820
FXPQ60 PGUM 040715
AFDPQ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
515 PM CHST THU APR 4 2019
MARIANAS SYNOPSIS
SATELLITE SHOWS WIDESPREAD CLOUDINESS ACROSS GUAM AND ROTA WATERS,
ASSOCIATED WITH A TROUGH EXTENDING NORTHWARD FROM A WEAK CIRCULATION
WELL SOUTH OF GUAM NEAR 5N145E. ON RADAR, SCATTERED MAINLY LIGHT
SHOWERS ARE SEEN ACROSS GUAM AND ROTA. FARTHER NORTH, TINIAN AND
SAIPAN ARE IN A DRY SLOT BETWEEN THE WEATHER OVER GUAM/ROTA AND A
WELL-DEFINED SHEAR LINE UP NORTH AROUND ANATAHAN. OTHERWISE, MODERATE
TRADE WINDS ARE PRESENT ACROSS THE REGION, WITH 4 TO 6 FT SEAS AT
THE GUAM BUOYS.
DISCUSSION
THE DISTURBANCE SOUTH OF GUAM SHOWS NO ORGANIZATION ON SATELLITE
IMAGERY, AND THE ASSOCIATED CONVECTION HAS WEAKENED THROUGH THE
DAY. WHILE EARLIER RUNS OF THE GFS HAD HELD OUT SOME HOPE FOR SOME
MUCH-NEEDED RAINFALL FOR THE MARIANAS, THE LATEST GFS KEEPS ANY
SIGNIFICANT RAIN SOUTH OF THE REGION, IN FAIR AGREEMENT WITH THE
ECMWF, WITH LESS THAN AN INCH OF ACCUMULATED RAINFALL IN BOTH MODELS
FOR THE NEXT TEN DAYS. FOR TONIGHT, HAVE GONE WITH SCATTERED SHOWERS
OVERNIGHT FOR GUAM AND ROTA BASED ON CURRENT RADAR AND SATELLITE,
BUT NOT EXPECTING MUCH MORE THAN A TENTH OF AN INCH. FOR THE NEXT
FEW DAYS, WEATHER STILL LOOKS SOMEWHAT UNSETTLED, AND HAVE RETAINED
MOSTLY CLOUDY SKIES AND ISOLATED SHOWERS THROUGH SATURDAY NIGHT.
AFTER THAT, HAVE STAYED WITH THE ECMWF, WHICH SHOWS A RETURN TO A
SHALLOW SURFACE-BASED MOIST LAYER TOPPED BY VERY DRY AIR ALOFT,
RESULTING IN JUST A SLIGHT CHANCE OF LIGHT SHOWERS NEXT WEEK.
MARINE
MARINE CONDITIONS WILL FEATURE MODERATE TO FRESH WINDS AND MODERATE
5-7 FT SEAS THROUGH SATURDAY NIGHT, FOLLOWED BY A SLOW DECLINE IN
SEAS AND WINDS NEXT WEEK. THE MAIN CHANGE OVER THE NEXT FEW DAYS
WILL BE THE DECREASING NORTH SWELL, FROM 4 FEET TONIGHT TO 2 FEET
ON SUNDAY. RIP RISK WILL REMAIN MODERATE ON EAST FACING SHORES
THROUGH THE FORECAST PERIOD, AND ON NORTH FACING SHORES THROUGH
SATURDAY NIGHT.
FIRE WEATHER
A DAMP PATTERN OF CLOUDS AND ISOLATED SHOWERS, ALONG WITH DECREASING
WINDS LATER ON, SHOULD MITIGATE THE WILDFIRE POTENTIAL THROUGH THE
WEEKEND. BUT WITH A RETURN TO DRY WEATHER NEXT WEEK, AND THE KBDI
ALREADY IN THE EXTREME RANGE ABOVE 600, FIRE CONDITIONS WILL BE
SET TO WORSEN AGAIN.
EASTERN MICRONESIA
A DISTURBANCE EMBEDDED IN THE NEAR-EQUATORIAL TROUGH IS CENTERED
SOUTHEAST OF KOSRAE NEAR 2N168E AND A LARGE AREA OF SHOWERS IS OVER
KOSRAE STATE AND THE SOUTHERN RMI. MAJURO IS IN RELATIVELY DRY FLOW
AND THE NORTHERN RMI REMAINS VERY DRY. SATELLITE ALSO SHOWS A BAND
OF SHOWERS DEVELOPING OVER POHNPEI THIS AFTERNOON. MODELS INDICATE
THE DISTURBANCE WILL VERY SLOWLY MOVE TOWARD WEST-NORTHWEST WITH
AREAS OF SHOWERS ACROSS THE REGION THROUGH THE NEXT COUPLE OF DAYS.
A SLIGHTLY DRIER TRADE-WIND FLOW IS EXPECTED TO ARRIVE FROM THE
NORTHEAST OVER THE WEEKEND THROUGH EARLY NEXT WEEK.
WESTERN MICRONESIA
ASCAT ANALYSIS SHOWS A NEAR-EQUATORIAL TROUGH RUNNING ACROSS PALAU
THRU WEAK CIRCULATIONS SOUTHEAST OF YAP NEAR 4N141E AND FARTHER EAST
AROUND 5N 145E, THEN EASTWARD ACROSS FAR SOUTHERN CHUUK STATE. ALSO,
A SURFACE TROUGH WITH MOSTLY LIGHT SHOWERS EXTENDS NORTHEASTWARD
FROM THE CIRCULATION TO EAST OF GUAM. RELATIVELY DRY NORTHEAST
SURFACE WINDS PERSIST AT YAP FOR THE NEAR TERM. MODELS INDICATE
THE CIRCULATION WILL MOVE WEST-NORTHWEST WITH PATCHY AREAS OF
SHOWERS ACROSS YAP AND PALAU THROUGH THE NEXT FEW DAYS, THEN DRY
WEATHER SHOULD RETURN NEXT WEEK. CONVERGENT EAST TO SOUTHEAST
WINDS HAVE CAUSED SHOWERS ACROSS THE CHUUK AREA TODAY, AND MORE
SHOWERS ARE EXPECTED TO ARRIVE AT CHUUK FROM THE EAST ON FRIDAY
INTO THE WEEKEND.
GUM WATCHES/WARNINGS/ADVISORIES
GU...NONE.
MARIANAS WATERS...NONE.
MIDDLEBROOKE/SIMPSON
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