Subject: Western Pacific: Synoptic Discussion For The Marianas

From: LDM Weather <[email-masked]>
Date: Mon, 4 Oct 2010 03:19:24 -0500

071 
FXPQ60 PGUM 040819
AFDPQ 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
619 PM CHST MON OCT 4 2010

.SYNOPSIS...SATELLITE SHOWS A TROUGH OF LOW PRESSURE TO THE
SOUTHEAST OF GUAM THIS AFTERNOON. THIS TROUGH WILL MOVE WEST AND
WILL BRING CLOUDS AND ISOLATED SHOWERS WITH A SLIGHT CHANCE OF
THUNDERSTORMS TONIGHT AND TUESDAY.

&&

.DISCUSSION...
SATELLITE AND SCATTEROMETER DATA BOTH SHOW A TROUGH OF LOW PRESSURE
APPROACHING THE MARIANAS FROM THE EAST. MODELS SHOW THIS TROUGH
PASSING ACROSS THE LOCAL AREA OVER THE NEXT 24 HOURS. AT FIRST IT
LOOKED LIKE CLOUDS AND POSSIBLE SCATTERED SHOWERS WOULD OVERSPREAD
THE ISLANDS AFTER SUNSET. DURING THE AFTERNOON MANY HOLES DEVELOPED
IN THE RAIN AREA TO THE SOUTHEAST OF GUAM SO DELAYED THE ONSET OF
MOSTLY CLOUDY UNTIL LATER TONIGHT. WAS DEBATING ABOUT SCATTERED
SHOWERS...HARD TO PINPOINT ANY TIME THAT SCATTERED SHOWERS MAY
OCCUR SO LEFT COVERAGE AS ISOLATED. WITH MANY CBS ASSOCIATED WITH
THIS TROUGH ADDED A SLIGHT CHANCE OF THUNDERSTORMS TONIGHT AND
TUESDAY. EARLIER FORECAST CONTINUED THE SLIGHT CHANCE OF
THUNDERSTORMS THROUGH FRIDAY. WHILE THE ODDS ARE LOW FOR THUNDER
TIME HEIGHT DEPICTS ENOUGH MOISTURE AND SO OPTED TO KEEP THEM IN
FOR NOW.

&&

.MARINE...
AN EAST TRADE-WIND SWELL WILL PERSIST THROUGH THE WEEK. BUOY SHOWS
SEA HEIGHT INCREASING TO OVER FOUR FEET THIS AFTERNOON. WW3 SHOWS
A FIVE FOOT SWELL ON TUESDAY AND THIS SEEMS LIKELY. THIS WILL BUMP
SURF ON EAST FACING REEFS TO 5 TO 7 FEET WHICH IS MODERATE. 

&&

.EASTERN MICRONESIA...
A DIFFUSE ITCZ STRETCHES EASTWARD ALONG 6N FROM JUST EAST OF
CHUUK TO THE DATE LINE...THEN CONTINUES EAST-NORTHEASTWARD THRU
9N165W. PERIODS OF PASSING SHOWERS ARE EXPECTED FOR ALL THE MAJOR
LOCATIONS THRU TUESDAY. THEN THE SW TO NE ORIENTATION OF THE ITCZ
EAST OF THE DATE LINE WILL ALLOW THE CONVERGENT ZONE TO SHIFT
NORTH OF MAJURO ON WEDNESDAY AND PROMOTE FAIRER WEATHER. LATEST
ASCAT SATELLITE DATA REVEAL A NORTHEASTERLY TRADE SURGE NEAR THE
HAWAIIAN ISLANDS. AS THIS FEATURE CROSSES THE DATE LINE AROUND
MIDWEEK...IT WILL ENHANCE CONVERGENCE ALONG THE ITCZ. THIS WILL
CAUSE STRONGER AND MORE CONCENTRATED CONVECTION TO FORM ALONG
6N...RESULTING IN WIDESPREAD SHOWERS FOR BOTH POHNPEI AND CHUUK.
ON THE OTHER HAND...KOSRAE SHOULD REMAIN RELATIVELY DRY SOUTH OF
THE MAIN CONVERGENCE ZONE. AFTER MIDWEEK...FAIRER WEATHER ALREADY
OVER MAJURO WILL MOVE WESTWARD AND PROVIDE A BRIEF PERIOD OF
PARTLY CLOUDY SKIES. HOWEVER THE RETURN OF EASTERLY TRADES MIGHT
INCREASE THE CHANCE FOR TRADE-WIND SHOWERS FOR THE ENTIRE AREA BY
THE WEEKEND.

&&

.WESTERN MICRONESIA...
A SURFACE TROUGH CURRENTLY BETWEEN GUAM AND CHUUK IS SHOWING
SIGNS OF SPLITTING UP. THE WEAKER NORTHERN BRANCH IS MOVING
TOWARD THE MARIANAS...WHILE THE MORE ACTIVE SOUTHERN BRANCH IS
APPROACHING YAP THIS EVENING. CLOUDS ARE ANTICIPATED TO THICKEN
THIS EVENING AND SHOWERS WILL ARRIVE OVER YAP AFTER MIDNIGHT.
SIMILAR CONDITIONS WILL ALSO SPREAD INTO KOROR ON TUESDAY BUT
FUTURE SHIFTS SHOULD HAVE BETTER TIMING ON THE ONSET OF SHOWERS.
THERE SHOULD BE A DECREASE IN SHOWERS AFTER THE PASSAGE OF THE
TROUGH DURING MIDWEEK BUT MIGHT PICK UP AGAIN TOWARD THE WEEKEND
AS THE LEADING EDGE OF THE ITCZ EXTENDS WESTWARD FROM EASTERN
MICRONESIA.

&&

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

$$

ZIOBRO/CHAN

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