000
FXPQ60 PGUM 190559
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
359 PM CHST WED JUN 19 2013

.SYNOPSIS...
AN UPPER LOW AND TROUGH NW AND WEST OF THE ISLANDS IS SETTING OFF
BRIEF ISOLATED THUNDERSTORMS NEAR AND WEST OF THE NORTHERN ISLANDS
NORTH OF SAIPAN. OTHERWISE...MODERATE TRADES AND ISOLATED SHOWERS
ARE SEEN ACROSS THE MARIANAS WATERS. THE DISTURBANCE IN THE CHUUK
AND POHNPEI AREA APPEARS TO BE GOING THROUGH A WEAKENING PHASE
WITH WARMING CLOUD TOPS.

&&

.DISCUSSION...
THE GFS AND UKMET HAVE BACKED OFF SLIGHTLY ON THE CHUUK/POHNPEI
DISTURBANCE AFFECTING THE MARIANAS...KEEPING NEARLY ALL THE
WEATHER SOUTH OF THE MARIANAS THU-FRI. BEYOND THAT...NO REAL
CHANGE THROUGH SUNDAY...WITH PARTLY CLOUDY SKIES AND ISOLATED
SHOWERS. STARTING MONDAY...GFS SHOWS A BROAD BUT WEAK CIRCULATION
TRYING TO GET GOING EAST OF THE ISLANDS AROUND 15N AND 155E. HAVE
MOSTLY CLOUDY STARTING MONDAY AND CONTINUING THROUGH MOST OF NEXT
WEEK AS THE DISTURBANCE SHOULD MOVE WEST AND BRING INCREASED CLOUDS
AND PERHAPS AN INCREASE IN SHOWERS AS WELL. PLENTY OF UNCERTAINTY
AS TO HOW AND IF THIS MAY DEVELOP...SO KEEPING SHOWERS ISOLATED
FOR NOW.

&&

.MARINE...
SEAS AT 4-6 FT SHOULD CHANGE LITTLE THROUGH FRIDAY...THEN WAVE
MODELS SHOW A SLIGHT DECREASE FOR THE WEEKEND. RIP RISK COULD FALL
TO LOW BY SATURDAY.

&&

.EASTERN MICRONESIA...
CONVECTION HAS PERSISTED ACROSS THE REGION FROM NEAR CHUUK EASTWARD
TO THE DATE LINE. SURFACE ANALYSIS SHOWS A WEAK CIRCULATION
SOUTHWEST OF POHNPEI WITH A SURFACE TROUGH CURVING TO THE EAST-
SOUTHEAST AND WEST-SOUTHWEST. CONVERGENCE FROM STRONGER TRADE WINDS
EAST OF THE MARSHALLS IS FUELING SHOWERS AND THUNDERSTORMS NEAR THE
MARSHALLS WHILE THE MAJORITY OF CONVECTION FARTHER WEST IS FOUND
ALONG AND JUST NORTH OF THE TROUGH NEAR POHNPEI AND KOSRAE. BECAUSE
MODELS HANDLE THESE FEATURES DIFFERENTLY...THERE IS LOW CONFIDENCE
IN EXPECTED WIND DIRECTIONS FOR BOTH POHNPEI AND KOSRAE THE NEXT
SEVERAL DAYS...HOWEVER...MODELS DO GRADUALLY LIFT CONVECTION
NORTHWARD BY THE WEEKEND WHICH WILL ALLOW DRIER CONDITIONS TO SPREAD
INTO ALL THREE LOCATIONS OVER THE WEEKEND.

&&

.WESTERN MICRONESIA...
SHOWERS HAVE SPREAD TO CHUUK FROM THE EAST AND AN ACTIVE WEATHER
PATTERN WILL PERSIST THE NEXT COUPLE OF DAYS UNTIL THE TROUGH LIFTS
TO THE NORTH. MODELS SHOW NO DEVELOPMENT OF THE WEAK CIRCULATION TO
THE EAST-SOUTHEAST BUT OPEN IT BACK INTO A TROUGH LATER IN THE WEEK.
SLIGHTLY QUIETER CONDITIONS ARE EXPECTED BY THE WEEKEND.

