Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
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976 FXUS61 KGYX 221444 AFDGYX Area Forecast Discussion National Weather Service Gray ME 944 AM EST Fri Nov 22 2024 .SYNOPSIS... Low pressure will track north tonight, bringing rain to the area overnight. The broad system will be slow to exit, with chances for precipitation continuing through Saturday. Conditions will start to dry out Sunday into Monday as the low pressure lifts into the Canadian Maritimes. && .NEAR TERM /THROUGH TONIGHT/... 930am Update...More of an overall update here to adjust morning trends. Much of the precip has pushed north into the mountains and Kennebec Valley at this hour. Here it may remain through early afternoon while the southern CWA resides in a dry slot. This will feature breaks of sun and fairly puffy cu. There is low level instability present, but not too much moisture. Thus these should be prominent through early afternoon. Can`t rule out a brief shower out of these, but more isolated. Next, will be focused on resumption of more widespread rain this evening and overnight. 8am Update...Quick update here to expire Gale headlines on the coastal waters and put up SCAs through this evening. Winds will fall off early this morning, but wave action of 5 to 8 ft is still expected through today. 628 AM Update... The steady rainfall will continue to quickly retreat to the north this morning. In its place a lighter southeast flow will develop. Scattered showers shown on latest KBOX radar imagery will cross the region from time to time, similar to the most recent HRRR solution. Winds will continue to diminish this morning from north to south as well this morning as the dry slot rolls through. Otherwise, only minor modifications to the latest forecast package. Prev Disc... Low pressure retrogrades through eastern New York this morning. A moisture band will finally pivot across the forecast area around the vertically stacked system. Rain will continue across the region this morning before a dry slot enters the region from the south. Will taper off pops from the mid morning hours to early this afternoon over southern and central portions of the forecast area. Across the far north, rain will continue into the afternoon hours with some snow mixing in over the higher elevations. The strong, gusty winds will diminish during the day as the gradient relaxes. Temperatures will climb into the 40s north by afternoon with lower 50s in the south. && .SHORT TERM /SATURDAY/... Models continue to develop an areas of low pressure well off the southern New England coastline tonight. There is some disagreement in the track and intensity of this system which impacts the timing of precipitation retrograding back into the forecast area from east to west during the night. In any case, will lean towards categorical pops after midnight in most areas. The NamNest and other models do show a fairly potent inverted trough entering the area. Rain will continue on Saturday as the system intensifies and briefly stalls over the Gulf of Maine. Ptype will be an issue as well as enough cold air will be present in the northern mountains and also portions of western New Hampshire to allow for snowfall. It will be cooler, with highs only in the 30s across the mountains with lower to mid 40s elsewhere. Have upped the winds a tad for Saturday and this may need to be increased further. A tight gradient behind a departing strong area of low pressure may lead to very gust winds out of the north and northwest. Bufkit profiles suggest a brief period of 35kt+ winds is possible during the day and into the evening hours. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... 04Z Long Term Forecast Update... Latest ensemble and global forecast guidance continues to indicate unsettled conditions to persist until Saturday night as low pressure drifts to the Canadian Maritimes. While doing so, colder air will be brought down from the north with northwesterly flow and this could allow for a brief period of wet snow to mix in south of the mountains before ending. Another s/wv trough looks to cross on Sunday, bringing additional rain/snow showers that will be mainly confined to the north/mountains. Brief s/wv ridging builds on Monday, allowing for dry and mainly sunny conditions. The pattern becomes more unsettled again mid-late week as the next storm system approaches the region. Broad upper low will be centered near Cape Cod Saturday morning, and waves of energy rotating to the north and west over the area will prolong cloudy and rainy conditions for at least the morning hours with snow toward the north and higher elevations (although a few flakes may mix in early farther to the south). The upper low will gradually move off to the northeast through the day and into Saturday night, and there`s still come uncertainty among the models on how quickly this occurs, but the general trend will be decreasing precip chances south of the mountains going into the afternoon and evening, although could be more Saturday night per the ECMWF. A surface low will also be deepening as it lifts northward into Nova Scotia, and with the tightening gradient expected breezy conditions to develop by the afternoon with gusts of 20 to 30 mph possible. Once precip tapers off, skies are expected to remain partly- mostly cloudy south of the mountains through Saturday night while the mountains stay cloudy with scattered upslope snow showers. Stacked low pressure will remain near the Canadian Maritimes on Sunday leaving northern New England in a northwest flow, which will be on the breezy side with a tight pressure gradient. Based on latest forecast soundings, we`re looking like upwards of 25-30mph. Rain and snow showers will likely continue across the north and mountains, and a few of these may occur downwind of the mountains if we can get enough daytime instability and Froude numbers are high enough (the NAM is more supportive of this) as there will be an upper trough nearby. The upslope precip in the mountains will wind down either Sunday night or early Monday as high pressure briefly builds into the region bringing a dry day with seasonable temperatures mainly in the 40s. As quickly as the high moves in, it will quickly give way to an upper trough and surface low moving across the Great Lakes that bringS the next shot at widespread precipitation Monday night and into Tuesday. Temperature profiles may be cold enough to support some snow or even a mix Monday night or Tuesday morning, but confidence is low and would probably be across northern areas if anywhere. After this system passes, there is a good support among the GFS and ECWMF ensembles members with dry conditions on Wednesday (other than mountain upslope snow showers). Going into next Thursday/Thanksgiving, the operational GFS is hinting at low pressure potentially bringing some snow to the area, but this is the faster solution with many of its ensemble members (as well as the ECWMF) keeping conditions mostly dry. The NBM PoPs of slight chance across southern areas capture this well. Lastly, there is pretty high confidence in a cooler airmass arriving toward the end of next week, and even though this is just beyond the extended forecast, there is a signal for what could be the first measurable snowfall of the season for many areas. This would potentially be in the day 8 or 9 time period, and as always this far out, details (such as amounts and timing) are uncertain. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/... Short Term...Winds slacken this morning as some improvement in restrictions with IFR becoming MVFR and perhaps VFR later in the afternoon. Another round of lowered ceilings arrives Friday night with RA. More in the way of SN may be possible along the western ME mountains and the Whites Friday night. These lowered condition continue Saturday. Long Term...Conditions look to improve to VFR late in the day into Saturday night with the exception of HIE and LEB, where MVFR ceilings and possibly rain and snow showers continue through Sunday or even Sunday night. . Elsewhere, mostly VFR expected Sunday and Monday with northwest wind gusts 25-30 kt possible on Sunday. A few rain or snow showers may also develop Sunday afternoon. Another low pressure system looks to bring increasing precipitation chances Monday night and Tuesday along with flight restrictions. && .MARINE... Short Term...Winds slacken early this morning, falling below SCA criteria. However, wave heights remain 5 to 8 ft today into the evening outside of Penobscot Bay. Another set of gales may be needed for Saturday. Long Term...Conditions may be able to fall to below SCA levels late Monday or Monday night as high pressure briefly builds in before winds increase ahead of and also behind a low pressure and front that look to cross around Tuesday. Another area of low pressure may approach the waters toward the end of next week, but confidence is low on timing and potential track of the low. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory until 10 PM EST this evening for ANZ150- 152>154. Small Craft Advisory until 11 AM EST this morning for ANZ151. && $$ NEAR TERM...Cannon/Cornwell SHORT TERM...Cannon LONG TERM...Tubbs