Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 091348 AFDGYX Area Forecast Discussion National Weather Service Gray ME 948 AM EDT Sun Aug 9 2020 .SYNOPSIS... Warmer and increasingly humid air will spread across the area through the first half of the new work week. Along with the building humidity will come the chance of a few showers and thunderstorms from time to time. A cold front will cross the area early Thursday...with a bit less heat and humidity to follow for Friday and the start of next weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 945 AM Update...Have updated the forecast mainly for minor adjustments to sky cover and temperatures based on latest observations. Any remaining fog or low clouds will burn off shortly. Still expecting isolated to widely scattered convection this afternoon as a short wave trough approaches from the west. Last few runs of the HRRR are pretty dry so will continue with very low PoPs, but at least a mention of thunder. Previously... 645 AM...Minor ESTF update to reflect the current mesonet and satellite trends in near term grids. Prev Disc... At 06z...a 1021 millibar high was centered over southeast New England. A weak surface trough extended from the Ottawa Valley through western New England. GOES water vapor showed a weak impulse vicinity of the Ottawa Valley and a second trailing impulse over the upper Great Lakes. NWS Doppler Radar mosaic showed a lone shower over northern New Hampshire likely associated with the weak trough and approaching impulse. Otherwise...some high and mid cloud was spilling into the area ahead of the approaching impulses. Some patchy valley fog and stratus had also developed over western New Hampshire. For today...the lead impulse will swing across northern sections today. CAMS and the remainder of the 00z model suite show scattered convection mainly across northern and western sections through early evening. Modified soundings show CAPE AOB 1000 j/kg and limited potential for strong convection. Highs today will be in the 80s...with a few upper 70s along the immediate coastline. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... For tonight...the trailing impulse will cross the area with widely scattered showers and isolated thunderstorms possible. Otherwise...a partly cloudy and humid night with patchy fog developing. Lows will be in the 60s. On Monday...the impulse will finally slide offshore by afternoon. Partly sunny skies along with the building heat and humidity should produce at least widely scattered convection...especially across inland sections. Highs will range from the mid 80s to lower 90s. Apparent temperatures will fall short of advisory criteria in southern New Hampshire...likely peaking in the lower 90s. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... No significant changes to model guidance or the forecast package with this latest update. Heat and humidity will continue to be a factor through the midweek period. 00Z model suite continues to show a large scale upper level low pressure system crossing central, then eastern Canada for much of this upcoming work week. Western Maine and New Hampshire will remain on the periphery of this system, with very high upper level heights. A southwesterly flow at all levels will allow for increasingly deep moisture and heat to enter the region. Warm air advection will allow for H8 temperatures in the +18C to +20C range by Tuesday. With the increased moisture and surface temperatures likely to top out in the upper 80s to mid 90s over interior locations, max apparent temperatures will soar well into the 90s in some areas. Heat advisories may be required for portions of southern New Hampshire and interior southwest Maine. Along the coastal areas, temperatures will be slightly cooler thanks to onshore winds of the Gulf of Maine. A short wave trough and accompanying weak frontal system will attempt to approach northern areas Tuesday afternoon and Tuesday night. This may allow for showers and with increased instability, a few thunderstorms. The heat continues on Wednesday as an upper level trough passes by to our north. There may be a few showers or thunderstorms once again with temperatures in the upper 80s to lower 90s in the south and central areas. The coastline will be warmer this day than Tuesday as the gradient becomes more out of the southwest. Thursday is the big question. Some of the models hint at the passage of a backdoor cold front during this time frame. The Euro brings the front through, but late in the day after the heat has already hit the region, while other models are more faster with the any cold air advection. In any case, moisture, heat and instability could pool over far southern areas of Maine and New Hampshire, fueling showers and thunderstorms during the day. High pressure will likely build over the Canadian Maritimes Friday and into next weekend. This will set up a cooler onshore flow and the chance for moisture arriving off the Gulf of Maine and beyond. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... Short Term /through Monday/...VFR with isold MVFR psb in -SHRA/-TSRA today through Monday. Lcl IFR possible once again tonight and early Monday in patchy stratus and fog. Long Term...Scattered showers and possibly a few thunderstorms expected through midweek, mainly during the afternoon and early evening hours and mainly away from the coast. Locally IFR conditions in patchy fog through midweek as well, mainly at KLEB, KCON and KHIE. && .MARINE... Short Term /Through Monday/...Gradient remains light across the waters through Monday with winds and seas remaining below SCA. Long Term...Winds and seas will remain mainly below SCA levels. However, southwesterly winds may gust as high as 25 knots along and near a frontal system Tuesday night. Pockets of fog possible from time to time. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM UPDATE...Ekster SHORT TERM...Schwibs LONG TERM...Ekster

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