Area Forecast Discussion
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712
FXPQ60 PGUM 111942
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
542 AM CHST FRI FEB 12 2016

.SYNOPSIS...
THE SHEAR LINE HAS MOVED SOUTHWARD TO NEAR GUAM AND IS HARD TO
DISTINGUISH IN SATELLITE FROM A TRADE-WIND DISTURBANCE PASSING
OVER AND SOUTH OF THE FORECAST ZONES. RADAR AND SATELLITE TRENDS
INDICATE SCATTERED LIGHT SHOWERS WILL AFFECT THE TINIAN AND SAIPAN
ZONES THIS MORNING...AND AFFECT THE GUAM AND ROTA ZONES THROUGH
THIS AFTERNOON.

&&

.DISCUSSION...
ONLY SIGNIFICANT CHANGE WAS TO ADD SCATTERED LIGHT SHOWERS TO THE
NEAR TERM FORECAST PER THE SYNOPSIS. WEATHER WILL GRADUALLY DRY
OUT BEGINNING TONIGHT...THEN SKIES WILL BECOME PARTLY CLOUDY ON
SUNDAY AS VERY DRY AIR BEHIND THE SHEAR LINE MOVES IN FOR THE
FIRST HALF OF NEXT WEEK. GFS BRINGS ANOTHER SHEAR LINE SOUTHWARD
DURING THE SECOND HALF OF NEXT WEEK...BUT IT STALLS NEAR THE FAR
NORTHERN MARIANAS ON THURSDAY.

&&

.MARINE...
WINDS AND SEAS ARE NOW VERIFYING THE SMALL CRAFT ADVISORY. WINDS
WILL BEGIN TO ABATE ON SATURDAY NIGHT...ALLOWING SEAS TO SUBSIDE
BELOW ADVISORY LEVELS ON MONDAY. SURF ON NORTH AND EAST FACING
REEFS HAS NOT YET REACHED ADVISORY LEVELS...BUT COULD DO SO
OVERNIGHT. AS SEAS CONTINUE TO BUILD. TANAPAG BUOY READINGS
INDICATED PREDOMINANT SWELL ENERGY FROM THE NORTH-NORTHEAST...
VERSUS THE IPAN BUOY...WHICH SHOWED PREDOMINANT SWELL ENERGY FROM
THE EAST. BLOCKING BY GUAM DOES NOT APPEAR TO RECONCILE THE
DIFFERENCE...AS COMBINED SEAS AT BOTH BUOYS ARE COMING IN AT CLOSE
TO 10 FT. DAYS SHIFT MAY NEED TO ADJUST THE SWELL GRIDS DEPENDING
ON HOW THESE BUOY READINGS EVOLVE. IF NORTH SWELL NEED TO BE
ADJUSTED UPWARD...HIGH SURF COMES INTO PLAY ALONG NORTH FACING
REEFS. ENTIRE HIGH SURF EVENT SHOULD WIND DOWN ON MONDAY.

&&

.FIRE WEATHER...
FIRE WEATHER WATCH REMAINS IN EFFECT...BUT SCATTERED LIGHT
SHOWERS SHOULD KEEP FUELS WET ALL DAY ON GUAM. WETTING RAINS ARE
NOT EXPECTED...BUT ARE POSSIBLE. IF THEY DO OCCUR...THIS WOULD
MITIGATE THE SHORT TERM FIRE DANGER.

&&

.EASTERN MICRONESIA...
A WEAK TRADE-WIND DISTURBANCE IS APPROACHING KOSRAE THIS MORNING.
IT WILL BRING A PERIOD OF SCATTERED SHOWERS AND A EVEN A
THUNDERSTORM OR TWO THIS EVENING AND SATURDAY. IT WILL THEN PASS
JUST SOUTH OF POHNPEI ON SATURDAY AND CHUUK ON SUNDAY AND TRIGGER
A FEW SHOWERS. THE SHEAR LINE HAS PROGRESSED SOUTH OF 12N LAST
NIGHT AND WILL REACH NEAR 10N ON SUNDAY. THIS WILL GREATLY
INCREASE NORTHEAST WINDS FROM CHUUK STATE EASTWARD TO THE MARSHALL
ISLANDS. A STRONGER TRADE DISTURBANCE IS APPROACHING THE DATE LINE
THIS MORNING. IT SHOULD MOVE INTO THE MARSHALL ISLANDS BY SATURDAY
AFTERNOON. WITH THE SHEAR LINE IN THE VICINITY...INCREASING LOW-
LEVEL CONVERGENCE MIGHT SPARK OFF SPORADIC CONVECTION NEAR MAJURO
THRU SUNDAY NIGHT. AS THIS DISTURBANCE PULLS FARTHER WESTWARD...
THIS SAME PROCESS WILL SPREAD OVER KOSRAE AND POHNPEI ON SUNDAY...
AND OVER CHUUK BY MONDAY. TOWARD MIDWEEK NEXT WEEK...THE SHEAR
LINE SHOULD GRADUALLY WEAKEN WHICH WILL ALLOW DRY TRADE WINDS TO
RETURN FROM EAST TO WEST.

THE INITIAL SET OF LARGE NORTHEAST SWELL PRODUCED BY STRONG WINDS
BEHIND THE SHEAR LINE WILL ARRIVE ON CHUUK...POHNPEI AND KOSRAE
THIS EVENING AND ON MAJURO SUNDAY. A HIGH SURF ADVISORY WILL BE
NEEDED BY THIS AFTERNOON FOR THE FIRST THREE LOCATIONS. WHEN
COMBINED WITH BUILDING WIND WAVES...SEAS WILL ALSO BE HAZARDOUS
FOR SMALL CRAFT FOR ALL LOCATIONS BY SATURDAY.

&&

.WESTERN MICRONESIA...
LATEST IR SATELLITE LOOPS REVEAL THE SOUTHWESTERN END OF THE
SHEAR LINE HAS ARRIVED OVER KOROR AND YAP. HOWEVER IT IS ALSO
BECOMING MORE DIFFUSED COMPARED TO THE SECTION FARTHER NORTHEAST.
WITH THIS IN MIND...SHOWER COVERAGE NEAR KOROR AND YAP WILL
PROBABLY REMAIN ISOLATED DURING THE NEXT COUPLE OF DAYS. ONCE THE
SHEAR LINE HAS DISSIPATED EARLY NEXT WEEK...DRIER MODERATE TO
FRESH TRADE WINDS WILL MOVE BACK IN FROM THE NORTHEAST.

SATELLITE-DERIVED SEA HEIGHTS INDICATE SEAS HAVE REACHED 8 TO 10
FEET NEAR YAP AND JUST NORTH OF KOROR. THIS VERIFIED WITH COMPUTER
MODEL GUIDANCE ON THE ARRIVAL OF THE LARGE NORTHEAST SWELL CREATED
BY THE STRONG WINDS NORTH OF THE SHEAR LINE. ANTICIPATE HAZARDOUS
SURF AND HAZARDOUS SEAS FOR SMALL CRAFT WILL AFFECT BOTH PLACES
THRU SATURDAY NIGHT. BOTH ELEMENTS SHOULD GRADUALLY SUBSIDE LATE
SUNDAY.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...FIRE WEATHER WATCH THROUGH SATURDAY AFTERNOON FOR GUZ001.

MARIANAS WATERS...SMALL CRAFT ADVISORY UNTIL 6 PM CHST MONDAY FOR
                  PMZ151>154.

&&

$$

MCELROY/CHAN



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