Subject: Western Pacific: Synoptic Discussion For The Marianas

From: LDM Weather <[email-masked]>
Date: Fri, 17 Sep 2010 15:37:47 -0500

217 
FXPQ60 PGUM 172037
AFDPQ 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
637 AM CHST SAT SEP 18 2010

.SYNOPSIS...
RADAR SHOWS SCATTERED SHOWERS EAST OF THE MARIANAS...DISSIPATING
AS THEY TRY TO MOVE INTO THE MARIANAS MARINE ZONES. AN UPPER-LEVEL
TROUGH IS EVIDENT IN WATER VAPOR IMAGERY WEST OF THE ISLANDS...AND
A WEAK SURFACE TROUGH IS PRODUCING SOME DISORGANIZED CONVECTION
EAST OF THE MARIANAS BETWEEN 150E AND 160E. WINDS IN THE MARIANAS
ARE LIGHT...NNE AT 5-10 KT.

&&

.DISCUSSION...
LATEST GFS/UKMET GIVE NO CLEAR SIGNAL FOR SCATTERED SHOWERS THE
NEXT FEW DAYS ACROSS THE MARIANAS...AS A WEAK CIRCULATION THAT
IS EXPECTED TO FORM ON THE SURFACE TROUGH EAST OF THE MARIANAS
MOVES NORTH AND TAKES MOST OF THE CONVECTION WITH IT. HAVE REMOVED
SCATTERED SHOWERS SUN-MON IN FAVOR OF ISOLATED SHOWERS AND
THUNDERSTORMS TODAY THROUGH SUNDAY NIGHT AS THE UPPER TROUGH LURKS
WEST AND NW OF THE REGION. ISLAND THUNDER IS ALSO POSSIBLE ON GUAM
THIS AFTERNOON IN LIGHT NNE WIND. 

&&

.EASTERN MICRONESIA...
ASCAT SATELLITE IMAGERY SHOWS THE LEADING EDGE OF AN ITCZ MIGRATING 
WESTWARD AND REACHES MAJURO THIS MORNING. 200MB ANALYSIS ALSO 
INDICATES A PRONOUNCED UPPER TROUGH EXTENDING SOUTHWESTWARD INTO 
EASTERN MICRONESIA FROM A LARGE TUTT CELL EAST OF WAKE ISLAND. 
FAVORABLE UPPER-LEVEL DYNAMICS ASSOCIATED WITH THE UPPER TROUGH WILL 
GREATLY ENHANCE CONVECTION ALONG THE ITCZ AS IT IMPACTS MAJURO TODAY 
INTO SUNDAY EVENING...AND ALSO KOSRAE SUNDAY AND MONDAY. 
MEANWHILE...A WEAK SURFACE TROUGH WEST OF THE ITCZ IS GOING TO 
MAINTAIN SOME SHOWERS OVER POHNPEI INTO THIS EVENING...AND CHUUK 
INTO SUNDAY AFTERNOON. THEN AN AREA OF DRIER TRADES AHEAD OF THE 
ITCZ WILL PROMOTE A BRIEF PERIOD OF IMPROVED WEATHER FOR POHNPEI ON 
SUNDAY...AND CHUUK ON MONDAY. AFTERWARD...CONVECTIVE ACTIVITY ALONG 
THE ITCZ WILL ALSO SPREAD OVER BOTH LOCATIONS BY EARLY NEXT WEEK. 
FINALLY...LIGHTER TRADE WINDS MIGHT CAUSE THE ITCZ TO GRADUALLY 
WEAKEN OVER EASTERN MICRONESIA AROUND MIDWEEK.

&&

.WESTERN MICRONESIA...
A PERSISTENT SURFACE RIDGE OVER THE PHILIPPINE SEA ALONG WITH DRIER
AIR ALOFT IS ANTICIPATED TO PROVIDE PLEASANT WEATHER FOR YAP AND
PALAU INTO SUNDAY. AS THE RIDGE SHIFTS FARTHER NORTHWEST EARLY
NEXT WEEK...THE SURFACE TROUGH CURRENTLY NEAR CHUUK WILL MOVE
WESTWARD AND ENCOURAGE SHOWER FORMATION OVER BOTH FORECAST POINTS.

&&

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

$$

MIDDLEBROOKE/CHAN

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