Area Forecast Discussion
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FXPQ60 PGUM 262000
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
600 AM CHST SUN JUL 27 2014

.MARIANAS SYNOPSIS...
A COMPLEX MONSOON PATTERN EXISTS ACROSS THE MARIANAS. THE MONSOON
TROUGH AXIS HAS MOVED JUST TO THE NORTH OF SAIPAN WATERS. A STRONG
GRADIENT OF WIND SPEEDS AND COMBINED SEA HEIGHTS ARE FOUND OVER
THE REGION WITH THE HIGHEST WINDS AND SEAS OVER SOUTHWEST GUAM
WATERS. EVIDENCE OF SOUTHWEST SWELL BEGINNING TO ARRIVE IS
OBSERVED IN BUOY DATA BUT SIGNIFICANT RISES IN COMBINED SEAS HAS
YET TO BE OBSERVED DIRECTLY. IN ADDITION TO THE MONSOON
TROUGH...TROPICAL DISTURBANCE 90W WAS CENTERED NORTH-NORTHWEST OF
POHNPEI NEAR 9N157E.

&&

.DISCUSSION...
AN UNSETTLED MONSOON PATTERN IS EXPECTED TO CONTINUE THROUGH
MIDWEEK. SCATTERED SHOWERS ARE EXPECTED TO DISSIPATE LATER TODAY
BEFORE RETURNING LATER TONIGHT. FOLLOWED THE DIURNAL CONVECTIVE
PATTERN MUSH LIKE YESTERDAY. PERIODS OF SCATTERED SHOWERS AND
ISOLATED TSTMS ARE LIKELY THROUGH MIDWEEK IN ADVANCE OF 90W.
MODELS INDICATE 90W WILL MOVE A BIT SLOWER THAN ANTICIPATED SO
ADJUSTED WINDS TO ACCOUNT FOR RECENT MODEL GUIDANCE. MINOR
CHANGES WERE MADE TO THE SHORT TERM MARINE GRIDS. THE FORECAST
FOR MIDWEEK STILL HEDGES ON INTENSITY AND THE SPEED OF MOVEMENT OF
90W EARLY THIS WEEK.

&&

.MARINE...
SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR GUAM WATERS. DECIDED
AGAINST EXTENDING ADVISORY INTO ROTA WATERS AS RITIDIAN BUOY
SHOWS ALMOST NO INDICATION OF SIGNIFICANT SEA HEIGHT INCREASES
WITH CURRENT COMBINED SEAS OF AROUND 6 FT. THE RITIDIAN BUOY DOES
SHOW THE PRIMARY SWELL DIRECTION IS NOW FROM SOUTHWEST BUT WAVE
PERIOD REMAINS IN THE WIND WAVE CATEGORY. SEAS WILL GRADUALLY
BUILD TODAY AND TONIGHT WITH SMALL CRAFT CRITERIA BEING MET ACROSS
CNMI WATERS BY THIS EVENING SO THE ADVISORY SHOULD BE EXTENDED TO
INCLUDE THESE ZONES LATER. HAZARDOUS SURF WILL ALSO DEVELOP FROM
GUAM NORTHEASTWARD ACROSS THE CNMI TONIGHT THROUGH MONDAY. EXPECT
SURF TO RISE TO HAZARDOUS LEVELS TODAY ON GUAM...TONIGHT ON ROTA
AND MONDAY ON TINIAN AND SAIPAN. THESE ADVISORIES MAY HAVE TO BE
EXTENDED DEPENDING ON THE DEVELOPMENT OF 90W.

