Subject: Western Pacific: Synoptic Discussion For The Marianas

From: LDM Weather <[email-masked]>
Date: Fri, 8 Oct 2010 03:17:59 -0500

647 
FXPQ60 PGUM 080817 CCA
AFDPQ 

AREA FORECAST DISCUSSION...CORRECTION
NATIONAL WEATHER SERVICE TIYAN GU
554 PM CHST FRI OCT 8 2010

CORRECTED TYPO

.SYNOPSIS...SATELLITE AND RADAR SHOW SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS JUST SOUTH OF THE GUAM MARINE ZONE.
FORECAST IS FOR THESE SHOWERS TO HOLD OFF MOVING INTO THE AREA
UNTIL TOMORROW NIGHT...BUT WE WILL HAVE TO KEEP A WATCHFUL EYE ON
DEVELOPMENT AS THE COMPUTER MODELS ALL ARE ITCHING TO PUT A
TROPICAL DISTURBANCE TO THE SOUTHWEST OF THE REGION OVER THE NEXT
SEVERAL OF DAYS.

&&

.DISCUSSION...SATELLITE AND RADAR SHOW THE ACTIVITY REMAINING
SOUTH OF US ALL DAY...AS PREDICTED BY THE VARIOUS NWP MODELS.
QUESTION IS HOW MUCH LONGER WILL EVERYTHING STAY TO OUR SOUTH WITH
THE UPPER-LEVEL TROUGH SHOWING EVIDENCE IN THE WATER VAPOR OF
PULLING OUT AND BEING REPLACED BY UPPER-LEVEL RIDGING...DIVERGENCE.
I HAVE TRIED TO KEEP THE FORECAST AS IS...FOR NOW...AS NO DISTINCT
FEATURE HAS APPEARED IN ANY OF THE DATA...SATELLITE
IMAGERY...SYNOPTIC...AND SCATTEROMETER. THE SCENARIOS ARE VARIOUS
WITH THE DIFFERENT MODELS...NOGAPS AND ECMWF GOING WITH TROPICAL
CYCLONE FORMATION AROUND 138 TO 140E...JMA AND UKMET SHOW MONSOON
TROUGHING ALONG 10 TO 12N...AND PERHAPS A WEAKER CIRCULATION
LATER NEAR 137E. GFS IS AN OUTLIER WITH TWO CIRCULATIONS FORMING OVER
THE NEXT 3 TO 5 DAYS...ONE WEAKER ONE TO OUR WEST SIMILAR TO THE
OTHER MODELS...AND ONE TO OUR EAST...WHICH PLACES IT PRACTICALLY
OVER HEAD BY TUESDAY OR WEDNESDAY. IN AN ATTEMPT NOT TO MAKE THIS
TOO COMPLICATED...I REPLACED THE CIRCULATION IN THE GFS GRIDS WITH
LIGHT SOUTHEAST WINDS. CLOUDS AND PRECIP REMAIN THE SAME AS IN THE
PREVIOUS FORECAST WITH THE EXCEPTION OF INCREASING THE SHOWERS TO
SCATTERED ON SUNDAY AS THIS SEEMED TO BE THE ONE CONSENSUS WITH
ALL MODELS.

&&

.MARINE...OUTSIDE OF A TROPICAL DISTURBANCE DEVELOPING TO OUR
WEST...NO SIGNIFICANT FEATURE IS SEEN IN THE WW3 AS WINDS AND WIND
WAVES REMAIN LOW. I DID INCREASE THE SWELLS AND COMBINED SEAS A
BIT BY MID WEEK...ESPECIALLY FOR THE NORTHERN MARINE ZONES TO
REFLECT A REFLECTION OF SWELLS ARRIVING FROM THE NORTH FROM A
FRONTAL ZONE EAST OF JAPAN.

&&

.TROPICAL SYSTEMS...SEE DISCUSSION ABOVE. NO FEATURE OF CONCERN IS
EVIDENT AS OF YET.

&&

.EASTERN MICRONESIA...
SATELLITE IMAGERY SHOWS THAT THE ITCZ OVER EASTERN MICRONESIA IS 
SLOWLY MOVING NORTHWARD AS FORECAST...LEAVING MAJURO...KOSRAE AND 
POHNPEI WITH ISOLATED SHOWERS AND PRIMARILY EAST TO SOUTHEAST WINDS. 
AS
THE ITCZ MOVES A BIT MORE TO THE NORTH OVER THE NEXT DAY OR TWO...
EXPECT SOME CLEARING ACROSS EASTERN MICRONESIA FOR THE WEEKEND BEFORE
RETURNING TO A MORE ACTIVE PATTERN EARLY NEXT WEEK.

&&

.WESTERN MICRONESIA...
AN ACTIVE CONVECTIVE PATTERN ASSOCIATED WITH THE ITCZ REMAINS 
SOUTHEAST OF YAP AND KOROR. THREE OF FOUR MODELS SPIN THIS AREA UP 
TO A CIRCULATION AND MOVE IT TO THE NORTHWEST OF YAP AND KOROR ON 
SUNDAY. A RIDGE TRIES TO BUILD INTO THE REGION LATE IN THE WEEKEND 
WHICH SHOULD ALLOW SOME CLEARING TO OCCUR EARLY NEXT WEEK FOR BOTH 
KOROR AND YAP. ONLY ISOLATED TO WIDELY SCATTERED SHOWERS ARE 
EXPECTED OVER CHUUK TONIGHT THROUGH TUESDAY. RECENT LIGHTNING AND 
SOUNDING DATA SUGGEST A SLIGHT CHANCE OF TSTMS OVER CHUUK WATERS 
TONIGHT...AND KOROR AND YAP WATERS THROUGH SATURDAY NIGHT.

&&

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

$$

EDSON/DEVITA

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