Subject: Western Pacific: Synoptic Discussion For The Marianas

From: LDM Weather <[email-masked]>
Date: Sun, 17 Oct 2010 16:54:20 -0500

541 
FXPQ60 PGUM 172153
AFDPQ 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
753 AM CHST MON OCT 18 2010

.SYNOPSIS...
PGUA WSR-88D SHOWS ISOLATED SHOWERS MOVING THROUGH THE MARIANAS.
AN UPPER-LEVEL LOW NORTH OF THE MARIANAS IS GENERATING SCATTERED
SHOWERS WELL EAST OF THE MARIANAS WHICH MAY AFFECT THE ISLANDS
LATER THIS WEEK.

&&

.DISCUSSION...
WESTWARD PROGRESS OF THE SHOWER AREA MENTIONED ABOVE IS LIMITED.
THEREFORE DID NOT CHANGE THE FORECAST AT THIS TIME. FOR NOW FAIRLY
DRY AND PARTLY CLOUDY IS THE WORD...BUT WILL HAVE TO MONITOR THAT
AREA TO THE EAST. THE GFS40 TRIES TO BRING A CIRCULATION FROM NEAR
KWAJALEIN TO NORTHEAST OF THE MARIANAS. THE MODEL PICTURES
EXTENSIVE DEEP CONVECTION OVER THE CIRCULATION WHICH IR SATELLITE
SHOWS IS SIMPLY NOT THERE. THEREFORE WOULD FAVOR THE ECMWF-HIRES
SOLUTION WHICH KEEPS IT AS A TROUGH. NOT SURPRISINGLY THE ECMWF
SOLUTION IS DRIER...ALTHOUGH AT LEAST THIS RUN THE DIFFERENCE IS
LESS. WITH EVEN THE GFS40 TRENDING A BIT DRIER OVER THE NEXT 10
DAYS...THE CURRENT ISOLATED SHOWERS GRIDS LOOKED JUST FINE.

&&

.EASTERN MICRONESIA...
CONVECTION HAS STEADILY DISSIPATED NEAR KWAJALEIN AND MAJURO BUT 
WIDESPREAD CLOUDINESS STILL REMAINS FROM THE CENTRAL MARSHALLS 
NORTHWARD TO NEAR WAKE ISLAND. WEAK SOUTH-SOUTHWEST WINDS HAVE 
MAJURO HAVE TURNED MORE SOUTHEASTWARD WHICH AGREES WELL WITH LATEST 
MODELS. DRY SOUTHEAST TRADE WINDS WILL CONTINUE TO MOVE INTO THE 
REGION TODAY AND TONIGHT LIMITING THE CHANCES FOR PRECIPITATION AT 
ALL LOCATIONS FOR THE WEEK. GFS IS RESOLUTE IN DEVELOPING A 
CIRCULATION NORTHWEST OF KWAJALEIN TODAY AND TONIGHT. UKMET 
INITIALLY AGREES BUT THEN BACKS OFF BY TUESDAY NIGHT...JOINING ECMWF 
IN DEPICTING A WSW-ENE ORIENTED TROUGH JUST NORTH OF 10N...NORTH OF 
POHNPEI. GFS ALSO SEEMS A BIT AGGRESSIVE IN DEVELOPING THE 
CIRCULATION WITH 20 TO 30 KT WINDS ALONG THE EASTERN EDGE BY 
WEDNESDAY...BUT THE PAST SEVERAL MODEL RUNS MAINTAIN A NORTHWESTWARD 
MOVEMENT...INCREASING CONFIDENCE THAT ITS IMPACT ON EASTERN 
MICRONESIA WILL BE MINIMAL. 

&&

.WESTERN MICRONESIA...
SCATTERED SHOWERS REMAIN JUST WEST OF KOROR...BUT BASED ON SATELLITE 
ANIMATIONS AND MODEL DATA SHOWING THE BULK OF MOISTURE REMAINING TO 
THE WEST...DECIDED TO DROP BACK TO ISOLATED SHOWERS FOR TODAY AND 
THE REST OF THE WEEK. MUCH THE SAME GOES FOR YAP. A WEAK CIRCULATION 
SOUTHEAST OF YAP THAT IS POORLY DEFINED BY MODELS...EXCEPT FOR 
UKMET...WILL SLOWLY DRIFT NORTHWESTWARD BRINGING A SLIGHT INCREASE 
IN SHOWERS FOR YAP TUESDAY AND WEDNESDAY. AFTERWARD...A DRY 
SOUTHEAST TRADE-WIND PATTERN SPREADING WESTWARD FROM POHNPEI AND 
CHUUK WILL SUPPRESS SHOWERS AT YAP AND KOROR. DECIDED TO REDUCE 
COMBINED SEAS FOR YAP AND KOROR BASED ON LATEST ALTIMETRY DATA 
SHOWING LOWER WAVE HEIGHTS COMPARED TO DATA OF THE PAST COUPLE DAYS. 

&&

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

$$

STANKO/W. AYDLETT

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