Subject: Western Pacific: Synoptic Discussion For The Marianas

From: LDM Weather <[email-masked]>
Date: Tue, 19 Oct 2010 02:10:57 -0500

829 
FXPQ60 PGUM 190710
AFDPQ 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
510 PM CHST TUE OCT 19 2010

.SYNOPSIS...
THE MARIANAS ARE SITUATED BETWEEN TWO CIRCULATIONS...ONE EAST OF
YAP AT ABOUT 9N141E AND THE OTHER ENE OF THE MARIANAS AT ABOUT
16N151E. THE MARIANAS LIE IN THE NEUTRAL POINT BETWEEN THE TWO
CIRCULATIONS...RESULTING IN LIGHT AND VARIABLE WINDS. ONLY
ISOLATED SHOWERS ARE PRESENT IN THE MARIANAS WATERS...AND THE
ISLAND SHOWERS OVER GUAM HAVE DISSIPATED. 

&&

.DISCUSSION...
THE MODELS ARE NOT HANDLING THE TWO CIRCULATIONS WITH ANY
CONSISTENCY AMONG THEMSELVES AT ALL...AND AS A RESULT THE FORECAST
UNCERTAINTY IS HIGH. GFS TAKES THE NE CIRCULATION WESTWARD NORTH
OF SAIPAN...SWINGING OUR WINDS AROUND TO SW FOR A FEW DAYS...AND
BRINGING SOME SHOWERS CLOSE TO SAIPAN OVERNIGHT...BUT IT
COMPLETELY WASHES OUT THE YAP CIRCULATION. THE UKMET DOES VERY
LITTLE WITH THE NE CIRCULATION...AND KEEPS THE YAP CIRCULATION SW
OF GUAM. THE NOGAPS TAKES THE NE CIRC NW WELL NORTH OF THE
MARIANAS...BUT IT TAKES THE YAP CIRC AND MOVES IT NE OVER GUAM THU
NIGHT AND FRIDAY! IN LIGHT OF THE DISPARATE MODEL GUIDANCE...HAVE
CONTINUED MOSTLY CLOUDY WITH ISOLATED SHOWERS/THUNDER THROUGH THU
NIGHT. LIGHT WINDS SHOULD DELIVER ISLAND SHOWERS TO GUAM THE NEXT
COUPLE OF DAYS...AND THE NE CIRCULATION MAY AFFECT THE NORTHERN
ISLANDS WITH ISOLATED THUNDER AS WELL. IT IS POSSIBLE THAT ONE OR
BOTH OF THE CIRCULATIONS MAY AFFECT THE ISLANDS MORE THAN
CURRENTLY EXPECTED...BUT WILL HAVE TO WAIT TO SEE WHAT DEVELOPS IN
THE NEXT 24-36 HOURS...BOTH WEATHERWISE AND MODEL-WISE.

&&

.MARINE...
EAST SWELL HAS COME UP A BIT TO 5 FEET AT TIMES...AND THIS WILL
KEEP SURF AT 5-7 FEET ON EAST FACING REEFS...AND 3-5 FEET ON NORTH
FACING...RESULTING IN A MODERATE RIP RISK.

&&

.EASTERN MICRONESIA...
PREVIOUS FORECASTS REMAIN CONSISTENT WITH MODEL ANALYSIS AND
OBSERVATIONS. VARIABLE WINDS WERE EXTENDED THROUGH TONIGHT FOR
POHNPEI BECOMING SOUTHEAST BY WEDNESDAY. ISOLATED SHOWERS EXIST
ACROSS ALL AREAS EXCEPT ACROSS THE NORTHERN MARSHALL ISLANDS
INCLUDING KWAJALEIN...WHERE SCATTERED SHOWERS ARE FOUND SOUTH OF A
TROUGH THAT SITS BETWEEN KWAJALEIN AND WAKE ISLAND. MODELS PUSH
THIS TROUGH NORTHWESTWARD BY WEDNESDAY. A WEAK TROUGH IS STILL
PROGGED TO PASS BY MAJURO LATE THURSDAY...PASSING NORTH OF KOSRAE
AND ACROSS POHNPEI THIS WEEKEND.

&&

.WESTERN MICRONESIA...
CHUUK FORECAST HOLDS STEADY WITH ISOLATED SHOWERS THROUGH THE
WEEK AND VARIABLE WINDS ADDED FOR TONIGHT. UNCERTAINTY LIES WITH
YAP AND KOROR AS BOTH SIT JUST WEST OF INVEST AREA 97W. VISIBLE
IMAGERY SHOWS THIS CIRCULATION GROWING IN SIZE...CENTERED NEAR
9N140E. MODELS EXHIBIT A POOR GRASP OF THIS SYSTEM...INITIALIZING
ITS LOCATION POORLY AND WASHING OUT WHAT CIRCULATION THERE IS TO
THE WEST OR ABSORBING IT INTO ANOTHER CIRCULATION NORTHEAST OF
GUAM AS IT MOVES WEST. DEEP CONVECTION BLEW UP TODAY JUST EAST OF
YAP AND IS NOW SHOWING SIGNS OF STRATIFICATION...AS OUTFLOW
SHOWERS ARE NOW SEEN MOVING WEST TOWARDS YAP. EASTWARD MOVING
SHOWERS HAVE BEEN PASSING OVER KOROR TODAY WHILE WINDS REMAIN
LIGHT AND VARIABLE. GFS SHOWS LITTLE SIGN OF ANY MAJOR RAINS THIS
WEEK FOR ANY OF THE LOCATIONS AS HEAVY RAINS ARE TO REMAIN EAST OF
YAP AND KOROR.

&&

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

$$

MIDDLEBROOKE/M. AYDLETT

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