Area Forecast Discussion
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FXPQ60 PGUM 250631
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
431 PM CHST FRI APR 25 2014

.MARIANAS SYNOPSIS...
A FEW SHOWERS ARE SEEN NEAR SAIPAN AND TINIAN FROM A PASSING
TRADE-WIND DISTURBANCE. MEANWHILE...A LARGER TROPICAL DISTURBANCE
IS SEEN SOUTHEAST OF GUAM NEAR 9N148E THAT IS GENERATING SHOWERS
AND THUNDERSTORMS FROM NORTHEAST OF YAP TO NORTH OF CHUUK.

&&

.DISCUSSION...
THE TROPICAL DISTURBANCE CONTINUES TO SLOWLY HEAD WEST-
NORTHWESTWARD. MODELS SHOW MORE SOLIDARITY IN THE OUTLOOK THROUGH
THE WEEKEND IN SHOWING THE CIRCULATION JUST SOUTHWEST OF GUAM
SUNDAY NIGHT. FELT THAT THE MODELS HAVE BEEN CONSISTENT ENOUGH THE
PAST SEVERAL RUNS TO GO AHEAD AND BOOST POPS FROM SATURDAY NIGHT
THROUGH SUNDAY NIGHT TO INDICATE SCATTERED SHOWERS. BEYOND
MONDAY...MODEL GUIDANCE DIVERGES SO FORECAST CONFIDENCE GREATLY
DIMINISHES. MODELS SHOW A RANGE OF SOLUTIONS FROM THE CIRCULATION
DRIFTING WESTWARD TOWARD YAP...NORTHWESTWARD OVER THE PHILIPPINE
SEA...OR EVEN NORTHWARD OVER THE MARIANAS IN RESPONSE TO A PASSING
FRONTAL SYSTEM NORTH OF THE NORTHERN CNMI. NEVERTHELESS...WITH AN
UNSETTLED WEATHER PATTERN IN THE AREA INTO NEXT WEEK DECIDED TO
EXTEND ISOLATED THUNDERSTORMS THROUGH MONDAY NIGHT.

&&

.MARINE...
NORTH SWELL IS STILL EXPECTED TO BUILD OVER THE WEEKEND FROM A
PASSING FRONTAL SYSTEM WELL NORTH OF THE NORTHERN CNMI. FOR
NOW...WAVE WATCH MODEL SHOWS LARGER SWELL AFFECTING TINIAN AND
SAIPAN WHILE SWELL WILL BE SOMEWHAT SMALLER FOR GUAM AND ROTA DUE
TO BLOCKING FROM THE ISLANDS TO THE NORTH. SURF WILL BUILD ALONG
NORTH FACING REEFS BEGINNING SUNDAY. WAVE WATCH MODEL ALSO SHOWS A
SMALL SOUTHEAST SWELL DEVELOPING AT GUAM EARLY NEXT WEEK FROM THE
CIRCULATION. CURRENT GFS SEEMS TOO AGGRESSIVE WITH THE WINDS SO
THE WAVE WATCH MODEL MAY BE OVERDOING SOUTHEAST SWELL...BUT WILL
STILL NEED TO KEEP AN EYE ON THAT FOR THE NEXT COUPLE OF DAYS.

