Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 192207 AFDGYX Area Forecast Discussion National Weather Service Gray ME 607 PM EDT Wed Oct 19 2016 .SYNOPSIS... High pressure will exit into the maritimes on Thursday as low pressure developing over the Ohio Valley tracks northeast towards the New England by Friday. This system will intensify as it reaches the southern New England coastline Friday night. A cold front pushes through from the west on Saturday as the storm further strengthens and moves through central New England. Cooler weather will arrive on brisk northwest winds for the latter part of the weekend and early next week. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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605 PM Update...Little change to the going forecast as it remains on track. Expect a pleasant evening to continue with diminishing winds. Previously... Initially gusty winds this evening should die down fairly quickly as high pressure skirts quickly through the area tonight. A clear sky and calm winds will bring excellent radiational cooling conditions, however, dewpoints will only be in the upper 30s to mid 40s, so overnight lows will be limited by this low level moisture. Despite the balmy start for much of the area south of the mountains, temperatures should drop about 30 degrees into the 40s. The northern valleys could dig under their dewpoints a bit and reach the mid 30s before fog forms.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... As the high moves east into the Canadian Maritimes it will set up an easterly flow over most of New England. As the upper trough approaches from the west it will spread cloud cover in from the west, initially just high clouds but lowering through the day. The combination of cloud cover, cooler temperatures aloft, and an onshore low level flow will keep temperatures about 20 degrees cooler on Thursday than they were on Wednesday, though this will be very close to normal high temperatures for this time of year. As clouds thicken through the day, eventually some rain may spread in during the afternoon, mainly in northern and western areas along a sharpening frontal boundary near the Canadian border. South of this boundary, the onshore flow will provide increasing low level moisture and clouds, but for the most part the more substantial rain should hold off. Some areas of drizzle will be possible Thursday evening into Friday morning along the coast. There will also be a better chance of rain by early Friday morning as a wave pushes northeast within the broader upper level flow and attempts to shove the surface warm front northeast through the area. Temperatures do not cool very much Thursday night. In fact, they may only cool a few degrees initially before warming by morning as the warm front brings warm/moist advection. Low temperatures in the upper 40s to low 50s are more than 10 degrees above normal for this time of year. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... A deep, long wave trough continues to dig over the Ohio Valley during the extended portion of the forecast. As energy drops into the base of the trough, the system continues to back and deepen a closed low over PA friday night. This allows surface cyclogenesis to occur along the southern New England coastline as the low remains tilted to the west aloft. Rain will enter the region Friday and become more widespread Friday night. There may be a moisture band developing over the Midcoast region with enhanced rainfall as +RA becomes quasi- stationary over a 12 hour period. The eventual track will play a large part in the upcoming wind fields. Gusty winds ahead of the system are a little less uncertain as the low will be intensifying overhead. However, a strong low level wind field in excess of 40 knots will develop as the system departs central and northern New England on Saturday and early Sunday. The upper level low may hold back strong wind gusts for a period on Saturday, especially over Maine. All areas will receive strong wind gusts by Sunday. Will begin to highlight the possibility for some power outages during this period, especially with leaves still on the trees. Cooler air will enter the region late this weekend and early next week. A short wave will enter the base of the trough as well, bringing scattered rain showers to the region with a few snow showers entering the favorable upslope region of the mountains. && .AVIATION /22Z WEDNESDAY THROUGH MONDAY/... Short Term...VFR conditions today through much of Thursday as high pressure moves off to the east. Should see some valley fog developing tonight at Lebanon and possibly Whitefield where VLIFR conditions will be possible for a few hours near sunrise. As Thursday wares on, clouds will be increasing from the top down and from west to east, eventually bringing MVFR conditions and showers to northern and western areas Thursday evening. Long Term...Rainfall is expected Friday and Friday night as low pressure moves through the area, likely keeping conditions IFR to LIFR. A cold front pushes east through the area Saturday, allowing for partial clearing conditions to VFR over southern areas while in the mountains and foothills MVFR conditions in scattered showers which will persist through much of the weekend and into early next week. && .MARINE... Short Term...An easterly flow develops on Thursday, shifting to southeasterly Thursday night. Although winds may stay below advisory levels, the onshore fetch will allow wave heights to build above 5 FT by Thursday night. Long Term...A strengthening system will bring southeasterly winds to the coastal waters Friday and Friday night. A cold front pushes east across the waters Saturday, with a west to northwesterly flow behind it which will likely gust above 30 KT at times. && .TIDES/COASTAL FLOODING... The Friday 4 pm astronomical tide in Portland will be 10.6 feet. A southeasterly flow ahead of the system may allow for building storm storm tides during the day. This will be monitored as we move through the workweek for possible advisory headlines. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM UPDATE...MLE is the U.S. government's official web portal to all federal, state and local government web resources and services.