Area Forecast Discussion
Issued by NWS Portland, ME

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661 FXUS61 KGYX 231718 AFDGYX Area Forecast Discussion National Weather Service Gray ME 118 PM EDT Sun Apr 23 2017 .SYNOPSIS... High pressure and drier air will finally build into the region today. A cold front will drop south into northern New England tonight into Monday and stall. Low pressure will slowly move up the Eastern Seaboard Tuesday and Wednesday with drizzle and periods of rain. A cold front will slowly approach from the west Thursday into Friday, before finally crossing the region on Saturday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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120 PM Update...Fine day underway across ME and NH with temperatures into the 50s and 60s with little in the way of clouds. Seabreeze should continue to push inland this afternoon. 945 AM Update...Have updated the forecast for minor adjustments to temperatures and sky cover based on latest trends in observational and mesoscale model data. Raised max temps a little bit, mainly inland. Have also increased cloud cover for eastern zones for the next several hours based on latest satellite data. 6am update... some `sunrise surprise` dense fog will quickly burn off over the next hour. prev disc...Overall look for a clearing trend today as high pressure builds in from the west. At 3 AM, clouds remained in place over much of Maine with a few pockets of clearing in New Hampshire. These clouds will move east and as they do areas which are able to clear before sunrise may see fog form. Augusta is the usual culprit here with visibilities already decreasing. Any fog will be patchy and brief as the sun rises and quickly burns off the moisture. The sun will allow for temperatures to climb to the mid to upper 50s by mid morning. High pressure crests over the region this afternoon, which will allow a sea breeze to develop. With a weak pressure gradient the sea breeze should be able to push inland as far as Sebago lake. This south flow will keep high temperatures cooler along the coast, especially from Portland east through Penobscot bay. South of Portland, highs will still approach 60 along the water and be in the low 60s inland.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... The evening will start off with clear skies across the region. A cold front will approach from Quebec, but the high pressure to our south will push it off to the north. The result is just a slight chance of showers along the northern border and increasing clouds through the mountains. Monday the same high pressure will be in control for much of the day with high temperatures once again getting into the 60s. Clouds will increase from the south ahead of an approaching low pressure system on Monday night. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Models continue to slowly lift an upper level low pressure system to the northeast. By Monday night, models in good agreement with surface low pressure near the North Carolina and South Carolina border. As the system moves northeast, precipitation will spread northward through our forecast area. Patchy drizzle may form along the coast as onshore winds begin to increase. By Tuesday night, models remain in relatively good agreement with the 00Z suite, bringing low pressure to the New Jersey coastline. Latest ensemble information supports this track as well. Thereafter, the system begins to fill as it reaches New England on Wednesday, however there will be plenty of moisture in place for areas of rain and drizzle to continue especially along the coast. QPF: Best estimates show about an inch to 1.5 inches along the coast. Lessor amounts will occur inland near the headwaters. Therefore, river flooding is not expected at this time. The system moves east Thursday as a cold front remains well to our west. Lots of low level moisture will remain in place with a developing southerly flow, so not much clearing expected. Latest models suggest that the long awaited cold front will cross the region Friday. Thunder will be possible with these showers. && .AVIATION /17Z SUNDAY THROUGH THURSDAY/... Short Term...The region will remain VFR through this afternoon and into Monday. Long Term...An onshore flow will lead to lowering ceilings into the MVFR or IFR category during the day Tuesday as rain and drizzle begins. Conditions continue to lower Tuesday night through Wednesday night possibly locally to LIFR. Conditions slowly begin to improve Thursday as a light southerly flow develops. && .MARINE... Short Term...Expect waves to continue to diminish as high pressure builds in for the day. Low chance of SCA conditions tonight on the ocean waters. Long Term...Onshore flow increases Monday night into Tuesday as low pressure slowly moves up the Eastern Seaboard. Winds will increase Tuesday night and waves will gradually build into early Wednesday as the persistent onshore flow continues. Wave forecasts may be underdone by the current model solutions with such a persistent onshore flow. && .FIRE WEATHER... High pressure builds in for Sunday as sunny skies help to dry out conditions. RH will drop to near 30 percent across much of New hampshire. The drier air will linger through Monday before another system approaches tuesday spreading rain into the region. && .TIDES/COASTAL FLOODING... High astronomical tides will continue for the week, increasing during the midweek period. At Portland the astronomical tide is forecast at 11 FT Tuesday night and 11.5 FT Wednesday night. With a prolonged period of onshore flow expected, the ESTOFS prediction for minor storm surge values of about a foot appears to be reasonable. Winds decrease Wednesday night, however high water anomaly`s will likely continue. Nearshore waves will not be overly large during this period, mainly ranging in the 5 to 9 foot range. However, with such high astronomical tides, NART wave runup matrices and in-house matrices suggest erosion and minor splash-over may occur beginning as early as Tuesday night. Very high astronomical tides will continue for the rest of the week, with tides peaking out at 11.7 feet on Thursday and Friday night in Portland Harbor. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$

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