PATTERN NEAR YAP AND KOROR REMAINS SOMEWHAT TRICKY WITH WEAK SHALLOW
RIDGING FOUND SOUTHWEST OF KOROR AND A TROUGH STRETCHING SOUTHEAST
FROM NEAR YAP. A LITTLE SURGE OF WEST WINDS SOUTHWEST OF KOROR WILL
LIKELY CONTINUE TO WEAKEN AS IT APPROACHES THE AREA AND COULD CAUSE
WINDS TO BRIEFLY SWING AROUND TO WEST OR SOUTHWEST...BUT WINDS WILL
GENERALLY BE FROM THE EAST. A TUTT DIGGING SOUTHWESTWARD JUST NORTH
OF YAP AND KOROR MAY HELP MAINTAIN SOME THUNDERSTORMS THURSDAY AND/OR
THURSDAY NIGHT. OTHERWISE...MODELS SHOW A MORE BENIGN SOUTHEAST FLOW
SETTING UP BY THE WEEKEND.

&&

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

$$

MIDDLEBROOKE/W. AYDLETT

000
FXPQ60 PGUM 181956
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
556 AM CHST WED JUN 19 2013

.SYNOPSIS...
A SMALL TUTT CELL IS CENTERED BETWEEN PAGAN AND SAIPAN. A FEW
THUNDERSTORMS HAVE BEEN OBSERVED DURING THE OVERNIGHT HOURS NEAR
THE CENTER OF THIS SYSTEM. AN INVERTED SURFACE TROUGH IS EVIDENT
IN THE LATEST ASCAT IMAGERY IN THE VICINITY OF POHNPEI BETWEEN 5N
AND 15N. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE
ASSOCIATED WITH THIS FEATURE.

&&

.DISCUSSION...
THE WEAK BUT CONVECTIVELY ACTIVE TUTT HAS BEEN DROPPING SOUTHWARD
TOWARD SAIPAN. BASED ON THIS ADDED SLIGHT CHANCE THUNDER TO THE
FORECAST JUST FOR TODAY. NEXT WEATHER MAKER IN LINE APPEARS TO BE
THE SYSTEM NEAR POHNPEI. MODEL GUIDANCE DIFFERS ON JUST HOW FAR
NORTHWARD SCATTERED SHOWERS WILL REACH AS THIS SYSTEM PASSES BY.
ALL THE MODELS AGREE THAT THE TROUGH WILL MOVE THROUGH ON
THURSDAY NIGHT AND FRIDAY...SO HAVE ADDED MOSTLY CLOUDY SKIES TO
THE FORECAST DURING THIS TIME FRAME FOR NOW. REMAINDER OF THE
FORECAST LOOKS UNSETTLED AS DEEPER MOISTURE AND CONVERGENT TRADES
ARRIVE FROM THE SOUTH. PERIODS OF SCATTERED SHOWERS WILL BE
POSSIBLE DAYS 5 THROUGH 7...BUT IT IS TOO EARLY TO DETERMINE THE
EXACT TIMING AND EXTENT OF THE RAINFALL.

&&

.MARINE...
ALTIMETRY AND BUOY READINGS INITIALIZE MARIANAS COMBINED SEAS IN
THE 4 TO 5 FOOT RANGE. MODERATE RIP CURRENT RISK WILL CONTINUE TO
PREVAIL ALONG EAST-FACING REEFS FOR THE REMAINDER OF THIS WEEK. A
TRADE-WIND SURGE CURRENTLY ON THE EAST SIDE OF THE SURFACE TROUGH
NEAR POHNPEI WILL ARRIVE JUST IN TIME FOR THE WEEKEND. SURF ALONG
EAST FACING REEFS SHOULD BUILD A FOOT OR TWO...BUT REMAIN AT
MODERATE RIP CURRENT RISK LEVELS.

&&

.EASTERN MICRONESIA...
SHOWERS AND THUNDERSTORMS CONTINUE ACROSS THE REGION NEAR ALL
LOCALES THIS MORNING. IR SATELLITE SHOWS SCATTERED SHOWERS OVER
KOSRAE AND POHNPEI THIS MORNING. THE LEADING EDGE OF A TRADE-WIND
SURGE IS JUST EAST OF POHNPEI AND WILL REACH THE ISLAND BY MID-
MORNING. SOMEWHAT DRIER WEATHER IS SEEN OVER MAJURO. HOWEVER...
SATELLITE ANIMATION SUGGESTS CONVECTION IS FILLING IN ACROSS THE
MARSHALLS THIS MORNING NEAR KWAJALEIN AND EVENTUALLY NEAR MAJURO.
MODELS STILL SHOW THIS ACTIVE PATTERN PERSISTING A COUPLE MORE
DAYS BEFORE GRADUALLY LIFTING NORTHWARD. DRIER WEATHER WILL BE IN
PLACE WITH LIGHTER WINDS OVER ALL LOCATIONS BY THE WEEKEND. WIND
FORECASTS FOR SPEED AND DIRECTION MAY BECOME VARIABLE ACROSS MOST
OF THE REGION BY THE END OF THE WEEK.

