661 FXUS61 KGYX 210713 AFDGYX Area Forecast Discussion National Weather Service Gray ME 313 AM EDT Sat Aug 21 2021 .SYNOPSIS... An onshore easterly flow develops this weekend keeping humid conditions in place. Tropical Storm Henri may affect our region Sunday into Monday with rain, a period of gusty winds, and possibly some minor coastal flooding. Thereafter, summery weather continues through the week with mainly dry weather, although a few rounds of scattered showers and thunderstorms cannot be ruled out. && .NEAR TERM /TODAY/... Calm conditions this morning becomes a light onshore southeasterly flow. This will keep the humid conditions around with one more day of warm temperatures as well, topping out in the 80s. Instability this afternoon will lead to some showers and thunderstorms especially in NH and the mountains of western Maine. With the wind flow at all levels so light, any storms that form will be of the pulse variety and likely to produce heavy downpours. && .SHORT TERM /TONIGHT THROUGH SUNDAY/... Another balmy night tonight with humid conditions continuing and lows in the 60s. By Sunday, the tropical cyclone to our south will be arriving in southern New England. The majority of the impacts will be down there, but we will eventually see some rain and a steady breeze on the north side of the cyclone. Inflow bands rotating around the storm may move into our area during the day. Within these bands will be the potential for some heavy rain, a bit gustier winds, and perhaps a brief tornado. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Henri continues to thread the needle between an upper level trough to its west and a ridge of high pressure building to its north. The system will move poleward today before retrograding somewhat as it pivots around the periphery of the upper level trough. See the National Hurricane Center for their latest official forecast track. The 00Z operational guidance suite did shift the track of Henri slightly to the east with the latest package. However, this still brings the core of the system with its heaviest rains and strongest winds to our west. Expect additional modifications to the forecast track over the weekend as the system is moving through a somewhat data void area. The remnants of Henri may shift east Sunday night through Monday night, so there still remains the possibility of locally heavy rainfall during this period. The next focus shifts to the period Tuesday through Thursday when very warm conditions will coincide with surface dew points around 70 degrees to create very uncomfortable conditions. This will be particularly true for Wednesday and Thursday where some locations over southernmost New Hampshire and extreme southwest interior Maine may reach Heat Advisory Criteria. Thunderstorms may produce locally heavy rainfall Tuesday and Thursday of next week. && .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/... Short Term...After some patchy morning fog, it should be mostly VFR today with some pop up showers and thunderstorms in the afternoon. A developing onshore flow may bring in some lower ceilings tonight. The first rain bands from Henri may begin to affect the area on Sunday with periods of squally rains. Long Term...MVFR with occasional IFR conditions expected to prevail Sunday and Monday in a moist east flow with occasional showers. Improving conditions foreseen Tuesday through Thursday, however there will be pockets of IFR conditions in scattered showers and thunderstorms. && .MARINE... Short Term...Onshore easterly flow develops and strengthens through the weekend as Henri approaches from the south. By Sunday wind gusts may reach into the Small Craft Advisory range with wave heights building as well. Long Term...Winds will continue out of the east to northeast Sunday night as seas build into the 4 to 6 foot range. Continue to monitor latest NHC forecast for details about Henri. It's possible that tropical storm conditions will impact the region late this weekend or on Monday. However, latest trends in track are westward and this may keep the tropical storm winds out of our region. && .HYDROLOGY... The track of Henri remains a bit uncertain, but the westward model trend has appeared to come to an end at least for now. In any case, very heavy rain has the potential to set up west of our forecast area. The exception may be southwestern NH where the main batch of tropical rainfall could move across that region late Sunday and Sunday night with flooding issues. && .TIDES/COASTAL FLOODING... Will continue to monitor trends for the possibility of minor coastal flooding for Portland and points south along the coast. The highest astronomical tide of the month will be late Sunday evening. During this period, the more robust ETSS runs have been indicating around a foot of storm surge at high tide. This would bring the water levels at Portland to around 11.8 feet. Flood stage is 12 feet. These water levels combined with a long period swell may necessitate coastal flood advisories down the road, mainly due to some splash-over. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR/SHORT TERM...Kimble LONG TERM...Cannon