Area Forecast Discussion
Issued by NWS Portland, ME

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412 FXUS61 KGYX 301915 AFDGYX Area Forecast Discussion National Weather Service Gray ME 315 PM EDT Sun Apr 30 2017 .SYNOPSIS... A warm front will remain south of the region tonight and Monday and will be followed by an occluded front Monday night. A trough of low pressure will approach from the west on Tuesday and will cross the region Wednesday. High pressure builds in from the west Wednesday night and before shifting offshore on Thursday. Low pressure approaches from the southwest and moves up the east coast for the end of the work week. && .NEAR TERM /THROUGH TONIGHT/... Clouds have spread across the region this afternoon accompanied by scattered showers. These clouds are the leading edge of a broad warm front extending from our area back across New York and southern Ontario to the great lakes ahead of a strong cyclone in the middle of the CONUS. This front will slowly move eastwards overnight spreading heavier rain into the northern portion of our region. Most widespread and heaviest rainfall will be in the mountains where around an inch of QPF is expected. && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... Monday the shower activity will decrease in the north with just a few scattered showers as our region is left in the warm sector of the cyclone. Sadly it won`t be very warm at the surface as north to easterly flow off the Gulf of Maine will keep temperatures in the upper 40s. In the CT valley of NH and along the Mass border the warmth will creep in with temperatures reaching the mid 60s. A cold front will approach the region on Monday night and move through early Tuesday morning with an additional 0.5" of rain. && .LONG TERM /TUESDAY THROUGH SUNDAY/... On Tuesday a broad area of upper level low pressure will be filling and shifting northeast out of the Great Lakes region and into southern Quebec Province. The system will become negatively tilted as it weakens to an open wave late Tuesday night. Tuesday morning a pre-frontal trough will be moving east through Maine along with a line of showers and some embedded thunderstorms. Surface low pressure will be nearly vertically aligned with the upper level system, with most of the surface energy moving north of us as well. Therefore not expecting any severe weather but there could be some heavy downpours along the boundary. Behind the pre-frontal trough but ahead of the actual cold front (essentially a wind shift to the NW), we will see warming during the day, with sections of southern NH and interior Maine reaching the upper 60s to lower 70s. WSW/near zonal flow will be in place Wednesday through Thursday. Skies will clear out over the coastal plain first before clearing occurs elsewhere on Wednesday. Low clouds and showers will linger over the mountains through late Wednesday night. Clouds return quickly Thursday night ahead of the next system. Temperatures for this 2 day period will range from the 50s in the mountains to the 60s south. Low pressure originating in the southern Plains will eject NE Thursday and extend a warm front into New England with precipitation developing by Thursday night in southern NH. Our area will remain in the warm sector Friday and Saturday, with additional showers/drizzle in the warm advection regime. Models have backed off on developing a coastal low as this system deepens, but a stronger surface reflection will move into southern Canada by Sunday morning. This will keep northern New England in onshore flow/somewhat dreary weather for the remainder of the weekend. A a pre-frontal trough passage is likely sometime Sunday with some drying occurring. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... Short Term...Conditions will steadily decrease from VFR to MVFR overnight and into IFR by tomorrow. Rain overnight in the north may briefly mix with snow or freezing rain at elevation Long Term...IFR/LIFR ceilings continue Tuesday morning with improvement to VFR Tuesday. Areas of MVFR ceilings linger in the mountains Tuesday night through Wednesday. VFR conditions will prevail Wednesday night through Thursday with deteriorating conditions Thursday night through Friday with some +SHRA. && .MARINE... Short Term... Winds will increase behind the cold front late Monday night into Tuesday and a Small Craft Advisory will likely be needed. Long Term...Marginal SCA conditions are possible Tuesday into Wednesday, mainly in the offshore waters. Stronger SCAs are possible Friday afternoon into Saturday as a coastal low passes nearby. && .FIRE WEATHER... Things moisten up substantially through Monday with low clouds and drizzle expected. Rainfall of around an inch is possible across northern NH and the western ME mountains late tonight and early Monday. && .HYDROLOGY... Some concern for river flooding on the Kennebec over the next 48 hours. Most of the rainfall in the next 24 to 48 hours will focus directly on the upper Kennebec basins. Moosehead lake is already very full and flows going into the Kennebec remain high. Downstream flooding is possible particularly at Skowhegan. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Curtis SHORT TERM...Curtis LONG TERM...Hanes

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