Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
720 FXUS61 KGYX 061447 AFDGYX Area Forecast Discussion National Weather Service Gray ME 947 AM EST Sat Dec 6 2025 .SYNOPSIS... A weak low pressure system brings light snow to the coast and southern NH today. High pressure builds in Sunday, with another low pressure system bringing the chance for light snow overnight into Monday morning. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 930am Update...Snow has been productive this morning, creating a dusting on most surfaces and reducing visibility below 2 miles in southern NH and up the ME coast. Will see a gradual weakening trend into early afternoon as layers of moisture aloft drift into the Gulf of Maine. Clouds have also kept inland temps cool this morning. Needed to bring in some 10th percentile NBM temps to match observations over the past couple hours, and do show a warming trend into the afternoon...but only into the mid 20s in from the coast. 300 AM Update... In coordination with WFO BOX, went ahead and issued a coastal flood statement for coastal Rockingham, coastal York, and coastal Cumberland. High astronomical tides will bring water levels to near minor flood stage late this morning into early this afternoon. In addition, radar is beginning to show some light returns across southern NH with ASOS/AWOS and webcams showing some light snow. Given the very cold temperatures, this will easily stick to untreated surfaces and may result in locally slick spots. Previously... Weak low pressure over southern New England early this morning will move northeastward along/near the Maine coast today. There`s not much to this system, as all forcing mechanisms are weak and the atmospheric column is progged to have several dry layers in it. Even still, a period of light snow or snow showers remains possible across southeastern NH. Patchy freezing drizzle is possible as well, but not confident on that. Several models keep whatever forcing for ascent there is offshore so it`s possible that most areas won`t see any precip at all. Otherwise it`ll just be cloudy with light winds. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... Skies will tend to clear out this evening but gradually increase again as another cold front approaches from the west. This front is expected to pass across the forecast area by 12z Sunday with little fanfare as the air mass preceding the front will be quite dry. Still, a few snow showers will be possible in the mountains. Clouds increase on Sunday ahead of the next low pressure system, but it will remain dry with highs near freezing on the coastal plain and the Merrimack Valley to the teens to lower 20s in the mountain valleys. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Evening update...Just a quick update tonight as the inclusion of the latest NBM to the forecast hasn`t yielded any significant changes. For Sunday, ensembles have backed off on any probabilities of greater than 3 inches with the latest runs, with probablilites of greater than 1 inch in the 40-60% range across much of New Hampshire and the coastal plain. The signal is still there for a potential Norlun trough type feature which may push totals on the coastal plain toward the higher end of the 1-2 inch range depending on how, and if, it evolves. The remainder of next week continues to look active with several small clipper systems moving through, with eyes still on a potentially larger system for mid-week. Previous Discussion... Key Messages: * Quick moving low pressure crossing the area Sunday night will strengthen further in the Gulf of Maine Monday morning. Light snow accumulation may make the Monday morning commute slick for a portion of the forecast area. Details: Sunday night into Monday, low pressure exits the Great Lakes into northern New England. Guidance agrees that strengthening takes place as it quickly moves into the Gulf of Maine Monday, but there are a couple differing features ahead of the low as well as how north/south the low`s center is as it pushes across Sunday night. The first feature to watch is the possible formation of a Norlun-esque trough developing along the southern ME coast late Sunday evening. This will be spurred on by the formation of local low pres off the NH Seacoast before swinging north as the night progresses. The localized inverted trough based on wind convergence would focus a band of precip perpendicular to the coast, gradually moving towards the Midcoast overnight. These can sometimes lead to locally enhanced precipitation totals. This feature, typically better represented best in near term guidance, should prove more or less confidence in the coming forecast cycles. Until then, there are some deterministic runs supporting the feature such as the NAM, Canadian, and GFS. Second to this, will be how progressive the band is. Main low, quickly moving east, would take over in the pre-dawn hours Monday. This would disrupt the channel of wind convergence, assimilating it into it`s own frontogenesis banding. Did delay precipitation exit per some forecast uncertainty into Monday morning. Should the quick moving system be efficient, a fresh 1 to 2 inches of snow may be present for the Monday morning commute. Locally higher can`t be ruled out should the aforementioned inverted trough linger. Of greater confidence is the southern third of the forecast area seeing lighter precipitation, with greatest QPF focused across central/northern NH and much of southern ME. The exiting system Monday brings another punch of cold air on NW flow as daytime highs only get to the teens and 20s. Winds will be breezy during the day, with wind chill values hovering in the single digits above (along the coast and interior) and below zero (across the NW mountains and US/CAN border). The dry airmass will see Monday night temps mirror last night`s lows in the single digits above and below zero. The well below normal temps will again be short lived as SW flow increases behind exiting high pressure. This opens the door to additional disturbances arriving from the Great Lakes midweek into late week. The second system features a stronger low coupled with a midlevel trough and strengthening LLJ along the East Coast. It represents another likely chance of precipitation for the area, but will also be a chance for warmer air to bring mixed precip types to the area. && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... Short Term...Light snow continues this morning for southern NH and coastal ME terminals. IFR vis has been the predominant restriction with MVFR ceilings. Will see improvement late this morning into early afternoon as the area of snow moves up the ME coast and into the Gulf of Maine. VFR conditions are expected tonight and Sunday except for perhaps a period of MVFR cigs in the northern NH mountains. Long Term...Ceilings lower during the overnight period Sunday. Light SN moves across the area overnight with some visibility restrictions as well as expected MVFR ceilings. These may linger towards coastal terminals into Monday morning, but trend VFR shortly after noon local. Monday features brisk NW winds, with some gusts to 25 kt across most area terminals. && .MARINE... Short Term...Other than an outside chance of a few 25 kt gusts off the Midcoast early Sunday morning in the wake of a cold front, conditions on the waters are expected to remain below SCA thresholds. Long Term...An SCA will likely be needed for the waters Monday, with a few gusts to Gale possible into the afternoon on the outer waters. Cold air temps Tuesday morning may result in light sea smoke. A lull in wind Tuesday will be met with increasing SW flow overnight into the middle of the week as a active pattern continues. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Cornwell/Ekster/Tubbs SHORT TERM...Ekster/Hargrove LONG TERM...Baron