&&

.WESTERN MICRONESIA...
WEATHER ON CHUUK WILL GRADUALLY DETERIORATE TODAY. SCATTERED
SHOWERS WILL ARRIVE BY EVENING. WEATHER SCENARIO HERE WILL FOLLOW
CLOSELY TO REASONING SEEN ABOVE FOR EASTERN MICRONESIA. CHUUK
CURRENTLY LIES ON THE WESTERN EDGE OF THE SWATH OF SHOWERS AND
THUNDERSTORMS THAT EXTENDS EASTWARD TOWARD THE MARSHALL ISLANDS.
SHOWERS WILL GRADUALLY TAPER TOWARDS THE END OF THE WEEK. THE BAND
OF SHOWERS CURRENTLY NEAR CHUUK WILL LIFT NORTHWARD...USHERING IN
DRIER WEATHER AND LIGHTER WINDS.

A WEAK DISTURBANCE WILL MAINTAIN CLOUDY SKIES AND A SLIGHT CHANCE
OF THUNDERSTORMS OVER YAP AND KOROR TODAY. MODELS KEEP SOMEWHAT
UNSETTLED WEATHER OVER BOTH LOCATIONS THROUGH THE WEEKEND...BUT
WITH A LACK OF WELL DEFINED WEATHER FEATURES. FORECAST WILL
FOLLOW PERSISTENCE FOR THE LONG TERM WITH MOSTLY CLOUDY SKIES...
ISOLATED SHOWERS AND LIGHT SOUTHEAST WINDS PREVAILING.

&&

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

$$

MCELROY/M. AYDLETT

000
FXPQ60 PGUM 180630
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
ISSUED BY NATIONAL WEATHER SERVICE HONOLULU HI
430 PM CHST TUE JUN 18 2013

.SYNOPSIS...
SURFACE RIDGING NEAR GUAM AND THE MARIANAS WILL KEEP QUIET WEATHER
OVER THESE ISLANDS THROUGH THE WEEK. THUNDERSTORMS ARE NOTED
NORTHEAST OF GUAM ASSOCIATED WITH AN UPPER LEVEL SYSTEM NORTH OF
GUAM.

&&

.DISCUSSION...
NO SIGNIFICANT CHANGES TO THE FORECAST PHILOSOPHY AT THIS TIME...SO
GRIDS REMAIN RELATIVELY UNCHANGED.

THE GFS...ECMWF AND NAVGEM SHOW VERY GOOD AGREEMENT FOR THE NEXT
SEVERAL DAYS WITH A HIGH NEAR 30N 170E...AND AN ASSOCIATED RIDGE
OVER THE AREA. THE MODELS REMAIN IN AGREEMENT FRIDAY AS THE HIGH
STARTS TO MOVE TO THE EAST. AS THE HIGH MOVES TO THE EAST...THE
RIDGE LIFTS NORTH OF THE MARIANAS ISLANDS. THE MODELS ARE IN GOOD
AGREEMENT THAT AS THAT HAPPENS...WINDS OVER THE MARIANAS WILL
LIGHTEN SOME. HAVE TWEAKED THE WIND GRIDS TO REFLECT THE SLIGHTLY
WEAKER WINDS FOR THE END OF THE WEEK.

THE 850-700 MB LAYER RELATIVE HUMIDITY SHOWS SOME ADDITIONAL
MOISTURE POSSIBLY MOVING OVER GUAM AND ROTA MID WEEK...BUT MORE
WIDESPREAD MOISTURE DOESN/T ARRIVE UNTIL THE WEEKEND OR EARLY NEXT
WEEK...WHICH WILL INCREASE SHOWER CHANCES.

&&

.MARINE...
NO CHANGES TO THE SWELL GRIDS AT THIS TIME...SO EXPECT A MODERATE
RIP CURRENT RISK TO CONTINUE ALONG EAST FACING REEFS FOR AT LEAST
THE NEXT COUPLE OF DAYS. COMBINED SEAS SHOULD REMAIN IN THE 4 TO 6
FT RANGE.

