Area Forecast Discussion
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000
FXPQ60 PGUM 290611
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
411 PM CHST TUE JUL 29 2014

.MARIANAS SYNOPSIS...
TROPICAL STORM HALONG (11W) IS CENTERED ABOUT 230 MILES EAST-
SOUTHEAST OF GUAM NEAR 13N148E. OUTER BANDS OF SHOWERS AND
ISOLATED THUNDERSTORMS ARE FOUND MAINLY IN THE COASTAL WATERS TO
THE EAST OF THE ISLANDS. AN UPPER-LEVEL LOW IS FOUND NORTHWEST OF
HALONG AND IS AIDING IN THE INTENSIFICATION OF HALONG.

&&

.DISCUSSION...
TROPICAL STORM HALONG WILL MOVE OVER THE MARIANAS WEDNESDAY AND
WEDNESDAY NIGHT. THE EXACT TRACK OF HALONG WILL DETERMINE THE
EXACT EFFECTS OF THIS SYSTEM ON EACH INDIVIDUAL ISLAND.
CONDITIONS WILL DETERIORATE TONIGHT AND WEDNESDAY AS HALONG NEARS
ROTA. THE APEX WINDS AND RAIN WILL BE LATE WEDNESDAY AFTERNOON
THROUGH WEDNESDAY NIGHT FOR GUAM AND ROTA. CONDITIONS WILL BE LESS
SEVERE ON TINIAN AND SAIPAN. HOWEVER...HALONG COULD STILL TAKE A
MORE NORTHWESTWARD TRACK WHICH COULD CAUSE WORSE CONDITIONS ON
TINIAN AND SAIPAN. GRIDS WERE UPDATED BUT MORE ATTENTION TO DETAIL
WAS DIRECTED IN THE SHORT TERM FORECAST. CONDITIONS WILL RAPIDLY
IMPROVE THURSDAY AS HALONG MOVES AWAY FROM THE MARIANAS.

&&

.MARINE...
COMBINED SEAS WILL QUICKLY BUILD TONIGHT ACROSS THE REGION.
COMBINED SEAS WILL PEAK BETWEEN 12 AND 16 FEET WEDNESDAY NIGHT
AND THURSDAY AS HALONG INTENSIFIES AND MOVES THROUGH THE
MARIANAS. SEAS WILL BEGIN TO FALL THURSDAY NIGHT AND FRIDAY. HIGH
SURF ADVISORY IS IN EFFECT BUT MAY HAVE TO BE UPGRADED TO A
WARNING THIS EVENING DURING THE ISSUANCE OF THE NEXT FORECAST
PACKAGE.

&&

.HYDROLOGY...
AN AVERAGE OF 6 TO 9 INCHES OF RAINFALL IS EXPECTED FOR GUAM AND
ROTA AS HALONG TRACKS ACROSS THE REGION. LESSER RAINFALL OF 2 TO
4 INCHES IS ANTICIPATED FOR TINIAN AND SAIPAN. HIGHER AMOUNTS ARE
POSSIBLE DEPENDING ON THE EXACT DISTRIBUTION OF DEEP CONVECTION
AROUND THE STORM. THE HEAVIEST SHOWERS ARE EXPECTED TO BE SOUTH
OF THE CENTER OVER GUAM. THE HEAVY RAINFALL WILL BE A MAJOR
THREAT TO GUAM AND ROTA SO MUDSLIDES COULD BE AN ADDITIONAL
THREAT ESPECIALLY ACROSS SOUTHERN GUAM.

&&

.TROPICAL SYSTEMS...
TROPICAL STORM HALONG HAS INTENSIFIED SUBSTANTIALLY OVER THE PAST
12 HOURS. HALONG HAS DEVELOPED AN OBVIOUS EYE AS OBSERVED IN
VISIBLE SATELLITE IMAGERY. THE CENTER IS BECOMING READILY VISIBLE
IN RADAR IMAGERY AS WELL. LATEST FORECAST TRACK TAKES HALONG NEAR
ROTA LATE WEDNESDAY EVENING. WINDS WILL INCREASE TONIGHT AND
WED AS HALONG MOVES WEST-NORTHWEST. IMPRESSIVE VISIBLE SATELLITE
DEPICTION OF HALONG INDICATES THAT HALONG HAS THE POTENTIAL TO
INTENSIFY TO TYPHOON STRENGTH BY THE TIME IT PASSES ROTA.

&&

.EASTERN MICRONESIA...
WILL BE ADDED LATER.

&&

.WESTERN MICRONESIA...
WILL BE ADDED LATER.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...TYPHOON WATCH FOR GUZ001-002.

     FLASH FLOOD WATCH THROUGH THURSDAY MORNING FOR GUZ001>004.

     HIGH SURF ADVISORY UNTIL 6 PM CHST THURSDAY FOR GUZ001>004.

     TROPICAL STORM WATCH FOR GUZ003-004.

MARIANAS WATERS...TYPHOON WATCH FOR PMZ151-152.

     TROPICAL STORM WATCH FOR PMZ153-154.

&&

$$

WILLIAMS/CHAN





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