&&

.TROPICAL SYSTEMS...
TROPICAL DISTURBANCE 90W IN POHNPEI STATE STILL LOOKS RATHER
DISORGANIZED ON SATELLITE IMAGERY WITH LITTLE SUSTAINED
CONVECTION NEAR THE LOW-LEVEL CIRCULATION CENTER. IN
ADDITION...THE TUTT TO THE NORTH OF POHNPEI AND KOSRAE STATES IS
STILL PROVIDING AMPLE SHEAR OVER 90W. HOWEVER...MODELS ARE COMING
INTO BETTER AGREEMENT IN BRINGING THIS DISTURBANCE NORTHWESTWARD
TOWARD THE MARIANAS OVER THE COMING DAYS LIKELY PASSING OVER THE
MARIANAS SOMETIME MIDWEEK. NAVGEM IS THE LEAST AGGRESSIVE MODEL IN
INTENSIFICATION WHILE THE PAST SEVERAL RUNS OF THE GFS MODEL SHOW
THE DISTURBANCE INTENSIFYING INTO A STRONG TROPICAL STORM BY
MIDWEEK BEFORE REACHING THE MARIANAS. ECMWF SHOWS A SIMILAR TRACK
AND BRINGS THE SYSTEM OVER THE MARIANAS AS A WEAK DEPRESSION. DUE
TO THE LACK OF REAL DEVELOPMENT OF 90W...DECIDED TO INCORPORATE
MINIMAL EFFECTS INTO THE MARIANAS FORECAST FOR NOW. FORECAST
CONFIDENCE IS STILL LOW REGARDING ITS INTENSITY AS IT CROSSES THE
MARIANAS WEDNESDAY OR THURSDAY. NONETHELESS...A SPECIAL WEATHER
STATEMENT MAY BE NEEDED LATER TODAY OR TONIGHT DEPENDING ON THE
SHORT TERM EVOLUTION OF 90W.

&&

.EASTERN MICRONESIA...
ASCAT ANALYSIS SHOWS THE MONSOON TROUGH REMAINS STRETCHED ACROSS
EASTERN MICRONESIA TO BEYOND THE DATE LINE. INVEST AREA 90W IS A
WEAK CIRCULATION NORTHWEST OF POHNPEI NEAR 9.5N157E AND ANOTHER
POSSIBLE CIRCULATION IS WELL NORTHEAST OF MAJURO NEAR 10.5N176E.
MODELS INDICATE THE MOST SIGNIFICANT WEATHER WILL CONTINUE
DRIFTING TOWARD THE NORTHWEST AS 90W CONTINUES TO DEVELOP AND
MOVE TOWARD THE MARIANAS IN THE COMING DAYS. THE WEATHER AND WIND
CONDITIONS ACROSS EASTERN MICRONESIA WILL BE CHANGEABLE THROUGH
THE NEXT COUPLE OF DAYS...BUT IMPROVING WEATHER SHOULD RE-DEVELOP
DURING THE COMING WORK WEEK.

THE HAZARDOUS SURF ADVISORY REMAINS IN EFFECT FOR POHNPEI AND THE
SPECIAL WEATHER STATEMENT FOR MICRONESIA REMAINS IN EFFECT.

&&

.WESTERN MICRONESIA...
MONSOON FLOW DOMINATES WEATHER ACROSS WESTERN MICRONESIA AND
LITTLE CHANGE IS EXPECTED THROUGH THE NEAR TERM. ASCAT ANALYSIS
INDICATES THE LOW-LEVEL CIRCULATION ASSOCIATED WITH INVEST 96W IS
NEAR 13N133E AND EDGING TOWARD NORTH-NORTHWEST. INVEST 90W IS
CENTERED NORTHEAST OF CHUUK AT 9.5N157E AND IS PROGGED TO MOVE
TOWARD THE NORTHWEST AS IT SLOWLY DEVELOPS IN THE COMING DAYS.
MODERATE TO STRONG SOUTHWEST WINDS WILL CONTINUE ACROSS KOROR AND
YAP FOR A COUPLE OF DAYS AND THEN GRADUALLY DECREASE THIS COMING
WEEK.

AT CHUUK...WET MONSOON-TYPE WEATHER WILL CONTINUE AND CONDITIONS
WILL BE VERY CHANGEABLE...DEPENDING ON JUST HOW THE ACTIVE
WEATHER ASSOCIATED WITH 90W DEVELOPS AND MOVES IN THE COMING
DAYS.

HAZARDOUS SURF ADVISORY REMAINS IN EFFECT FOR KOROR...YAP...AND
CHUUK. SPECIAL WEATHER STATEMENT FOR MICRONESIA REMAINS IN
EFFECT.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...NONE.
MARIANAS WATERS...SMALL CRAFT ADVISORY UNTIL 6 AM CHST TUESDAY FOR PMZ151.

&&

$$

WILLIAMS/SIMPSON





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