426
FXPQ60 PGUM 032148
AFDPQ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
748 AM CHST THU APR 4 2019
MARIANAS SYNOPSIS
ISOLATED SHOWERS AND EAST TO NORTHEAST TRADE WINDS PREVAIL OVER THE
MARIANAS THIS MORNING.
DISCUSSION
A SMALL CHANGE MADE TO THE FORECAST. SATELLITE IMAGERY DEPICTS MOSTLY
CLOUDY SKIES OVER THE LOCAL AREA. FORECAST FOR TODAY ONLY HAD PARTLY
CLOUDY SKIES SO ADJUSTED FORECAST TO REFLECT THIS.
UNCERTAINTY STILL EXIST ABOUT THE WEATHER TONIGHT INTO THE WEEKEND.
MODELS SHOW A CIRCULATION SOUTH OF THE MARIANAS TODAY. IT WILL MOVE
SLOWLY WEST THE NEXT FEW DAYS. WHILE THE CIRCULATION WILL REMAIN
SOUTH OF THE LOCAL AREA...LOW-LEVEL CONVERGENCE NORTH OF IT WILL
PRODUCE AN AREA OF SCATTERED SHOWERS. SATELLITE IMAGERY DOES SHOW
SHOWERS TO THE SOUTHEAST OF GUAM. GFS IS STILL THE WETTEST AND HAS
SHOWERS OVER MARIANAS TONIGHT THROUGH FRIDAY WITH A SECOND BATCH
SUNDAY THROUGH TUESDAY. THE ECMWF...ICON...AND NAVGEM HAS THIS ONLY
TONIGHT THROUGH FRIDAY NIGHT. TENDED TO FAVOR THE DRIER MODELS AND
EVEN IF SHOWERS DID INCREASE FEEL THAT ISOLATED WILL BE THE
PREDOMINANT COVERAGE OVER THE MARIANAS. AT LEAST SKIES WILL BE MOSTLY
CLOUDY TODAY THROUGH AT LEAST SATURDAY NIGHT.
MARINE
OBSERVATIONS FROM RITIDIAN AND IPAN BUOYS SHOW SEAS HEIGHTS BETWEEN
4 AND 5 FEET. MODELS KEEP SEAS AROUND 4 TO 6 FEET THROUGH TODAY
INCREASING SLIGHTLY TONIGHT.
AN EAST SWELL AND A NORTH SWELL WILL PREVAIL THROUGH THE FORECAST.
NEITHER SWELL WILL GET TOO LARGE AND WILL PRODUCE A MODERATE RISK OF
RIP CURRENTS ON NORTH AND EAST FACING REEFS FOR A FEW DAYS.
FIRE WEATHER
RELATIVELY DRY WEATHER WILL PREVAIL THE NEXT FEW DAYS. AS MENTIONED
ABOVE...THERE IS THE POSSIBILITY OF AN INCREASE IN THE CHANCE OF
SHOWERS TONIGHT THROUGH THE WEEKEND. IF GFS IS CORRECT THAN A WETTING
RAIN MAY OCCUR ON A FEW DAYS. GFS PREDICTS UP TO 4 INCHES TOTAL
RAINFALL ACCUMULATION FROM NOW THROUGH TUESDAY. ECMWF HAS TOTALS LESS
THAN AN INCH. EVEN IF THERE WAS A WETTING RAIN IT WOULD ONLY KEEP
THINGS MOIST FOR A FEW DAYS AT MOST.
EASTERN MICRONESIA AND CHUUK
THE SOUTHEASTERN PORTION OF A NEAR-EQUATORIAL TROUGH PERSISTS JUST
SOUTH OF CHUUK, POHNPEI AND KOSRAE THIS MORNING. GENTLE TO MODERATE
ZONAL TRADE WINDS NORTH OF THE TROUGH SHOULD ALLOW LESS SHOWER
COVERAGE NEAR CHUUK AND POHNPEI THRU THIS EVENING. FARTHER EAST, A
MODERATE TO FRESH TRADE-WIND SURGE IS MOVING ACROSS THE MARSHALL
ISLANDS, INCREASING LOW-LEVEL CONVERGENCE NEAR THE END OF THE NEAR-
EQUATORIAL TROUGH. THIS HAS CAUSED WIDESPREAD CONVECTION FROM KOSRAE
EASTWARD TO BUTARITARI AND TARAWA ATOLLS, AND THIS TREND WILL CONTINUE
THRU TONIGHT. MEANWHILE, MUCH DRIER TRADE WINDS WILL REMAIN NEAR
MAJURO THRU THIS WEEKEND. STARTING LATE TONIGHT AND FRIDAY, THE NEAR-
EQUATORIAL TROUGH IS EXPECTED TO GRADUALLY LIFT NORTHWESTWARD CLOSER
TO ALL THREE LOCATIONS. THIS WILL INTRODUCE WETTER CONDITIONS TO
POHNPEI AND CHUUK BY FRIDAY MORNING AND ALSO PROLONG IT NEAR KOSRAE
THRU SATURDAY. THE LEADING ELEMENT OF THE SURGE WILL TRIGGER A FEW
SHOWERS NEAR MAJURO TODAY. OTHERWISE, A DRY TRADE- WIND PATTERN WILL
CONTINUE THRU SATURDAY. THIS MUCH DRIER AIR MASS WILL SLOWLY SHIFT
WESTWARD, REACHING KOSRAE SATURDAY, POHNPEI AND CHUUK EARLY NEXT WEEK.
WESTERN MICRONESIA FOR YAP AND KOROR
A NEAR-EQUATORIAL TROUGH IS QUASI-STATIONARY NEAR 4N142E. A SURFACE
TROUGH MERGING INTO THE NEAR-EQUATORIAL TROUGH WILL SPARK OFF SHOWERS
AND POSSIBLE THUNDERSTORMS NEAR KOROR BY NOON TODAY. FOR YAP, MAINLY
ISOLATED SHOWERS AND A FEW THUNDERSTORMS ARE EXPECTED. AFTER THE
PASSAGE OF THIS SURFACE TROUGH, GENTLE TO MODERATE TRADES WILL RETURN
TO KOROR ON FRIDAY AND YAP BY TONIGHT. A BROAD SURFACE TROUGH
CURRENTLY EAST OF THE MARIANAS IS RUNNING INTO A RIDGING PATTERN OVER
THE PHILIPPINE SEA. THIS SHOULD SLOW IT DOWN AND DELAY ITS ARRIVAL
AT YAP TO FRIDAY AND KOROR BY FRIDAY MORNING WITH MORE WET WEATHER.
AFTERWARD, MODEST CONVERGING SOUTHEAST WINDS IN THE WAKE OF THE
SURFACE TROUGH WILL SUSTAIN UNSTABLE CONDITIONS THRU THE WEEKEND.
GUM WATCHES/WARNINGS/ADVISORIES
GU...NONE.
MARIANAS WATERS...NONE.
ZIOBRO/CHAN
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page