&&

.EASTERN MICRONESIA...
SHOWERS AND THUNDERSTORMS ARE MOVING OVER THE MARSHALL ISLANDS THIS
AFTERNOON...AND ARE EXPECTED TO CONTINUE TO PERSIST IN THE AREA
THROUGH MUCH OF THE WEEK. CURRENTLY CONDITIONS ARE IMPROVED OVER
POHNPEI AND KOSRAE...BUT THE PROXIMITY OF THE ABOVE MENTIONED ACTIVE
WEATHER WILL KEEP THE CHANCE IN THE FORECAST. THE MODELS DO SHOW
AGREEMENT WITH THIS CONVERGENCE BAND LIFTING TO THE NORTH AS WE HEAD
INTO THE WEEKEND...WHICH WILL BRING LIGHTER WINDS AND DRIER
CONDITIONS.

&&

.WESTERN MICRONESIA...
A DRIER AIRMASS MOVED OVER KOROR TODAY...AND THAT DRIER WEATHER IS
EXPECTED TO CONTINUE UNTIL THE MIDDLE OF THE WEEK WHEN INCREASED
MOISTURE WILL MOVE IN. THAT MOISTURE BETWEEN CHUUK AND YAP WILL
CONTINUE TO BRING THE CHANCE FOR SHOWERS AND THUNDERSTORMS OVER THE
NEXT COUPLE OF DAYS. SOME DRIER WEATHER IS EXPECTED TO MOVE IN FOR
THE WEEKEND.

&&

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

$$

M BALLARD

000
FXPQ60 PGUM 171943
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
543 AM CHST TUE JUN 18 2013

.SYNOPSIS...
RELATIVELY QUIET WEATHER PATTERN REMAINS IN PLACE WITH DEEP-LAYER
RIDGING AND UPPER-LEVEL SUBSIDENCE OVERHEAD. IR SATELLITE LOOP
SHOWS AN ACTIVE TRADE-WIND CONVERGENCE ZONE STRETCHED ACROSS
MICRONESIA... BUT ALL THE SIGNIFICANT SHOWER COVERAGE IS CONFINED
WELL TO THE SOUTH OF GUAM BETWEEN 2N AND 10N.

&&

.DISCUSSION...
FORECAST CLOSELY FOLLOWS PERSISTENCE. DID CONSIDER SLIGHT CHANCE
WORDING FOR TODAY BUT SLIGHTLY DEEPER MOISTURE APPEARS TO BE
ARRIVING FROM THE EAST SOUTHEAST. WEATHER PATTERN REMAINS
RELATIVELY QUIET THROUGH FRIDAY...THEN MODEL GUIDANCE
INCREASINGLY HINTS AT A PATTERN CHANGE BEGINNING THIS WEEKEND.
NOGAPS...GFS AND ECMWF ALL BRING DEEPER MOISTURE IN FROM THE
SOUTHEAST. NOGAPS AND GFS ON SUNDAY...AND THE ECMWF ON MONDAY.
FOR NOW...MAINTAINED A SUNDAY ONSET OF MOSTLY CLOUDY SKIES IN THE
FORECAST GRIDS. STAYED WITH SCATTERED SHOWERS DURING THIS TIME
FRAME AS WELL...BUT REDUCED POPS TO 30 PERCENT. PERIODS OF
SCATTERED SHOWERS CAN BE EXPECTED FROM TIME TO TIME DURING DAYS 6
THROUGH 10...BUT EXACTLY WHERE OR WHEN THE RAINS WILL TAKE PLACE
WILL DEPEND ON THE EXACT TRACK AND EVOLUTION OF MESOSCALE
CONVECTIVE SYSTEMS. MODELS DIFFER AMONG THEMSELVES AND ALSO FROM
RUN TO RUN ON WHERE QPF WILL OCCUR...SO ELECTED TO BROAD BRUSH
RAINFALL DURING THIS TIME FRAME WITH A 30 PERCENT POP.

&&

.MARINE...
MARINE SWELL GRIDS REQUIRED ONLY A FEW COSMETIC CHANGES. STILL
EXPECT MODERATE RIP CURRENT RISK TO PERSIST ALONG EAST FACING
REEFS FOR AT LEAST THE NEXT SEVERAL DAYS. COMBINED SEAS IN THE
OPEN OCEAN SHOULD REMAIN IN THE 4 TO 6 FOOT RANGE FOR THE
REMAINDER OF THIS WEEK.

