NWS Forecast Discussion
For Fremont, NH
000 FXUS61 KGYX 300229 AAA AFDGYX Area Forecast Discussion...UPDATED National Weather Service Gray ME 929 PM EST Sun Jan 29 2023 .SYNOPSIS... This week will be seasonably cool with occasional snow showers, mostly over the mountains. Exceptions will be light rain and snow through this evening... and another round of light snow late in the day Monday, which will impact areas outside of the mountains. The coldest air of the season is likely to arrive late this week with temperatures potentially dropping well below zero Fahrenheit. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... 9:30 PM Update...Forecast is in good shape, just a few lingering flurries across Coos County and the Western Maine Mountains through midnight tonight. No significant updates to the remainder of the forecast except for trending cloud cover down along Southern New Hampshire and coastal areas. 6:30 PM Update...Quick update this evening to drop the Winter Weather Advisory a few hours early across Central Somerset County. Current webcams and observations are showing visibilities above 5 miles with flurries expected to continue through a few more hours, but accumulating snow has mostly ended. Remainder of forecast is in good shape with the cold front beginning to push into the International Border Area of the Western Maine Mountains. A quick shot of cooler air will mover into the region through the overnight hours. Broad, weak low pressure is located around or just to the east Lake Erie per latest surface analysis, and this low will track roughly along or just south of the International Border through this evening and toward the Canadian Maritimes overnight. Light snow has broken out over the area with moistening and lift out ahead of this low, mainly across northern areas so far, but there have been reports of light snow as far south at IZG and AUG recently. To the south of these areas, temperatures have warmed up quite nicely with a warm front lifting through the area, and while coverage of precip is expected to be much less for southern areas, anything that does fall should be mostly light rain at this point. Toward the foothills, ptype should continue to be snow for a few more hours, but there could be a mix of rain/snow toward early this evening as the warmer air slowly advances northward. Across the north, temperature profiles are expected to remain subfreezing keeping precip type as all snow, with a few inches of snow still possible through this evening, especially across the far north. The Winter Wx Advisory continues for central Somerset county through this evening where the higher accums are expected, generally 2-4", possibly up to 5". While the low lifts to the north and east early this evening, some drier air will push into the region from the south and west, gradually ending precip for central and southern areas while it hangs on a little longer across the north. Temperatures will actually be fairly mild through this evening and tonight, but the low pressure will eventually drag a cold front through, and cold air advection will drop temperatures back into the teens across the north and generally the 20s to the south, except lower 30s across southern NH. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... Monday starts off dry, but another in our series of weak systems will approach and cross through later in the day, bringing another round of light precip to the region from late afternoon into the evening hours. Models are in good agreement on the track of the weak low, roughly across north MA or southern NH and into the Gulf of Maine, which will give most the area snow as precip type. The exception may be across southern NH and far SW ME early Monday evening where temperature profiles are expected to be warm enough to start as rain before switching over to a brief period of light snow. Hi-res guidance along with the globals and their ensembles members remain consistent in this being a light event ranging from a few hundredths to around a tenth of an inch of QPF, which will generally translate to an inch or two of snow accum from the foothills to northern areas and less than an inch to the south. Once the low passes far enough east, northwest winds on its backside will carry in some drier air, which will end the light snow from west to east from late evening into the early overnight hours along with a partial clearing of skies south of the mountains. As per usual though, scattered upslope snow showers are expected to continue in the mountains. Overnight lows are forecast to be in the teens to lower twenties south of the mountains and single digits to teens to the north. && .LONG TERM /TUESDAY THROUGH SUNDAY/... While the weather pattern will be fairly quiet for mid-winter, the primary story for the extended forecast period will be a plunge of Arctic air into New England by this weekend. After a cool, zonal flow regime through mid-week... medium range ensembles heading through the end of the week show departures of multiple standard deviations below average in temperature fields. While there is still some wiggle room WRT how significant the event will eventually be... dangerously cold temperatures and wind chills can be expected at least across the mountains by this weekend. Starting off Tuesday... breezy westerly flow and a mix of sun and