424
FXPQ60 PGUM 022101
AFDPQ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
701 AM CHST WED APR 3 2019
MARIANAS SYNOPSIS
ISOLATED SHOWERS AND EAST TO NORTHEAST TRADE-WINDS WINDS PREVAIL OVER
THE MARIANAS THIS MORNING.
DISCUSSION
A FEW SMALL TWEAKS MADE TO THE FORECAST. DID EXTEND THE MOSTLY
CLOUDY PERIOD INTO SATURDAY NIGHT. RADAR AND SATELLITE IMAGERY SHOWED
ISOLATED SHOWERS MOVING OVER THE MARIANAS THIS MORNING. SATELLITE
PRECIPITABLE WATER IMAGERY DEPICTED AN AREA OF DRIER AIR PUSHING
TOWARDS THE MARIANAS. THIS DRIER AIR WILL KEEP SKIES PARTLY CLOUDY
AND SHOWERS ISOLATED THROUGH THURSDAY.
UNCERTAINTY ABOUT WEATHER THURSDAY NIGHT INTO THE WEEKEND. MODELS ARE
DEPICTING A CIRCULATION PASSING SOUTH OF THE MARIANAS THURSDAY NIGHT.
MODELS SEEM TO AGREE ON THE PLACEMENT OF THE CIRCULATION BUT DISAGREE
ON THE EFFECTS IT MAY HAVE ON THE MARIANAS. WHILE THE CIRCULATION
WILL REMAIN SOUTH OF THE LOCAL AREA...LOW-LEVEL CONVERGENCE NORTH OF
IT WILL PRODUCE AN AREA OF SCATTERED SHOWERS. GFS HAS SHOWERS OVER
MARIANAS THURSDAY NIGHT THROUGH SATURDAY, THE ECMWF HAS THIS ONLY
ON FRIDAY AND FRIDAY NIGHT. NAVGEM KEEPS THE SHOWERS IN THURSDAY
NIGHT THROUGH MONDAY WHILE CMC HAS SCATTERED SHOWERS ONLY ON
FRIDAY NIGHT. THIS INDICATES THE UNCERTAINTY IS STILL HIGH ON
WHEN OR IF SCATTERED SHOWERS WILL OCCUR OVER THE MARIANAS. IN FACT
YESTERDAY THE GFS AND NAVGEM HAD THE CIRCULATION PASSING EAST OF
GUAM. BECAUSE OF THE UNCERTAINTY LEFT FORECAST BASICALLY UNTOUCHED
WITH MOSTLY CLOUDY SKIES LIKELY THURSDAY NIGHT THROUGH SATURDAY
NIGHT.
WHEN THE CIRCULATION PASSES SOUTH OF THE MARIANAS IT WILL
CAUSE A SLIGHT INCREASE IN THE PRESSURE GRADIENT RESULTING IN A
SMALL INCREASE IN WINDS THURSDAY THROUGH FRIDAY.
MARINE
OBSERVATIONS FROM RITIDIAN AND IPAN BUOYS SHOW SEAS HEIGHTS BETWEEN
5 TO 6 FEET. MODELS KEEP SEAS AROUND 4 TO 6 FEET THROUGH THURSDAY
INCREASING SLIGHTLY THURSDAY NIGHT.
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 THURSDAY NIGHT THROUGH THE WEEKEND. IF GFS IS CORRECT THAN A
WETTING RAIN MAY OCCUR ON A FEW DAYS. GFS PREDICTS BETWEEN 1 TO 2
INCHES TOTAL RAINFALL ACCUMULATION FROM NOW THROUGH SUNDAY NIGHT.
ECMWF HAS LESS WITH ONLY A HALF AN INCH TOTAL. EVEN IF THERE WAS A
WETTING RAIN IT WOULD ONLY KEEP THINGS MOIST FOR A FEW DAYS. MODELS
DO SHOW A SLIGHT INCREASE IN WINDS THURSDAY THROUGH FRIDAY AND
THIS MAY INCREASE DRYING AND ALSO PRODUCE FAVORABLE CONDITIONS FOR
FIRES TO SPREAD.
EASTERN MICRONESIA AND CHUUK
THE NEAR-EQUATORIAL TROUGH REMAINS STRETCHED ACROSS THE REGION SOUTH
OF CHUUK, POHNPEI AND KOSRAE WITH SHOWERS AND THUNDERSTORMS ACROSS
POHNPEI AND KOSRAE STATES. WEATHER IS IN A LULL THIS MORNING AT
CHUUK WHILE TRADE WIND SHOWERS AND THUNDERSTORMS ARE FOUND SOUTH AND
SOUTHWEST OF MAJURO.
MODEL GUIDANCE DIFFERS SIGNIFICANTLY WITH THE GFS STILL DEVELOPING
THE CIRCULATION CENTERED SOUTHWEST OF POHNPEI AND MOVING IT TO THE
WEST-NORTHWEST ACROSS CHUUK STATE WHILE THE ECMWF MAINTAINS A STATUS-
QUO OF THE CURRENT PATTERN. FORECAST CONFIDENCE REMAINS LOW AT THIS
TIME, PARTICULARLY FOR CHUUK. MODELS COME INTO BETTER ALIGNMENT OVER
THE WEEKEND WITH A PREVAILING TRADE WIND PATTERN ACROSS THE REGION.
TRADE-WIND SWELL AND WIND WAVES WILL MAINTAIN HAZARDOUS SURF ALONG
EASTERN EXPOSURES AT KOSRAE TODAY. SURF SHOULD SURF SHOULD SUBSIDE
BELOW HAZARDOUS LEVELS BY THIS EVENING.
WESTERN MICRONESIA FOR YAP AND KOROR
GENERALLY DRY WEATHER IS FOUND AT YAP AND KOROR THIS MORNING.
HOWEVER, SHOWERS AND A FEW THUNDERSTORMS ARE JUST EAST AND SOUTHEAST
OF YAP NEAR A WEAK CIRCULATION WITHIN THE NEAR-EQUATORIAL TROUGH.
THE TROUGH AND CIRCULATION WILL KEEP NEARLY STATIONARY A COUPLE DAYS
BEFORE MOVING WEST. ISOLATED SHOWERS AND THUNDERSTORMS ARE EXPECTED
AT YAP TODAY AND KOROR TONIGHT AND THURSDAY. GFS ATTEMPTS TO DEVELOP
A CIRCULATION SOUTHWEST OF POHNPEI AND BRINGING IT TOWARD YAP FRIDAY
AND SATURDAY WHILE THE ECMWF MAINTAINS THE CURRENT PATTERN WITH THE
NEAR-EQUATORIAL TROUGH STILL TO THE SOUTH THROUGH THE END OF THE
WEEK. FORECAST STILL FOLLOWS CLOSELY WITH THE ECMWF, PARTICULARLY IN
THE MID TO LONG-RANGE.
GUM WATCHES/WARNINGS/ADVISORIES
GU...NONE.
MARIANAS WATERS...NONE.
ZIOBRO/M. AYDLETT
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