Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 211627 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1227 PM EDT Fri Apr 21 2017 .SYNOPSIS... Low pressure in southeast Ontario this morning will move across southern Quebec tonight as a secondary low develops in the Gulf of Maine. The secondary low will pass south of Nova Scotia Saturday evening. Weak high pressure builds into the region Sunday. A cold front will cross the region Sunday night. && .NEAR TERM /THROUGH TONIGHT/... 1215 pm update...No changes at this time. An initial look at 12Z data indicates measurable snow will likely stay north of Bangor and a heavier period of snow towards midnight will likely affect areas north of the Katahdin Region and Houlton and cause storm totals to increase a bit. Prev discussion blo... Low clouds continue acrs most of the CWA tonight especially in Downeast zones. Clds are fairly thin acrs the far north and this has resulted in ocnl dense fog under clr skies in the St. John Vly. Stratiform rain is lifting northeast into srn New England attm in area of upglide/warm advection. Sfc low responsible for overrunning is located in the central Great Lakes and wl track east twd the Ontario/Quebec brdr this mrng. Upr lvl low is rotating thru Ontario this mrng and with height falls off to the northeast expect that it wl continue to head off to the northeast thru the day. As it does so expect that pcpn wl mv into wrn zones arnd daybreak. Most of the forcing from the upr wv wl bring steady rain or snow into nrn zones late this afternoon thru the ovrgnt. Temps wl cool enuf to bring accumulating snow to the north with btwn 1-3 inches of snow expected to the north of a Dover-Monticello line with temps on Fri night dropping into the lwr 30s. Snow ratios look to drop from about 5:1 in the evening to 8:1 twd daybreak so this wl be another round of heavy, wet snow. Further to the south acrs Downeast with vry little frcg expected as main lows go to the north and well south of the area this area wl lkly experience low clds, drizzle, fog and ocnl lgt rain thru the bulk of the aftn and nighttime hrs. && .SHORT TERM /SATURDAY THROUGH SUNDAY/... The weekend starts cold and unsettled as a secondary low takes shape in the southern Gulf of Maine Saturday morning and passes just south of Nova Scotia Saturday evening. The mid and upper level low will move across the area Saturday night. Brief ridging builds across the area Sunday morning, but a cold front will approach the Saint Lawrence River valley by Sunday evening. Saturday starts with snow across northern areas, especially from the Katahdin Region north through the Saint John Valley. There will likely be a mix of rain and snow to the south of the Katahdin Region to the Bangor area, with mostly rain along the coast. The snow may continue to accumulate through at least late morning or midday across northern areas. The afternoon remains cloudy and damp with a rain and snow in the north and rain in the south. Model soundings in the north indicate any above freezing layer is confined to the lowest several hundred feet, so wet snow will remain favored over rain in the north. Highs Saturday will be unseasonably cold with highs only in the mid to upper 30s across the Crown of Maine to around 40 degrees in the Greater Bangor Region. The models and model soundings indicate a lot of low and mid level moisture, so it will remain cloudy Saturday night. An isolated snow shower can`t be ruled out with the residual moisture and upper trough working across the area. Clouds early Sunday will give way to breaks of sunshine, but an increase in clouds are expected late in the day across northwest Maine in advance of the cold front. The air mass moderates Sunday and high temperatures will be about 10 degrees milder than Saturday ranging from the mid 40s north to the low 50s across interior Downeast Maine. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... A cold front will work across the area Sunday night with rain showers in the north that will likely end as some snow showers overnight with any snow accumulation to likely be an inch or less. It appears that most of the shower activity falls apart before reaching the coast. High pressure builds into the region Monday with dry weather, but with below average temperatures temperatures in the north with highs mostly in the low to mid 40s. Temperatures will be more seasonable in the south with highs in the mid 50s in the Bangor Region. The dry weather will continue into Tuesday with some increase in clouds from the south as low pressure develops off the Virginia Coast. Moisture associated with this low may work north into the area Tuesday night into Wednesday, but the air mass will be mild enough that any showers will take the form of rain an and not snow. The models differ on the track of the low and whether there are just a few glancing showers or some steadier rain. The last two runs of the ECMWF remain the most aggressive and the ECMWF is the odd model out at bringing steadier rainfall to the region. An upper trough following the low passage could bring a few more showers to the area Thursday. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... NEAR TERM: IFR across southern terminals this morning with cigs lifting to MVFR by mid-afternoon. Light rain expected for a few hours this morning before drizzle develops this afternoon and evening. Northern terminals will see IFR intially then MVFR by mid- morning. A mix of rain/snow moves in around 00z before becoming all snow between 02 and 03z and continuing into Sat morning. SHORT TERM: Unsettled Saturday with snow north and rain south with widespread IFR and potentially LIFR Saturday. Mostly MVFR Sat night into Sun morning with the potential for improvement to VFR by afternoon. MVFR and local IFR Sun night at the northern terminals as rain showers and possible later night snow showers move across the area. Predominately VFR Sun night at the Downeast terminals. VFR should return to all terminals across northern and eastern Maine Monday. && .MARINE... NEAR TERM: Conditions will become marginal for SCA level this evening and through the overnight. Confidence is not high enough to issue a small craft advisory at this time though it may be needed later. SHORT TERM: The wind and seas will be close to small craft advisory levels Sat into Sat eve as low pressure passes south of the waters. The wind will diminish and the seas will subside Sunday with conditions to remain below small craft advisory levels Monday and Tuesday. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...Farrar/MCW Short Term...CB Long Term...CB Aviation...Farrar/MCW/CB Marine...Farrar/MCW/CB is the U.S. government's official web portal to all federal, state and local government web resources and services.