Area Forecast Discussion
Issued by NWS

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FXPQ60 PGUM 310540
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
340 PM CHST FRI OCT 31 2014

.MARIANAS SYNOPSIS...
TROPICAL DEPRESSION 20W HAS FORMED IN THE PHILIPPINE SEA AND IS
CENTERED ABOUT 550 MILES TO THE WEST OF GUAM. THE MONSOON TROUGH
EXTENDS EAST-SOUTHEASTWARD FROM 20W TO BETWEEN GUAM AND CHUUK.
CONVECTION ASSOCIATED WITH THE TROUGH IS DISPLACED TO THE NORTH AND
SOUTH OF THE TROUGH AXIS...WHERE THE STRONGEST LOW-LEVEL CONVERGENCE
IS OCCURRING. AT PRESENT...THESE AREAS LIE OVER TINIAN AND SAIPAN
AND BETWEEN GUAM AND YAP...RESPECTIVELY.

&&

.DISCUSSION...
MODELS HAVE COME INTO BETTER AGREEMENT IN NOT DEVELOPING A SECONDARY
TROPICAL SYSTEM TO THE SOUTHEAST OF 20W. BASED UPON THIS...FAVORED
FORECAST SCENARIO REVOLVES AROUND THE BEHAVIOR OF THE MONSOON TROUGH
TO THE EAST OF 20W. BOTH THE ECMWF AND GFS40 MAINTAIN THE STRONGEST
TRADE-WIND CONVERGENCE OVER THE TINIAN AND SAIPAN ZONES THROUGH
SATURDAY NIGHT...THEN MONSOON TROUGH BEGINS TO SLOWLY RETREAT TOWARD
THE SOUTHWEST...ALLOWING SCATTERED SHOWERS TO OVERSPREAD ALL OF THE
FORECAST ZONES SUNDAY AND SUNDAY NIGHT. TROUGH CONTINUES TO WEAKEN
AND HEAD SOUTHWEST EARLY NEXT WEEK...ALLOWING DRIER TRADES TO
INFILTRATE BY MID WEEK.

&&

.MARINE...
LATEST ALTIMETRY AND BUOY READINGS ONLY INDICATE 3 TO 5 FT SEAS IN
THE MARINE ZONES. TRIMMED TRADE SWELL A FOOT TO AGREE WITH THE
LATEST READINGS. LATEST ASCAT ANALYSIS INDICATES A LARGE FETCH
GENERATION AREA FORMING ON THE SOUTH SIDE OF 20W. WAVE WATCH MODEL
IS PICKING UP ON THIS...SO HAVE BEEFED UP WEST TO WEST-NORTHWEST
SWELL IN THE MARINE GRIDS BEGINNING WITH NEXT TUESDAY. WOULD NOT BE
SURPRISED TO SEE HIGH SURF ON WEST-FACING REEFS BY THE MIDDLE OF
NEXT WEEK. IT IS TOO EARLY TO TELL IF LONG PERIOD SWELL WILL BE HIGH
ENOUGH TO BRING COMBINED SEAS TO SMALL CRAFT ADVISORY HEIGHTS DURING
THIS TIME FRAME.

&&

.EASTERN MICRONESIA...WILL BE SENT LATER.

&&

.WESTERN MICRONESIA...WILL BE SENT LATER.

&&

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

$$

MCELROY




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