Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 210658 AFDGYX Area Forecast Discussion National Weather Service Gray ME 258 AM EDT Sun Oct 21 2018 .SYNOPSIS... High pressure will build in from the west today through tonight and will shift offshore on Monday as a weak warm front lifts into western New England. Weak low pressure will slowly track southeast from western Quebec Monday night and Tuesday. Low pressure will shift east into the maritimes Tuesday night. High pressure will slowly build in from the west Wednesday through Friday. && .NEAR TERM /THROUGH TODAY/... Weak shortwave passing south of the region early this morning is pushing mid level clouds into southern New Hampshire and southwest Maine. Showers associated with this system are gradually shifting northeast through southern New England and may brush far southern New Hampshire zones along with portions of southwest coastal Maine through the mid morning hours. Elsewhere high and mid level clouds will continue to stream northeast and will be around through the morning hours across much of the forecast area before moving east this afternoon. Northwest pressure gradient will tighten across the region as high pressure builds in from the west. Brisk northwest winds will also transport much cooler air into the region with highs not getting out of the 40s in southern zones. Highs in the north will range from the mid 30s to lower 40s. && .SHORT TERM /TONIGHT THROUGH 6 PM MONDAY/... High pressure will continue to build in from the west overnight and will crest over the region by Monday morning. Weak over- running pattern setting up to the west will produce variable clouds overnight. Lows will range from the upper teens to mid 20s north and lower to mid 20s south. High pressure will shift offshore on Monday and a weak warm front will nose into the region from the west. After morning sun expect increasing clouds in the afternoon and perhaps a late day sprinkle in the mountains. Temperatures will remain below normal with highs ranging through the 40s to near 50 in the south. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... On Tuesday large scale trough continues to rotate over central and eastern Canada with the base of the trough coming across the Ohio Valley, New England, and offshore towards Nova Scotia. Thus we will see several impulses affecting the region over the next 8 days. High pressure at the surface is quickly suppressed as a surface cyclone dives towards the Ohio Valley Monday night into Tuesday morning. A surface cyclone will deepen over the Gulf of Maine, possibly bringing some gusty winds and heavier precipitation to the region...depending on where the low develops. At any rate, increasing cloud cover and winds will help overnight lows stay in the 30s most areas, with a few 20s far northwest for Tuesday morning. Showers will begin and spread across the area, with snow mixing in at the peaks in the morning before changing over to rain. As mentioned the winds behind the system will be gusty. Additional upslope snow showers will be possible Wednesday. High pressure will attempt to edge in from the west for the end of the week but won`t make it very far. Northerly winds will stubbornly stick around Thursday allowing cool air to flow south from Canada. Another storm system over the OH Valley- possibly joining up with another cyclone developing along the east coast- may bring additional precipitation for next weekend. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... Short Term...VFR today through Monday. Long Term...Deteriorating conditions to MVFR/IFR Tue and possibly into Wed in -SHRA/-SHSN. Cyclonic flow aloft will keep MVFR conditions in snow showers in the mtns but downsloping areas on the northwest flow will keep those areas VFR through Thu. && .MARINE... Short Term...Continuing SCAs for the bays and outer waters through late tonight. Long Term...Timing and location of development of potential coastal low in the Gulf of Maine late Tuesday into Wed will determine strength and timing of backing northwest winds in its wake. A lot of uncertainty remains for Tue night into Wed but Gales may be needed by Wed. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory from 6 AM this morning to 3 AM EDT Monday for ANZ150>154. && $$ Sinsabaugh/Hanes is the U.S. government's official web portal to all federal, state and local government web resources and services.