Subject: Western Pacific: Synoptic Discussion For The Marianas

From: LDM Weather <[email-masked]>
Date: Mon, 07 Jan 2008 01:20:51 -0600

411 
FXPQ60 PGUM 070720
AFDPQ 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
520 PM CHST MON JAN 7 2008

.SYNOPSIS...
INHERITED FORECAST AND SYNOPTIC FEATURES ARE IN SYNC WITH NO 
FORECAST UPDATES REQUIRED. MAIN WEATHER PLAYER IS NOW THE SHEAR LINE 
BISECTING THE FORECAST ZONES. THE ONLY OTHER UPSTREAM SYSTEM OF NOTE 
IS A BROAD AND WEAK TRADE-WIND DISTURBANCE CENTERED NORTH OF 
POHNPEI. SURFACE HIGH PRESSURE SOUTHEAST OF JAPAN WAS BUILDING IN 
THE WAKE OF LOW PRESSURE HEADED EASTWARD TOWARD THE DATE LINE.

&&

.DISCUSSION...
TIMING OF SHEAR LINE PASSAGE WAS ALREADY REPRESENTED WELL IN THE 
GRIDS. MODEL GUIDANCE SUGGESTS SCATTERED POPS WILL TAPER FROM NORTH 
TO SOUTH TUESDAY NIGHT...SO MODIFIED THE GRIDS ACCORDINGLY. REDUCED 
NEAR-TERM HIGHS AND LOWS TO GIVE WEIGHT TO INCREASED CLOUD COVER AND 
RAIN-COOLED AIR. HAVE ADDED MOSTLY CLOUDY SKIES FOR WEDNESDAY TO 
RECOGNIZE PASSAGE OF TRADE-WIND DISTURBANCE CURRENTLY NORTH OF 
POHNPEI AS SEEN BY BOTH THE ECMWF AND GFS. OTHERWISE...LEFT FORECAST 
GRIDS ALONE.

&&

.EASTERN MICRONESIA...
RELATIVELY DRY WEATHER ACROSS EASTERN MICRONESIA OVER THE NEXT
COUPLE DAYS. BY MID WEEK BOTH GFS AND ECMWF PROG A TRADE SURGE
EXTENDING WEST BEYOND POHNPEI. HAVE INCLUDED SCATTERED POPS IN THE
FORECAST TO REFLECT THIS.

ON SATURDAY...SURF HEIGHT CALCULATIONS USING WW3 COMBINED SEAS
MODEL OUTPUT APPROACH 16 FEET ON MAJURO. THIS WILL OCCUR DURING
HTE TIME OF NEW MOON. A SPECIAL WEATHER STATEMENT FOR INUNDATION
OVER PARTS OF THE ATOLL MAY BE NECESSARY. THIS SITUATION WILL BE
MONITORED CLOSELY.

&&

.WESTERN MICRONESIA...
KEPT MOSTLY CLOUDY AND ISOLATED SHOWERS IN WORDING FOR YAP AND PALAU 
THROUGH MID WEEK. FOR THE LATTER HALF OF THE WEEK...FORECAST WILL 
DEPEND ON TRACK AND INTENSITY OF CIRCULATION THAT LATEST 
GFS...NOGAPS AND ECMWF SOLUTIONS TAKE OVER PALAU. THIS CIRCULATION
IS APPARENT ON THE LATEST VISIBLE SATELLITE IMAGERY. FOR NOW HAVE
BROUGHT IN SCATTERED PRECIP AND INCREASED WINDS...BUT LEFT OUT
THUNDER. FARTHER TO THE EAST...CHUUK WILL REMAIN FAR ENOUGH WEST
OF THE AFOREMENTIONED TRADE SURGE TO NEGATE SIGNIFICANT WEATHER
DEVELOPMENT.

&&

.MARINE...
MAINTAINED PREVIOUS FORECAST PHILOSOPHY. NO MAJOR ADJUSTMENTS TO 
SWELL GRIDS. HAVE ISSUED SMALL CRAFT ADVISORIES IN CONJUNCTION WITH 
COMBINED SEAS REACHING 10 FEET JUST NORTH OF THE SHEAR LINE. NO HIGH 
SURF ADVISORIES ARE ANTICIPATED DURING THE NEXT FEW DAYS. WAVE WATCH 
TABULAR DATA SUGGEST A MARGINAL HIGH SURF EVENT WILL BE POSSIBLE ON 
EAST-FACING REEFS ON SATURDAY.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...NONE.
MARIANAS WATERS...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 6 PM CHST TUESDAY 
     FOR PMZ153-154.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 6 AM CHST 
     WEDNESDAY FOR PMZ151-152.

&&

$$

MCELROY/LEE

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