Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 180734 AFDGYX Area Forecast Discussion National Weather Service Gray ME 334 AM EDT Wed Oct 18 2017 .SYNOPSIS...
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High pressure will pass by to the south of New England today with warm weather expected through Thursday. A cold front will move east through the region Thursday night bringing cooler, but still above normal temperatures into the weekend. A deep southerly flow develops into the beginning of next week keeping the warm weather in place and bringing increasing humidity as well. The next significant chance of rain arrives by the middle of next week.
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&& .NEAR TERM /TODAY/...
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Some cloudiness will linger this morning over the upslope region of the mountains and foothills of New Hampshire and western Maine. However, as the gradient relaxes today and the upper trough shifts to the east, clouds will diminish with time. As the upper level ridge shifts east over our region this afternoon, H8 temperatures will be on the rise as well, reaching +8 to +10C. Good mixing will allow temperatures to climb into the 60s in most areas, with lower 70s possible over far southwestern Maine and southeastern New Hampshire.
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&& .SHORT TERM /TONIGHT AND THURSDAY/...
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Mainly clear skies and increasing dew points tonight will allow for inland valley fog to develop. A west to southwesterly gradient will eventually increase late tonight over the region. On Thursday, a weak trough will pass well north of the region. A gusty west, southwesterly flow will develop, allowing our warming trend to continue further with temperatures topping out in the 70s. Winds will be off the water along the Midcoast region, so expect cooler temperatures in the coastal areas. Dew point values will slowly be on the increase as well with readings in the 50s over southern areas. The record high temperature in Portland is 81 degrees set back in 1963. We will fall quite a bit short of the figure.
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&& .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
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Big Picture: Although we get a glancing blow from a trough to our north later this week, the story for the weekend and into next week will be a building ridge over the East Coast. This will bring continued warmth to the area. A deep trough is eventually expected to develop over the center of the country and make its way eastward, but this will not occur until the middle of next week. Expect it to bring a good chance of rainfall and eventually some colder temperatures. The Details: A cold front will push eastward through the area Thursday night associated with low pressure moving through northern Canada. There could be a stray shower as far south as the northern part of our forecast area, but for the most part expect this to be a dry frontal passage. With the core of the colder air still well to the north, expect temperatures to only be a few degrees cooler behind this front for the rest of the week and into the weekend. As the high builds in behind the front on Friday expect temperatures to top out in the 60s. With the high moving across New England overnight Friday night, expect good radiational cooling conditions to exist with temperatures falling into the 30s for most areas and near freezing in the colder valleys. Went below the standard blend of model guidance for lows Saturday morning especially over southwestern parts of the area closer to the center of the surface high. This puts the forecast more in line with the MEX guidance for this period. High pressure shifts east on Saturday with a southerly flow developing at the surface and an upper ridge building overhead. This will bring warmer temperatures back into the area with 70s becoming more and more widespread with time. Dewpoints will be climbing into the upper 50s and low 60s which will keep nighttime lows quite balmy. Some models would like to bring a preceding cold front through the area as early as Monday, but it seems unlikely that this will do much to change the sensible weather in our area even if it does move through. There is a better consensus that a deep upper trough over the center of the country will slowly move east toward our area on Tuesday bringing a more organized frontal system into the area with widespread rainfall possible. Although models are in great agreement on the potential for rainfall next Tuesday, it is worth noting that the movement of these high amplitude patterns tend to have fairly low predictability, with the bias being toward a slower progression of these systems. Thus it seems a fair forecast would be for the warmth to continue through midweek with increasing chances of rain through Wednesday. Would not expect the colder air behind the trough to be felt in our area until late next week.
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&& .AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
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Short Term...VFR through Thursday, except for some patchy valley fog tonight. Areas of LLWS are expected through early this morning as a 30-40 kt westerly low level jet continues over portions of the region. LLWS possible once again late tonight and early Thursday as the gradient increases once again. Long Term...Generally expect VFR conditions through Friday, though there could be some MVFR in the mountains as a cold front moves through Thursday night. High pressure this weekend brings a clear sky but a good chance of morning fog in the valleys this weekend and into early next week.
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&& .MARINE...
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Short Term...SCA for ocean waters into this morning as southwesterly winds increase and gust around 25 kt. Winds should decrease this morning, however seas will still run in the 3 to 5 foot range over the eastern outer waters. Long Term...Expect winds to shift to the WNW behind a cold front Thursday night into Friday morning, with gusts to 25 or 30 KT possible. These stronger wind gusts will diminish through the day on Friday as high pressure builds in. It may take a bit longer for the higher seas to subside, but the trend will be for quieter conditions this weekend.
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&& .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...None. NH...None. MARINE...Small Craft Advisory until 11 AM EDT this morning for ANZ150- 152-154.
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&& $$ NEAR TERM...Cannon SHORT TERM...Cannon LONG TERM...Kimble

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