Area Forecast Discussion
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000
FXPQ60 PGUM 230439
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
239 PM CHST THU OCT 23 2014

.MARIANAS SYNOPSIS...
A WEAK CIRCULATION IS CENTERED JUST SOUTHEAST OF GUAM NEAR 12.5N
AND 145.5E. SCATTERED SHOWERS OVER GUAM AND ROTA THIS MORNING
THIS MORNING DISSIPATED RAPIDLY BEFORE NOON. RADAR AND SATELLITE
IMAGERY SHOW MORE SHOWERS DEVELOPING ON THE DOWN SHEAR SIDE OF
THE CIRCULATION OVER THE COASTAL WATERS EAST OF GUAM. MOST OF THE
SHOWERS APPEAR TO BE CONCENTRATED ON THE EAST SIDE OF THE
CIRCULATION BETWEEN 10N AND 15N FROM 148E TO 150E.

&&

.DISCUSSION...
THE WEAK CIRCULATION JUST EAST OF GUAM IS EMBEDDED WITHIN THE
MONSOON TROUGH AND IS EXPECTED TO PASS OVER GUAM TONIGHT. FELT
GFS INITIALIZED WELL IN TERMS OF SPATIAL CHARACTERISTICS OF
CONVECTION THIS MORNING. GFS AND HIGHER RESOLUTION MODELS
INDICATE THAT MUCH OF THE SHOWER ACTIVITY ASSOCIATED WITH THE
SYSTEM WILL DEVELOP TO THE NORTH OF THE CIRCULATION CENTER OVER
TINIAN AND SAIPAN LATER TONIGHT SO OPTED FOR SCATTERED WORDING
LATE TONIGHT. THIS CORROBORATES WELL WITH CURRENT SATELLITE
IMAGERY SHOWING SHOWER ACTIVITY INCREASING EAST AND NORTH OF THE
CIRCULATION. UPPER-LEVEL DYNAMICS ARE NOT IDEAL FOR THUNDERSTORM
DEVELOPMENT BUT CANNOT RULE OUT A THUNDERSTORM OR TWO OVERNIGHT
NORTH OF ROTA. IN THE LONG TERM...GFS AND NAVGEM ARE STILL THE
DRIER SOLUTIONS COMPARED TO THE ECMWF. ECMWF INCREASES MOISTURE
AND SHOWERS AND DEVELOPS A BROAD CIRCULATION SOUTH OF THE
MARIANAS MORE AGGRESSIVELY THAN THE GFS AND NAVGEM OVER THE
WEEKEND. UNCERTAINTY STILL EXISTS REGARDING SHOWER COVERAGE
DURING THE 3 TO 5-DAY TIME FRAME BUT MAINTAINED THE DRIER
SCENARIO UNTIL MODELS COME INTO MORE OF A CONSENSUS DURING THE
NEXT SEVERAL RUNS.

&&

.MARINE...
TANAPAG AND RITIDIAN BUOYS SHOW N-NE SWELL CONTINUING TO SLOWLY
DIMINISH ACROSS THE MARIANAS. A SECOND...LONG-PERIOD NORTHEAST
SWELL EVENT WILL COMMENCE FRIDAY BEGINNING WITH SAIPAN. THIS WILL
CAUSE SURF TO RISE TO HAZARDOUS LEVELS FRIDAY AFTER A BRIEF DROP
IN SURF HEIGHTS TONIGHT. SURF HEIGHTS OF 7 TO 9 FEET ARE EXPECTED
THROUGH MUCH OF THE WEEKEND WITH SURF EXPECTED TO DROP BELOW
HAZARDOUS LEVELS SUNDAY AFTERNOON.

&&

.EASTERN MICRONESIA...WILL BE UPDATED LATER.


&&

.WESTERN MICRONESIA...WILL BE UPDATED LATER.


&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...HIGH SURF ADVISORY UNTIL 4 PM CHST SUNDAY FOR GUZ001>004.

MARIANAS WATERS...NONE.
&&

$$

WILLIAMS/MCELROY





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