Area Forecast Discussion
Issued by NWS Portland, ME

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KGYX 180415 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1215 AM EDT Sun Jun 18 2017 .SYNOPSIS...
-- Changed Discussion --
A warm front will slowly push east of the region overnight. A warm and humid airmass will prevail on Sunday. A cold front will approach from the Great Lakes Region on Monday and will stall along the coast Monday night. On Tuesday, the cold front will gradually dissipate. The next cold front will move in on Wednesday and exit the region on Wednesday night. High pressure will build in on Thursday.
-- End Changed Discussion --
&& .NEAR TERM /UNTIL 6 AM THIS MORNING/...
-- Changed Discussion --
1210 AM...Minor ESTF update to reflect the current mesonet in near term grids. Prev disc... 1030PM UPDATE... Have made a few minor adjustments to overnight temperatures based on latest trends. Still watching for the possibility of fog along the coast as well as in interior valleys northwest of the mountains. Could need a dense fog advisory if the fog gets dense enough along the coast, but for now confidence is not high enough to issue. 7PM UPDATE... Have updated the forecast mainly to adjust sky cover and precipitation chances overnight. Not seeing much forcing for precipitation overnight, though it will be cloudy, foggy, and possibly drizzly at times over the coastal plain to the east of the mountains. Model forecasts show patchy areas of light precipitation which is likely just a representation of this low cloud layer and possible drizzle. Thus have reduced rain chances, but kept mention of fog and drizzle. It`s quite clear to the northwest of the mountains at the moment, and if this continues expect fog to commence in the valleys this evening as low level moisture is quite rich. Fog may also occur along the coastal plain where dewpoint depressions are already only about 5 degrees, but considering the low clouds already in place there and the limited cooling this time of year radiation fog may be harder to accomplish here. But with some cooling and added moisture, we certainly could see the fog again. ORIGINAL DISCUSSION... Plenty of low level moisture will remain in place. This will allow fog to develop overnight, especially along and near the coastline. Low clouds will keep temperatures fairly uniform across the region with lows in the upper 50s to mid 60s from north to south. There could be some cooler locations in the far north if this area remains cloud- free through late this evening. There will be a low chance for a passing shower overnight as the warm front lifts north of our area.
-- End Changed Discussion --
&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 AM MONDAY/... On Sunday, fog will gradually dissipate during the morning hours. Plenty of cloud cover will remain, especially in the south. There is a lack of a focusing mechanism for precipitation, but there will be a low chance of a passing, quick shower or two. Where there is any sunshine, daytime heating will lead to increased instability, allowing for thunderstorms as well. It will be warmer and more muggy than today with dew points on the increase and temperatures in the lower to mid 80s in some areas away from the coast. By Sunday night, a cold front will slowly be approaching from the northwest. The steadier, heavier precipitation will remain outside our forecast area through the night, leading to the threat of heavy, tropical rainfall in the extended portion of the forecast. && .LONG TERM /MONDAY THROUGH SATURDAY/... The combination of a large bermuda high anchored off the east coast and a trof over the Great Lakes will allow a warm and very moist southwest flow along the east coast to be transported north into the region Mon into Tue. The source region will be straight from the Gulf of Mexico so high PWATS will prevail. During Mon the air mass will destabilize as the trof over the Great Lakes slowly pushes east. Heavy showers and some strong scattered thunderstorms are expected Mon through Mon night. QPF amounts of 1.5 to 2 inches is expected in the mountains with lesser amounts further south. Have opted to hold off on issuing a Flash Flood Watch for the mountains and foothills until we have a higher confidence for even higher amounts, which is certainly possible considering the source region of the air mass, and also some training of convection possible. Some of the scattered thunderstorms may approach severe limits in the afternoon and evening as per SPC suggests. Due to the high dewpoints over the cooler waters expect fog to be an issue at times...especially along the coast. By late Tuesday a trof moves across the area allowing a more westerly flow and clearing out much of the precipitation by late in the day. Some low level moisture will remain and areas of fog may redevelop Tue night. Wednesday through Friday could see scattered showers as weak impulses move swiftly along the west to southwest flow aloft. Temps will remain near seasonal levels. && .AVIATION /04Z SUNDAY THROUGH THURSDAY/... Short Term.../00Z TAFS/ MVFR cloud deck currently over the coastal plain from southern New Hampshire right through central Maine will gradually lower in height overnight as cooling occurs. Conditions are likely to go IFR again for most of the coastal plain, while LIFR conditions are possible near the coast and across much of Maine. Some fog is also possible. Further to the north across the mountains, Whitefield has been reporting HZ all day which seems erroneous given no other observations reporting this. However, as the sun goes down up there, nighttime cooling may lead to valley fog through the morning, possibly as far south as Lebanon. Long Term...A tropical southerly flow will allow for plenty of low level moisture that will produce areas of fog into Mon and then numerous showers and scattered thunderstorms Mon into early Tue. Mainly MVFR to IFR conditions can be expected across the area Mon through early Tue. Conditions slowly improve to VFR by late Tue into Wed except MVFR in any scattered lingering showers. && .MARINE... Short Term...Wave guidance continues to run a tad high today. Have capped off seas no higher than four feet for the night. Gradient continues to increase out of the south on Sunday, with gradually building waves. Therefore, have hoisted a Small Craft Advisory beginning Sunday morning. Long Term...SCA`s will be needed through Monday and probably extended into Tue due to the increasing southerly flow keeping seas above 5 feet. && .GYX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
ME...None. NH...None. MARINE...Small Craft Advisory from 8 AM this morning to 6 PM EDT Monday for ANZ150>154.
-- End Changed Discussion --
&& $$ ES

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.