141 FXUS61 KGYX 221647 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1247 PM EDT Tue Aug 22 2023 .SYNOPSIS... High pressure builds into the Northeast for the next few days, bringing seasonably cool temperatures and dry conditions. The high slides south and east by Thursday as a slow moving frontal system approaches from the west, bringing with it rounds of showers at times for Thursday night through Friday night. The system moves offshore on Saturday, with high pressure returning behind the front for the second half of the weekend and early next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 1245 PM Update... Another round of minor adjustments were made based on surface observations but otherwise it continues to be a very quiet day of weather with just some diurnally driven cumulus streaming overhead. 1000 AM Update... Minor changes to reflect latest observational trends. It will continue to be a comfortable morning with abundant sunshine and a refreshing northwesterly wind. 657 AM Update...Very little to tweak this morning with mostly clear skies, except for a stripe of high cirrus streaming over New Hampshire this morning. Dense valley fog in the north did manage to form, but most other places already have a light wind this morning. Previously...A thermal trough dips down into the region today, accompanied by a reinforcing shot of dry air as an upper level trough digs through Maritime Canada. The result is a breezy and mostly sunny day with the smallest hint of fall especially at elevation, freshened by a northerly wind. Am expecting a great day for mixing, both mechanically from steady midlevel flow and from sfc heating as the wave aloft clears most smoke (and a lot of the humidity) from the column. Leaning on stronger mixing due to these and a fairly weak inversion above the mixed layer, I have high temperatures in the 70s to as warm as the low-80s along the coastal plain and southern interior. Though dry aloft, the top of the mixed layer is forecast to have enough moisture to conjure up a scattered cumulus field through the day especially toward the coastal plain with some sfc convergence. Hires guidance suggests a few sprinkles may result near the Midcoast but in general the thought it that virga is more likely. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... A 600 dm dome of high pressure remains large and in charge over the central CONUS through the middle of this week. Tonight and tomorrow, a short wave ridge extending from this dominant high is forecast to poke NEward toward New England, allowing sfc pressure to build into the Northeast and Eastern Seaboard. Thus tonight should be a mostly clear, calm, and cool night... nearly an ideal radiational cooling scenario with river valley fog forming as air temperatures cool to below water temperatures. The wider the river (looking at you, Connecticut River Valley), the more likely there is to be fog development. Low temperatures are forecast to run in the mid-40s on average, right around today's lowest dew points, however upper-30s and low-40s can be expected for the most sheltered interior valleys especially toward the north. Mid-level pressure and wind charts suggest the SW ridge comes nearly overhead on Wednesday as it sinks SEward across the East Coast. Continued mostly clear conditions and a dry column support another day of good mixing with an afternoon cu field. Highs are forecast to be similar to today, in the 70s with a few places potentially touching the 80 degree mark... though weak flow will allow a sea breeze to develop and limit warming along the coast, especially the Midcoast. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Overview... High pressure remains in control of our weather pattern on Thursday as it slides off to the east. Low pressure approaches from the west on Friday along a slow moving frontal boundary. The system lingers nearby into Saturday before a second stronger front pushes the system off to the east. High pressure builds in behind this front for the second half of the weekend and early next week. Details... As the high pressure moves off to the east on Thursday, clouds begin to spill into western New Hampshire by the afternoon hours. This keeps highs closer to 70, while areas farther east warm into the low to mid 70s. Showers start to spread into western areas toward sunset as moisture rides around a strong ridge centered in the middle of the country. The showers will slowly progress toward the north and east Thursday night, likely not reaching eastern areas until the mid to late morning hours on Friday. While is doesn't look to be raining at all times, rounds of showers will keep most of the day wet and cool with highs primarily in the 60s to near 70. Western areas start to see some relatively drier air move in toward Friday evening, with this spreading eastward through the overnight hours. On Saturday, the front is likely to be offshore as a second and stronger front moves in and pushes it offshore. This second front will bring with it its own chance of showers, as well as much drier and cool air behind it. Despite lots of sunshine and drier conditions, temperatures on Sunday likely only top out in the mid 60s to low 70s across the area, giving a bit of an early taste of fall with temps 5-10 degrees below average. Temperatures then begin to moderate on Tuesday as the airmass modifies and highs push back into the low to mid 70s. By this time, what is now Tropical Storm Franklin is likely to be sitting somewhere off the East coast and has the chance to bring some increased surf to the area, through the details of this hinge greatly on the evolution of the system. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... Short Term...VFR today through tomorrow, except in valley fog tonight... most likely at KLEB but also possible for KAUG, KCON, KHIE, and KMHT. Northerly winds today gust 15-20 kts later this morning and this afternoon, before going light and variable or calm overnight. Light flow out of the west is expected tomorrow, with an increasing southerly/onshore component along the coast and into the I95 corridor. Long Term...Nighttime valley fog is likely Wednesday night, but otherwise VFR conditions are expected through the day on Thursday. Showers then spread from west to east from Thursday evening through Friday morning across the forecast area, and linger into Friday evening. Scattered showers and fog remain possible Friday night, and then VFR conditions return late Saturday and persist into early next week. && .MARINE... Short Term...Mainly northerly flow is expected today through tonight with gusts around 25 kts early this morning gradually diminishing. Similarly wave action 2-3 ft today diminish to 1-2 ft by tomorrow. High pressure slides to the south of the waters tomorrow, pulling winds southwesterly AOB 15 kts. Long Term...High pressure slides east of the waters on Thursday, with low pressure along a frontal boundary approaching from the west. The front takes until early Saturday to cross the waters, likely bringing increased southerly flow and SCA conditions from late Thursday night through early Saturday. A stronger front clears the waters late Saturday, with high pressure building in for Sunday and early next week. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Tubbs SHORT TERM...Casey LONG TERM...Clair