Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 251352 AFDGYX Area Forecast Discussion National Weather Service Gray ME 952 AM EDT Sun Jun 25 2017 .SYNOPSIS... A series of upper level disturbances will cross the area today into next week bringing chances for showers or thunderstorms, especially in the mountains. Otherwise temperatures will be near normal with lower humidity into mid week. Warmer and more humid conditions move in at the end of the week, with a chance of showers and thunderstorms by Friday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Update... Have issued a Beach Hazard Statement for high paddle craft risk after coordination with WFO Caribou and the United States Coast Guard. Otherwise, only minor changes to the forecast for today. Cu will continue to build, initially over northern sections with scattered showers and thunderstorms developing this afternoon. Latest mesoscale models suggest these storms will cross northern areas between 19Z and 23Z, with less activity further to the south. Prev Disc... 5 AM Update... Only minor changes to the forecast database this morning. Quiet weather continues with temperatures in the 50s to near 60 and low dew points. An area of stratus remains over the northern NH and western ME mountains this morning and should dissipate within a couple hours. Previous discussion... The first half of today will be nice and fair for much of the area with drier air still working in from the WSW. Cloud cover gradually builds this morning however as a front begins to near the international border as an ejecting short wave swings through the Great Lakes. Lapse rates and wind fields are better to our west, but we could see a brief window with a few widely scattered rotating strong storms...mainly across northern NH and the western ME mtns. Have included small hail and gusty winds for a few hours in these areas this afternoon. Again not expecting most of the area to see anything outside of the higher terrain. Temperatures should warm into the 70s north to upper 70s to mid 80s across the interior with west winds in place.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... Precipitation will come to an end in the evening hours with the loss of instability and as the main short wave moves east. Downsloping winds will allow for clearing for the coastal plain and support additional drying and cooling into the 50s areawide with cooler spots across the north. A frontal zone remains in the region and expect more showers and thunderstorms Monday as surface heating ensues. Again this will mainly be over the mountains but we will probably see more showers in the foothills. Westerly winds will bring temperatures up once again but cloud cover and overall falling thicknesses will bring readings down a few degrees compared to today. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Upper trough over the Great Lakes shifts east across New England on Tuesday. This will bring another round of showers and possibly a few thunderstorms during the day Tuesday, this time a little more widespread than prior days. Overall instability is fairly weak given pretty dry low levels, but better forcing arriving with the trough axis should trigger more widespread afternoon convection. Although the trough moves to the east Tuesday night, another one slides in behind it for Wednesday, triggering another round of showers and possible thunderstorms mainly in the northern half of the forecast area. After a brief break Wednesday night, the next wave approaches the area from the west on Thursday. This will be a better developed pressure system with a developing warm front lifting out ahead of a surface low tracking through the northern Great Lakes. Models are showing some differences in the track of this low and the preceding warm front with some increasing uncertainty as to whether the warm front will lift north into our area on Thursday (if at all). This would have a substantial effect on temperature and precipitation forecasts for Thursday and Friday. To the south of the warm front, temperatures will warm well into the 80s. But as is typical for our area, a preceding onshore flow to the north of the warm front sucks in the cool maritime air and delays or prevents the northward advance of the warmth. Because of this, we have decided to lower high temperatures a bit along the coast of Maine on Thursday, generally into the 60s, while still offering some 80 degree readings to southern New Hampshire. Surface low pressure tracks east along the warm front Thursday night, with rain expected mainly along and to the north of the warm front. While the low moves east on Friday, another stronger low will be forming to the west over the Great Lakes. This will prevent the trailing cold front from getting a good push through our area, leaving the remnant boundary near our area. This could provide the focus for some showers and possibly a thunderstorm on Friday. This Great Lakes low then tracks northeast into Canada on Saturday sending a front eastward through New England providing another chance of showers. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... Short Term... Pockets of MVFR conditions are occurring this morning in portions of the mountains where low level moisture is trapped. Expect increasing cloud cover to arrive late with a frontal boundary sagging into the mountains this afternoon and evening and triggering widely scattered -TSRA. HIE and LEB have the highest chances of being affected out of the TAF sites in NH and ME. Heavy downpours and gusty winds are also possible with the stronger storms. Some gusty SW winds are likely this afternoon. Long Term... Expect prevailing VFR conditions this week, but there will be occasional chances for showers. The best chance of showers will be each afternoon, primarily across the interior. An onshore flow ahead of a warm front on Thursday could bring some IFR ceilings to much of western Maine. && .MARINE... Short Term...Westerly winds are expected today with some showers and thunderstorms crossing the waters. Fog may occur tonight but winds and seas will stay below SCA criteria. Long Term...Winds over the Gulf of Maine will be fairly light out of the west or southwest for the next several days. A stronger pressure gradient will develop on Thursday as a warm front approaches, leading to southerly winds increasing to as high as 25 KT. && .TIDES/COASTAL FLOODING... Another high astronomical tide will occur tonight around 1 AM at Portland. The total tide will likely come in around 12 feet MLLW with a light WSW wind in place. Very minor coastal flooding is possible along the most vulnerable low lying side streets near the wharfs in Portland, as well as Granite Point road in Biddeford and the Backbay area of Hampton, New Hampshire. && .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...Beach Hazards Statement until 8 PM EDT this evening for MEZ023>028. NH...Beach Hazards Statement until 8 PM EDT this evening for NHZ014. MARINE...None.
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