Subject: Western Pacific: Synoptic Discussion For The Marianas

From: LDM Weather <[email-masked]>
Date: Tue, 19 Oct 2010 16:27:45 -0500

498 
FXPQ60 PGUM 192127
AFDPQ 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
727 AM CHST WED OCT 20 2010

.SYNOPSIS...
PGUA WSR-88D SHOWS SCATTERED SHOWERS ASSOCIATED WITH A TROPICAL
DISTURBANCE MOVING INTO THE MARIANAS FROM THE NORTHEAST. WINDS IN
THE MARIANAS HAVE TURNED TO THE SOUTHWEST AND PRESSURES HAVE
FALLEN AS THE WEAK CIRCULATION COMES NEAR.

&&

.DISCUSSION...
THIS WEAK CIRCULATION SHOULD BE AT ITS PEAK NOW...IT IS MOVING
INTO A REGION OF INCREASED VERTICAL WIND SHEAR AND SUBSIDENCE. IT
WOULD HAVE TO SIGNIFICANTLY MODIFY ITS ENVIRONMENT TO HAVE A GOOD
SHOT AT DEVELOPING FURTHER. WHILE THIS IS POSSIBLE...IT IS NOT
EXPECTED. NEVERTHELESS...ON RADAR AT 4 AM IT SEEMED LIKE A GOOD
IDEA TO UPGRADE TINIAN AND SAIPAN TO SCATTERED SHOWERS. MOST
LIKELY CAUSE FOR ANY UPDATES WOULD BE IF IT BECAME NECESSARY TO
EXTEND THE SCATTERED SHOWERS TO GUAM AND ROTA. AT THE NEXT
ISSUANCE IT MAY ALSO BE NECESSARY TO EXTEND THE SHOWERS IN TIME...
DEPENDING ON HOW THE SITUATION DEVELOPS ON RADAR AND SATELLITE.
THE SHEAR AND OTHER HAMPERING ENVIRONMENTAL FEATURES ARE WHY JTWC
HAS LISTED THIS AS A POOR AREA FOR TROPICAL DEVELOPMENT VS A FAIR.

&&

.EASTERN MICRONESIA...
ONCE AGAIN...FEW CHANGES MADE TO THE FORECASTS AS PREVIOUS FORECASTS 
REMAIN WELL SUPPORTED BY CURRENT MODEL DATA AND SATELLITE IMAGERY. 
WITH THE UPPER LOW JUST SW OF WAKE ISLAND PUSHING WESTWARD AND SE 
WINDS AT THE SURFACE SPREADING FROM EAST TO WEST...NO MORE THAN 
ISOLATED SHOWERS ARE EXPECTED AT EACH LOCATION. GFS HAS REMAINED 
CONSISTENT DEPICTING A WEAK TROUGH MOVING THROUGH THE REGION IN A 
COUPLE OF DAYS. FOR NOW...THE TROUGH IS ONLY EXPECTED TO INCREASE 
CLOUD COVER AT MAJURO FOR LATE THU THROUGH SAT AND POHNPEI OVER THE 
WEEKEND.

&&

.WESTERN MICRONESIA...
LATEST ASCAT PASS SHOWS THE WEAK CIRCULATION NEAR YAP WITH LIGHT 
WEST WINDS NEAR KOROR. MOST CONVECTION HAS DISSIPATED NEAR YAP AND 
KOROR WITH A FEW SHOWERS AND THUNDERSTORMS CONTINUING ABOUT 300 
MILES EAST OF YAP. ALTHOUGH MODELS DO NOT AGREE ON WHETHER THE 
CIRCULATION WILL LIFT NORTHWARD TOWARD GUAM OR PASS WESTWARD AS A 
TROUGH...THEY DO MELD TOGETHER BY PROGGING SHOWERS TO STAY IN THE 
AREA SOUTH OF GUAM...KEEPING KOROR...YAP AND CHUUK WITH JUST 
ISOLATED SHOWERS FOR THE REST OF THE WEEK. HOWEVER...LOW CONFIDENCE 
IN MODEL PERFORMANCE CONCERNING THE INTERACTION BETWEEN THE YAP 
CIRCULATION AND THE CIRCULATION EAST OF SAIPAN CREATES A FAIR
AMOUNT OF UNCERTAINTY CONCERNING THE POSSIBLE DEVELOPMENT OF AND
LOCATION OF SCATTERED SHOWERS DURING THE NEXT SEVERAL DAYS SO THE
SITUATION WILL NEED TO BE WATCHED CLOSELY FOR ANY DEVELOPMENTAL
CHANGES.

&&

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

$$

STANKO/W. AYDLETT

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