Subject: Western Pacific: Synoptic Discussion For The Marianas

From: LDM Weather <[email-masked]>
Date: Tue, 12 Oct 2010 14:57:18 -0500

411 
FXPQ60 PGUM 121957
AFDPQ 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
557 AM CHST WED OCT 13 2010

.SYNOPSIS...
JTWC INVEST 90W IS CENTERED SW OF GUAM NEAR 12N142E...AND ITS
CYCLONIC TURNING IS CLEARLY EVIDENT ON RADAR. RADAR ALSO SHOWS
WIDESPREAD RAIN SOUTHWEST OF A NW-SE LINE BISECTING GUAM...WITH
SCATTERED SHOWERS NORTH THRU EAST OF GUAM AS FAR AS ROTA AND VERY
LITTLE BEYOND THAT UP TOWARD TINIAN AND SAIPAN. 

&&

.DISCUSSION...
GFS IS VERY GENEROUS WITH RAINFALL ACROSS GUAM/ROTA TODAY THROUGH
THURSDAY NIGHT...WHILE UKMET AND ECMWF PULL THE SHOWERS SOUTHWEST
AWAY FROM GUAM BY LATE TODAY. BUT ALL THE MODELS KEEP TINIAN AND
SAIPAN OUT OF THE BULK OF THE RAIN...AS IS CURRENTLY THE CASE. IN
LIGHT OF CURRENT SATELLITE/RADAR TRENDS AND THIS DISPARATE MODEL
GUIDANCE...HAVE SPLIT GUAM/ROTA FROM TINIAN/SAIPAN TO GIVE G/R
SCATTERED SHOWERS AND ISOLATED THUNDER THROUGH TONIGHT WHILE
GIVING T/S JUST ISOLATED SHOWERS WITH A SLIGHT CHANCE OF THUNDER.
THE TIMING OF SCATTERED AT G/R WILL DEPEND TO A LARGE DEGREE ON
HOW QUICKLY 90W DEVELOPS. IF 90W ORGANIZES FASTER THAN CURRENTLY
EXPECTED...SCATTERED SHOWERS MAY INDEED END SOONER THAN FORECAST
AS THE CONSOLIDATING SYSTEM CONCENTRATES RAIN NEAR ITS CENTER
WHILE SUPRESSING SHOWERS FURTHER OUT. IF 90W REMAINS RELATIVELY
DISORGANIZED FOR A WHILE...SHOWERS MAY LINGER ACROSS G/R WELL INTO
THURSDAY. BUT IN ANY CASE...IT APPEARS MID-LEVEL DRY AIR OVER
TINIAN AND SAIPAN WILL KEEP THEM RELATIVELY DRY. 

&&

.EASTERN MICRONESIA...
A TROUGH STRETCHES ACROSS THE MARSHALLS FROM SOUTHWEST TO NORTHEAST
BETWEEN KWAJALEIN AND MAJURO. SCATTERED SHOWERS AND PERHAPS A FEW
THUNDERSTORMS EXIST ALONG THE TROUGH AXIS BETWEEN THE TWO ATOLLS.
OBSERVATIONS FROM BOTH LOCATIONS CORRESPOND WELL WITH MODEL ANALYSIS
OF A WEAK CIRCULATION JUST TO THE NORTH...NEAR 10N171E. THIS WILL
SLOWLY MOVE OFF TO THE WEST PASSING NORTH OF KOSRAE AND POHNPEI.
HOWEVER...CLOUD COVER WILL INCREASE TONIGHT FOR KOSRAE AND THURSDAY
NIGHT FOR POHNPEI.

&&

.WESTERN MICRONESIA...
YAP...KOROR AND CHUUK ARE FREE OF CONVECTIVE WEATHER THIS MORNING 
BUT JTWC INVEST AREAS 91W AND 90W ARE JUST NORTH OF KOROR AND YAP. 
ANOTHER CLUSTER OF SHOWERS AND THUNDERSTORMS IS JUST WEST OF CHUUK. 
MOST OF THE REGION WILL KEEP ISOLATED SHOWERS THROUGH THE WEEK BUT 
MODELS KEEP SHOWERS IN THE VICINITY OF KOROR THROUGH THE WEEK AS 
PART OF THE INFLOW TO 90W. 90W IS THE SUBJECT OF A TROPICAL CYCLONE 
FORMATION ALERT...AND IS EXPECTED TO MOVE WESTWARD...EVENTUALLY 
TURNING TO THE NORTH AWAY FROM WESTERN MICRONESIA.

&&

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

$$

MIDDLEBROOKE/M. AYDLETT

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