&&

.EASTERN MICRONESIA...
A BUSY WEATHER PATTERN REMAINS IN PLACE ACROSS THE REGION THIS
MORNING. MOST SHOWERS AND THUNDERSTORMS ARE LOCATED ACROSS THE
MARSHALL ISLANDS. MAINLY SHORT TERM ADJUSTMENTS WERE MADE FOR
SLIGHTLY IMPROVED WEATHER OVER KOSRAE AND POHNPEI. WETTER WEATHER
IS EXPECTED TO REDEVELOP OVER THESE TWO LOCATIONS BY MIDWEEK AS
SHOWERS ACROSS THE MARSHALLS MOVE WEST. FOR THE LONG TERM...
MODELS STILL SHOW A NORTHWARD SHIFT OF THE CONVERGENCE BAND THAT
WILL BRING LIGHTER WINDS AND DRIER WEATHER TO THE THREE LOCALES
BY THE WEEKEND. SATELLITE AND LONG-RANGE RADAR IMAGERY FROM
KWAJALEIN INDICATES RAINFALL OVER SOME OF THE NORTHERN ATOLLS OF
THE MARSHALLS. MODELS SHOW ADDITIONAL MUCH NEEDED RAIN WILL FALL
OVER THE NORTHERN ATOLLS DURING THE NEXT SEVERAL DAYS.

&&

.WESTERN MICRONESIA...
THE EASTERN END OF THE MONSOON TROUGH PASSES OVER KOROR. THIS
FEATURE IS HELPING TO FOCUS SHOWERS AND THUNDERSTORMS NEAR THERE
THIS MORNING. THIS TROUGH WILL LIFT NORTHWARD TODAY AS DRIER
WEATHER SPREADS TOWARDS KOROR FROM YAP. RIDGING WILL PROMOTE
DRIER CONDITIONS ON KOROR BRIEFLY BEFORE SHOWERS NEAR A
DISORGANIZED TRADE-WIND DISTURBANCE CURRENTLY SOUTH OF GUAM
SPREAD WEST. A BAND OF SHOWERS ASSOCIATED WITH TRADE-WIND
CONVERGENCE WILL DEVELOP AND EXTEND WESTWARD ACROSS THE REGION
DURING THE LAST HALF OF THE WEEK. PERIODS OF SCATTERED SHOWERS
WILL BE POSSIBLE DURING THIS TIME OVER ALL THREE LOCATIONS...BUT
THEIR EXACT TIMING IS HARD TO DETERMINE.

&&

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

$$

MCELROY/M. AYDLETT

000
FXPQ60 PGUM 170640
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
ISSUED BY NATIONAL WEATHER SERVICE HONOLULU HI
500 PM CHST MON JUN 17 2013

.SYNOPSIS...
EXPECT LIGHT TO MODERATE EASTERLY TRADE WINDS ACROSS THE MARIANAS
AND ADJACENT WATERS THROUGH THE FORECAST PERIOD. CLOUDS AND SHOWERS
WILL INCREASE OVER THE WEEKEND AS DISTURBED WEATHER MOVES UP FROM
THE SOUTHEAST. WATER VAPOR LOOP INDICATES THE WESTERN HALF OF AN
UPPER-LEVEL TROUGH AND ASSOCIATED SUBSIDENCE OVER THE FORECAST ZONES.

&&

.DISCUSSION...
THERE ARE NO SIGNIFICANT CHANGES TO FORECAST PHILOSOPHY OR GRIDS
THROUGH DAY FIVE. HOWEVER...GFS SHOWS TROUGHING SOUTH OF 10N AND
WEST OF 150E WILL SHIFT NORTH A BIT OVER THE COMING
WEEKEND...POSSIBLY INTRODUCING INCREASED MOISTURE AND UNSETTLED
WEATHER TO THE AREA. POP...SKY AND WX GRIDS WERE ALTERED A BIT FOR
DAYS 6 AND 7 TO ACCOUNT FOR THIS. IT IS TOO EARLY TO DETERMINE JUST
HOW FAR NORTH THE INCREASED MOISTURE AND UNSETTLED WEATHER WILL
SPREAD THIS WEEKEND...SO GRIDS WERE ALTERED JUST ENOUGH TO BUMP
POP...SKY AND WX UP ONE CATEGORY. WATER VAPOR LOOP SHOWS THE
MARIANAS CURRENTLY LIE BENEATH THE WESTERN...MORE STABLE...HALF OF
AN UPPER TROUGH...LIKELY ACCOUNTING FOR THE DECREASE IN CLOUD COVER
AND SHOWERS NOTED ON RADAR THIS AFTERNOON. WITH WEAK SURFACE RIDGING
EXPECTED TO REMAIN INTACT NORTH OF THE ISLANDS FOR THE NEXT FEW
DAYS...LIGHT TO MODERATE EASTERLY TRADE WINDS WILL CONTINUE THROUGH
THE FORECAST PERIOD.

