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Area Forecast Discussion
Issued by NWS Tiyan, Guam
Issued by NWS Tiyan, Guam
000 FXPQ50 PGUM 052200 AFDGUM Area Forecast Discussion National Weather Service Tiyan GU 800 AM ChST Wed Dec 6 2023 .Marianas Synopsis... Satellite shows scattered showers near and east of the Marianas. They are associated with a trade-wind trough near the islands. The buoys reveal combined seas of 5 to 7 feet, mainly composed of a medium east-northeast swell and smaller north swell plus wind waves. && .Discussion... A weak trough is passing through the Marianas. Scattered showers will be around today. After today, a couple days of drier conditions, then we may get a moister day again around Sunday. After that, we will get a bit drier again. Not quite there yet, but we are moving toward dry season. && .Marine... Winds will be 10 to 15 knots the next day or two. They will build to 15 to 20 knots afterward. Seas will be 5 to 7 feet the next few days, then they could build to between 6 and 8 feet. Conditions are expected to remain below small craft advisory criteria, not far below though. && .Tropical systems... Invest 90W is located near 3N160E, southwest of Kosrae. This disturbance is heading in the general direction of Pohnpei main island and Chuuk atoll. Models are suggesting that this disturbance will catch a ride with the tradewind flow before it gets to these island/atolls. Then 90W will likely head west in the general direction of Yap and Palau. Currently, there is little to no circulation in this disturbance, however, models are suggesting circulation will become more noticeable this weekend. Showers associated with this system maybe locally heavy at times. Time will tell whether this disturbance will develop into something significant or not. This system is still several days out and models will change as this disturbance develops, so stay tuned. && .Eastern Micronesia... On top of the above tropical disturbance (90W), a convergence zone is setting up near 1 to 2 north and from the Date line to 90W. Spotty convection has been seen along this line. For Pohnpei and Kosrae, the POPs (Probability of Precipitation) have been increased to numerous for Pohnpei and scattered for Kosrae, and expected to remain wet through the weekend. This is due to a few factors: the first is 90W, the second is a Near-Equatorial Trough, and lastly the convergence zones. The combination of these 3 features will be what keeps these islands wet for the foreseeable future. These showers maybe locally heavy at times. For Majuro, the main concern is winds for this discussion. Winds over the next few days are expected to be breezy with gusts nearing 25 mph. This combination of elevated winds with a long-fetch easterly swell later this week and in to the weekend may make it hazardous for small craft. Altimetry shows combined seas near 7 to 9 feet east of Majuro, Kalo buoy shows about 8 feet. Winds are expected to be gentle to strong. Seas may increase as the week progresses. A Small Craft Advisory may be needed later this week as seas may reach the 10 foot mark. && .Western Micronesia... For Yap and Palau, a dry season-like regime has set up, and is expected to last through the beginning of next week. The week trough that is north of Palau may graze the northern waters. However, this trough is expected to harmlessly drift westward. For Chuuk, the system that is effecting Pohnpei is expected to move westward and effect Chuuk. POP`s (Probability of Precipitation) has been increased to show this. Currently, the leading edge is nearing the eastern side of Chuuk waters. The showers at the leading edge are expected to be short lived. A calm will set up for 12 to 24 hours then the main line will begin to push into Chuuk waters. Showers are expected to hang around until 90W moves out of the region. Long range models are suggesting a wet pattern is in store for all of western Micronesia as a disturbance could push into the region from eastern Micronesia. The weather may become a concern if the models hold true. However, it is remains several days out and will change with each new model run. This will be closely monitored. Altimetry shows combined seas of 4 to 5 feet between Chuuk and Yap, and 4 to 6 feet to between Philippines and Palau. Winds are expected to be light to gentle for Palau, light to moderate for Yap, and light to fresh for Chuuk. Seas are not expected to meet hazardous conditions. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...None. MP...None. Marianas Waters...None. && $$ Marianas: Stanko Micronesia/Tropical: Bowsher
