![National Oceanic and Atmospheric Administration](/build/images/header/noaa.d87e0251.png)
![National Weather Service](/build/images/header/nws.4e6585d8.png)
![United States Department of Commerce](/build/images/header/doc.b38ba91a.png)
Area Forecast Discussion
Issued by NWS Tiyan, Guam
Issued by NWS Tiyan, Guam
417 FXPQ50 PGUM 140820 AFDGUM Area Forecast Discussion National Weather Service Tiyan GU 620 PM ChST Fri Jun 14 2024 .Marianas Synopsis... Partly cloudy to mostly cloudy skies are seen across the islands, with scattered showers moving in from the east. Gentle to moderate trade winds prevail. Ritidian buoy shows seas around 4 feet while altimetry shows seas of 4 to 7 feet east of the waters. && .Discussion... A modest trade-wind trough is evident on satellite and ASCAT analysis to the east of the Marianas. Along with the trough, A TUTT cell is seen to the northeast of the islands. The TUTT cell is providing upper-level divergence across the region. As the trough to the east moves closer to the islands, the divergence is expected to increase convection over the Marianas. Satellite and Global Lightning Detection (GLD) show numerous showers with embedded thunderstorms east of the Marianas coastal waters. Showers are slowly increasing now, with scattered showers likely to be over the area through the evening. Near midnight, the showers and thunderstorms ahead of the trough will move into the area, bringing numerous showers and isolated thunderstorms to the islands. The trough and TUTT cell are expected to drift slowly westward, maintaining a wetter pattern over the islands through Saturday night. Numerous showers and isolated thunderstorms are expected to continue through the day Saturday, decreasing to scattered during the afternoon. As the features move through the Marianas, they will also increase the potential for gusty winds with the heavier showers and thunderstorms, with gusts to 30 mph possible. By Sunday, a drier pattern looks to return to the region. This dry pattern looks to be short lived, however, for Guam and Rota as a weak circulation is expected to push through just south of Guam, bringing another round of increased convection to Guam and Rota Monday through Tuesday. By Tuesday evening, the dry pattern is expected to return to Guam and Rota and continue through Friday. Meanwhile, Tinian and Saipan look to remain dry Sunday through the end of next week. && .Marine... Other than the showers and thunderstorms expected over the next few days, not much going on in the marine environment. Gentle to moderate trade winds will prevail across the Marianas through most of next week. However, occasional strong gusts are possible tonight through Saturday afternoon with heavier showers and thunderstorms. Combined seas of 4 to 6 feet will build slightly to between 5 and 7 feet over the weekend. This is expected increase the rip current risk along north facing reefs to moderate for a short time. Seas will then subside a bit beginning early next week. && .Eastern Micronesia and Chuuk... The Inter-Tropical Convergence Zone (ITCZ) continues to extend across from the Marshall Islands to Pohnpei State, but it has pulled back from Chuuk State. Also at Chuuk, trade-wind flow is fairly diffuse and unsupportive of showers and thunderstorms, but weak convergence is expected to rebuild at Chuuk later tonight bringing scattered showers back to Chuuk after midnight. Otherwise, scattered to numerous showers and isolated thunderstorms extend along the ITCZ and is affecting all the primary forecast points from Majuro to Pohnpei. Some occasional gusty winds up to 25 to 30 mph over land and 25 to 30 knots over the waters are in the forecast for Kosrae and Pohnpei with the heavier showers and thunderstorms. The ITCZ will shift north and south through the weekend, while a trough is expected to break off from the ITCZ and move into Chuuk Saturday night increasing showers to numerous. By Monday, the ITCZ is expected to fragment into a series of troughs, keeping periods of scattered showers and isolated thunderstorms through most of next week. Altimetry shows combined seas across the region are around 4 to 6 feet, though seas will be locally higher near showers and thunderstorms. Scatterometer data shows winds are gentle to moderate along the ITCZ with pockets of fresh winds embedded within the heavier convection, with strong gusts possible, especially around Kosrae and Pohnpei. The trade swell subsides slightly this weekend, decreasing seas by a foot, and then rebuilds early next week. && .Western Micronesia... Satellite imagery shows scattered showers and isolated thunderstorms across Yap Proper and Palau this evening. Winds are also light and variable at Palau and Yap as a weak surface trough extends from the Phillipines towards Palau and then merges with the weak trade-wind troughs in eastern Yap State. This surface trough is potentially a developing weak monsoon trough, as it struggles to extend back towards southeast Asia ,and is an early indication of a transition to the monsoonal pattern that occurs during the summer. The surface trough is expected to linger in far western Micronesia while models show the trade-winds trying to push back over Yap and Palau late this weekend. This transitional period to the monsoonal pattern will continue to support low-end scattered showers across Palau and Yap over the next several days. The TUTT cell near the Marianas is starting to move through the northern islands of the Marianas this evening. The TUTT is slightly further north than expected, but kept isolated thunderstorms in the forecast through Saturday night to highlight the potential for thunderstorms south of the TUTT, but fairly confident the risk of thunderstorms from the TUTT will diminish Sunday and Monday. Around Monday night and Tuesday, a trough that is expected to break off from the ITCZ will move out of Chuuk State and into Yap State and then Palau. As this trough moves through it will increase the potential for thunderstorms once again for Monday night and Tuesday. The buoys near Palau and Yap and altimetry data show seas are around 2 to 3 feet. Winds will remain light around Palau through at least the weekend, but easterly winds are expected to become light to gentle at Yap around Saturday. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...None. MP...None. Marianas Waters...None. && $$ Marianas: Kleeschulte Micronesia: Schank