Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 200200 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1000 PM EDT Mon Jun 19 2017 .SYNOPSIS... A warm and very humid airmass will remain across the region through Tuesday. A cold front approaching from the Great Lakes Region will bring widespread shower and thunderstorm activity to the region through tonight. Some of the thunderstorms could produce damaging winds and torrential downpours into this evening. On Tuesday, the cold front will gradually weaken as it slides offshore. The next weak trough will move across the area on Wednesday producing a few showers mainly in the mountains and foothills. The next more significant system approaches late Thursday into Friday bringing a return to unsettled weather. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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1000 pm Update... Have updated the grids based on current conditions and radar imagery. Showers continue to move east and weaken. Will still include a slight chance of a thunderstorm for the next few hours, however this will be limited in scope and area. Patchy fog will be developing shortly as temperatures are very close to their dew point values. 805 pm Update: The Severe thunderstorm watch #355 has expired and we have also cancelled the flood watch across the CWA. Have made adjustments to grids to reflect the diminishing convection. Some areas of convection continues across the area but the heaviest precipitation is over as the convection will continue to wane and become scattered over the next few hours as per the HRRR suggests. Downpours still possible in some of the convection the rest of the night but training of lighter showers will have no impact. Previous Discussion: The tropical air mass will remain in place through tonight ahead of the approaching cold front so widespread showers and scattered thunderstorms are expected to continue. The severe thunderstorm watch will remain in effect until 8 pm tonight. The primary threat with the severe thunderstorm watch is due to potentially damaging winds. With very high PWATS exceeding 200 percent of normal torrential downpours are likely. Some lines of convection will occur and may produce a training effect, this may cause some flash flooding so the Flash Flood will remain in effect until 8 am Tue morning.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Tue morning the front slowly moves across the area and then off the coast. This will bring an end to the showers except in the mountains where some will linger. Surface temps will be very warm as h85 temps aloft remain around +12C. This will mean highs should reach into the 80s over most areas. Tue night a drier westerly flow will develop lowering the dewpoints and temps. Overnight lows should be in the 50s. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Looks like an activer period with a front/surface low moving through every few days. For Wednesday a cold front will move through Wednesday morning with showers and possible thunderstorms. High pressure builds in for Thursday but the next front will be arriving Friday first with a warm front moving through followed by the cold front Friday night. Expect likely POPS with showers and thunderstorms. The ECMWF moves the front through Saturday morning but the GFS forms a surface wave on the front which delays the progress of the front with the front moving through Sunday morning. Another cold front or trough moves through Monday afternoon. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... Short Term...Tonight variable conditions in showers and thunderstorms. Some storms may contain high winds into this evening. MVFR to IFR conditions will occur in the areas of convection otherwise VFR. Tue - conditions become VFR behind the exiting frontal passage by later in the morning and afternoon. Tue night...VFR. Long Term...Expect MVFR?IFR in showers and thunderstorms Wednesday. VFR Thursday. MVFR/IFR returns for Friday afternoon with conditions lingering into Saturday and possibly Sunday. && .MARINE... Short Term...SCA conditions will continue tonight into Tue in a persistent Sly flow. There will be some gusts above 25 kts. Seas will be mainly above 5 ft mainly outside of the bays. By late Tue and Tue night the winds will shift to the west and seas will slowly subside. An SCA for just seas will likely be needed over just the outer waters late Tue into Tue night. Long Term...SCA possible Friday and Saturday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory until 6 PM EDT Tuesday for ANZ150>154. && $$ JC

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