FXUS61 KGYX 040749 AFDGYX Area Forecast Discussion National Weather Service Gray ME 249 AM EST Wed Dec 4 2024 .SYNOPSIS... A complex series of upper level troughs will cross the forecast area tonight and Thursday with snowfall across the interior and a mix of rain and snow closer to the coast. This system will be a followed by a very cold airmass and gusty winds to finish up the workweek and to start the weekend. && .NEAR TERM /THROUGH TODAY/... Not a bad weather day today as the region will find itself in short period of short wave ridging in a broad warm air advection regime. Lots of clouds will be around but winds will be rather light with high temperatures similar to yesterday's readings. Late in the day, a short wave trough will approach from the west with attendant SFC low pressure. Forcing for ascent may be strong enough by sunset to allow for some light snow to break out in westernmost New Hampshire. && .SHORT TERM /TONIGHT THROUGH 6 PM THURSDAY/... The overall mass fields and thermal profiles for tonight in association with redeveloping coastal low pressure have not changed much in the various sources of guidance. The main fly in the ointment is once pressure falls commence with the developing low over Massachusetts, inland pointed warming winds will also commence. This will aid in stronger forcing for ascent to develop over the area, allowing for mainly snow to overspread much of the region this evening. On the other hand, there does not seem to be much of a mechanism to keep the SFC cold air in place at the coast and also portions of central ME as the southeasterlies strengthen. While our snowfall forecast holds fairly high confidence in the interior, there will be a stripe of much higher uncertainty within 25-35 miles of the coast - perhaps even farther inland from the Midcoast. Will the forcing for ascent be strong enough on the nose of the low level jet to force 2" per hour snows for a time just inland from the coast before it gets too warm? It's possible. But if the deeper omega fails to develop then it will be much easier to change to rain earlier. With that said, will keep all winter weather advisories in place without any changes for the time being. It's possible we'll need to add another row of zones closer to the coast (if anything for the potential impact to the Thu morning commute) but will hold off for the time being due to the uncertainty in thermal profiles. The main area of forcing leaves the area around 12z Thursday allowing for much lighter precipitation during the day which will allow for SFC warming and more iffy precip types, especially on the coastal plain where additional accums are expected past mid to late morning. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... Update...Overall trend in guidance is similar from Friday through the weekend. Friday biggest hazard will be the strong gusty winds and localized blowing snow concerns. This threat will be limited due to the fact that water bodies aren't frozen over yet, which are one of the primary blowing snow source regions. One trend that continues is for the warm front moving further north the beginning of next week, will the potential for more rain rather than mixed precipitation as most the area should be in south of the frontal boundary. Will see if this warming trend continues in the ensemble families. Low pressure responsible for the snow Wednesday night and Thursday is forecast to be centered over or just east of far northern Maine Thursday evening. It will continue to lift northward into the Canadian Maritimes through the course of Thursday night and Friday, further tightening the pressure gradient across the region. Breezy conditions will develop overnight Thursday and continue during the day on Friday with forecast soundings supporting gusts of 30-35 mph out of the W-WNW with a few possibly hitting the 40-45 mph range. These gusty winds will make for a raw, blustery day with wind chills in the teens, possibly even single digits in the morning hours south of the mountains. In the mountains, wind chills will likely be in the single digits either side of zero in the lower elevations and well below zero in the higher terrain. The mountains will also see upslope snow showers, and Froude numbers from both the NAM/GFS suggest unblocked flow Thursday night and Friday, so I do have some PoPs for snow showers south of the mountains along with going above guidance on cloud cover. However, by Friday afternoon, the low levels may dry out enough to where it's only flurries downwind of the mountains. Even though winds will be diminishing Friday night, there may be a period of subzero wind chills south of the mountains as temperatures are forecast to become quite cold with single digits to teens for lows. It will be partly sunny and not as breezy Saturday with temperatures in the mid 20s to lower 30s for highs. A chance of snow showers will continue in the mountains with a couple possibly extending downwind into the foothills. From Sunday into early next week...models are in pretty good agreement showing low pressure moving across Quebec with some light wintry precipitation possible along a warm front over portions of the area on Sunday. For right now, the better chance will be across northern areas. The 12Z operational GFS and ECWMF hint at a better potential for precip early next week with low pressure across the Great Lakes and potentially a stalled frontal boundary somewhere across the area. There are mixed signals within the ensembles so I have gone a touch lower than the NBM PoPs. && .AVIATION /07Z WEDNESDAY THROUGH SUNDAY/... Short Term...VFR conditions expected thru today. Then as precip overspreads the region conditions quickly drop to widespread IFR or lower this evening. The exception may be north of the mtns...where southerly winds keep places like HIE MVFR or VFR for much of the event due to downsloping. IFR or lower conditions continue in SN/RA thru Thu and begin to improve slowly by Thu afternoon. Near the coast...especially PWM...AUG...and RKD...Wed night some LLWS is possible as the LLJ swings thru the area. Long Term...Mostly VFR Thursday night through Saturday except for occasional MVFR ceilings and snow showers causing reduced visibility at HIE. Thursday night and Friday will be breezy with gusts out of the W-WNW 25 to 30 kt, possibly exceeding 35 kt from time to time. There may also be a few snow showers develop south of the mountains from late Friday morning into the afternoon, but confidence on crossing any of the TAF sites is low at the moment. A warm front looks to move through the region around Sunday, potentially bringing a round of light wintry precip and some degree of flight restrictions as well. && .MARINE... Short Term...Light winds continue for much of the day today. As the clipper approaches a southerly LLJ will develop overnight. A gale warning has been posted north of Cape Elizabeth for tonight. There will likely be a pause in gale force wind gusts as LLJ lifts northeast during the day on Thursday. However, westerly gales are then expected to commence all waters by early Thu evening. Long Term...Westerly gales are likely Thursday night and Friday as the deepening surface low lifts into the Canadian Maritimes, further tightening the pressure gradient across the region. Conditions improve Friday night but will probably remain above SCA levels over the outer waters for most of the upcoming weekend. Another low pressure may then cross the waters sometime early next week. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Winter Weather Advisory from 7 PM this evening to noon EST Thursday for MEZ007>009-012>014-033. NH...Winter Weather Advisory from 7 PM this evening to noon EST Thursday for NHZ001>009-011-015. MARINE...Gale Warning from 7 PM this evening to 7 PM EST Friday for ANZ150>152. Small Craft Advisory from 4 PM this afternoon to 4 PM EST Thursday for ANZ153-154. Gale Watch from Thursday afternoon through Friday evening for ANZ153-154. && $$ NEAR TERM...Ekster SHORT TERM...Ekster LONG TERM...Combs/DD