Area Forecast Discussion
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FXPQ60 PGUM 200825 AAA
AFDPQ

AREA FORECAST DISCUSSION...ADDED MICRONESIAN DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
625 PM CHST SAT SEP 20 2014

.MARIANAS SYNOPSIS...
RADAR SHOWS ISOLATED SHOWERS ACROSS THE COVERAGE AREA...A FEW HAVE
CONTAINED SMALL CORES OF HEAVY RAINFALL. SATELLITE SHOWS THAT THE
MORE SIGNIFICANT CONVECTION HAS MOVED WEST OF OUR FORECAST ZONES.
ANOTHER AREA OF DEEP CONVECTION IS WELL EAST OF THE MARIANAS NEAR
155E. ASCAT ANALYSIS INDICATES A WEAK CIRCULATION SOUTH OF GUAM
NEAR 4N143E. VAD GRADIENT WINDS ARE ENE ABOUT 10 KT. BUOYS SHOW
COMBINED SEAS OF 3 TO 4 FEET FROM WEST...AND NORTHEAST TO EAST.

&&

.DISCUSSION...
A RELATIVELY DRY AIRMASS REMAINS OVER THE AREA FOR NOW...BUT BY
NEXT WEEK A MORE ACTIVE MONSOON-TYPE WEATHER PATTERN IS EXPECTED.
LATEST GFS AND ECMWF STILL INDICATE THAT AS THE CIRCULATION SOUTH
OF GUAM MOVES TOWARD WEST AND NORTHWEST...A MONSOON TROUGH WILL
FORM SOUTHEAST OF GUAM ALONG 12N WITH A BROAD MONSOON CIRCULATION
DEVELOPING NORTH OF THE POHNPEI-KOSRAE AREA BY MONDAY OR TUESDAY.
THIS CIRCULATION IS THEN PROGGED TO MOVE NORTHWEST TOWARD THE
NORTHERN MARIANA ISLANDS AS NEXT WEEK PROGRESSES. LATER MARIANA
FORECASTS WILL LIKELY NEED ADJUSTMENTS AS THE SITUATION BECOMES
BETTER DEFINED.

&&

.MARINE...
PLEASANT MARINE CONDITIONS ARE EXPECTED NEXT FEW DAYS. BUT...MODELS
INDICATE INCREASING WIND AND WAVE CONDITIONS WILL DEVELOP BY ABOUT
THURSDAY OR FRIDAY NEXT WEEK. ADJUSTMENTS WERE MADE TO WAVE GRIDS
FOR NEXT WEEK BASED ON WW3 MODEL AND REFRESHED WIND GRIDS WITH
LATEST GFS DATA.

&&

.EASTERN MICRONESIA...
A SERIES OF WEAK DISTURBANCES HAVE GIVEN WAY TO A NEAR EQUATORIAL
TROUGH EXTENDING NORTHEASTWARD FROM 4N162E TO 9N177E. THE MODELS
INDICATE THAT THIS WILL GIVE WAY TO A MONSOON TROUGH EXTENDING
ACROSS THE REGION. WEAK RIDGING IS BUILDING IN BEHIND THE NEAR
EQUATORIAL TROUGH AND EXPECT IT TO BRING IN A PERIOD OF FAIR WEATHER
TO MAJURO SUNDAY AND SUNDAY NIGHT. STILL EXPECT INCREASING CLOUDS
AND CONVECTION FOR KOSRAE THROUGH MONDAY AND TO POHNPEI THROUGH THE
MIDDLE OF THE WEEK. MAJURO WILL SEE THE LEAST AFFECT FROM THIS
SYSTEM AS A RIDGE BUILDS BACK INTO THE MARSHALLS TUESDAY. THIS RIDGE
WILL SPREAD WESTWARD...BRINGING DRY CONDITIONS TO BACK TO KOSRAE BY
MIDWEEK. MOST OF THE ACTIVITY WITH THE NEAR EQUATORIAL TROUGH WILL
REMAIN NORTH OF 10N.

&&

.WESTERN MICRONESIA...
A BROAD CIRCULATION TO THE SOUTHWEST OF CHUUK CONTINUES TO PRODUCE
SCATTERED SHOWERS OVER PORTIONS OF PALAU THIS AFTERNOON. CONVECTION
WILL DECREASE SUNDAY WITH LINGERING SHOWERS AND THUNDERSTORMS
CLEARING UP LATE SUNDAY NIGHT. A MONSOON TROUGH IS STILL EXPECTED TO
BE NORTH OF 10N IN THE NEXT COUPLE DAYS. SHOWER ACTIVITY ASSOCIATED
WITH THE TROUGH SHOULD REMAIN MAINLY NORTH OF PALAU AND YAP THROUGH
THE MIDDLE OF THE WEEK.

A RIDGE OF HIGH PRESSURE HAS MOVED IN OVER CHUUK BUT SATELLITE
IMAGERY INDICATES CLOUDS AND CONVECTION NEARBY TO THE NORTH. A
TROPICAL DISTURBANCE IS NOW NORTH OF CHUUK. CONVERGING WINDS SOUTH
OF THE MONSOON TROUGH WILL RESULT IN INCREASING CLOUDS AND SHOWERS
OVER CHUUK BY MONDAY.

&&

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

$$

SIMPSON/DEVITA







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