&&

.EASTERN MICRONESIA...
A TRADE-WIND DISTURBANCE WITH ATTENDANT DEEP CONVECTION IS LOCATED
SOUTHEAST OF THE MARSHALL ISLANDS. SATELLITE IMAGERY SHOWS CLOUDS
AND SHOWERS ARE SLOWLY EDGING TOWARD THE MARSHALL ISLANDS.
TRADE-WIND CONVERGENCE ZONE IS EXPECTED TO SET UP SOUTH OF MAJURO
AND MOVE NORTHWARD BRINGING SCATTERED SHOWERS TO THE ATOLL BY
SUNDAY. MODELS INDICATE FAIRLY ACTIVE WEATHER WILL PERSIST BUT
TIMING AND SPATIAL DISTRIBUTION OF CONVECTIVE CLUSTERS WILL BE
DIFFICULT TO DETERMINE SO LEFT ISOLATED COVERAGE IN THE LONG TERM
FORECAST FOR MAJURO. A LINE OF SHOWERS ASSOCIATED WITH A CONVERGENCE
ZONE ON THE EASTERN END OF A NEAR-EQUATORIAL TROUGH WILL AFFECT
KOSRAE TONIGHT. GENERALLY ACTIVE PATTERN WITH SCATTERED SHOWERS
EXPECTED WILL CONTINUE AT KOSRAE THROUGH THE WEEKEND. A BREAK IN THE
LINE OF CONVECTION OVER KOSRAE IS OBSERVED OVER POHNPEI WATERS.
SHOWERS ARE EXPECTED TO INCREASE EARLY SATURDAY MORNING TO SCATTERED
COVERAGE WITH ACTIVE WEATHER EXPECTED TO PERSIST THROUGH SATURDAY
NIGHT.

&&

.WESTERN MICRONESIA...
THE CENTER OF TROPICAL DISTURBANCE 99W HAS MOVED WEST OF CHUUK AND
IS CENTERED NEAR 9N148E. MOST OF THE SHOWER ACTIVITY ASSOCIATED WITH
99W HAS PUSHED NORTH OF CHUUK WITH DRY SOUTHEAST FLOW FOUND OVER
MUCH OF THE STATE. MODELS INDICATE CONVECTIVE ACTIVITY ASSOCIATED
WITH 99W WILL CONTINUE TO MOVE FARTHER TO THE NORTH OF CHUUK OVER
THE WEEKEND AS THE SYSTEM MAKES A NORTHWARD TURN TOWARDS THE
MARIANAS. IN ADDITION...SHOWERS OVER POHNPEI AND KOSRAE SHOULD STAY
EAST OF CHUUK FOR THE NEXT SEVERAL DAYS ALLOWING FOR A RELATIVELY
DRY SCENARIO FOR CHUUK THROUGH EARLY NEXT WEEK.

THE LEADING EDGE OF CONVECTION FROM 99W WILL IMPACT YAP LATE TONIGHT
OR EARLY SATURDAY MORNING. SATELLITE IMAGERY SHOWS AN OUTFLOW
BOUNDARY GENERATED BY COLLAPSING CONVECTION EAST OF 140E ABOUT TO
MOVE INTO YAP WATERS. HOWEVER...UNCERTAINTY REMAINS AS TO WHETHER
THE OUTFLOW BOUNDARY WILL ACT AS A FOCUSING MECHANISM FOR CONVECTION
LATER TONIGHT. FOR NOW...LEFT ISOLATED WORDING IN THE FORECAST AS
MODELS REDEVELOP CONVECTION JUST TO THE SOUTH OF YAP LATE TONIGHT
AND EARLY SATURDAY MORNING. OTHERWISE...RELATIVELY DRY WEATHER
WILL CONTINUE AT YAP SUNDAY ONWARD AS 99W PULLS TO THE NORTH-
NORTHWEST. ONLY MINOR CHANGES WERE MADE TO KOROR FORECAST IN THE
SHORT TERM. SHOWERS RAPIDLY DISSIPATED AND MOVED SOUTH OF KOROR
TODAY. VISIBLE SATELLITE IMAGERY SHOWS ALMOST CLOUDLESS REGION
JUST TO THE NORTH OF KOROR. ANIMATION OF IR AND WV IMAGERY
INDICATE VERY DRY AIR MASS WILL SETTLE SOUTH OVER KOROR TONIGHT SO
REMOVED MENTION OF MOSTLY CLOUDY LATER TONIGHT. FAIRLY QUIET
PATTERN IS EXPECTED OVER PALAU FOR THE NEXT SEVERAL DAYS WITH MUCH
OF THE ACTIVE WEATHER GENERALLY EAST OF 140E.

&&

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

$$

W. AYDLETT/WILLIAMS




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