Scientific Forecaster Discussion
000 FXPQ60 PGUM 192021 AFDPQ Area Forecast Discussion National Weather Service Tiyan GU 620 AM ChST Sat Jan 20 2018 .Marianas Synopsis... Partly cloudy skies with moderate trade winds prevail across the Marianas this morning. Only a few showers are evident over the region on satellite and radar. Latest buoy data shows seas between 5 and 7 feet. && .Discussion... A few minor changes made to the inherited forecast. Latest time- height products show very dry conditions across the Marianas over the next week or so. Therefore, decided to lower POPs over the area to slight chance of showers for today and isolated light showers through Monday. Otherwise, the only real forecast problem lies with the winds. Winds look to pick up to fresh by tonight and Sunday, with breezy conditions likely for the same time period. This could continue on into the middle of next week. && .Marine... Latest buoy data shows seas between 5 and 7 feet this morning with periods of around 11 to 12 seconds. This shows the possibility that surf could continue to marginally hit around 9 feet through Sunday on east facing reefs, resulting in a high risk of rip currents. Surf could briefly fall below 9 feet over the weekend, however, expect rip current risk to remain high through most of the weekend and early next week. Seas will begin to build Sunday night and Monday, resulting in the rip current risk possibly remaining high through midweek. && .Eastern Micronesia and Chuuk... A broad trade-wind disturbance can be seen near Pohnpei this morning. Wet weather associated with this system will persist near Pohnpei thru Sunday morning and Kosrae thru tonight. As this system steadily pushes westward, it will also impact Chuuk with similar weather by this evening. Farther east, a fresh trade-wind surge is approaching the Date Line. Drier northeasterly trades within this surge should prolong fair conditions near Majuro thru Sunday evening, spread them to Kosrae and Pohnpei by Sunday afternoon and Chuuk early next week. The leading edge of a trade-wind convergence zone is visible east of the Date Line near 6N175W. This feature will put an end to the fair trade-wind weather from east to west starting early next week. Trade-wind swell and wind waves should continue to decline today which should allow surf on Kosrae to drop below hazardous levels by this evening. Due to the combination of longer period trade-wind swell and a King Tide cycle, minor coastal inundation remain possible on Majuro thru Sunday night. A new set of trade-wind swell generated by the surge might cause surf on Kosrae to reach hazardous levels again early next week. && .Western Micronesia for Yap and Koror... A surface trough related to a weak circulation south of Koror will gradually depart the area this afternoon and evening. In the wake of this trough, weak surface ridging building in from the east will provide a period of drier weather for Yap today and Koror this evening. Latest ASCAT and IR satellite imagery reveal two trade-wind disturbances upstream, one west of Chuuk near 145E and another one near Pohnpei. These disturbances will generate more showery weather for Yap by late this evening and Koror by Sunday. After the passage of these disturbances, a fair trade-wind pattern should return to far western Micronesia toward midweek next week. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...High Rip Current Risk through Thursday afternoon for GUZ001>004. Fire Weather Watch through Monday evening for GUZ001. Marianas Waters...None.