 9N175E WITH THE MONSOON TROUGH CURVING NORTH OF THE
MARSHALLS AND EASTERN MICRONESIA. SHOWERS AND THUNDERSTORMS ARE
EDGING WESTWARD...JUST NORTH OF MAJURO AND NEARING KWAJALEIN.
SHOWERS SHOULD REMAIN ISOLATED ON MAJURO...BUT THERE WILL BE
ENOUGH INSTABILITY IN THE AREA TO SUPPORT ISOLATED THUNDERSTORMS
THROUGH THE WEEKEND. KOSRAE WILL SEE INCREASING CLOUDS TODAY BUT
THE BULK OF THE SHOWERS WILL STAY JUST TO THE NORTH. SHOWERS WILL
INCREASE OVER THE WEEKEND ON POHNPEI AS THE MONSOON BUILDS OVER
THE AREA.

WAVE MODELS CONTINUE TO INDICATE INCREASING NORTH SWELL OVER THE
WEEKEND AND EARLY NEXT WEEK AS TY KILO DRIFTS BY WAKE ISLAND. THE
LARGEST IMPACT WILL BE IN THE FAR NORTHERN ATOLLS OF THE MARSHALL
ISLANDS THIS WEEKEND AND EARLY NEXT WEEK. THE NORTHERN ATOLLS WILL
REDUCE THE SIZE OF THE SWELL REACHING MAJURO. POHNPEI AND CHUUK
WILL SEE LONG PERIOD NORTH SWELL BUILDING EARLY NEXT WEEK. MODELS
SHOW SIMILAR TRENDS FOR KOSRAE...BUT OVERALL SWELL IS EXPECTED TO
BE SLIGHTLY SMALLER.

&&

.WESTERN MICRONESIA...
SHOWERS AND THUNDERSTORMS HAVE INCREASED ON YAP OVERNIGHT AND
WILL CONTINUE THERE UNTIL EARLY NEXT WEEK AS THE MONSOON REMAINS
IN THE AREA. CLOUDS AND SHOWERS HAVE DRIFTED FARTHER SOUTH TOWARD
KOROR. BUT FOR NOW...HAVE KEPT SHOWERS ISOLATED AS THE MAIN FOCUS
OF CONVECTION REMAINS FARTHER NORTH. A DRIER PATTERN HAS BECOME
BETTER ESTABLISHED OVER CHUUK BUT SHOWERS WILL BUILD INTO THE AREA
SUNDAY NIGHT AS A DISTURBANCE WITHIN THE MONSOON TROUGH SHIFTS TO
THE WEST-NORTHWEST.

COMBINED SEAS ARE STILL EXPECTED TO INCREASE NEAR CHUUK NEXT
WEEK. SEE EASTERN MICRONESIA DISCUSSION FOR MORE DETAILS ON
TIMING.

&&

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

$$

MCELROY/W. AYDLETT



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.