Subject: Western Pacific: Synoptic Discussion For The Marianas

From: LDM Weather <[email-masked]>
Date: Sat, 23 Oct 2010 16:54:59 -0500

976 
FXPQ60 PGUM 232154
AFDPQ 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
754 AM CHST SUN OCT 24 2010

.SYNOPSIS...
RECENT WATER VAPOR SATELLITE IMAGERY SHOWS A NEARLY STATIONARY TUTT
CELL CENTERED EAST OF SAIPAN NEAR 15N149E. A LOBE OF VORTICITY
APPEARS TO HAVE SHARPENED UP A BIT ON THE NORTH SIDE OF THE TUTT.
THIS HAS LED TO THE FORMATION OF MAINLY STRATIFORM CONVECTION IN
THE CNMI NEAR AND NORTH OF TINIAN AND SAIPAN. 88D SCAN SHOWS
MAINLY VIRGA FALLING FROM THE CLOUDS OVER SAIPAN AND TINIAN. IF
THE RAIN AND CLOUDS PERSIST...A FORECAST UPDATE WILL PROBABLY BE
NECESSARY. OTHERWISE...SURFACE RIDGING REMAINS IN CONTROL OF THE
WEATHER. VAD WIND PROFILE AND PWAT OF 2.09 FROM THE 12Z SOUNDING
SUGGEST ISOLATED PM THUNDER FOR THE MARINE ZONES WEST OF GUAM
TODAY.

&&

.DISCUSSION...
ONLY MINOR CHANGES TO FORECAST GRIDS NEEDED BEYOND THE FIRST
PERIOD. MODEL GUIDANCE KEEPS RELATIVELY DRY PATTERN IN PLACE
THROUGH THE FORECAST PERIOD AS WINDS GRADUALLY BACK FROM EAST-
SOUTHEAST TO EAST-NORTHEAST WITH TIME. RIDGE BUILDING NORTH OF THE
MARIANAS WILL TIGHTEN THE PRESSURE GRADIENT AND CAUSE A MODEST
INCREASE IN WIND SPEEDS DURING THE SECOND HALF OF THE WEEK. SURF
ON NORTH AND EAST FACING REEFS SHOULD BUILD ABOVE THE MODERATE RIP
CURRENT RISK THRESHOLD BY MID WEEK.

&&

.EASTERN MICRONESIA...
SHOWERS ASSOCIATED WITH TRADE-WIND CONVERGENCE ARE EXPECTED TO
REMAIN NORTH OF THE MARSHALLS THROUGH AT LEAST MONDAY. SATELLITE
IMAGERY SHOWS DEVELOPING CONVECTION ALONG A SURFACE TROUGH
APPROACHING THE DATE LINE. MODELS HANDLE THIS FEATURE WELL AS FAR
AS PLACEMENT SO OPTED FOR SCATTERED SHOWER COVERAGE FOR MAJURO
BEGINNING LATE MONDAY OR MONDAY NIGHT. HOWEVER...TIMING OF THIS
FEATURE IS STILL QUESTIONABLE AND MAY OUTPACE WHAT MODELS ARE
CURRENTLY SHOWING. RELATIVELY DRY CONDITIONS SHOULD PREVAIL OVER
KOSRAE AND POHNPEI THROUGH MONDAY. MODEL GUIDANCE SUGGEST THE
AFOREMENTIONED TROUGH WILL ATTENUATE BEFORE IT REACHES KOSRAE OR
POHNPEI.

&&

.WESTERN MICRONESIA...
MODELS SHOW SURFACE TROUGH NEARING CHUUK MAY PROVIDE A ROUND OF
SHOWERS TODAY BUT IT APPEARS MOST OF THE CONVECTION HAS ALREADY
PASSED TO THE WEST. ACCORDINGLY...ONLY ISOLATED SHOWER COVERAGE
IS EXPECTED. MODELS HAVE BACKED OFF ON SHOWER COVERAGE FOR
YAP...KEEPING MOST OF THE ACTIVITY TO THE NORTH OF YAP TODAY.
THIS WILL BE WHERE LOW-LEVEL CONVERGENCE TO THE SOUTHEAST OF 16W
IS STRONGEST. HOWEVER...AN AREA OF CONVECTION CURRENTLY A COUPLE
HUNDRED MILES TO THE SOUTHEAST OF YAP MAY STILL PROVIDE SCATTERED
SHOWERS THERE LATER TODAY AND TONIGHT. KOROR SHOULD SEE MOSTLY
DRY CONDITIONS THROUGH THE FORECAST PERIOD AS A RIDGE AXIS BUILDS
OVER THE AREA.

&&

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

$$

MCELROY/WILLIAMS

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