WPAC: Invest 99W

[RL3AO]

4.0N 155.0E
15kts, 1010mb

[senorpepr]

WFO in Guam vaguely discusses with invest as unsettled weather moves through Micronesia:

406
FXPQ60 PGUM 220742
AFDPQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
542 PM CHST MON JUL 22 2013

SYNOPSIS
LIGHT SOUTHEAST WINDS AND A FEW SHOWERS PREVAILED
ACROSS THE MARIANAS THIS AFTERNOON.



DISCUSSION

ONLY A FEW CHANGES MADE TO FORECAST. WINDS WERE A BIT MORE
SOUTHEASTERLY THIS AFTERNOON THAN MODELS PREDICTED. TWEAKED WINDS
TO REFLECT THIS. THESE SOUTH-EASTERLIES WILL PREVAIL THROUGH
TUESDAY.

CBS COULD BE SEEN ON THIS AFTERNOONS SATELLITE AND RADAR IMAGERY
TO THE SOUTHEAST OF GUAM AND A FEW TO THE WEST OF GUAM. WATER
VAPOR IMAGERY DOES SHOW A WEAK UPPER-LEVEL FEATURE THAT IS
POSSIBLY CAUSING THIS DEVELOPMENT. LIGHTNING DETECTORS SHOW THAT
SOME OF THE CBS DO HAVE ACTIVITY ASSOCIATED WITH THEM. FELT THAT
THE ODDS ARE LOW FOR THUNDER BUT NOT ZERO SO ADDED A SLIGHT
CHANCE OF THUNDERSTORMS TONIGHT.

LIGHT WINDS ARE EXPECTED THROUGH MUCH OF THE WEEK. USUALLY THIS
WOULD EQUAL A GOOD CHANCE OF AFTERNOON THUNDERSTORMS ON AT LEAST
ONE DAY. 700 MB RH REMAINS BELOW 70 PERCENT THROUGHOUT THE
FORECAST. WITH DEEP LAYER MOISTURE LACKING AFTERNOON SHOWERS ARE
POSSIBLE BUT THUNDERSTORMS ARE A LOW PROBABILITY.



MARINE

THE EAST TRADE-WIND SWELL WILL CONTINUE THROUGH THE FORECAST. THE
RIP CURRENT RISK WILL REMAIN LOW ON ALL REEFS THE NEXT FEW DAYS.



EASTERN MICRONESIA

SCATTERED SHOWERS AND THUNDERSTORMS PERSIST ACROSS THE REGION AS A
TRADE-WIND SURGE PUSHES WEST. VISIBLE SATELLITE IMAGERY SHOWS A VERY
ACTIVE PATTERN AIDED BY DIVERGENT UPPER LEVEL WINDS EXTENDING FROM
NEAR MAJURO TO CHUUK STATE. GUSTY AND SHOWERY CONDITIONS WILL
PERSIST AT LEAST THROUGH MID-TUESDAY AT KOSRAE AND POHNPEI...BUT
WILL TAPER JUST A BIT BY WEDNESDAY. CONVECTION ACROSS THE MARSHALLS
WILL MOSTLY BE ISOLATED THE NEXT FEW DAYS. MODELS MAINTAIN A
CONVERGENT TRADE-WIND PATTERN ACROSS THE REGION THROUGH THE END OF
THE WEEK WHICH WILL ALLOW AN UNSETTLED WEATHER PATTERN TO PERSIST.

TRADE-WIND SWELL AND WIND WAVES WILL KEEP HAZARDOUS SURF FOR KOSRAE
THRU TUESDAY AFTERNOON. SURF SHOULD GRADUALLY SUBSIDE BELOW ADVISORY
LEVELS TUESDAY EVENING.



WESTERN MICRONESIA

CHUUK SITS ON THE EDGE OF THE TRADE-WIND SURGE SEEN ACROSS EASTERN
MICRONESIA. SCATTERED SHOWERS WILL REACH THERE THIS EVENING. MODELS
SHOW THE SURGE GRADUALLY WEAKENING THE NEXT DAY OR TWO...BECOMING
LESS PROMINENT THAN WHAT IS CURRENTLY SEEN IN VISIBLE IMAGERY.
MIDWEEK WILL SEE A BIT OF A LULL IN ACTIVITY BUT THE END OF THE WEEK
COULD BECOME SOMEWHAT UNSETTLED WITH A CONVERGENCE ZONE POISED TO
SET UP AGAIN THEN.

THE AXIS OF THE MONSOON TROUGH PASSED OVER KOROR THIS AFTERNOON. VIS
IMAGERY SHOWS ISOLATED SHOWERS AND A FEW THUNDERSTORMS ALONG THE
TROUGH AND TO THE NORTHEAST OF THE NORTHWEST-SOUTHEAST ORIENTED
AXIS...WHILE SCATTERED SHOWERS WERE SEEN TO THE SOUTHWEST. THIS
TROUGH WILL SLOWLY LIFT NORTH NEXT FEW DAYS WITH LIGHT AND VARIABLE
WINDS AT BOTH YAP AND KOROR ON TUESDAY. MODELS STILL DEPICT A WEAK
MONSOON CIRCULATION FORMING JUST EAST OR SOUTHEAST OF YAP THE NEXT
COUPLE DAYS...BUT TIMING AND LOCATION VARY. GFS SHOWS A
MORE-CONSISTENT NEAR-EQUATORIAL TROUGH SETTING UP SOUTH OF CHUUK AND
YAP ON WEDNESDAY AND THURSDAY. OVERALL...MODELS LACK CONSISTENCY...
BUT DO INDICATE SOMEWHAT UNSETTLED CONDITIONS THE NEXT SEVERAL
DAYS.



GUM WATCHES/WARNINGS/ADVISORIES

GU...NONE.
MARIANAS WATERS...NONE.

[senorpepr]

I'm not expecting much out of this wave...
I touch on this system and Invest 98W in my tropical outlook video:

[youtube]https://www.youtube.com/watch?v=GDPJ47SZLoA[/youtube]