Area Forecast Discussion
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000
FXPQ60 PGUM 012105
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
705 AM CHST THU JUL 2 2015

.SYNOPSIS...NORTHEAST WINDS AND ISOLATED SHOWERS WILL PREVAIL TODAY.
SHOWERS AND WINDS WILL INCREASE AS CHAN-HOM APPROACHES THE
MARIANAS.

&&

.DISCUSSION...
THE MAIN CONCERN IS WHAT WILL CHAN-HOM DO. THE TRACK FORECAST IS
STILL NOT CERTAIN AS PROJECTIONS HAVE SHIFTED BETWEEN A PASSAGE
TO THE NORTH OF GUAM AND ALSO TO THE SOUTH OF GUAM. DESPITE THE
EARLY MORNING PREDICTION OF CHAN-HOM PASSING THROUGH THE ROTA
CHANNEL LEFT THE OLD FORECAST THAT SHOWS THE STORM PASSING SOUTH
OF GUAM. FEEL UNCOMFORTABLE WITH FLIP-FLOPPING THE TRACK UNTIL THE
MODELS SETTLE DOWN ON THEIR PREDICTIONS. AT ANY RATE FELT THAT
THIS DID NOT SACRIFICE ACCURACY ALL THAT MUCH AS THE FORECAST
PREDICTS THAT TROPICAL STORM OR EVEN TYPHOON CONDITION ARE
POSSIBLE FOR ALL THE ISLANDS. CHANGED THE ARRIVAL TIME AS THE
STORM HAS SLOWED ITS FORWARD SPEED. THE EARLIER FORECAST HAD CHAN-
HOM PASSING SATURDAY AFTERNOON...NOW BECAUSE OF THE SLOWER SPEED
PASSAGE IS CLOSER TO SATURDAY NIGHT. WINDS SHOULD START TO PICK-UP
FRIDAY BECOMING BREEZY FRIDAY NIGHT. TROPICAL STORM FORCE WINDS
ARE POSSIBLE BY NOON SATURDAY WITH TYPHOON CONDITION A
POSSIBILITYBY SATURDAY NIGHT.

IF FIGURING OUT WHAT CHAN-HOM WILL DO SEEMS COMPLICATED THEN THE
ADDITION OF THE CIRCULATION SOUTH OF GUAM KNOWN AS 94W ADDS MORE
DIMENSIONS TO THAT COMPLICATION. THIS CIRCULATION IS STILL AN
INDEPENDENT CIRCULATION BUT IS EXPECTED TO BE ABSORBED BY CHAN-
HOM AS TIME GOES ON. MERGERS ARE COMPLICATED AS THE INTERACTION OF
THE TWO MAY CHANGE THE TRACK IN STILL UNFORESEEN WAYS. AFTER CHAN-
HOMS PASSAGE THE MARIANAS WILL BE IN SOUTHWEST WINDS AS THE STORM
WILL DRAG THE MONSOON TROUGH NORTH OF THE LOCAL AREA.

&&

.MARINE...
BUOY DATA SHOWED AN EAST SWELL OVER THE MARIANAS THIS MORNING. THERE
IS WINDS GENERATED ALONG THE MONSOON TROUGH SOUTH OF THE MARIANAS
IS PUSHING WAVES IN THIS DIRECTION GENERATING A SOUTHWEST SWELL.
COMBINED SEAS OF 5 TO 6 FEET TODAY WILL BEGIN INCREASING BY
FRIDAY. COMBINED SEAS ARE PROJECTED TO REACH 15 TO 17 FEET

&&

.EASTERN MICRONESIA...
A MONSOON TROUGH MEANDERS EASTWARD FROM A CIRCULATION...JTWC INVEST
94W CENTERED WEST OF WENO CHUUK NEAR 8N148E THRU TROPICAL STORM CHAN-
HOM CENTERED NORTHWEST OF POHNPEI NEAR 11N155E AND ANOTHER CIRCULATION
...JTWC INVEST 97W CENTERED EAST OF MAJURO NEAR 7N175E TO BEYOND
180 AT 7N. CONVERGING FRESH TO STRONG SOUTHWEST WINDS FEEDING
TOWARD CHAN-HOM AND THE MONSOON TROUGH WILL MAINTAIN SHOWERY
WEATHER NEAR CHUUK AND POHNPEI THRU FRIDAY. FARTHER EAST...MONSOONAL
WEST TO SOUTHWEST WINDS ASSOCIATED WITH 97W WILL ALSO SUSTAIN
SIMILAR CONDITIONS NEAR KOSRAE AND MAJURO THRU FRIDAY. ENHANCED BY
AN UPPER- LEVEL TROUGH IN THE VICINITY...DEEP CONVECTION IS
POSSIBLE NEAR MAJURO TONIGHT AND FRIDAY.

