Area Forecast Discussion
Issued by NWS Tiyan, Guam
Issued by NWS Tiyan, Guam
504 FXPQ50 PGUM 182040 AFDGUM Area Forecast Discussion National Weather Service Tiyan GU 640 AM ChST Sun May 19 2024 .Marianas Synopsis... Satellite shows some patchy clouds across the region, especially near Guam. Local airports report gentle to moderate trade winds and combined seas are ranging from 5 to 8 feet, with larger sets mainly toward the northeast. && .Discussion... Spotty showers can always be expected this time of year, but mainly fair weather should prevail for the next few days. Next week, there could be an increase of atmospheric moisture flowing our way from the southeast. Meanwhile, winds will be a little gusty during the next few afternoons, as the pressure gradient tightens between high pressure developing to our north and a tropical disturbance persisting well south of the Marianas. && .Marine/Surf... As the pressure gradient tightens across the region, moderate trade winds will become fresh to possibly strong. Combined seas of 5 to 8 feet could build up to 6 to 9 feet. A Small Craft Advisory may be needed by Monday. Waves and surf may build by 1 to 2 feet and there may be a high risk of rip currents along east facing reefs, while a moderate risk is expected along north reefs. && .Fire weather... Rainfall yesterday at Guam airport was 0.10 inch and the KBDI is up to 557 today; in the high category. The countryside of Guam is relatively dry, the winds will be gusty at times, and humidities low during afternoon hours. There could be a risk of rapidly spreading fires during afternoon hours of the next few days. && .Tropical systems... The Special Weather Statement for Western Micronesia remains in effect. JTWC Invest Area 93W remains weak and was centered roughly near 3N142E overnight. Areas of showers and thunderstorms are mainly around the periphery of 93W, from over and southeast of Koror to southwest Chuuk State and in patchy areas over southeast Yap State. Models still differ in the forecast details, but 93W could slowly develop during the next few days and start drifting toward the west- northwest. People in Chuuk and Yap States, and The Republic of Palau should continue to monitor forecasts for updates in the coming days. && .Eastern Micronesia... A convergence zone/ITCZ has set up over the region. Partly cloudy to mostly cloudy skies are expected for the next few days. People can expect to see scattered showers through Monday. Majuro is expected to get the most of the showers but will remain around the middle of the scattered category. Pohnpei and Kosrae are anticipated to be near the lower end of scattered. Near the middle of the week, a weak ridge appears to set up and drying the region out. Altimetry shows combined seas of 7 to 8 foot to the east of Arno Atoll and 7 to 9 feet for northern RMI, and between Pohnpei and Chuuk has 4 to 6 feet. Winds are expected to be gentle to moderate for below 10 north and above 10 north is expected to be moderate to fresh. Seas are on an upward trend, however are expected to be below high surf and small craft advisory level. && .Western Micronesia... Key message: the potential for heavier showers still exists for all of western Micronesia over the next several days, but the location and coverage of showers will shift depending on the location and interaction of 93W and the weak circulation south of Weno. This info is also summarized in the Special Weather Statement (SPSPQ2), issued under the WMO header WWPQ82 PGUM. The Near-Equatorial Trough that has the embedded Invest 93W remains near 3N142E. Convection across the disturbance remains loosely- defined. Showers still may be heavy at times near the circulation and the trough axis. For Yap, a fairly dry pattern remain, while showers still linger around Palau this morning. Yap is expected to the the first to get noticeable showers around Monday, then Palau will get them a day or so later. For the rest of the week showers are anticipated to gradually increase in probability. For Chuuk, be prepared for a moist week. Between the ITCZ/convergence zone and 93W showers are anticipated for rest of the week. Altimetry shows 4 to 6 feet near Chuuk. The altimetry did not get a good pass near Yap or Palau. Winds are expected to be light to moderate, and seas are expected to be fairly benign. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...None. MP...None. Marianas Waters...None. && $$ Marianas: Simpson Micronesia: Bowsher