Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 270219 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1019 PM EDT Wed Jul 26 2017 .SYNOPSIS... High pressure will move offshore tonight. A cold front moves across the area on Thursday bringing scattered showers and thunderstorms. High pressure will attempt to build into the region Friday and into the weekend as low pressure moves south of the area. This high will remain established over the Northeast through early next week. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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1000 PM Update... Quick update to adjust temp/td/sky grids. Showers pushing into northwest Vermont beginning to fade and IR sat PIC showing warming tops so not looking for this activity to hold together as it continues east. Second batch moving through the eastern Great Lakes will likely enter northwest zones after midnight and will continue to push east through the early morning hours. Current pops still looking good at this point so no changes attm. Pre disc... 700 PM Update... Clouds continue to advance from the west early this evening and will quickly overspread the region through midnight. Area radar composite showing precipitation moving into northern New York ahead of cold front back over the Great Lakes. Looking for showers to edge into far northwest zones after midnight and will gradually drop southeast through the remainder of the forecast area through daybreak. HRRR seems to be doing a good job on timing and extent and current pops looking good. Have made minor adjustments to temps/tds but no major changes planned to current forecast attm. Next update will be around 1000 pm. Previous discussion... Clouds will advance eastward during the night. This will limit the patchy fog as compared to last night. Nevertheless, there will be some fog, especially before midnight. Showers will work their way east ahead of an approaching cold front. This front will reach the Saint Lawrence River Valley by daybreak. With the cloud cover and light southerly gradient, temperatures will stay in the upper 50s to lower 60s for overnight lows. There will be a couple readings in the mid 50s over far northern areas.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... As the surface cold front approaches the region Thursday, scattered showers and thunderstorms will break out across the region. Dependent on the amount of morning sunshine, the atmosphere will destabilize through the morning and early afternoon, yielding CAPE values of over a 1000 J/KG. The threat will primarily be in areas away from the immediate shoreline where conditions will be more stable. A few of the storms may be sufficiently strong to produce damaging wind gusts. Hail is less of a threat on Thursday. Increasing surface dew points and precipitable water values will allow for locally heavy rainfall. The slow moving nature to the front may allow for training of storms over any particular region. As the precipitation ends Thursday night, patchy fog may form over areas that receive heavy rainfall during the day. Scattered convection expected to continue until sunset at the slow moving front remains over central and northern areas. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... The front drops south of the area on Friday with low pressure forming and moving eastward along that front south of New England Friday night into Saturday. It is looking like the rain from this system will stay to our south, with our area remaining under high pressure with seasonable temperature and low humidity this weekend. The center of high pressure shifts east across the area on Monday, with a westerly flow developing aloft which will transport warmer, slightly more humid air from the center of the continent eastward into New England. There are no significant rain chances in the forecast through midweek as we will broadly be under the influence of high pressure. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... Short Term...Mainly VFR conditions will yield to lowering ceilings and visibilities in showers and storms on Thursday. Locally, IFR and LIFR conditions expected in any of those storms which will last into Thursday evening. Patchy fog develops thereafter. Long Term...VFR conditions are expected with fog possible each morning in the usual locations, Lebanon and Whitefield. && .MARINE... Short Term...Winds and seas will remain below Small Craft Advisory levels. Long Term...Expect light winds and low seas through the weekend and into next week as high pressure builds through the area. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$

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