clouds prevail with upslope snow showers early on mostly over the mountains as low pressure departs to the east. Temperatures will be noticeably cooler behind this wave, with highs generally in the teens and 20s. Surface high pressure building into New England eventually allows winds to relax overnight with a cold night on tap. Since clouds are still forecast to be around in fast zonal flow... won`t go all-in on coolest projections at this point... but low temperatures in the single digits either side of 0F (perhaps low-teens along southern and coastal peripherals) according to the operational blend could potentially lower by another 5-10 degrees should the sky/wind forecast trend more favorably. Daytime Wednesday will continue the theme with highs again in the teens and 20s under a mix of sun and clouds. Mountain snow shower chances return with a wave passing well to our north late Wednesday into early Thursday, offering little for the lower elevations as forcing and sufficient moisture depth appears to be limited to the upslopes. Temperatures rebound toward normal on Thursday with flow turning southwesterly ahead of the next wave of low pressure approaching from Canada. This largely moisture- starved wave will offer another round of low-end PoPs from light snow showers, again mostly in the mountains... but what follows is more significant. Model consensus continues to point to a significant intrusion of Arctic air over New England early Friday into Saturday. This will likely be the coldest airmass that has descended over the region thus far this season, with t850 of -20C a near-guarantee for northern areas by Friday evening. There is increasing confidence in this significant plunge of cool air as ensemble averages continue to trend cooler and with less variance both at the surface and aloft. Generally speaking, while the GEFS has more variance/less confidence versus the ENS... there is still a > 50% chance of temperatures AOB 0 deg F Friday night across the entire area with the GEFS, versus a near- guarantee from the ENS. With this airmass overhead, temperatures as low as the negative-20s will be possible during the coldest period... Friday night into Saturday... across the north with negatives present to the south. For high temperatures, Friday will be cooler than Thursday... but Saturday is likely to be the coldest day with highs for now forecast in the single digits on either side of 0F. On top of all of this... brisk northwest winds will make these temperatures feel even colder, with wind chill headlines of some kind likely to result. Let`s end this discussion on warm note with a rebound back toward average temperatures on Sunday, which has as strong of model consensus as the preceding Arctic airmass. This comes as the progressive and amplified pattern brings a stout ridge of high pressure across the CONUS to our doorstep with an increasing SWerly flow through the column. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... Short Term...The majority of flight restrictions the rest of today into tonight are expected to be from LEB to AUG and points northward as a result of low ceilings and reduced visibility from light snow. In general, these are expected to be MVFR but could drop to IFR at times. Low-end VFR ceilings are expected elsewhere, but there could be a few MVFR ceilings tonight as a weak cold front crosses through northern New England. VFR conditions expected through Monday afternoon, but then ceilings will lower to MVFR in the afternoon and evening as a low pressure brings more light snow (or rain/snow mix for MHT/PSM). Conditions will improve through Monday night as the low exit to the east, but upslope snow showers and MVFR ceilings will probably continue at HIE and perhaps LEB. Long Term...VFR prevails except for occasional MVFR CIGs in the mountains (mostly KHIE) through the end of the week. Winds will have a general westerly clip, varying between NWerly and SWerly from day- to-day. Wind gusts are forecast to be highest Friday and Saturday when a bitterly cold air mass descends on the region, with northwesterly gusts potentially exceeding 25-30 kts. && .MARINE... Short Term...Gusts to or in excess of Gale Force across the eastern waters will continue into this evening, perhaps a few across Penobscot Bay as well, while SCA conditions continue elsewhere. Conditions then improve overnight as winds diminish as they veer to the northwest and then north behind a cold front that will cross through. Conditions will continue to improve through Monday, but then another weak low pressure will move across the waters late Monday into Monday night bringing another increase in winds and seas across the waters. However, these look just shy of SCA levels at this point. Long Term...This week will feature a general westerly flow over the Gulf of Maine, turning more SWerly or NWerly on a day- by-day basis. Highest confidence in 25+ kt winds developing come in the wake of a cold front Thursday night with potential for gale force winds developing behind a reinforcing cold front late Friday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Gale Warning until midnight EST tonight for ANZ150-152. Small Craft Advisory until 4 AM EST Monday for ANZ151-153-154. && $$ SYNOPSIS... NEAR TERM...Combs/Dumont SHORT TERM...Combs LONG TERM...Casey AVIATION...Dumont MARINE...Dumont