Area Forecast Discussion
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000
FXPQ60 PGUM 052225
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
825 AM CHST WED MAY 6 2015

.SYNOPSIS...
PGUA DOPPLER WEATHER RADAR SHOWS ONLY A FEW SHOWERS WITHIN THE
MARIANAS WATERS. THE VAD WIND PROFILE REVEALS WINDS JUST A LITTLE
SOUTH OF EAST BETWEEN 13 AND 22 KNOTS THROUGH THE LOWEST 6
THOUSAND FEET OF THE AIR.

&&

.DISCUSSION...
TRADE-WIND REGIME REMAINS IN PLACE THROUGH THE WEEKEND. AFTER
THAT...THINGS GET A BIT DICEY. THE ECMWF-HIRES AND GFS40 CONTINUE
THEIR EXCELLENT RUN-TO-RUN AND MODEL-TO-MODEL CONSISTENCY WITH
SPINNING UP A TROPICAL CYCLONE SOUTH OF POHNPEI THEN MOVING IT
NORTHWEST TOWARD THE MARIANAS. UNTIL IT STARTS TO ACTUALLY
FORM...WILL KEEP ANYTHING REALLY WILD OUT OF THE FORECAST. WENT
AHEAD AND POPULATED THE WIND GRIDS FROM THE ECMWF-HIRES THEN
CAPPED THEM AT 22 KNOTS...JUST A LITTLE ABOVE THE BACKGROUND
TRADE-WIND FLOW. DID SOMETHING SIMILAR FOR THE WAVES FROM WW3
GLOBALWAVE...CAPPED THEM AT 12 FEET. DID GO AHEAD AND INTRODUCE
SCATTERED SHOWERS FOR NEXT WEEK THOUGH. THE CONSISTENCY HAS BEEN
IMPOSSIBLE TO DENY...EVEN THE GFS ENSEMBLE CLEARLY SHOWED IT.

WAVE HEIGHTS WILL REMAIN 4 TO 6 FEET THROUGH FRIDAY...THEN BUILD
TO BETWEEN 6 AND 9 FEET OVER THE WEEKEND. WHERE THEY GO FROM THERE
WILL DEPEND HEAVILY ON WHETHER THIS CIRCULATION FORMS AND WHERE IT
GOES IF IT DOES FORM.

&&

.TROPICAL SYSTEMS...
A TYPHOON WARNING REMAINS IN EFFECT FOR YAP THIS MORNING. NEWLY-
UPGRADED TYPHOON NOUL CONTINUES TO DRIFT SLOWLY WESTWARD AWAY FROM
YAP WITH MAXIMUM SUSTAINED WINDS OF 75 MPH. TY NOUL PASSED VERY
NEAR YAP A FEW HOURS AGO AND IS NOW HEADED OUT TO SEA.

A WEAK CIRCULATION...JTWC INVEST AREA 93W...IS CENTERED SOUTH-
SOUTHWEST OF POHNPEI AT 4N156E. 93W CONTINUES TO GENERATE WEATHER
NEAR CHUUK...POHNPEI AND KOSRAE. MODEL GUIDANCE INDICATES FURTHER
DEVELOPMENT OF THIS CIRCULATION THE NEXT SEVERAL DAYS. THIS SYSTEM
WILL REMAIN NEARLY STATIONARY THE NEXT COUPLE DAYS BEFORE TRACKING
TOWARDS THE NORTHWEST.

&&

.EASTERN MICRONESIA...
93W WILL MAINTAIN SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS AT
POHNPEI THE NEXT SEVERAL DAYS. UNSETTLED CONDITIONS WILL ALSO
PERSIST AT CHUUK AND KOSRAE THROUGH THE END OF THE WEEK. MODEL
GUIDANCE SHOWS A LITTLE LESS MOISTURE AT KOSRAE AND CHUUK BUT
PERIODS OF SCATTERED SHOWERS ARE POSSIBLE THE NEXT FEW DAYS. 93W
WILL REMAIN NEARLY-STATIONARY ANOTHER DAY OR TWO BEFORE TRACKING
TOWARDS THE NORTHWEST. GFS QUICKLY SPINS THIS DISTURBANCE INTO A
TROPICAL STORM BY FRIDAY...BUT OTHER MODELS SHOW SLOWER
DEVELOPMENT. FORECASTS AT POHNPEI AND CHUUK REFLECT A PASSING
CIRCULATION...BUT FOR NOW MAINTAIN A CONSERVATIVE APPROACH TO WIND
FORECAST.

AT MAJURO...DRY CONDITIONS AND FRESH NORTHEAST TRADES ARE EXPECTED
TODAY. A WEAK CIRCULATION AND SURFACE TROUGH SOUTHEAST OF MAJURO
WILL SHIFT WEST TONIGHT BRINGING CLOUDS...SHOWERS AND ISOLATED
THUNDERSTORMS TO THE CENTRAL MARSHALLS TONIGHT THROUGH THURSDAY
NIGHT. WINDS WILL DECREASE JUST A BIT OVER THE WEEKEND BUT A
GENERALLY UNSETTLED PATTERN WILL LINGER. MODELS INDICATE A SLIGHTLY
WETTER TRADE-WIND PATTERN THRU THE WEEKEND.

WAVE WATCH MODELS SHOWS BUILDING SEAS ON FRIDAY AND THIS TOO WILL
HAVE TO BE WATCHED CLOSELY. IN THE MEANTIME...EXPECT SLIGHTLY
ELEVATED SEAS ACROSS THE REGION FROM MAJURO TO CHUUK DUE TO THE
LARGE SWATH OF FRESH TRADE WINDS BETWEEN 5N AND 20N EAST OF 150E.

&&

.WESTERN MICRONESIA...
THE CHUUK DISCUSSION IS INCLUDED WITH EASTERN MICRONESIA BECAUSE
OF SIMILAR SYNOPTIC CONDITIONS.

TY NOUL WILL CONTINUE TO HEAD SLOWLY WEST AWAY FROM YAP...BUT
TYPHOON CONDITIONS WILL PERSIST THROUGH THE MORNING DUE TO THE
SLOW FORWARD MOTION OF NOUL. WIND FORECASTS FOR TODAY MAY NEED TO
BE ADJUSTED FOR SPEED AND DIRECTION IF A SOUTHERN PASSAGE OF THE
EYE DOES OCCUR...AND FOR ANY CHANGES IN FORWARD MOTION. IT DOES
APPEAR THAT CONDITIONS WILL TAPER THIS AFTERNOON AND OVERNIGHT
WITH RAPID IMPROVEMENT AT YAP ON THURSDAY. MUCH BETTER WEATHER IS
EXPECTED FOR THE WEEKEND.

AT KOROR...CLOUDS WILL BUILD IN TODAY AS NOUL HEADS SLOWLY WEST.
MOST OF THE WEATHER IS STILL EXPECTED TO REMAIN NORTH. WINDS AND
SEAS WILL INCREASE TODAY. SURF ADVISORY REMAINS IN EFFECT FOR
NORTH AND WEST FACING REEFS. WAVE WATCH MODEL INDICATES SURF COULD
REACH DANGEROUS LEVELS OVERNIGHT...POSSIBLY REQUIRING A HIGH SURF
WARNING. DAY SHIFT WILL HAVE TO MONITOR MODEL TRENDS AND ALTIMETRY
CLOSELY. LIGHTER WINDS AND DRY CONDITIONS ARE EXPECTED FOR THE END
OF THE WEEK.

&&

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

$$

STANKO/M. AYDLETT



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