Subject: Western Pacific: Synoptic Discussion For The Marianas

From: LDM Weather <[email-masked]>
Date: Sun, 27 Jan 2008 01:48:25 -0600

000 
FXPQ60 PGUM 270748
AFDPQ 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
548 PM CHST SUN JAN 27 2008

.SYNOPSIS...
SHEAR LINE SEEN SOUTHEAST OF GUAM ON RECENT VISIBLE SATELLITE
IMAGERY IS BEGINNING TO BACK UP TOWARD THE NORTHWEST. CLOUD COVER
TO THE REAR OF THE SHEAR LINE HAS BEEN GRADUALLY DECREASING
DURING THE COURSE OF THIS SHIFT. 88D LOOP SHOWS ONLY A FEW
SPRINKLES.

&&

.DISCUSSION...
BASED ON DOWNTREND OF CLOUD COVER SEEN ON SATELLITE WILL ADHERE
TO THE PARTY LINE CALLING FOR PC SKIES AFTER TONIGHT. MODELS ARE
IN AGREEMENT IN BACKING THE SHEAR LINE TO THE NW AND THRU THE
MARIANAS MON AM. TRADE-WIND SURGE WILL STILL BE IN STORE FOR THE
FIRST HALF OF THE WEEK. MODELS HINT A SOME WEAK TRADE-WIND
DISTURBANCES LATER IN THE WEEK...BUT WILL PASS ON SCATTERED
POPS/ADDED CLOUD COVER FOR NOW. HAVE REDUCED POPS TO SLIGHT
CHANCE MON NITE THROUGH TUE NITE BASED ON SHALLOW LOW LEVEL
MOISTURE SEEN IN GFS TIME-HEIGHT AND CLOSE TO ZERO QPF. RAN GUST
GRIDS THRU DAY 9 USING A 35 PERCENT FACTOR AND 5 KNOT GUST
DIFFERENTIAL. USED GFS40 WINDS THRU DAY 3 AND GFS75 WINDS DAYS 4
AND 5.

&&

.EASTERN MICRONESIA...
THE BIGGEST STORY FOR THE EASTERN MICRONESIAN STATES WILL BE THE
SURF BUILDING ALONG NORTH FACING REEFS DUE TO LONG PERIOD SWELLS.
LATEST MODEL GUIDANCE INDICATES SURF HEIGHTS AT 9 TO 11 FT FOR
CHUUK AND POHNPEI BY THIS EVENING THAT LASTS THRU WEDNESDAY...AND
FOR KOSRAE BY MONDAY EVENING INTO WEDNESDAY. HIGH SURF ADVISORY
IS ISSUED FOR CHUUK AND POHNPEI...AND ANTICIPATE THE SAME FOR
KOSRAE MONDAY AFTERNOON.

WEATHER WILL BE RELATIVELY QUIET AS DRY NORTHEAST TRADES CONTINUE
TO DOMINATE THE AREA THROUGH THE PERIOD. MODELS ARE A LITTLE BIT
BULLISH ON THE WEAK TRADE DISTURBANCE CURRENTLY MOVING WESTWARD
THRU THE MARSHALL ISLANDS TOWARD CHUUK BY MID WEEK. BOTH VISIBLE
SATELLITE IMAGERY AND 00Z SOUNDINGS SUGGEST SHOWERS SHOULD REMAIN
ISOLATED WITH ABUNDANT DRY AIR AT MID TO UPPER LEVELS. FORECAST
IS VERY SIMILAR TO THE PREVIOUS ONE.

&&

.WESTERN MICRONESIA...
COOL DRY AIR ASSOCIATED WITH HIGH PRESSURE SOUTHEAST OF JAPAN
WILL PROVIDE FAIRER WEATHER FOR PALAU AND YAP THRU TONIGHT. THE
REMNANTS OF THE OLD SHEAR LINE TO THE SOUTHEAST ARE EXPECTED TO
MOVE OVER BOTH ISLANDS DURING MONDAY WITH SOME CLOUDINESS. AFTER
THAT... DRY TRADE PATTERN FROM THE EAST WILL TAKE CONTROL INTO
FRIDAY. ALONG WITH THE HIGH SURF BUILDING ON NORTHERN
SHORES...CHUUK IS UNDER THE SAME WEATHER PATTERN MENTIONED ABOVE
AS THE EASTERN MICRONESIAN STATES.

&&

.MARINE...
IPAN BUOY CURRENTLY COMES IN WITH ONLY 6 FT SEAS. 6 TO 7 FOOT
NORTH SWELL IS BLOCKED AT THE BUOY...BUT PYTHAGOREAN COMPUTATION
GIVES 9 FOOT COMBINED SEAS. BELIEVE SMALL CRAFT ADVISORY FOR
COMBINED SEAS WILL BECOME NECESSARY ON TUESDAY AS THE TRADE WIND
SURGE REVS UP. IF THE SURGE IS ROBUST ENOUGH...WE MAY NEED TO
SWAP EXPOSURES FROM NORTH THROUGH TUESDAY MORNING TO EAST BY MID
WEEK ON THE HIGH SURF ADVISORY.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...HIGH SURF ADVISORY UNTIL 6 AM CHST TUESDAY FOR GUZ001>004.

MARIANAS WATERS...NONE.
&&

$$

MCELROY/CHAN

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