&&

.MARINE...
LIGHT WINDS MEAN THAT SWELL WILL CONTRIBUTE MOST TO COMBINED SEAS.
MODELS SHOW 3 TO 5 FT SWELL WILL INCREASE BRIEFLY TO 4 TO 6 FT
TUESDAY BEFORE DROPPING BACK TO 3 TO 5 FEET WEDNESDAY THROUGH
FRIDAY. SWELL IS EXPECTED TO INCREASE BACK TO 4 TO 6 FEET OVER THE
COMING WEEKEND. STILL EXPECT LOW END MODERATE RIP CURRENT RISK TO
PERSIST ALONG EAST AND SOUTH FACING REEFS FOR THE NEXT COUPLE OF
DAYS.

&&

.EASTERN MICRONESIA...
A CONVERGENCE BAND ALONG 06N HAS TRIGGERED AN AREA OF LAYERED CLOUDS
AND SCATTERED THUNDERSTORMS FROM 05N TO 08N BETWEEN 153E AND 165E.
THIS ACTIVITY IS SPREADING TOWARD THE WEST. TRADE-WIND CONVERGENCE
WILL MAINTAIN A PRESENCE ACROSS THE REGION WITH PERIODS OF ACTIVE
WEATHER AFFECTING THE FORECAST LOCATIONS THROUGH THE REST OF THE
WEEK. MODELS SHOW TRADE-WIND CONVERGENCE ZONE SHIFTING NORTH OF THE
ISLANDS LATER IN THE WEEK. THIS MAY CONTRIBUTE TO A DRIER
SCENARIO...AT LEAST DURING THE SHORT TERM...FOR POHNPEI...KOSRAE AND
MAJURO. SEAS WILL DIMINISH THROUGH THE WEEK AS TRADE-WINDS DECREASE
OVER THE NEXT FEW DAYS.

&&

.WESTERN MICRONESIA...
A MONSOON TROUGH EXTENDS ACROSS WESTERN MICRONESIA...ACTUALLY ALMOST
ACROSS YAP AND JUST EAST OF KOROR. INVEST AREA 93W IS BEING WATCHED
AND IS MARKED BY OVERCAST LAYERED CLOUDS AND THUNDERSTORMS ROUGHLY
FROM 01N TO 10N BETWEEN 138E AND 150E. AS THIS ACTIVITY SPREADS
WEST...YAP AND KOROR CAN EXPECT INCREASED THUNDERSTORM PROBABILITY.
CHUUK LIES ALONG THE WESTERN EDGE OF ANOTHER AREA OF
THUNDERSTORMS...OUTSIDE OF THE 93W AREA OF CONCERN BUT A MAKER OF
WET WEATHER ANYWAY.

&&

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

$$

POWELL

000
FXPQ60 PGUM 161855
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
455 AM CHST MON JUN 17 2013

.SYNOPSIS...
LATEST ASCAT ANALYSIS SHOWS VERY WEAK SURFACE TROUGHING
APPROACHING THE FORECAST ZONES FROM THE VICINITY OF 150E.
CLOUDINESS AND SHOWER COVERAGE ASSOCIATED WITH THIS FEATURE ARE
CONFINED TO A RATHER NARROW BAND THAT EXTENDS WESTWARD TO JUST
SOUTH OF THE GUAM MARINE ZONE. WATER VAPOR LOOP INDICATES AN
UPPER-LEVEL TROUGH AND ASSOCIATED SUBSIDENCE OVER THE FORECAST
ZONES.

