803
FXPQ60 PGUM 042127
AFDPQ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
727 AM CHST FRI APR 5 2019
MARIANAS SYNOPSIS
ISOLATED SHOWERS AND EAST TO NORTHEAST TRADE WINDS PREVAIL OVER THE
MARIANAS THIS MORNING.
DISCUSSION
NO CHANGES MADE TO THE FORECAST. SATELLITE IMAGERY DEPICTS MOSTLY
CLOUDY SKIES AND RADAR SHOWS ISOLATED SHOWERS OVER THE LOCAL AREA.
LITTLE CHANGE THROUGH SATURDAY NIGHT AS SKIES AND SHOWER COVERAGE WILL
REMAIN THE SAME. WHILE THERE MAYBE A FEW SHOWERS, MODELS KEEP THINGS
RELATIVELY DRY THROUGH THE FORECAST. BOTH GFS AND ECMWF TOTAL RAINFALL
ACCUMULATION THROUGH NEXT SUNDAY IS LESS THAN ONE INCH.
MARINE
OBSERVATIONS FROM RITIDIAN AND IPAN BUOYS SHOW SEA HEIGHTS BETWEEN 5
AND 8 FEET. RITIDIAN HAD A LARGE INCREASE TO 8 FEET OVERNIGHT AND AT
ONE POINT TOUCHED 9 FEET. SATELLITE ALTIMETRY CONFIRMS THIS DEPICTING
SEA HEIGHTS OF 7 TO 8 FEET OVER THE MARIANAS. THE NORTH SWELL IS UP
TO 3 TO 4 FEET. NOT CERTAIN THE REASON FOR THE INCREASE BUT
SCATTEROMETER HINTS AT SLIGHTLY HIGHER WINDS NORTH OF THE LOCAL AREA,
POSSIBLY JUST NORTH OF A WEAK SHEAR LINE. EXPECT THESE CONDITIONS TO
PREVAIL THROUGH TONIGHT BEFORE DECREASING SATURDAY.
THE NORTH SWELL AND AN EAST SWELL WILL PERSIST THROUGH THE FORECAST.
THE NORTH SWELL WITH A HEIGHT OF 3 TO 4 FEET AND PERIOD OF 10 TO 11
SECONDS IS EXPECTED TO PRODUCE SURF OF 5 TO 7 FEET ON NORTH FACING
REEFS. THIS SWELL SHOULD DECREASE BY SATURDAY.
EASTERN MICRONESIA AND CHUUK
THE EASTERN PORTION OF A NEAR-EQUATORIAL TROUGH PERSISTS SOUTH OF
CHUUK, POHNPEI AND KOSRAE THIS MORNING. CONVERGING EAST-SOUTHEAST
WINDS NORTH OF THIS TROUGH WILL CONTINUE TO COUPLE WITH MODEST
DIVERGENT SOUTHEASTERLY FLOW ALOFT TO TRIGGER PERIODIC CONVECTION NEAR
CHUUK THRU SATURDAY, POHNPEI THRU TONIGHT AND KOSRAE THRU THIS
AFTERNOON. AT THE END OF THE NEAR-EQUATORIAL TROUGH, THERE IS A WEAK
CIRCULATION AND RELATED SURFACE TROUGH NEAR 3N168E. THESE FEATURES ARE
EXPECTED TO PROGRESS WESTWARD STARTING TONIGHT, WHICH WILL PROLONG
SHOWERY WEATHER NEAR KOSRAE UNTIL SATURDAY AFTERNOON, POHNPEI THRU
SATURDAY EVENING AND CHUUK UNTIL SUNDAY. FARTHER EAST, MUCH DRIER
FRESH TO STRONG TRADE WINDS WILL CONTINUE TO DOMINATE WEATHER NEAR
MAJURO THRU THIS WEEKEND. THESE SAME TRADES WILL EVENTUALLY MAKE THEIR
WAY TO KOSRAE BY SATURDAY EVENING, POHNPEI AND CHUUK BY SUNDAY
AFTERNOON. TOWARD MIDWEEK NEXT WEEK, INCREASING MID-LEVEL MOISTURE
FROM EAST TO WEST CAN SPARK MORE FREQUENT TRADE-WIND SHOWERS ACROSS
THE REGION.
THE FRESH TO STRONG TRADE WINDS WILL CAUSE SWELL AND SURF TO BUILD
ACROSS THE REGION THIS WEEKEND. NEED TO MONITOR THE POTENTIAL FOR
HAZARDOUS SURF AND ALSO MARINE CONDITIONS HAZARDOUS FOR SMALL CRAFT.
WESTERN MICRONESIA FOR YAP AND KOROR
A BROAD CIRCULATION EMBEDDED WITHIN A NEAR-EQUATORIAL TROUGH REMAINS
SOUTHEAST OF KOROR AND YAP NEAR 5N139E. A SURFACE TROUGH CAN BE SEEN
EXTENDING NORTHWARD FROM IT TO NEAR ROTA IN THE MARIANA ISLANDS THIS
MORNING. MODEST CONVERGENT NORTHEAST WINDS NORTHWEST OF THE
CIRCULATION WILL KEEP SPORADIC CONVECTION OVER BOTH LOCATIONS THRU
EARLY THIS EVENING. AS THE SURFACE TROUGH STEADILY PUSHES WESTWARD
TOWARD FAR WESTERN MICRONESIA TONIGHT, IT WILL FURTHER ENHANCE SHOWER
ACTIVITY NEAR YAP AND KOROR THRU SATURDAY NIGHT. AFTER THE SURFACE
TROUGH HAS PASSED WEST OF THE AREA ON SUNDAY, CONVERGENT SOUTHEAST
WINDS IT ITS WAKE WILL MAINTAIN A RELATIVELY UNSTABLE CONDITIONS UNTIL
TUESDAY.
GUM WATCHES/WARNINGS/ADVISORIES
GU...NONE.
MARIANAS WATERS...NONE.
ZIOBRO/CHAN
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