Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 220702 AFDGYX Area Forecast Discussion National Weather Service Gray ME 302 AM EDT Wed Aug 22 2018 .SYNOPSIS... An upper level trough will move east towards the region today, bringing a chance of showers and thunderstorms as a cold front moves through. This cold front will usher somewhat cooler and drier air for late this week before a gradual warming trend occurs over the upcoming weekend. A frontal system will bring a chance for showers very late in the weekend and into early next week. && .NEAR TERM /THROUGH TODAY/... Patchy fog and showers will continue to spread eastward across the forecast area today as an upper level trough approaches the region. A weak wave will likely form during the morning hours over southern New England allowing for increased southerly flow ahead of the system. This will advect moisture into the region and allowing for a few briefly moderate to heavy showers in a few locations. Mesoscale models suggest this weak surface low will likely follow a track over southeastern New Hampshire later this morning and along the Maine coastline this afternoon before perhaps moving inland in the Midcoast region. This track minimizes significant destabilization across much of the region. However, will still include a risk for a thunderstorm over southern areas for the possibility of elevated convection. Over far southern New Hampshire, dew points expected to climb to near 70 degrees today and there is still a slight possibly gusty winds as wind fields aloft will continue to be increasing. Daytime maxes will be help down in the 60s over far northern and eastern sections due to the onshore flow with 70s most elsewhere. If southeast New Hampshire were to briefly break out into some sunshine, the MHT to ROC corridor may nudge 80 degrees. && .SHORT TERM /TONIGHT THROUGH 6 PM THURSDAY/... A cold front sweeps through the region this evening allowing for drying and a weak west to northwesterly flow to set up. Gradient however may be too weak to prevent fog from redeveloping in some of the sheltered valley locations, especially in areas that received heavy rainfall. Full clearing may be slow to arrive with the upper low remaining to our west. Expect overnight lows mainly in the 50s. On Thursday, cold air advection will allow H8 temperatures to drop into the +8C to +10C range. Downsloping will allow for the warmest readings, mainly in the mid to upper 70s. It will feel very comfortable with dew point values dropping into the 50s. There may be a few clouds building during the midday hours with the passage of the upper trough. This would mostly be confined to the mountains. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... High impact weather: None We`ll see a fairly quiet pattern evolve over the end of the week and into the weekend. A long wave trough will shift east out of the area on Thursday night allowing for high pressure to build in for Friday into Saturday. By Saturday night a short wave trough develops near the Great Lakes, moving east into our area to bring rain Sunday night into Monday. Here there is some variation within the models with the GFS bring more progressive and the ECMWF lagging behind a bit while the Canadian washes out the wave almost entirely. All of this forward progression is dependent on the breakdown of the block which has lingered over the Pacific for the past few days and is currently just starting. Expect to see better agreement tomorrow when more of the block has eroded, for now will stick with a blend of models which leaves general showers in the area for Sunday into Monday. In all cases the northward passing wave will favor more rainfall in the mountains. && .AVIATION /07Z WEDNESDAY THROUGH SUNDAY/... Short Term...Areas if IFR conditions in showers, patchy fog and isolated thunderstorms today. Some fog redeveloping in sheltered valleys tonight before a drier, northwesterly flow kicks in. Long Term...VFR conditions will prevail under high pressure to end the week. Low pressure approaches from the Great Lakes on Sunday night into Monday. Ahead of this increasing moisture may lead to sheltered valley fog overnight. Showers will develop on Monday with scattered MVFR ceilings possible. && .MARINE... Short Term...Winds and seas will approach SCA levels later today as a southerly flow ahead of the front picks up, then switches to NW behind the front tonight and becomes gusty for a few hours. Long Term...High pressure will build over the waters to start the weekend. Sunday night southwesterly flow will develop ahead of the next low pressure passing to our north. This will result in gusts to SCA on the outer waters Sunday night into Monday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ Curtis/Cannon

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