000 FXUS61 KCAR 162106 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 506 PM EDT Sat Oct 16 2021 .SYNOPSIS... A cold front will approach from the west tonight then cross the area early Sunday morning. An upper level low will remain over the region Monday into Tuesday, then move into the Maritimes Wednesday. High pressure builds in by Thursday morning. && .NEAR TERM /THROUGH SUNDAY/... 503 PM Update: Added mention of heavy rainfall as radar estimates showing up to 0.25" per hr w/the higher reflectivities moving across N and E Aroostook County. Dayshift has tstm mentioned well through the rest of the afternoon, and then ending as the warm front lifts n of the state. Ltg detection showed some flashes w/the more enhanced cells. Could see brief wind gust to 30+ mph w/any tstm cell. Previous Discussion... Intensifying sfc low just to the north of Montreal with a cold front draped into NY State and pushing east this afternoon toward the region. Warm front is lifting toward Baxter SP as of 19z with convection developing to the north of front and wl be lifting thru nrn and ern areas this evening. South of the front wl likely see low clouds, fog and possibly drizzle but areas to the north will see rain become more widespread toward evening along with isolated thunderstorms. Hv kept temps warming to the north of the warm front this afternoon with near steady temps to the south. Fairly potent line of storms extends fm nrn VT down into the mid- Atlantic. Watching the line move into the Champlain Vly with wind gusts between 35-40 kts as it moved through. Instability will wane as the line moves east tonight and bcm more elevated. Plenty of shear is available for organized storms as the front crosses the area. LLJ increases ahead of the front after 00z this evening. Front wl enter CWA after 03z and cross the region before exiting around 12z. As it crosses, 0-6km bulk shear values wl be extremely impressive with 50-60kts out ahead of the main line so any storm that is able to develop wl have the potential to bring locally gusty winds to the sfc. Especially with 925-850mb winds on the order of 40- 50kts surging in ahead of the cold front. Cannot rule out an isolated strong storm during the overnight but without surface-based storms expected confidence in this scenario is low. Any storms that can mix down the wind, wl likely de-leaf trees in the process, and with locally heavy rainfall possible in a very humid environment with PW values approaching 1.5 inches, this may lead to ponding of water on roadways due to storm drains becoming clogged by leaf litter. Cold front exits into NB by morning with upr lvl trof hanging out to the north of the area into the middle of the week. This wl likely lead to isolated to scattered showers acrs northern area in the afternoon. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... Sun night expect a deep slightly negative 500mb trough over New England. At the surface the departing cold front over New Brunswick will be ushering in colder air on a northwest flow. This classic cold air advection will bring 850mb temps to around 0C and given the upper level energy we will see showers along and northwest of the Longfellow Mtns. Elsewhere, expect mainly dry conditions with a light breeze but not expecting strong mixing given the weakening pressure gradient and stable air mass. Temperatures across the Downeast coast and along I-95/Route 1 fall back into the low 40s by morning. Areas west of Route 11 and north of the Golden Road will see morning lows in the upper 30s with it falling to freezing on the summit of Mt. Katahdin. Any shower activity should remain rain but on Katahdin snow showers are possible as 850mb temps fall to around 0C. On Monday it doesn't look promising for sunshine across the northern 2/3rd of the FA with the upper level trough overhead, 1000mb-500mb RH values 80-90% and cold air aloft. This time of year these are the ingredients for stratocu and mostly cloudy days. A NW wind of 10-15mph will result in downsloping in Downeast areas with the best chance of some drying resulting in sunny breaks. Highs will varying depending on how much sunshine you get, mid to upper 50s from Bangor to the coast and upper 40s to low 50s across the north. Given the upper level energy cannot rule out some scattered showers during the day with the best bet across the northern half of the FA. Mon night could we be seeing our first snow showers across the area? It is possible especially in the North Woods from Moosehead northward. Axis of the 500mb trough will push into New Brunswick putting much of us on the southwest side with vort maxes zipping through the flow. 850mb temps falling into the -3C to -5C range and low-mid level moisture with falling freezing levels. Isolated to scattered showers will have the chance to mix with some wet snowflakes and perhaps as surface temps fall to 32-35F we may see a full switch to mainly snowflakes. The best chances of this will be in far northern Somerset, northern Piscataquis and western Aroostook counties but not expecting any accumulations given the warm ground temps. Temperatures will start out Tuesday in the low to mid 30s across the North Woods so hunters may experience some snowflakes and cool start to the day. Elsewhere, mainly mid to upper 30s across the northern half of the CWA with low 40s around Bangor to the coast. During the day 500mb upper level low will be up over the Gaspe Peninsula and we remain under an unsettled air mass with northwest flow aloft down to the surface. Another day with 1000-500mb RH values 75%+ so expecting a ton of clouds about with chance of rain showers thanks to areas of vorticity maxes in the flow. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Tue Night expect the upper level low to slowly drift out over the Maritimes but a shortwave will pivot around and keep a slight chance of showers going across the area into Wed. A ton of moisture with cool air aloft will mean expect clouds to continue with just some breaks of sunshine. Lows in the upper 30s to low 40s with highs in the low to upper 50s from north to south. 12z global ops runs suggesting a brief 500mb ridging works in for most of Thurs. Thurs night into Fri looks to be unsettled with a large trough moving in over New England from Quebec. Majority of the guidance shows this but there is significant differences in strength, timing and how many shortwaves pivot through the flow. Didn't want to get fancy in the D6-D7 timeframe so went with 50% chance POPs for stratiform rain. Lows in the upper 30s to mid 40s from north to south with highs in the 50s north with low 60s south. After this system clears into Saturday expect the general troughing to remain based on the trends. So another stratocu day with chance of showers but with cooler temperatures in the morning we may see some more rain/snow showers mixed. && .AVIATION /21Z SATURDAY THROUGH THURSDAY/... NEAR TERM: IFR/LIFR will persist through tonight in low cigs, fog and potentially heavy rainfall. LLWS will be present at all terminals through 10z. Restrictions improve toward 12z with most sites, with the exception of KFVE, seeing MVFR cigs after 15z. SHORT TERM: Mon...Generally MVFR cigs with potentially IFR cigs in the AM. Chance of showers all day from BGR northward. NW winds 5-15kts. Tue...Generally MVFR cigs with potentially IFR cigs in the AM. Chance of showers all day from BGR northward. NW winds 5-15kts. Wed...VFR/MVFR cigs. Slight chance of showers across northern sites. NW winds 5-15kts. Thu...VFR/MVFR cigs. S winds 5-10kts. && .MARINE... NEAR TERM: SCA continues tonight with winds diminishing before daybreak with seas remaining elevated into the morning hours of Sunday. SHORT TERM: Winds/seas remain below SCA through Mon evening. NW wind gusts to 20kts possible with seas generally 1-3 feet. Mon night seas build to between 2 and 4 feet across the outer waters. During the day NW wind gusts may approach SCA levels around 25kts. Seas will be generally around 2 to 4 feet. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...Small Craft Advisory until 11 AM EDT Sunday for ANZ050>052. && $$ Near Term...Farrar/Hewitt Short Term...Sinko Long Term...Sinko Aviation...Farrar/Hewitt/Sinko Marine...Farrar/Hewitt/Sinko