Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 280113 AAC AFDGYX Area Forecast Discussion...UPDATED National Weather Service Gray ME 913 PM EDT Thu Oct 27 2016 .SYNOPSIS... Low pressure will slowly move east through the region tonight and Friday, bringing heavy rain for most of the region with snow at the highest elevations. Winds will be gusty at the coast. A ridge of high pressure will build in from the west Friday night. A weak trough moves through Saturday which drags a cold front through the area late Sunday. High pressure will build in from the west Monday. Low pressure will pass by well to our north midweek. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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915 PM update... Large area of light to moderate rain and drizzle is now over most of NH and a good portion of western Maine. Temperatures remain above freezing within the CWA while just into MA and VT snow is falling. Accumulations as much as 6" have been reported so far. Stronger dynamics will develop overnight and as temperatures fall across the higher terrain precipitation will mix with and changeover to snow. Near Long Island sound a coastal low pressure system is beginning to form. No major changes to the forecast. Updated to include latest thermal and moisture trends. 635 PM update... Ocean effect showers continue ahead of a warm frontal boundary this evening and are delivering moderate rainfall in some cases. Visibilities may go down briefly in these showers which are mainly affecting western Maine and east towards the Mid coast. Isobars are beginning to kink along the coast in anticipation of surface low formation overnight which will prompt a more substantial precipitation shield shifting ENE with time...especially after midnight and during the morning commute. This update adjusted temperatures and dew points as well as P-type. Snow is noted just across the border from NH into VT...but as the warm front advances any snow or rain/snow mix should be confined to the foothills and mountains and perhaps portions of the CT River Valley. Previous discussion... A potent short wave trough will approach the region tonight allow for rapid surface cyclogenesis over southern New England tonight which will move into the Gulf of Maine on Friday. As a result there are a few relatively minor impacts to talk about, including snow, wind, and rain. Precipitation will continue to gradually spread northeastward across the CWA this evening, with a good chunk of the precipitation type being rain. However, at elevations mainly above 1000 FT in W/SW NH some light snow accumulations are likely this evening (generally less than 1 inch). Also, scattered ocean-effect showers will move inland on the Maine coast from time to time through the early evening hours. As pressure falls rapidly occur over southern New England tonight (mainly after midnight), forcing for ascent will correspondingly increase as well causing a more rapid northeast advancement and higher intensity of precipitation. The column should be cold enough for snow at higher elevations across northern NH and the western ME mountains, with snow amounts highly dependent on elevation. It`s possible that from late tonight through Friday that elevations above 2500-3000 FT will see greater than 6 inches of snow. Below that level, amounts will be lighter. Have issued a winter weather advisory mainly for snow for northern Franklin and central Somerset counties, due to the early nature of the snowfall and the potential for a period of wet snow that may weigh down branches and power lines. Rainfall is expected for the vast majority of the populous, with the rain increasing in intensity, especially late tonight and Friday morning. Strong ascent owing to large scale and mesoscale forcing (including a potential coastal front), should allow for heavy rainfall, most likely on the coastal plain, with 1 to 2 inches expected through midday-ish Friday. It would not be surprising to see upwards of 2.5 inches in spots due to strong nature of the inflow pointed toward the coast. Some localized poor drainage flooding is likely during the morning commute, especially where leaves clog storm drains. Winds will be another issue as well. Strong onshore flow should begin to affect the coast...most likely the immediate coast...late tonight and Friday morning as strong pressure falls aid in generating an onshore jet. The strongest winds (gusts to 50 mph) are most likely on the Midcoast of Maine during this time as the system matures (and subsequently resulting in the issuance of a wind advisory). Further south along the coast, winds should not be quite as strong but still could gust up to 40 MPH. The rain and wind will subside from S to N during the day on Friday, with only linger showers expected for southern zones during the afternoon hours. Rain and snow should continue in the mountains, but probably be more rain than snow as the day progresses outside of the highest elevations.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... Low pressure will gradually move away from the region Friday night with gradual clearing and gusty NW winds. Clouds may increase late friday night as the next short wave approaches. && .LONG TERM /SATURDAY THROUGH THURSDAY/... A fast moving flow aloft will have numerous weak systems embedded along it and several of these will pass through during the outlook period. Timing of these systems will be difficult and varies some from model to model. A weak trough moves through the westerly flow aloft Saturday and will produce scattered showers mainly in mountain areas with maybe a few isolated showers reaching southern areas. Models indicate a much stronger digging trough moving through the Northeast on Sunday dragging a strong cold front across the region by later in the day. Scattered showers are expected with this cold front and then followed by clearing and colder temperatures by late Sunday night. Winds will be gusty from the northwest behind the cold front Sunday night. Monday high pressure quickly builds east across the area allowing winds to quickly diminish as the center of high pressure crests over the area by Monday afternoon and then moves off the coast Tuesday afternoon. Another fast moving trough will move north of the area Tuesday night allowing a warmer southwest flow to develop Tuesday night into Wednesday. Another short wave approaches late Wednesday possibly bringing more showers to the area. Stayed very close to superblend model guidance. && .AVIATION /01Z FRIDAY THROUGH TUESDAY/... Short Term...Conditions will lower to IFR to LIFR overnight with moderate to heavy rain in most places, especially on the coastal plain. Snow will be found at the highest elevations. Gusty easterly winds will be found at the coastal terminals late tonight and Friday morning with LLWS possible. Improving conditions are foreseen gradually from S to N across the region Friday afternoon and night. Long Term...Some MVFR possible mainly in the mountains Saturday and all areas Sunday afternoon with with cold frontal passage that occurs late Sunday afternoon. VFR conditions for early next week. && .MARINE... Short Term...Gales continue for all waters tonight into Friday for frequent gusts around 45 kt. Seas on the ocean waters should build to in excess of 10 feet. Winds switch to NW and slowly diminish later Friday afternoon and night. Long Term...Winds and seas remain light Saturday and Sunday. A cold front moves across the waters Sunday night with strong gusty northwest winds behind the front that continue through early Monday. By Monday afternoon winds quickly subside and become light as high pressure builds over the waters. && .COASTAL FLOODING... Some minor splashover is possible during Friday morning`s high tide. However major problems are not expected due to relatively low astronomical tides. && .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...Wind Advisory from 4 AM to 2 PM EDT Friday for MEZ025>028. Winter Weather Advisory until 4 PM EDT Friday for MEZ008-009. NH...None. MARINE...Gale Warning until 8 PM EDT Friday for ANZ150>154.
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&& $$ NEAR TERM...Hanes SHORT TERM...Ekster LONG TERM...Marine is the U.S. government's official web portal to all federal, state and local government web resources and services.