Subject: Western Pacific: Synoptic Discussion For The Marianas

From: LDM Weather <[email-masked]>
Date: Tue, 16 Nov 2010 14:57:32 -0600

968 
FXPQ60 PGUM 162056
AFDPQ 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
656 AM CHST WED NOV 17 2010

.SYNOPSIS...
INGREDIENTS SEEM TO BE LINING UP FOR SIGNIFICANT RAINFALL NEAR
GUAM AND ROTA. SHEAR LINE IS STILL HOVERING SOUTH OF GUAM NEAR
12N. ANIMATED WATER VAPOR SATELLITE IMAGERY SUGGESTS A TUTT IS
DEVELOPING IN THE PHILIPPINE SEA. THIS MEANS INCREASING UPPER-
LEVEL DIVERGENCE OVER THE FORECAST ZONES. HOWEVER...LATEST IR
SATELLITE IMAGERY SUGGESTS DEEP CONVECTION ALONG THE LEADING EDGE
OF THE SHEAR LINE WAS PROPAGATING SOUTHWARD.

&&

.DISCUSSION...
NEAR TERM MODEL GUIDANCE IS IN GOOD AGREEMENT IN BRINGING THE
SHEAR LINE BACK TO THE NORTH OVER GUAM AND ROTA DURING THE NEXT
24 HOURS OR SO. RADAR IMAGERY...IF AVAILABLE...WOULD BE USEFUL IN
DIAGNOSING THE MESOSCALE BEHAVIOR OF THE CONVECTION IN THE
VICINITY OF THE SHEAR LINE IF IT WERE AVAILABLE. IF THE DEEP
CONVECTION CONTINUES TO REMAIN SOUTH OF GUAM...FORECAST UPDATE
WILL BE NEEDED TO REDUCE CLOUD COVER AND POPS FOR GUAM AND ROTA
TODAY AND TONIGHT. SIGNAL FOR SCATTERED SHOWERS OVER GUAM AND ROTA
FADES IN THE MODELS AFTER TONIGHT AS THE SHEAR LINE BECOMES MORE
DIFFUSE AND SHIFTS OFF TO THE NORTH. NO SIGNIFICANT WEATHER MAKERS
ARE FORESEEN DURING THE REMAINDER OF THE FORECAST PERIOD.

&&

.MARINE...
IPAN BUOY CONTINUES TO REPORT COMBINED SEAS AROUND 8 FEET COMING
FROM THE ENE. THIS AGREES WELL WITH THE MARINE SWELL GRIDS SO NO
SHORT TERM ADJUSTMENTS WERE NECESSARY. STILL EXPECT WINDS...SEAS
AND SURF TO PEAK TODAY AND TONIGHT JUST BELOW ADVISORY CRITERIA.
A SLIGHT NORTHEAST SWELL WILL HELP MAINTAIN MODERATE RIP CURRENT
RISK LEVEL SURF ON NORTH FACING EXPOSURES THROUGH EARLY NEXT
WEEK.

&&

.EASTERN MICRONESIA...
CONVECTION ALONG THE BACK SIDE OF A TROUGH WEST OF POHNPEI IS
SLOW TO EXIT THE AREA SO WILL CARRY SCATTERED SHOWERS UNTIL
MIDDAY TODAY. A DEVELOPING BAND OF CONVECTION IS VISIBLE IN IR
SAT IMAGERY STRETCHING FROM THE NORTH END OF THE TROUGH NEAR
POHNPEI EASTWARD TO JUST BEYOND THE MARSHALLS BETWEEN 7N AND 8N.
KWAJALEIN RADAR SHOWS SCATTERED SHOWERS SOUTH OF KWAJALEIN WHILE
SATELLITE IMAGERY SHOWS THE MAJURO MARINE ZONE BISECTED WITH
SCATTERED SHOWERS IN THE NORTHERN HALF. ACCORDINGLY...HAVE
INCLUDED SCATTERED SHOWERS THIS MORNING NORTH OF THE MAJURO
ATOLL. AS THE CONVECTION SHIFTS FARTHER WESTWARD...SHOWER
COVERAGE OVER THE MAJURO MARINE ZONE SHOULD DECREASE TO ISOLATED
BY NOON TODAY. PROXIMITY OF TRADE-WIND CONVERGENCE ZONE WILL KEEP
SKIES OVER MAJURO MOSTLY CLOUDY OVER THE WEEKEND.

&&

.WESTERN MICRONESIA...
CONDITIONS HAVE QUIETED DOWN NEAR CHUUK FOR THE SHORT TERM...BUT
THE NORTHERN TIP OF A TRADE-WIND TROUGH WILL PASS THROUGH TONIGHT
AND THURSDAY...BRINGING SCATTERED SHOWERS TO THE AREA. MODEL
GUIDANCE BRINGS AN END TO SCATTERED SHOWERS BY LATE TOMORROW AND
PORTENDS DRIER CONDITIONS FOR THE REMAINDER OF THE WEEK. A NEAR-
EQUATORIAL TROUGH PASSING SOUTH OF KOROR WILL COMBINE WITH TWO
SEPARATE WEAK CIRCULATIONS SE OF YAP AND SOUTHWEST OF CHUUK TO
POSE MORE OF A FORECAST CHALLENGE FOR THE NEXT SEVERAL DAYS IN
THE WEST. FORTUNATELY...LATEST GFS40 IS SHOWING BETTER CONSENSUS
WITH RECENT IR SATELLITE IMAGERY TRENDS. ACTIVE CONVECTION IS
CONSOLIDATING SOUTH AND SOUTHEAST OF KOROR PALAU BETWEEN THE
EQUATOR AND 5N FROM 133E TO 141E...WHILE CIRRUS OUTFLOW PASSES
NORTHWARD OVER YAP AND PALAU. GFS KEEPS SHOWERS ISOLATED OVER
BOTH LOCATIONS FOR THE NEXT COUPLE OF DAYS BUT INDICATES
SCATTERED SHOWERS WILL MOVE IN BY SATURDAY. THE WEATHER COULD
POSSIBLY ARRIVE AS EARLY AS FRIDAY NIGHT OVER YAP AS THE TROUGH
MOVES ACROSS WESTERN MICRONESIA. FORECAST UPDATES ARE NOT OUT OF
THE QUESTION FOR THE NEXT COUPLE OF DAYS...ESPECIALLY FOR
YAP...AS ACTIVE CONVECTION PERSISTS ALONG 11N NORTHWEST OF YAP
AND SOUTHWEST OF GUAM.

&&

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

$$

MCELROY/W. AYDLETT

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