Area Forecast Discussion
Issued by NWS

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000
FXPQ60 PGUM 290911 AAA
AFDPQ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TIYAN GU
711 PM CHST SAT AUG 29 2015

UPDATED TO ADD MICRONESIAN DISCUSSION SECTIONS

.SYNOPSIS...
EXCEPT FOR A FEW ISLAND SHOWERS OVER GUAM AND ROTA...PARTLY
CLOUDY SKIES...VERY ISOLATED LIGHT SHOWERS AND LIGHT WINDS ARE
SEEN OVER THE MARIANAS WATERS. COMBINED SEAS ARE BETWEEN 7 AND 8
FEET AT THE RITIDIAN AND TANAPAG BUOYS.

&&

.DISCUSSION...
NO CHANGES WERE NEEDED TO THE ONGOING FORECAST OF LIGHT WINDS AND
ISOLATED SHOWERS. WINDS SHOULD FINALLY COME AROUND TO EAST ABOUT
MIDWEEK. WITH MAINLY DRY CONDITIONS AT MID AND UPPER LEVELS...ANY
SHOWERS SHOULD BE LIGHT EXCEPT FOR LOCALLY HEAVY BUT BRIEF ISLAND
SHOWERS OVER GUAM SUNDAY AFTERNOON...PRODUCED BY STRONG SOLAR
HEATING OF THE LAND MASS.

&&

.MARINE...
WITH WAVE WATCH GUIDANCE SOMETIMES AS MUCH AS 4 FEET BELOW THE
COMBINED SEAS INDICATED AT THE BUOYS...FELT COMPELLED TO BOOST
SEAS AND NORTH SWELL BY 2-3 FEET OR SO THE NEXT FEW DAYS. THIS
WILL KEEP THE HIGH SURF ADVISORY GOING THROUGH SUNDAY AFTERNOON.

&&

.EASTERN MICRONESIA...
SHORT TERM WEATHER PATTERN FOR MAJURO AND KOSRAE WILL BE RATHER
QUIET DURING THE NEXT FEW DAYS AS WEAK MONSOONAL FLOW AND UPPER-
LEVEL CONVERGENCE LIMIT CLOUD AND SHOWER COVERAGE. MODELS SUGGEST
MONSOONAL FLOW COULD STRENGTHEN BY DAY 5 FOR BOTH LOCATIONS...SO
LONG TERM UPWARD ADJUSTMENTS IN BOTH CLOUD AND SHOWER COVERAGE MAY
BE NECESSARY.

FOR POHNPEI AND CHUUK...UNSETTLED WEATHER PATTERN IS ALREADY IN
PLACE. HAVE GONE WITH SCATTERED SHOWER COVERAGE OVERNIGHT AS
MONSOONAL SHOWERS ARE ALREADY UNDERWAY. DRIER WEATHER PATTERN IS
EXPECTED TO WORK IN FROM THE EAST DURING THE NEXT COUPLE OF
DAYS...BUT MORE UNSETTLED WEATHER COULD WORK IN BY DAY 5 AS
MONSOONAL FLOW STRENGTHENS ONCE AGAIN.

ALTIMETRY INDICATES A 1 TO 2-FOOT INCREASE IN SEA HEIGHTS FROM
JUST EAST OF CHUUK TO NEAR KOSRAE. LATEST ASCAT INDICATES
MONSOONAL WINDS BETWEEN 10 AND 20 KNOTS IN THIS GENERAL AREA.
NORTH SWELL GENERATED BY THE LARGE EXTRATROPICAL LOW CENTERED EAST
OF KAMCHATKA ARE EXPECTED TO GRADUALLY SUBSIDE AS THE LOW
CONTINUES TO WEAKEN. THIS LOW EVOLVED FROM TYPHOON ATSANI. MODELS
SUGGEST MONSOONAL WINDS OVER THIS REGION WILL SUBSIDE DURING THE
NEXT FEW DAYS...BUT WINDS AND SEA HEIGHTS IN THIS AREA WILL HAVE
TO BE MONITORED.

&&

.WESTERN MICRONESIA...
REASONING FOR CHUUK FORECAST IS INCLUDED IN THE EASTERN
MICRONESIA SECTION DUE TO A SIMILAR WEATHER PATTERN.

WATER VAPOR SATELLITE LOOP INDICATES SUBSIDENT ATMOSPHERE OVER
YAP AND KOROR...BUT AN AREA OF UPPER-LEVEL DIVERGENCE IS
APPROACHING FROM THE EAST. MODELS DO BRING IN MORE UNSTABLE
CONDITIONS BY MORNING. SATELLITE IMAGERY SHOWED LIGHTNING TO THE
SOUTH AND EAST DURING THE PAST SEVERAL HOURS. HAVE ACCORDINGLY
INCREASED CLOUD COVER AND ADDED ISOLATED THUNDER TO BOTH LOCATIONS
OVERNIGHT. NIGHT SHIFT MAY NEED TO INCREASE CLOUD COVER AND
THUNDER CHANCES FOR SUNDAY AS WELL FOR BOTH LOCATIONS IF
ENVIRONMENT FOR CONVECTION REMAINS MORE FAVORABLE. MODEL TIME-
HEIGHTS SUGGEST UNSETTLED WEATHER PATTERN WILL CONTINUE THROUGH
DAY 5. MODEST LOW-LEVEL CONVERGENCE GENERATED BY MONSOONAL WINDS
AND INCREASING MID TO UPPER-LEVEL MOISTURE WILL MAINTAIN A
SOMEWHAT WETTER REGIME FOR BOTH LOCALES. FUTURE SHIFTS MAY NEED TO
ADD A PERIOD OR TWO OF SCATTERED SHOWERS TO THE FORECASTS FOR BOTH
YAP AND KOROR...BUT THE EXACT TIMING FOR SUCH FORECAST ADJUSTMENTS
IS UNCLEAR AT PRESENT. NO WELL DEFINED WEATHER SYSTEMS ARE EXPECTED
THROUGH DAY 5 OVER WESTERN MICRONESIA AND CONVECTION WILL BE
ORGANIZED ON THE MESOSCALE.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...HIGH SURF ADVISORY UNTIL 6 PM CHST SUNDAY FOR GUZ001>004.

MARIANAS WATERS...NONE.
&&

$$

MIDDLEBROOKE/DEVITA



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