Area Forecast Discussion
Issued by NWS Portland, ME

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
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 201227 AFDGYX Area Forecast Discussion National Weather Service Gray ME 727 AM EST Sat Jan 20 2018 .SYNOPSIS... A weak ridge of high pressure will build into the region today with warmer temperatures than yesterday. A milder flow and above normal temperatures follow for the upcoming weekend. A storm system moving into the Great Lakes will bring wintry precipitation Monday into Tuesday with temperatures warming. A cold front Tuesday night brings colder air back into the region. Canadian high pressure will gradually build towards the region towards the latter half of the work week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Update... Temperatures continue to slowly climb and are already in the lower 30s along the coast. Readings will reach the 40s in many areas today. A few echoes on radar along the Midcoast, but most of this continues to not reach the ground from a mid level deck of clouds. Have added a slight chance of mix for this last batch. Scattered snow showers will continue over far northern areas. Prev Disc... Warm air aloft early this morning will be replaced by the first in a series of cold fronts that will cross the region. Despite cold air advection, downsloping and increasing sunshine will allow for temperatures to climb into the 40s for most areas today. Portland will reach around 48 degrees which is well short of the record high of 55 degrees set in 2006. In the northern mountains, expect mid to upper 30s for highs. Scattered snow showers will occur over the upslope regions of the mountains through this afternoon. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... A secondary push of cold air associated with another weak cold front will push through the region tonight. This will continue the scattered snow showers in the mountains with mainly clear skies in the south. The clearing conditions may allow for readings to drop more quickly in a few of the more sheltered interior valley locations. This front will weaken and dissipate somewhat over southern portions of the forecast area on Sunday. This front will set up the boundary for the next system approaching from the southwest in the extended portion of the forecast. Some overunning aloft will allow for additional cloudiness and yet another chance for snow showers in the far northern mountains. It will still be above normal in terms of temperatures for this time of the year. Expect highs in the 30s north to the lower 40s south. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... A cold front will drop down into the northern part of the area Sunday night and slide through the rest of the area on Monday with a light northeast wind behind it as axis of Canadian high pressure slides into northern Maine. Meanwhile, a large upper level low pressure system will be moving into the Great Lakes. Warm advection ahead of this system will bring some light snow Monday night. Generally 1 to 3 inches expected across the entire forecast area. The wound up surface low moves into Ontario and Quebec and occludes on Tuesday, with secondary low pressure forming along the remnant cold front which will be trying to push northward as a warm front. Unfortunately it won`t make a lot of progress inland across eastern New Hampshire and western Maine as easterly low level winds promote cold air damming. Thus the warm air will ride right over the top of the colder surface air just as the next round of precipitation arrives with the main synoptic system. Thus we should expect snow changing to sleet and freezing rain for much of the area. Thankfully the light snow preceding the freezing rain should limit the impact of the icing, though up to a quarter inch of ice is possible in the typical ice prone areas from Fryeburg to Augusta. The warm front may make it into southern New Hampshire and push onshore at the Maine coastline, allowing temperatures to warm well above freezing, reducing the duration of freezing rain here. Temperatures behind the warm/coastal front will warm into the upper 40s to low 50s, but do not expect interior areas to benefit from this until after the cold/occluded front moves through Tuesday afternoon/evening. Models have come into better agreement on the track and especially the timing of this wave, though the details of the cold air damming are notoriously difficult for models to pick up on especially in the longer range of the forecast. All models, however, do show the kinks in the surface isobars and northeast winds in the interior, the best indicator that damming will be present. The track of the newly emerging surface low runs just inland of the coast, suggesting that coastal areas will indeed see warming behind the coastal/warm front. However, would not be surprised if this track shifts just a bit to the right as we get closer in time and models start getting a better handle on the low level cold air, so we cannot rule out the icing for the coast. Cold front pushes eastward across the area Tuesday night, but the cold air will primarily be moving in aloft, with temperatures at the surface not falling too much considering the better mixing behind the front relative to ahead of it. Secondary front drops in from the north on Wednesday bringing better cold air and some snow showers. This cold lasts through Thursday and Friday with highs below freezing and lows in the single digits and teens. && .AVIATION /13Z SATURDAY THROUGH WEDNESDAY/... Short Term...LLWS in most areas this morning in developing warm air advection pattern. Mainly VFR conditions across the region, however northernmost regions such as HIE and HIE will likely have a period of MVFR conditions in lower stratus and -SHSN. Gusty SW winds will develop today. Long Term...Should see increasing clouds and lowering ceilings Monday into Monday night with snow arriving from southwest to northeast. Expect widespread IFR conditions with a wintry mix of precipitation on Tuesday for most areas. Low level wind sheer will be likely to the north of a warm/coastal front. A cold front Tuesday night brings drier conditions and should see ceilings improve to VFR at least by Wednesday except for northern mountain areas. && .MARINE... Short Term...Winds and seas will increase with a period of SCAs, especially out over the outer waters. Winds may approach gales, but we will only see 2-3 hours of them over the far outer waters. Therefore, continuing with SCAs. Long Term...Expect increasing southerly flow over the waters ahead of a cold front on Tuesday. Winds will likely reach gale force with a possibility for some storm force gusts in the eastern waters. Winds shift to the west behind the cold front Tuesday night with wind speeds possibly reaching gale force again. && .HYDROLOGY... Many rivers continue to be affected by ice. With the upcoming precipitation, it is possible that additional flow in these rivers could cause renewed ice jam flooding Tuesday into Wednesday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory until 6 PM EST this evening for ANZ151- 153. Small Craft Advisory until 6 AM EST Sunday for ANZ150-152-154. && $$ JC is the U.S. government's official web portal to all federal, state and local government web resources and services.