Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 241514 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1014 AM EST Fri Feb 24 2017 .SYNOPSIS... High pressure will briefly ridge across the region today. A warm front will lift northward across the region tonight. The warm front will lift north of the area on Saturday as low pressure moves into Ontario, Canada. && .NEAR TERM /THROUGH SATURDAY/...
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950 AM Update: The biggest chg for tdy was to raise hi temps a few deg spcly across the N with latest sfc Obs already at or even a little abv the prev hi temp fcst. Temps should lvl off across the far N by midday and then begin to fall later in the day as a back door cold front works Swrd into Nrn ME. Otherwise, fcst PoPs were re-worked using fcst QPF for tngt into Sat morn, resulting in higher max PoP values for mixed precip tngt into erly morn Sat across the N. Orgnl Disc: A bit cooler today with rain and mixed precip later today into tonight. 08Z sfc analysis showed the cold front sliding across the CWA early this morning w/cooler air in its wake. Temps are forecast to cool down further this morning. Areas of fog have developed across downeast areas this morning as skies had cleared. Further n, clouds have held on longer keeping the fog at bay. Weak high pressure will move across the region early today bringing cooler and drier air into the region. The NAM and RAP show this setup well and are supported by the 00z GFS. Temps are expected to rebound some w/the help of the sun and a west wind. We are talking upper 30s to lower 40s n and w while central and downeast will see mid 40s. Clouds will return by early afternoon as a warm front lifts n into the region. Some precip in the form of rain can be expected to break out across portions of the central and downeast areas. The NAM shows decent llvl convergence in this area. Further n, the drier air looks like it will keep the precip shield at bay until late afternoon or early evening. The NAM and GFS support this w/evaporative cooling allowing temps to fall back w/the column moistening. The precip across the northern areas will start out intially as some snow/sleet but will quickly transition to freezing rain overnight into Saturday morning. Based on ice will be the main impact for this event, decided to issue a Freezing Rain Advisory for Northern Maine and portions of the Central Highlands including Millinocket and Greenville from late this evening into Saturday morning. Total ice accumulation of around a tenth of an inch is expected. Confidence attm is low for the central areas including Dover-Foxcroft and Lincoln as temps will be marginal(32-33F). This will need to be monitored today and if that cooler air seeps further s, then some light icing could occur. Across the downeast and coast, temps will be well above freezing w/low clouds and light rain or drizzle as the warm front lifts into Northern Maine.
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&& .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY/... For Saturday morning, will lean towards the NAM with a very gradual warming due to cold air damming under a persistent frontal inversion. Maintained freezing rain in the forecast in northern Aroostook until late morning. The moist southeast flow and warm air advection will likely cause a lot of very low clouds, fog and drizzle...especially in the upslope terrain of Piscataquis and northern Penobscot counties. The warming will arrive earlier for Bangor and most of the Down East region with highs reaching near 50F by late afternoon. These temperatures and dew points in the mid to upper 40s will accelerate snow melt in the Flood Watch area. The cold front will work its way into the forecast area Saturday night with temperatures and dew points still rising before midnight. In general, most areas are expected to receive a quarter to a half inch of rain. The front will move quickly across the area and that`s good news. On the other hand, with a sharp, negatively-tilted upper trough and the entrance region to a strong upper jet, the potential for locally heavy showers or even a thunderstorm will have to be monitored. Forecast soundings are showing instability aloft on Saturday night with up to 400 J/kg along the front. Did add mention of heavy rain in the forecast. The frontal precipitation will end as snow early Sunday morning with potential for a quick coating of a half-inch or less. This much colder air aloft...and comparatively less cold air advection at the surface will mean steep low level lapse rates and a lot of wind on Sunday. West winds with gusts to 40 mph will be the primary story on Sunday...besides watching the rivers. Temperatures will tend to drop during the afternoon with all areas below freezing by later in the afternoon. The winds will likely continue well into the evening. All areas will fall well into the 20s and reduce ice movement concerns. Due to the winds and increasing clouds later in the night, did go well above MOS lows. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... For Monday, most guidance is indicating a fast-moving shortwave crossing in the morning with most precipitation falling in northern zones as snow. Less than an inch of snow is forecast. Winds will continue to be strong with gusts up to 35 mph. The winds will finally decrease Monday night with high pressure building and an opportunity for radiational cooling. As a result, will go below consensus guidance. The picture becomes more confused Tuesday afternoon into Thursday. Guidance is starting to lean towards a two separate events. The first arrives later Tuesday into Tuesday night with a fast-moving shortwave causing a mix of rain and snow. This is mostly an overrunning situation ahead of the primary system that will arrive for Wednesday into Thursday. For the first system, a couple inches of snow are possible...mostly in the southern portions of the CWA. For the second system, the rain/snow line will move much further north as the parent low is expected to move through Quebec. The warm advection may be blunted by the development of a secondary low moving across the Down East region and have maintained all snow for northern Aroostook County. Steered away from MOS highs on Wednesday between the threat of precip and the probability of another frontal inversion. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/... NEAR TERM: MVFR for the northern terminals this morning w/conditions holding much of the day w/a tempo period of VFR by the afternoon. KBGR was VFR this morning while KBHB was IFR w/low vsbys. BHB will see improving conditions after 12Z to VFR. Conditions are expected to drop back to MVFR by later afternoon and then to IFR w/rain and fog. Across the northern terminals, conditions will deteriorate to MVFR by evening and then IFR overnight w/sleet and freezing rain. Icing potential is there for up to 0.10 inches. SHORT TERM: IFR cigs are forecast Saturday and Saturday night with thicker fog by later in the afternoon and evening. Freezing drizzle will be an issue on Saturday morning for CAR and FVE. An embedded thunderstorm is possible Saturday night with a cold front. The cold front will bring mostly VFR conditions for Sunday, but strong west winds with gusts to 40 mph. The predominant VFR conditions continue into Tuesday with the exception of snow showers north of HUL on Monday. These could bring temporary IFR vis. && .MARINE... NEAR TERM: No headlines this term as high pres ridges across the region. Light winds becoming sse this evening and increasing to 10-15 kts as a warm front lifts n. Seas will drop off today back to 2-4 ft, but are expected to gradually build later tonight to 5 ft. SHORT TERM: Fog is expected Saturday into Saturday night. A long duration SCA will likely develop Saturday night and continue through Monday. Another SCA...with some risk of gale conditions...will arrive Wednesday into Thursday. && .HYDROLOGY... No changes to the Flood Watch were made with this forecast cycle. Snow melt from the deep snowpack continues today through Saturday night with rainfall amounts of just over a half inch by Sunday morning. Water levels are starting to rise modestly on the river gauges on the Piscataquis and its branches, but the best response should be later Saturday night into Sunday. NERFC and ensemble river forecasts continue to rises into Sunday morning, but nothing that generates strong concerns at this point. The focus will remain on the southern half of the forecast area where temperatures will stay above freezing into Sunday and where more melting has already occurred with this thaw. Localized ice movement followed by jams is the scenario to watch...mostly for southern Piscataquis and Penobscot basins. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...Freezing Rain Advisory from 11 PM this evening to 10 AM EST Saturday for MEZ001>006-010. Flood Watch from Saturday morning through Sunday evening for MEZ010-011-015>017-031-032. MARINE...None. && $$ Near Term...VJN Short Term...MCW Long Term...MCW Aviation...VJN/MCW Marine...VJN/MCW Hydrology... is the U.S. government's official web portal to all federal, state and local government web resources and services.