Subject: Western Pacific: Synoptic Discussion For The Marianas

From: LDM Weather <[email-masked]>
Date: Sat, 12 Jan 2008 13:44:42 -0600

411 
FXPQ60 PGUM 121944
AFDPQ 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
544 AM CHST SUN JAN 13 2008

.SYNOPSIS...
WEATHER MAP LOOKS RELATIVELY QUIET. IR SATELLITE IMAGERY SHOWS 
TRADE-WIND DISTURBANCES UPSTREAM OF THE MARIANAS...CENTERED NEAR 
155E AND 162E. A ROBUST TRADE-WIND FETCH GENERATION REGION WAS 
EVIDENT IN THE EVENING QUIKSCAT EAST OF THE MARIANAS. 12Z SOUNDING 
SHOWED A WELL DEFINED TRADE-WIND INVERSION AT 800 MB AND A PWAT OF 
1.64 INCHES.

&&

.DISCUSSION...
PRIMARY FORECAST CONCERN RELATES TO SEAS AND SURF. PLEASE SEE THE 
MARINE DISCUSSION SECTION FOR MORE DETAILS.

INHERITED FORECAST GRIDS IN GOOD SHAPE. MADE MINOR GRID EDITS 
INCLUDING REFRESHING DEW POINTS AND WINDS. REDUCED OVERNIGHT LOWS 
TONIGHT AS RAIN-COOLED AIR WILL BE A FACTOR. STILL LOOKS LIKE 
TRADE-WIND DISTURBANCES WILL BEGIN ARRIVING LATER THIS AFTERNOON. 
LOW MODEL QPFS ARGUE FOR MAINTAINING MOSTLY CLOUDY/ISOLATED WORDING 
THROUGH MONDAY NIGHT. RELATIVELY DRY TRADE-WIND REGIME TAKES HOLD 
TUESDAY THROUGH THE END OF THE FORECAST PERIOD. GFS STILL HINTS AT A 
SHEAR LINE KNOCKING ON THE DOOR ON DAY NINE...SO LEFT MOSTLY CLOUDY 
SKIES IN THE GRIDS FOR THEN.

&&

.EASTERN MICRONESIA...
TRADE-WIND CONVERGENCE IS STILL IMPACTING POHNPEI AND THE MARSHALL 
ISLANDS WITH MORE SHOWERS AND SHOULD LAST UNTIL TUESDAY. A FEW
THUNDERSTORMS ARE POSSIBLE OVER POHNPEI DUE TO DIFFLUENT FLOW
ALOFT. MEANWHILE...KOSRAE IS SOUTH OF THE ACTION FOR NOW BUT SHOWERS
ARE EXPECTED TO SPREAD OVER KOSRAE MONDAY NIGHT THROUGH WEDNESDAY.
A DRIER TRADE-WIND REGIME SHALL RETURN TO THE ENTIRE AREA BY
THURSDAY.

LATEST WW3 MODEL OUTPUT INDICATES SURF HEIGHTS WILL DROP BELOW HIGH 
SURF ADVISORY CRITERIA TONIGHT AND MONDAY FOR CHUUK...POHNPEI AND
KOSRAE...AND THEN RISE BACK TO ADVISORY LEVELS BY MONDAY NIGHT.
SURF HEIGHTS ON MAJURO ARE EXPECTED TO REMAIN AT ADVISORY LEVELS
THROUGH MONDAY.

&&

.WESTERN MICRONESIA...
TRADE-WIND CONVERGENCE SHOWERS ARE ENTERING COASTAL WATERS EAST OF CHUUK
THIS MORNING AND WILL SPREAD OVER WENO ISLAND BY THIS AFTERNOON.
SHOWERS AND A SLIGHT CHANCE FOR THUNDER WILL PERSIST THROUGH TUESDAY.
FRESH TRADES SHALL ARRIVE FROM THE EAST ON WEDNESDAY. THE NEAR-
EQUATORIAL TROUGH WILL BE TOO FAR SOUTH TO PRODUCE SCATTERED
SHOWERS ON PALAU AND YAP THROUGH TUESDAY. A TRADE-WIND DISTURBANCE
CURRENTLY NEAR CHUUK WILL FINALLY PROPAGATE WESTWARD ALONG THE
NEAR-EQUATORIAL TROUGH AND BRING INCLEMENT WEATHER TO KOROR AND
YAP BY MIDWEEK.

&&

.MARINE...
SWELL GRID SET LOOKS GOOD AND KEEPS TRADE-WIND SWELL DOMINANT...WITH 
SECONDARY NORTH SWELL EVENT PEAKING LATE WED AND EARLY THURSDAY. 
INITIALIZED TRADE-WIND SWELL USING CDIP SEA AND SWELL PLOT FROM THE 
IPAN BUOY. LOOKS LIKE MODERATE RIP CURRENT RISK ON NORTH AND EAST 
FACING REEFS DURING THE NEXT FEW DAYS. SURF ON EAST FACING REEFS 
WILL BE CLOSE TO THE ADVISORY THRESHOLD...BUT BELIEVE SURF HAS 
PEAKED FOR NOW AND IS BEGINNING TO FALL PER BUOY OBS AND WAVE WATCH 
GUIDANCE.

&&

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

$$

MCELROY/CHAN

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