AS TROPICAL STORM CHAN-HOM DRIFTS WEST-NORTHWESTWARD PASSING NORTH
OF CHUUK ON FRIDAY...IT MIGHT MERGE WITH 94W WHICH CAN CAUSE ITS
WIND FIELD TO EXPAND. IF SO...WET WEATHER PRODUCED BY CONVERGENT
SOUTHWEST WINDS WILL CONTINUE OVER CHUUK THRU SATURDAY. 97W AND THE
MONSOON TROUGH ARE ALSO EXPECTED TO LIFT SLOWLY WEST-NORTHWESTWARD
OVER THE NEXT COUPLE OF DAYS. THIS SHOULD ALLOW WEAKER MONSOONAL
WINDS FARTHER SOUTH TO SHIFT OVER POHNPEI...KOSRAE AND MAJURO BY
THIS WEEKEND. UNDER THIS SCENARIO...SHOWER COVERAGE SHOULD BEGIN TO
DECREASE OVER THESE THREE LOCATIONS. BY EARLY NEXT WEEK...GENTLE
SOUTH TO SOUTHEAST TRADES MIGHT RETURN TO KOSRAE AND MAJURO WITH
FAIR WEATHER. HOWEVER...LINGERING MONSOONAL WINDS CAN STILL TRIGGER
ISOLATED CONVECTION FOR POHNPEI AND CHUUK THRU MONDAY.

LATEST SATELLITE-DERIVED SEA HEIGHTS INDICATE 9 TO 12 FEET NEAR
CHUUK AND POHNPEI STATES...AND 8 TO 10 FEET ACROSS KOSRAE AND THE
MARSHALL ISLANDS. THESE VALUES ARE RELATIVELY CLOSE WITH WW3 MODEL
PREDICTIONS. SOUTHWEST SWELL AND WIND WAVES PRODUCED BY FRESH
MONSOONAL WINDS WILL PROLONG HAZARDOUS SURF ACROSS CHUUK...POHNPEI
AND KOSRAE STATES THRU THIS WEEKEND. THESE SAME ELEMENTS WILL ALSO
CAUSE SEA CONDITIONS HAZARDOUS FOR SMALL CRAFT ACROSS THE MARSHALL
ISLANDS...KOSRAE UNTIL FRIDAY AFTERNOON AND POHNPEI...CHUUK THRU
SATURDAY AFTERNOON. COINCIDED WITH A PEAKING SPRING TIDE CYCLE...
MINOR COASTAL INUNDATIONS ARE POSSIBLE ALONG SOUTH AND WEST FACING
SHORES NEAR MAJURO.

&&

.WESTERN MICRONESIA...
DISCUSSION FOR THE CHUUK FORECAST IS INCLUDED IN THE EASTERN
MICRONESIA SECTION ABOVE DUE TO A SIMILAR WEATHER PATTERN.

A STRONG MONSOON TROUGH EXTENDS EAST-SOUTHEASTWARD FROM LUZON
PASSING 13N130E AND NORTH OF KOROR AND YAP NEAR 11N TO TROPICAL
STORM CHAN-HOM CENTERED NORTHEAST OF CHUUK NEAR 11N155E. MONSOONAL
WINDS SOUTH OF THE TROUGH WILL CONTINUE TO GENERATE SPORADIC
CONVECTION NEAR KOROR AND YAP THRU FRIDAY. AS CHAN-HOM GRADUALLY
TRACKS WEST-NORTHWESTWARD TOWARD THE MARIANA ISLANDS FRIDAY NIGHT
AND SATURDAY...IT WILL REINFORCE ANOTHER MONSOONAL WIND SURGE ACROSS
KOROR AND YAP. THEREFORE ANTICIPATE EVEN WETTER WEATHER FOR BOTH
LOCALS THRU SATURDAY. DEPENDS ON THE INTENSITY OF CHAN-HOM AFTER IT
HAS MOVED OVER THE PHILIPPINE SEA NORTH OF PALAU AND YAP EARLY NEXT
WEEK...IT MIGHT STILL MAINTAIN A WET MONSOONAL REGIME OVER THE AREA.

SATELLITE-DERIVED SEA HEIGHTS DATA TREND FOR THE PAST COUPLE OF DAYS
REVEALS RISING SEAS ACROSS THE REPUBLIC OF PALAU AND YAP STATE.
LATEST DATA SUGGEST SEAS ARE REACHING 10 FEET THIS MORNING. THIS IS
A GOOD INDICATION OF RISING SWELL AND WIND WAVES CAUSED BY
PERSISTENT MONSOONAL WINDS. EXPECT THIS TREND TO CONTINUE THRU THIS
WEEKEND WHICH WILL PROLONG HAZARDOUS SURF AND SEA CONDITIONS
HAZARDOUS TO SMALL CRAFT ACROSS THE REPUBLIC OF PALAU AND YAP STATE
INTO NEXT WEEK.

&&

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

$$

ZIOBRO/CHAN



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