Scientific Forecaster Discussion

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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
623 AM CHST SAT APR 19 2014

.MARIANAS SYNOPSIS...EAST TRADE-WINDS AND A FEW SHOWERS ARE PRESENT
ACROSS THE MARIANAS AS A WEAK TROPICAL DISTURBANCE PASSES SOUTH OF GUAM
THIS MORNING.

&&

.DISCUSSION...
LITTLE CHANGE WAS MADE TO THE FORECAST. A CIRCULATION IS LOCATED
SOUTH OF GUAM THIS MORNING. A SURFACE TROUGH EXTENDS NORTH FROM
THE CIRCULATION TO JUST EAST OF THE MARIANAS. AS THE CIRCULATION
MOVES WEST THE TROUGH WILL PASS ACROSS THE ISLANDS. MODELS
CONTINUE TO DEPICT SCATTERED SHOWERS OVER THE MARIANAS IN
ASSOCIATION WITH THE CIRCULATION AND TROUGH. REALITY DIFFERS FROM
THE MODEL PREDICTIONS. RADAR AND SATELLITE DOES SHOW SHOWERS BUT
THE COVERAGE IS ISOLATED. AN UPPER-LEVEL DRY LAYER AND
CONVERGENCE HAS PREVENTED SHOWERS FROM BECOMING WIDESPREAD. THERE
WERE A FEW THUNDERSTORMS SEEN ON RADAR AND DISTANT LIGHTNING WAS
SPOTTED AFTER MIDNIGHT SO A SLIGHT CHANCE OF THUNDERSTORMS IS
POSSIBLE THROUGH SUNDAY. LITTLE IN THE WAY OF WET WEATHER IS
EXPECTED THROUGH THE FIRST HALF OF THE COMING WEEK. MODELS DO
SHOW ANOTHER CIRCULATION PASSING SOUTH OF THE LOCAL AREA WEDNESDAY
AND THURSDAY. THIS LOOKS LIKE A REPEAT OF THE CURRENT SITUATION
AND WILL WAIT AND SEE BEFORE ADDING ANY SIGNIFICANT RAINFALL TO
THE FORECAST.

&&

.MARINE...
AN EAST TRADE-WIND SWELL AND A NORTH SWELL WILL PREVAIL OVER THE
REGION THROUGH THE WEEKEND. THESE SWELLS WILL BE LARGE ENOUGH TO
GENERATE A MODERATE RIP CURRENT RISK ON NORTH FACING REEFS TODAY
AND ON EAST FACING REEFS THE NEXT FEW DAYS.

&&

.EASTERN MICRONESIA...
DRIER WEATHER HAS MOVED OVER THE MARSHALL ISLANDS FROM THE
NORTHEAST AS CONVECTION ASSOCIATED WITH A DISTURBANCE APPROACHING
KOSRAE MOVES FARTHER SOUTHWEST OF THE MARSHALL ISLANDS. MODELS
ARE IN GOOD AGREEMENT IN BRINGING SCATTERED SHOWERS TO MAJURO
LATE SUNDAY AS LOW-LEVEL CONVERGENCE INCREASES IN RESPONSE TO A
DEVELOPING DISTURBANCE NEAR THE GILBERT ISLANDS. A TRADE-WIND
CONVERGENCE PATTERN IS EXPECTED TO PERSIST ACROSS THE REGION BUT
SHOWERS SHOULD STAY JUST TO THE SOUTH OF MAJURO EARLY NEXT WEEK.
SATELLITE SHOWS AN AREA OF PERSISTENT SHOWERS MAKING WESTWARD
PROGRESS TOWARDS KOSRAE. SCATTERED SHOWERS SHOULD BEGIN THIS
AFTERNOON OVER KOSRAE WATERS AS THE MAIN FORCING MOVES OVER THE
STATE. RELATIVELY DRY CONDITIONS WILL CONTINUE AT POHNPEI THROUGH
THE WEEKEND. MODELS INDICATE ACTIVE WEATHER RETURNING FOR MOST OF
EASTERN MICRONESIA TUESDAY OR WEDNESDAY.

&&

.WESTERN MICRONESIA...
INFRARED SATELLITE IMAGERY SHOWS DIMINISHING CLOUD COVER ACROSS
CHUUK WATERS. CONVECTION TO THE NORTHEAST OF CHUUK CONTINUES TO
WEAKEN AND WILL PASS MAINLY NORTH OF CHUUK WATERS. A FEW SHOWERS
SHOULD REDEVELOP NORTH OF A NEAR-EQUATORIAL TROUGH LATER TODAY
AND TONIGHT BUT SHOULD REMAIN ISOLATED IN COVERAGE. THE NEXT
WEATHER MAKER IS PROGGED TO AFFECT CHUUK LATE IN THE FORECAST
PERIOD POSSIBLY BRINGING SCATTERED SHOWERS TO THE AREA ON
TUESDAY. EXTENSIVE MID TO UPPER-LEVEL CLOUD COVER IS STREAMING
WESTWARD OVER YAP FROM CONVECTION ASSOCIATED WITH TROPICAL
DISTURBANCE 98W CENTERED SOUTH OF GUAM NEAR 11N145E. SHOWERS ARE
ANTICIPATED TO INCREASE LATE THIS MORNING INTO EARLY AFTERNOON AT
YAP AS THE CENTER OF 98W NEARS. MODELS SHOW THE LLCC OF 98W
PASSING VERY NEAR YAP SUNDAY MORNING SO ALTERED WINDS DURING THIS
TIME FRAME. SHOWERS COULD LINGER INTO SATURDAY NIGHT BUT 98W HAS
DISPLAYED SEEMINGLY RANDOM CONVECTIVE BURSTS OVER THE LAST 48
HOURS SO DIFFICULTY REMAINS IN PINPOINTING EXACT LOCATION AND
TIMING OF THE HEAVIER SHOWERS. MOST OF THE SHOWER ACTIVITY WITH
98W SHOULD PASS TO THE NORTH OF KOROR EARLY NEXT WEEK. RELATIVELY
DRY CONDITIONS ALONG WITH LIGHT AND VARIABLE WINDS WILL EXIST AT
KOROR FOR THE NEXT SEVERAL DAYS.

&&

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

$$

ZIOBRO/WILLIAMS