High Surf Warning 4, NWS Guam

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
533 PM CHST THU JUL 3 2014

.MARIANAS SYNOPSIS...
RADAR SHOWS ISOLATED TO SCATTERED SHOWERS MOVING BRISKLY ACROSS
THE COVERAGE AREA...AND SOME SHOWERS WERE CAUSING LOCALLY HEAVY
RAIN. THE VAD DISPLAY SHOWS GRADIENT WINDS FROM EAST AT 20 TO 30
KT. NEWLY-FORMED TROPICAL DEPRESSION 08W IS CENTERED NEAR 9N146E
AND MOVING TOWARD THE WEST-NORTHWEST. CURRENT SATELLITE IMAGERY
SHOWS SHOWERS CONCENTRATED ACROSS THE CNMI WITH LESS SHOWER
COVERAGE FOUND OVER GUAM WATERS.

&&

.DISCUSSION...
TD 08W IS BECOMING BETTER ORGANIZED AND COULD BECOME A TROPICAL
STORM LATER TONIGHT. THE MARIANAS SPECIAL WEATHER STATEMENT WAS
UPDATED AND SMALL CRAFT ADVISORY HAS BEEN ISSUED. EXTENSIVE
CHANGES TO THE WIND AND MARINE GRIDS WERE NEEDED AS ADVERSE
EFFECTS FROM TD 08W ARE BECOMING MORE PROBABLE FOR FRIDAY. IN
ADDITION...GRID WORK FOR HIGH SURF AND WIND ADVISORY WAS DONE SO
ONCOMING SHIFT WILL NEED TO ISSUE THE ACTUAL ADVISORY PRODUCTS.
MODEL SOLUTIONS STILL DIFFER BUT GENERALLY INDICATE 08W WILL TURN
TOWARD THE NORTHWEST AND PASS SOUTHWEST OF GUAM ABOUT FRIDAY
EVENING. WINDY WEATHER AND PERIODS OF SHOWERS WILL LIKELY DEVELOP
ACROSS THE MARIANAS TONIGHT THROUGH SATURDAY. AMENDMENTS TO THE
FORECAST MAY BE NEEDED ESPECIALLY DURING THE SATURDAY TIME FRAME
AS LATEST MODEL DATA INDICATES THE HEAVIEST SHOWERS WILL HAVE
SHIFTED WEST OF THE MARIANAS WATERS BY LATE FRIDAY AND EARLY
SATURDAY. IMPROVING WEATHER AND RELATIVELY DRIER TRADE WINDS ARE
EXPECTED TO RETURN SATURDAY NIGHT.

&&

.MARINE...
SMALL CRAFT ADVISORY HAS BEEN ISSUED AND A SURF ADVISORY WILL BE
IN EFFECT FOR EARLY FRIDAY. WINDS AND WAVES WILL GRADUALLY
INCREASE ACROSS THE AREA TONIGHT THROUGH FRIDAY. WIND GRIDS WERE
REFRESHED WITH GFS MODEL DATA BUT TRIMMED DOWN A BIT. WAVES GRIDS
WERE ADJUSTED WITH WW3 GUIDANCE AND ALSO TRIMMED DOWN TO MORE
REALISTIC VALUES.

&&

.EASTERN MICRONESIA...
THE ONLY FEATURE OF NOTE THIS EVENING IS A WEAK TROUGH EXTENDING
EAST-WEST ALONG 5 TO 6N ACROSS THE MARSHALL ISLANDS...WITH LOTS OF
SHOWERS JUST EAST OF MAJURO. THESE SHOULD MOVE THROUGH MAJURO
OVERNIGHT...WHERE A THUNDERSTORM HAS ALREADY BEEN REPORTED. THE
SHOWERS SHOULD MOVE NORTH OF MAJURO BY MORNING...AND ONLY ISOLATED
SHOWERS AND THUNDERSTORMS ARE EXPECTED FOR THE REST OF THE FORECAST
PERIOD. FOR POHNPEI AND KOSRAE NO SIGNIFICANT WEATHER MAKERS ARE
FORESEEN...AND ONLY ISOLATED SHOWERS AND THUNDERSTORMS ARE EXPECTED.
THE GFS SETS UP A NARROW CONVERGENCE BAND ALONG 9N ON MONDAY...BUT
THIS IS NORTH OF ALL FORECAST LOCATIONS AND TOO UNCERTAIN AT THAT
TIME RANGE TO TAKE SERIOUSLY FOR NOW.

&&

.WESTERN MICRONESIA...
TD08W SHOULD CONTINUE SLOWLY TO THE WNW THE NEXT FEW DAYS AS REACHES
TROPICAL STORM STATUS OVERNIGHT...AND BECOMES A TYPHOON ON SATURDAY.
THE MONSOON TAIL IS EXPECTED TO STAY OVER YAP THROUGH FRIDAY NIGHT
OR EARLY SATURDAY MORNING...WITH THE HIGHEST WINDS AND HEAVIEST RAIN
LATE TONIGHT THROUGH FRIDAY NIGHT. RAINFALL OF 4-5 INCHES IS A GOOD
POSSIBILITY. SATURDAY AND SATURDAY NIGHT WILL SEE IMPROVING
WEATHER...BUT SEAS WILL PEAK AT 9-11 FT DURING THAT TIME.

AT KOROR...WINDS ARE ALREADY AT THEIR PEAK...AND SHOULD SLOWLY
SUBSIDE FRIDAY NIGHT AND SATURDAY. SCATTERED SHOWERS MAY PRODUCE
LOCALLY HEAVY RAIN...BUT LESS THAN YAP...MAYBE UP TO 2 INCHES.

CHUUK IS BASICALLY OUT OF ANY HEAVY WEATHER FROM 08W...WITH MAINLY
LIGHT WINDS AND MODERATE SEAS...AND ISOLATED THUNDERSTORMS THROUGH
FRI NIGHT.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...HIGH SURF ADVISORY FROM 6 AM FRIDAY TO 4 PM CHST SUNDAY FOR
     GUZ001>004.

     WIND ADVISORY FROM 6 AM FRIDAY TO 6 AM CHST SATURDAY FOR
     GUZ001>004.

MARIANAS WATERS...SMALL CRAFT ADVISORY UNTIL 4 PM CHST SUNDAY FOR PMZ151>154.

&&

SIMPSON/WILLIAMS/MIDDLEBROOKE