Strong Wind in Guam, July 17, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
704 AM CHST SUN JUL 17 2011

.SYNOPSIS...TYPHOON MA-ON IS LOCATED MORE THAN 800 MILES TO THE
NORTHWEST OF GUAM THIS MORNING. AS THE TYPHOON CONTINUES TO PULL
AWAY FROM THE ISLANDS HIGH PRESSURE HAS BUILT OVER THE AREA IN ITS
WAKE. RADAR SHOWS A FEW ISOLATED SHOWERS OVER THE REGION THIS
MORNING. A WEAK TROUGH OF LOW PRESSURE IS LOCATED SOUTHEAST OF THE
GUAM AS IS MOVING WESTWARD.

&&

.DISCUSSION...
TWEAKED WINDS A BIT IN THE FORECAST. PERIPHERAL RIDGE OF TYPHOON
MA-ON WILL BUILD OVER THE MARIANAS TODAY SO WINDS EXPECTED TO
DECREASE AND BECOME THEIR LOWEST ON MONDAY.

MODELS INDICATE A WEAK TROUGH OF LOW PRESSURE PASSING THROUGH THE
MARIANAS MONDAY NIGHT. SATELLITE DOES SHOW A FEW CBS SOUTHEAST OF
THE AREA ASSOCIATED WITH THIS TROUGH. FOR THAT REASON ADDED A
SLIGHT CHANCE OF THUNDERSTORMS TO THE FORECAST. REMAINDER OF THE
FORECAST WAS LEFT AS IS AS MODELS KEEP ONLY ISOLATED SHOWERS OVER
THE AREA THROUGH THE END OF THE FORECAST.

&&

.MARINE...
COMBINED SEAS HAVE DECREASED ENOUGH TO END THE SMALL CRAFT ADVISORY.
IPAN BUOY SHOWS SOME WAVE HEIGHTS UP TO 5 FEET. BUMPED UP SWELL TO 3
FEET FROM THE EAST WHICH RESULT IN SURF OF 3 TO 5 FEET ON EAST
FACING REEFS. HIGH SURF ON WEST FACING REEFS EXPECTED TO CONTINUE
THROUGH MONDAY MORNING.

&&

.EASTERN MICRONESIA...
A TRADE-WIND DISTURBANCE PASSING OVER THE MARSHALL ISLANDS WILL
BRING SCATTERED SHOWERS AND POSSIBLE TSTMS TO POHNPEI AND KOSRAE
THROUGH TONIGHT WHILE SHOWERS CURRENTLY OVER MAJURO ARE EXPECTED
TO TAPER OFF BY THIS AFTERNOON. A SHORT BREAK FROM WIDESPREAD
SHOWER ACTIVITY MONDAY FOR KOSRAE BUT MODEL SOLUTIONS SHOW WET
CONDITIONS RETURNING TUESDAY AS THE NEXT DISTURBANCE APPROACHES
THE AREA. MODELS SHOW MUCH OF THE CONVECTION WILL REMAIN SOUTH OF
POHNPEI SO FOR NOW LEFT ISOLATED WORDING IN THE LONG-TERM
FORECAST. MODEL SOLUTIONS SHOW ANOTHER TROPICAL SYSTEM DEVELOPING
BY MIDWEEK AND PROGGED TO AFFECT YAP AND KOROR. NO MAJOR FEATURE
EXISTS CURRENTLY SO THIS SCENARIO MAY TAKE LONGER TO COME TO
FRUITION.

SATELLITE-DERIVED SEA HEIGHTS INDICATE TRADE WIND WAVES AND SWELL
HAVE NOT INCREASED SIGNIFICANTLY IN THE LAST 24 HOURS NEAR KOSRAE
AND ARE MAINTAINING SEAS OF 4 TO 6 FT.

&&

.WESTERN MICRONESIA...
MODELS INITIALIZED ONGOING SHOWER ACTIVITY WELL ALONG A
CONVERGENT BOUNDARY SOUTH OF THE RIDGE AXIS. WARMING CLOUD TOPS
OBSERVED IN INFRARED SATELLITE IMAGERY INDICATE SHOWERS ARE
BECOMING STRATIFIED SO EXPECT DECREASING SHOWERS THROUGHOUT THE
DAY. THE RIDGE AXIS SOUTH MA-ON WILL SHIFT WESTWARD OVER YAP AND
KOROR OVER THE COMING DAYS ALLOWING WINDS TO BECOME LIGHT AND
VARIABLE. STILL EXPECT A MOSTLY DRY SCENARIO WITH THE RIDGE BEING
OVER THE REGION. FOR CHUUK...A WEAK BUT DISCERNIBLE TROUGH HAS
GENERATED SCATTERED SHOWERS AND A FEW TSTMS ACROSS MAINLY
NORTHEAST OF CHUUK. MODEL SOLUTIONS INDICATE A FAIRLY ACTIVE
WEATHER PATTERN EMERGING LATE MONDAY AS THE DISTURBANCE CURRENTLY
PASSING THE MARSHALL ISLANDS NEARS BUT SHOULD CLEAR OUT SOMEWHAT
BY MIDWEEK.

SOUTHWEST WINDS ARE DECREASING AS MA-ON MOVES FARTHER AWAY
ALLOWING WIND WAVES AND SWELL TO DIMINISH FURTHER TODAY ACROSS
YAP STATE. SURF SHOULD FALL BELOW THE 9 FT CRITERION BY THIS
EVENING.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...HIGH SURF ADVISORY UNTIL 10 AM CHST MONDAY FOR GUZ001>004.

MARIANAS WATERS...NONE.
&&

ZIOBRO/WILLIAMS