Subject: Western Pacific: Synoptic Discussion For The Marianas

From: LDM Weather <[email-masked]>
Date: Mon, 25 Oct 2010 03:30:15 -0500

034 
FXPQ60 PGUM 250830
AFDPQ 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
630 PM CHST MON OCT 25 2010

.SYNOPSIS...
A DISTURBANCE SE TO S OF GUAM IS MOVING WESTWARD. SATELLITE SHOWS
HEAVIER CONVECTION WAS DEVELOPING ALONG 8N-10N NEAR 144E BUT OTHER
BANDS OF LIGHT TO MODERATE SHOWERS WERE E-SE OF GUAM BETWEEN 146E
AND 150E. WATER VAPOR LOOP SHOWS HIGH PRESSURE HAS DRIFTED WEST OF
GUAM AND OUR UPPER-LEVEL WINDS ARE BECOMING MORE DIVERGENT. PGUA
RADAR SHOWS ONLY ISOLATED SHOWERS ACROSS THE AREA SO FAR THIS
AFTERNOON. FORMER TD 17W APPEARS TO BE REVIVING NEAR 22N154E.
ALSO...VAAC WASHINGTON HAS ISSUED VOLCANIC ASH ADVISORY FOR PAGAN.

&&

.DISCUSSION...
INTRODUCED SLIGHT CHANCE OF TSTMS FOR GUAM LATE TONIGHT...BUT KEPT
SHOWER COVERAGE ISOL AND DID NOT SEPARATE ZONES. RISK OF TSTMS
WILL INCREASE WITH MORE UNSTABLE NIGHT-TIME CONDITIONS DEVELOPING
NEAR GUAM AND SOUTHWARD...WHILE SCATTERED COVERAGE IS STILL
EXPECTED TO REMAIN SOUTH OF GUAM ZONES. MODELS DIFFER
SIGNIFICANTLY ABOUT SHOWER COVERAGE FOR THE MARIANAS DURING NEXT
24 HOURS. GFS MORE THAN OTHER MODELS INDICATES SOME INCREASE IN
SHOWERS ACROSS THE MARIANAS...OTHER MODELS ARE DRIER...AND FOR NOW
A CONSERVATIVE FORECAST IS PREFERRED.

&&

.MARINE...SLIGHT ADJUSTMENTS WERE MADE TO MARINE GRIDS...BUT
CONTINUED THE TREND FOR A MARGINAL WIND SHIFT AS THE DISTURBANCE
PASSES BY OUR SOUTH EARLY TUESDAY. EAST WINDS AND LARGER NE SWELL
ARE EXPECTED THROUGH THE REST OF THIS WEEK.

&&

.EASTERN MICRONESIA...
A TRADE-WIND DISTURBANCE IS EXPECTED TO KEEP SHOWERY CONDITIONS OVER 
THE MARSHALL ISLANDS THRU TUESDAY. AS IT SLIDES WESTWARD...IT WILL 
ALSO SPREAD SIMILAR WEATHER OVER KOSRAE AND POHNPEI BY TUESDAY 
NIGHT. A DIFFUSE ITCZ IS VISIBLE EAST OF THE DATE LINE ON THE
LATEST SATELLITE IMAGERY. THIS FEATURE WILL LIKELY MAINTAIN A
RELATIVELY WET PATTERN OVER THE REGION AFTER MIDWEEK.

&&

.WESTERN MICRONESIA...
CONVERGING WINDS EAST OF A SURFACE TROUGH EMBEDDED WITHIN THE 
TRADE-WIND FLOW ARE GOING TO INTRODUCE SOME SHOWERS FOR CHUUK LATE 
THIS EVENING AND TUESDAY MORNING. THEN WEAKER SOUTHEASTERLIES 
FARTHER EAST OF THE TROUGH WILL PROVIDE A DRIER PERIOD THRU MIDWEEK. 
TOWARD THE WEEKEND...THE TRADE DISTURBANCE MENTIONED EARLIER SHOULD 
BEGIN TO IMPACT THE ISLAND WITH INCREASING SHOWER COVERAGE. THIS 
SAME SURFACE TROUGH IS STEADILY APPROACHING YAP WITH GRADUAL 
INCREASE IN SHOWER ACTIVITY THRU TONIGHT. THE BULK OF THE WET 
WEATHER IS ANTICIPATED TO REACH YAP ON TUESDAY AND THEN KOROR ON 
TUESDAY EVENING. SOME IMPROVEMENT IS POSSIBLE AFTER MIDWEEK AS THE 
TROUGH PULLS FARTHER WEST INTO THE PHILIPPINE SEA.

&&

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

$$

SIMPSON/CHAN

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