Area Forecast Discussion
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FXPQ60 PGUM 191948
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
548 AM CHST MON OCT 20 2014

.MARIANAS SYNOPSIS...
MONSOON TROUGH PASSES SOUTH OF GUAM NEAR 11N. LATEST ASCAT
ANALYSIS INDICATES A MILD TRADE-WIND SURGE SLIDING SOUTHWESTWARD
INTO THE SAIPAN AND TINIAN ZONES. RADAR AND SATELLITE SHOW A
SLIGHTLY HIGHER CONCENTRATION OF CLOUDS AND SHOWERS TO THE SOUTH
OF THE SURGE...OVER THE GUAM AND ROTA ZONES. OTHERWISE...NO
SIGNIFICANT WEATHER MAKERS LOOM ON THE HORIZON.

&&

.DISCUSSION...
MILD TRADE-WIND SURGE IS CREATING INCREASED LOW-LEVEL CONVERGENCE
OVER THE ROTA AND GUAM ZONES...BUT NOT ENOUGH TO GENERATE
SCATTERED SHOWER COVERAGE. WINDS WILL INCREASE FOR ALL ZONES THIS
AFTERNOON...SO BEST CHANCES FOR ISLAND THUNDER NEAR GUAM WILL BE
IN THE LATE MORNING TO EARLY AFTERNOON. DRIER WEATHER IS EXPECTED
BEHIND THE SURGE THROUGH TUESDAY NIGHT. LOW-LEVEL MOISTURE WILL
BE DEEPER WEDNESDAY THROUGH SATURDAY AS TRADES VEER TO SOUTHEAST.
MOISTURE DOES NOT LOOK DEEP ENOUGH TO SUPPORT MCS DEVELOPMENT.
RIGHT NOW...TUTT IS LOCATED TOO FAR WEST OF THE FORECAST ZONES TO
ACT AS A FAVORABLE INFLUENCE ON DEEP CONVECTION. IF TUTT SHIFTS
FARTHER EAST...ISOLATED THUNDER MAY BE NEEDED IN THE FORECAST FOR
LATER THIS WEEK. DRIER NORTHEAST TRADES APPEAR TO BE IN STORE
ONCE AGAIN FOR NEXT WEEKEND.

&&

.MARINE...
COMBINED SEAS HAVE FALLEN INTO THE 3 TO 4-FOOT RANGE. LATEST
ASCAT/WINDSAT ANALYSIS SHOWS AREA OF NEAR GALE NORTHEAST WINDS
HAS FORMED SOUTHEAST OF JAPAN. LONG PERIOD SWELL FROM THIS FETCH
GENERATION REGION WILL BEGIN ARRIVING ON TUESDAY NIGHT...THEN
CONTINUE FOR SEVERAL DAYS. LONG PERIOD SWELL DO NOT APPEAR TO BE
HIGH ENOUGH TO PRODUCE HIGH SURF...BUT IF THE FETCH GENERATION
REGION PROVES TO BE MORE POTENT THAN PRESENTLY THOUGHT...HIGH
SURF WOULD BE POSSIBLE ON NORTH-FACING REEFS AS EARLY AS TUESDAY
NIGHT.

&&

.EASTERN MICRONESIA...
A WEAK CIRCULATION CENTERED SOUTHWEST OF MAJURO AT 5N170E
CONTINUES TO GENERATE ISOLATED SHOWERS AND THUNDERSTORMS ACROSS
KOSRAE STATE AND PARTS OF THE MARSHALL ISLANDS. SCATTERED SHOWERS
WERE SEEN ON KOSRAE EARLY THIS MORNING ASSOCIATED WITH AN MCS.
THIS FEATURE IS DISSIPATING NOW WITH CLOUD DEBRIS DRIFTING
TOWARDS POHNPEI. ANOTHER MCS IS DEVELOPING SOUTH OF KWAJALEIN
NEAR THE CENTER. WILL HAVE TO WATCH FOR SIMILAR DEVELOPMENTS OVER
THE NEXT 24 TO 36 HOURS OR SO WITH THIS FEATURE IN CASE SHORT-
TERM UPDATES ARE NEEDED. OTHER THAN THIS POSSIBILITY...MODELS
MAINTAIN ISOLATED SHOWERS AND A SLIGHT CHANCE OF THUNDERSTORMS
THROUGH TUESDAY ACROSS THE REGION FROM MAJURO TO POHNPEI. ANOTHER
SURFACE TROUGH IS PROGGED TO BRING SHOWERS TO THE MARSHALL
ISLANDS THURSDAY AND FRIDAY AS IT HEADS WEST.

&&

.WESTERN MICRONESIA...
LIGHT WINDS AND DRY CONDITIONS ARE SEEN ACROSS CHUUK AND YAP
STATES...AS WELL AS THE REPUBLIC OF PALAU THIS MORNING. A WEAK
TROUGH STRETCHES FROM WEST TO EAST JUST NORTH OF THE THREE
FORECAST LOCATIONS WITH ISOLATED SHOWERS AND A FEW THUNDERSTORMS
SEEN ALONG THE TROUGH. GFS GENERALLY MAINTAINS A DRY BIAS THROUGH
THE END OF THE WEEK...BUT ECMWF SUGGESTS A LITTLE MORE MOISTURE
AROUND MIDWEEK AS THE TROUGH SINKS SOUTHWARD. OTHERWISE...NO
SIGNIFICANT WEATHER FEATURES ARE ANTICIPATED AT THIS TIME ACROSS
THE REGION.

&&

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

$$

MCELROY/M. AYDLETT





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