National Weather Service (2024)

Area Forecast Discussion
Issued by NWS Portland, ME

-- Highlight Changed Discussion --

-- Discussion containing changed information from previous version are highlighted. --985FXUS61 KGYX 181926AFDGYXArea Forecast DiscussionNational Weather Service Gray ME326 PM EDT Sun Aug 18 2024.SYNOPSIS...
-- Changed Discussion --
Widespread showers and some thunderstorms are expected Mondayinto Tuesday as the trough and associated frontal system crossesthe region. Long period swell from Ernesto tracking welloffshore will bring a high surf and a rip current risk throughMonday. High pressure builds in from the west Wednesday formostly dry weather through the end of the week.
-- End Changed Discussion --&&.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
-- Changed Discussion --
Sfc ridging is weakening this afternoon, which helps keep anyshowers that are moving in from the SW more of the gardenvariety, and keeping torrential downpours out of the area,especially considering back building cells in SW CT haveproduced over 8 of rain in some spots, we will be in fine shapefor the rest of the day and overnight, with amounts likelylimited to half an inch in most. Otherwise, as the 500 MB troughslowly moves in from the W, it will break down the sfc ridge ,and showers will become more numerous later tonight. However weget into a lull late this afternoon into this evening, as wepass between waves moving in from the SW on the downstream sideof the trough. So, while there will likely be a few showersaround this evening, they will become more numerous andwidespread after midnight. Itll be on the muggy side as wellwith fog developing again (at least where it didn`t last allday), and mins in the low to mid 60s.
-- End Changed Discussion --&&.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
-- Changed Discussion --
Monday will feature showers in the morning, as one wave movesthrough, and then maybe a bit of break midday to mid afternoonbefore another round of showers moves in just ahead of the coldfront while will move into the NH mtns late in the day. Iftheres going to be heavier showers, or a stronger TSRA, it willlikely be right ahead of the front late afternoon and tomorrowevening. And there will be some dependence on some clearing orthinning of the clouds ahead of the front as well, which willprobably be limited to S NH and the CT vly. Highs will be around70 in the mtns to the low to mid 70s elsewhere.As the evening showers move out, the front will begin to pushacross the mtns, and it will start cooling and drying in themtns tomorrow evening, but the questions remains as to how muchthe front mixes down SE of the mtns. Models say there is some NWsfc flow behind the front, but its something that bearswatching. Anyway, while lows will fall into low to mid 50s inthe N, they will be closer to 60 or in the low 60s in the S.There should be a fair amount of fog in this area too, as thelow level moisture struggles to mix out.
-- End Changed Discussion --&&.LONG TERM /TUESDAY THROUGH SUNDAY/...
-- Changed Discussion --
A vigorous upper level trough will remain west of the region onTuesday. At the same time, a wave of low pressure will developalong a frontal boundary over our coastal waters. This willallow for more shower activity across Maine and New Hampshireespecially over northern and eastern portions of the forecastarea. Sufficient instability will be in place for the chance ofa thunderstorm as well across eastern areas. The cloud coverand showers will keep most areas in the 60s for hightemperatures with 50s across the northern mountains.On Wednesday, scattered showers will mostly be confined toupslope regions of the mountains as a westerly, northwesterlyflow develops in the lower levels of the atmosphere.Temperatures will remain below normal for this time of the year.Similar conditions will follow on Thursday with scatteredshowers mainly confined to the mountains.On Friday, operational models and ensemble solutions suggestheight rises and some ridging will finally begin across theNortheast. As surface high pressure settles off the MidAtlantic coastline, a warmer return flow out of the southwestwill develop. Afternoon highs will reach the 70s to lower 80s,even along the coastline as sea breezes will be limited.Relatively dry and seasonably mild conditions will follow forthe upcoming weekend.
-- End Changed Discussion --&&.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
-- Changed Discussion --
Short Term...All terminals, with the exception of KHIE, whichwill benefit from SE downsloping, should drop to IFR or lowerduring this evening, and stay there overnight, as light onshoredoes little to mix anything out. KHIE may stay VFR thru much ofthe night, but should eventually go down to MVFR around daybreak. Its hard to see much improvement during the day onMonday, with most terminals stuck at IFR most of the day.Theres a small chance for a few hours of MVFR in the afternoonaway from the coast, but will see everything drop back downagain Mon evening.Long Term...IFR conditions in any showers and possibly athunderstorm into Tuesday. There will also be patchy fog,mainly during the nighttime and early morning hours. Conditionsgradually improve Wednesday into Thursday, however there stillbe will isolated showers mainly confined to KHIE and themountains. VFR conditions will end out the week.
-- End Changed Discussion --&&.MARINE...
-- Changed Discussion --
Short Term...Seas are beginning to rise as long period swellfrom Ernesto moves into the waters. The forecast remains ontrack with 5-6 ft near shore seas,, and 7-9 ft in the openwaters. It look like the swell peaks Monday afternoon, andshould start subsiding Monday night, but itll happen slowly.Long Term...Long period swell from Ernesto will continue intoTuesday. Conditions fall below SCA thresholds by midweek.
-- End Changed Discussion --&&.Tides/Coastal Flooding...
-- Changed Discussion --
Splash-over possible tonight,especially along the southwest coast of Maine. Minor coastalflooding and splash-over remains possible Monday night.
-- End Changed Discussion --&&.GYX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
ME...High Surf Advisory until 8 PM EDT Monday for MEZ023. High Surf Advisory until 8 PM EDT Monday for MEZ024>028.NH...High Surf Advisory until 8 PM EDT Monday for NHZ014.MARINE...Small Craft Advisory until 8 AM EDT Tuesday for ANZ150-152-154. Small Craft Advisory until 8 PM EDT Monday for ANZ151. Small Craft Advisory until 8 AM EDT Tuesday for ANZ153.
-- End Changed Discussion --&&$$NEAR/SHORT TERM...CempaLONG TERM...Cannon