Area Forecast Discussion
Issued by NWS Tiyan, Guam
Issued by NWS Tiyan, Guam
096 FXPQ50 PGUM 032012 AFDGUM Area Forecast Discussion National Weather Service Tiyan GU 612 AM ChST Thu Jul 4 2024 .Update... Trimmed back the showers today and tonight, as the expected coverage just never materialized, and now the upper-level low is starting to move away, and clearer skies to the east will start moving in. There is a disturbance farther east though, so added scattered showers Friday night to account for that. Also increased showers next week, when it looks like wet season might start trying to build in at last. Multi-model consensus that showers will start increasing in a fairly dramatic way. Hope so, as that could finally put an end to our drought. && .Eastern Micronesia... .Short-Term Update... Satellite imagery, satellite-based remote sensors and model guidance indicate the trade-wind surge to move in sooner and be more intense across eastern Micronesia. As such, increased shower coverage and intensity in Pohnpei`s and Kosrae`s forecast for the next several days. Meanwhile, upped the shower intensity for Majuro`s forecast tonight and Friday due to larger support from MIMIC TPW and model time heights. Across the board, the marine forecast remains unchanged for the time being. && .Western Micronesia... .Short-Term Update... Little change in the forecast for Western Micronesia. Benign marine conditions will remain in place through the weekend and even beyond. Mariners should enjoy these conditions while they last. && Marianas: Stanko West Micronesia: Stanko East Micronesia: Montvila .Prev discussion... /issued 551 PM ChST Wed Jul 3 2024/ Marianas Synopsis... Satellite shows a few patches of showers across the region, and isolated heavier showers that could trigger lightning at times tonight. Ritidian buoy showed combined seas around 4 feet, but seas could be a little higher toward the east and northeast. Surface winds are gentle to moderate this afternoon. Discussion... A modest convergence of surface winds coupled with an upper-level trough just to our northwest will produce scattered showers and isolated thunderstorms at times for the next few days. Atmospheric moisture is deeper toward the south and the risk of thunderstorms will mainly affect Guam and Rota, especially over the weekend into next week. Otherwise fairly benign conditions are expected for the Mariana Islands. Marine/Surf... Gentle to moderate trade winds and combined seas of 3 to 5 feet will continue. Gusty winds and choppy seas are possible near showers and thunderstorms, mainly over Guam and Rota waters, as an upper-level trough lingers nearby and weak disturbances pass by just south of the Marianas. A moderate risk of rip currents continues along east facing reefs, while the risk remains low along all other reefs. A moderate risk of lightning is expected through this weekend. Eastern Micronesia and Chuuk... Scattered showers are expected for Majuro and Kosrae tonight. Main forecast concern is numerous showers at Kosrae for Thursday evening and Friday. Trade-wind convergence to the south of Majuro is expected to continue to develop and produce abundant precipitation as it slowly passes Kosrae. The GFS Precip rate showed a 6-hourly value of close to 4.0 inches passing straight through Kosrae. More showers are expected to develop near Majuro as this systems tracks west. Models indicate much of the heavier showers will dissipate just before reaching Pohnpei. At any rate, expect isolated showers for Pohnpei tonight and Thursday becoming scattered Thursday evening. For Chuuk, expect mostly low-end scattered showers until Friday evening, then shower coverage will increase for the weekend. Altimetry indicates combined seas of 3 to 5 feet across the region, but models show some increase in swell waves arriving from the east by next week, especially for the Marshall Islands. Western Micronesia for Yap and Palau... More or less on and off again scattered showers are expected for Palau and Yap tonight and tomorrow. There is a lower confidence on forecasts during the mid to longer-range, since models go back and forth on developing a weak circulation or a trough over the region. Next week looks somewhat similar with GFS and ECMWF models showing a broad circulation developing and the GFS being a bit more aggressive. Altimetry, Koror and Yap buoys are reporting 3 to 4 foot seas. Little change in sea heights is expected. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...None. MP...None. Marianas Waters...None. && $$