&&

.DISCUSSION...
NO SIGNIFICANT CHANGES TO FORECAST PHILOSOPHY OR GRIDS.
CONSIDERED ADDING MOSTLY CLOUDY SKIES BACK TO THE FORECAST GRIDS
FOR TODAY AND TONIGHT...BUT SHORT TERM MODEL GUIDANCE AND
SATELLITE TRENDS SUGGEST CLOUDINESS AND SHOWERS CURRENTLY EAST
AND SOUTH OF THE FORECAST ZONES WILL DIMINISH AS THE DAY
PROGRESSES IN RESPONSE TO THE HOSTILE UPPER-AIR ENVIRONMENT.
REMAINDER OF THE WORK WEEK LOOKS RELATIVELY DRY. BEYOND
FRIDAY...MODELS ARE IN AGREEMENT THAT CONVECTION ALONG THE ITCZ
WILL BECOME MUCH MORE ACTIVE BY EARLY NEXT WEEK. MAINTAINED A DRY
BIAS IN THE FORECAST GRIDS FOR NOW AS IT IS TOO EARLY TO
DETERMINE JUST HOW FAR NORTH THE CONVECTION WILL SPREAD. IF
MODELS COME INTO BETTER AGREEMENT...A FUTURE SHIFT MAY WANT TO
CONSIDER ADDING MOSTLY CLOUDY WORDING FOR THE FORECAST DURING THE
DAY 7 THROUGH DAY 10 TIME FRAME.

&&

.MARINE...
LATEST ALTIMETRY AND BUOY REPORTS FROM AROUND THE MARIANAS
INITIALIZE COMBINED SEAS IN THE MARINE ZONES BETWEEN 3 AND 5
FEET. MARINE SWELL GRIDS ALREADY FACTOR THIS IN SO NO SIGNIFICANT
CHANGES WERE NEEDED. STILL EXPECT LOW END MODERATE RIP CURRENT
RISK TO PERSIST ALONG EAST AND SOUTH FACING REEFS FOR THE NEXT
COUPLE OF DAYS.

&&

.EASTERN MICRONESIA...
SATELLITE SHOWS ONGOING BAND OF DEEP CONVECTION ASSOCIATED WITH
THE ITCZ ACROSS THE REGION. SHOWERS AND POSSIBLE TSTMS WILL
AFFECT KOSRAE TODAY...POHNPEI LATER THIS MORNING WITH SHOWERS
DISSIPATING OVER MAJURO THIS AFTERNOON. TRADE-WIND CONVERGENCE
WILL MAINTAIN A PRESENCE ACROSS THE REGION WITH PERIODS OF ACTIVE
WEATHER AFFECTING THE FORECAST LOCATIONS THROUGH THE REST OF THE
WEEK. MODELS SHOW TRADE-WIND CONVERGENCE ZONE SHIFTING NORTH OF
THE ISLANDS LATER IN THE WEEK. THIS MAY CONTRIBUTE TO A DRIER
SCENARIO...AT LEAST DURING THE SHORT TERM...FOR POHNPEI...KOSRAE
AND MAJURO. SEAS WILL DIMINISH THROUGH THE WEEK AS TRADE-WINDS
DECREASE OVER THE NEXT FEW DAYS.

&&

.WESTERN MICRONESIA...
CHUUK WILL BE SIMILARLY INFLUENCED BY ITCZ-RELATED CONVECTION.
MODELS INDICATE INCREASING SHOWER ACTIVITY BEGINNING LATER TODAY
AND TONIGHT. SHOWER COVERAGE IS EXPECTED TO GRADUALLY DECREASE
TUESDAY NIGHT...BECOMING ISOLATED BY MIDWEEK. DEVELOPING TROPICAL
DISTURBANCE 91W EAST OF THE PHILIPPINES WILL CONTINUE NORTHWARD...
ALLOWING WEAK RIDGING TO BUILD OVER YAP STATE AND PALAU. THIS HAS
REDUCED CONVECTION ACROSS THE REGION SIGNIFICANTLY. MODELS
INDICATE THE QUIETER PATTERN WILL CONTINUE FOR THE NEXT SEVERAL
DAYS AS 91W PULLS FARTHER AWAY FROM THE REGION. WIDESPREAD
CONVECTION TO THE SOUTHEAST OF YAP IS EXPECTED TO DISSIPATE AS
THE RIDGE BUILDS OVER YAP STATE.

&&

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

$$

MCELROY/WILLIAMS