Area Forecast Discussion
Issued by NWS Portland, ME

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566 FXUS61 KGYX 211622 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1222 PM EDT Fri Jul 21 2017 .SYNOPSIS... A weak front crosses the region today with a trend toward cooler weather expected this weekend. Several areas of low pressure will track through southern New England late this weekend and into early next week, providing a chance of rain while keeping temperatures cool. && .NEAR TERM /UNTIL 8 PM THIS EVENING/... 1220 PM...Minor ESTF update to ingest the current mesonet into near term grids. Prev disc... 912 AM...Modified BUFKIT soundings support afternoon CAPES of 1000 to 1500 j/kg across our northern Maine zones and coupled with strong wind field expect any storms that develop there to have the potential for strong winds gusts and to a lesser extent hail. Have added enhanced wording there for gusty winds and small hail with this ESTF update. some haze and fog was introduced to our far eastern offshore marine zone per GOES imagery trend. Prev disc... Light westerly flow expected today with continued warm but slightly less humid conditions. A cold front will drop in from the north late in the day and could trigger a few showers and thunderstorms in the far north. Expect temperatures in the upper 80s to low 90s for most areas, with only some minor cooling right along the Maine coastline. && .SHORT TERM /8 PM THIS EVENING THROUGH 6 PM SATURDAY/... Front drops south across the area tonight. Any lingering showers should dissipate as the night goes on. While winds will be out of the northwest on Saturday with cool advection ongoing, we should still see temperatures warm into the mid to upper 80s with downsloping conditions on the coastal plain. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... We head into a rather cool period for Sunday through the start of next week.The long wave pattern will transition to a trough over the eastern United states as a short wave digs south out of Saskatchewan on Saturday. By Sunday night a trough is entrenched over the Northeast and will hold there through the start of the week. This will lead to below normal temperatures with highs struggling to reach 70 /about 10 degrees below normal/ by Tuesday. A series of short waves will move through this broad upper trough leading to several rounds of showers. On Sunday a quick moving wave will rotate through the trough. Consensus seems to be to keep most precipitation south of our area but southern New Hampshire may still see some shower activity. A stronger wave approaches on Monday as the trough digs further south. This will spin up a surface low south of Long Island. This low will then pass over the Cape Cod canal and cross the Gulf of Maine during the day on Monday. With northeasterly flow ahead of the low we set up a surface pattern more familiar for the cold season. The northeasterly surface flow will keep colder air dammed at the surface while aloft 850mb winds will remain easterly at around 30kts. Expect this set up to result in a region of heavy rain within Maine as the saturated easterly flow runs into the mountains. Still quite a bit of spread in the timing and location within various guidance but overall have kept likely pops in the mountains overnight Monday into Tuesday. The showers will continue as the low moves off to the east on Tuesday with temperatures again remaining below normal. Brief ridging will move in for Wednesday returning temperatures to more seasonable values under clearing skies. && .AVIATION /16Z FRIDAY THROUGH TUESDAY/... Short Term...VFR conditions are expected outside some early morning fog in valley locations. Long Term... Cool and unsettled weather returns with showers and MVFR ceilings being the norm for the daytime and IFR in fog returning into the overnight from Sunday night right through Wednesday. && .MARINE... Short Term...Light winds expected over the waters with wave heights remaining generally less than 2 feet. Long Term...A low will cross the waters on Monday into Tuesday. Ahead of it we may approach SCA on the outer waters as northeasterly flow develops. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ ES is the U.S. government's official web portal to all federal, state and local government web resources and services.