Subject: Western Pacific: Synoptic Discussion For The Marianas

From: LDM Weather <[email-masked]>
Date: Thu, 25 Nov 2010 01:45:05 -0600

278 
FXPQ60 PGUM 250744
AFDPQ 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
544 PM CHST THU NOV 25 2010

.SYNOPSIS...
SATELLITE IMAGERY SHOWS A RATHER COMPACT TRADE-WIND DISTURBANCE
PASSING TO THE SOUTH OF GUAM. NO SIGNIFICANT UPSTREAM WEATHER
MAKERS COULD BE SEEN ON SATELLITE EASTWARD TO THE DATE LINE.
RADAR SHOWS FEW IF ANY SHOWERS OVER THE FORECAST DOMAIN AT THIS
TIME.

&&

.DISCUSSION...
00Z PWAT CAME IN AT 2.04 INCHES. BELIEVE SUBSTANTIAL DRYING HAS
OCCURRED SINCE THEN WITH LATEST WATER VAPOR SATELLITE IMAGERY
INDICATING INCREASING UPPER-LEVEL CONVERGENCE. LATEST GFS TIME-
HEIGHT CROSS SECTION SHOWS VERY SHALLOW MOISTURE OVERNIGHT
TONIGHT SO WILL REDUCE POPS TO SLIGHT CHANCE. SAME GUIDANCE ALSO
SUGGESTS SIMILAR CONDITIONS ARE POSSIBLE AGAIN ON SATURDAY BUT
WILL HOLD OFF ON THIS FOR NOW. OTHERWISE...PARTLY CLOUDY SKIES
AND ISOLATED SHOWERS ARE FORESEEN THROUGH THE FORECAST PERIOD.

&&

.MARINE...
PRIMARY FORECAST CONCERN CENTERS ON THE LONG PERIOD SWELL THAT
HAVE BEEN GENERATED DURING THE PAST SEVERAL DAYS NORTH OF WAKE
ISLAND. BELIEVE SURF ON NORTH AND NORTHEAST FACING EXPOSURES WILL
REMAIN HIGH FOR AT LEAST THE NEXT SEVERAL DAYS. ASCAT IMAGERY HAS
CONTINUED TO SHOW THE FETCH GENERATION AREA FOR THESE SWELL HAS
BEEN IN PLACE SINCE TUESDAY MORNING. THE LONG PERIOD NNE SWELL
CONTINUED TO BE BLOCKED AT THE IPAN BUOY. OBS FROM SAIPAN EMO ARE
UNAVAILABLE DUE TO A BUDGET SHORTFALL. SWELL MAY BE BLOCKED BY
SAIPAN AS WELL...BUT WILL ERR ON THE SIDE OF CAUTION AND MAINTAIN
THE SURF FORECAST BASED ON THE WAVE WATCH MODEL SWELL GRIDS.

&&

.EASTERN MICRONESIA...
CONVECTION ASSOCIATED WITH A TRADE-WIND DISTURBANCE MOVING OVER
THE RMI HAS REMAINED ALMOST ENTIRELY IN THE NORTHERN COASTAL
WATERS OF MAJURO TODAY BUT IS STARTING TO NUDGE SOUTHWARD OVER
MAJURO ITSELF. SATELLITE AND MODEL DATA SUGGESTS ONGOING SHOWERS
THROUGH THE EVENING OVER MAJURO BEFORE TAPERING OFF LATE TONIGHT.
SHOWERS REMAIN WELL TO THE NORTH OF KOSRAE WITH RELATIVELY DRY
CONDITIONS CONTINUING THROUGH EARLY NEXT WEEK. ASCAT ANALYSIS
SHOWS ANOTHER DISTURBANCE MOVING OVER POHNPEI...WITH SHOWERS
ANTICIPATED TO CONTINUE TONIGHT. MODEL SOLUTIONS SHOWS ACTIVITY
DISSIPATING STEADILY BEFORE THE WEEKEND ACROSS ALL FORECAST
LOCATIONS...WITH CLEARING AND DRY NORTHEAST TRADE-WIND FLOW
RETURNING OVER THE REGION FOR THE WEEKEND.

&&

.WESTERN MICRONESIA...
VISIBLE SATELLITE IMAGERY SHOWS CONVECTION SOUTH AND EAST OF
CHUUK. EXPECT MOST OF THE ACTIVITY TO PASS SOUTH OF THE AREA
THROUGH TONIGHT. THE CLEARING TREND ACROSS THE RMI AND POHNPEI
WILL EXTEND TOWARD CHUUK BY THE WEEKEND...WITH DRY CONDITIONS TO
CONTINUE THROUGH EARLY NEXT WEEK. SURFACE TROUGH NEARING YAP
SHOULD BRING A PERIOD OF SCATTERED SHOWERS TO BOTH YAP AND KOROR
FRIDAY. MODELS INDICATE THE TROUGH SHOULD SLOW ITS WESTWARD
PROGRESSION ALLOWING SHOWERS TO LINGER OVER KOROR THROUGH MOST OF
SATURDAY...EVENTUALLY CLEARING OUT EARLY SUNDAY. A LARGE AREA OF
NNE GALES ASSOCIATED WITH A STRONG MID-LATITUDE LOW PRESSURE
SYSTEM CENTERED NORTH OF WAKE ISLAND HAS GENERATED SWELL CAPABLE
OF CAUSING HIGH SURF ON NORTH SHORES OF CHUUK BEGINNING LATE
TONIGHT AND EARLY FRIDAY MORNING. MANUAL CALCULATION OF GENERATED
SWELL YIELDED SIMILAR RESULTS AS THE WAVE WATCH MODEL...ALBEIT
MARGINAL FOR AN ADVISORY. NONETHELESS...A HIGH SURF WAS ISSUED
FOR CHUUK BEGINNING LATE TONIGHT AND ENDING SOMETIME ON SATURDAY.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...HIGH SURF ADVISORY UNTIL 3 PM CHST SUNDAY FOR GUZ001>004.

MARIANAS WATERS...NONE.
&&

$$

MCELROY/WILLIAMS

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