Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 240310 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1010 PM EST Thu Feb 23 2017 .SYNOPSIS... Low pressure will move through Quebec today bringing a cold front through the region tonight. High pressure will return on Friday. A warm front will cross the region Friday night. && .NEAR TERM /THROUGH FRIDAY/... 1010 pm update... Last gasp of rain is exiting nrn zones attm. Temps are hvg a hard time dropping blo 40F outside of a few clr areas in cntrl and Downeast areas, thus hv bumped mins up by a couple of degrees. Fog is hvg a hard time dvlpng tonight as winds just off the deck are still high but expect these wl begin to diminish ovr the next 3-5 hrs and where skies are able to clr, areas of fog wl lkly dvlp ovr the snowpack. Hv adjusted grids accordingly with this update. Prev discussion blo... Low pressure is expected to pass to the north of the State Tonight. This system will produce light rain across the north this evening as it passes. There is also a chance of isolated thunder in western and northern areas. Later tonight skies will partially clear and with low level moisture in place and higher dew points across southern areas expect areas of fog to develop. Weak high pressure will move across the region early Friday then off to the east. Another low pressure system will approach from the southwest late Friday. This system is expect to spread rain into the area during the day Friday. Snow and or mixed precipitation is possible in the far north late Friday as a layer of warmer colder air moves in at lower levels. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... A weak cold front will sag south across northern areas Friday evening. Cold air in the low levels will funnel in behind the front Friday night. Meanwhile. low pressure across the Great Lakes region will track northeast overnight Friday and draw the front back north as a warm front. This will result in a period of light overrunning precipitation Friday evening into Saturday morning. Based on critical thicknesses, the precipitation should be mainly in the form of sleet and freezing rain north of a Greenville to Houlton line, with just plain rain south of there. As the warm front lifts north of the state later Friday night and Saturday morning, expect any lingering precipitation to be in the form of rain showers. Any ice accumulation across far northern areas will be light, generally less than a tenth of an inch. A freezing rain advisory will likely be needed for Friday night through early Saturday morning for northern areas. Otherwise, Saturday will be a mainly cloudy with the chance for a few showers or drizzle, as the best forcing remains to our west during the daylight hours Saturday. It will be a mild day Saturday as southerly winds usher in much milder temperatures in advance of an approaching cold front from the west. Expect temperatures across the forecast area to range from the upper 30s to near 40 degrees across the St. John Valley to the mid to upper 40s across downeast areas. Rain chances will increase by Saturday evening as a cold front approaches from the west, with all areas expected to see some measurable rain Saturday night in advance of the approaching front. Expect areas of fog Saturday night. The combination of an extended period of above freezing temperatures, along with the anticipated rainfall, may result in some ice movement on areas rivers and streams across central and portions of interior downeast Maine. Thus, after coordination with neighboring WFO GYX, a flood watch has been issued for this area. (Please see hydrology section below). The cold front will cross the region late Saturday night with rain ending after midnight. The rain could end as a brief period of snow across the north and west after midnight Saturday but little in the way of accumulation is expected. It will turn cooler on Sunday as a secondary cold front crosses the region. Along with the cooler temperatures will be the chance of a few snow showers, mainly across the north, with partly cloudy skies across downeast areas. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... A cold front approaching from the west Sun night will move across the state during the day Monday. Some snow showers are possible with the front, mainly from the Central Highlands northward, and our snow squall parameter is putting out values suggestive of possible snow squalls as the front passes through. Indeed, looking at BUFKIT GFS soundings reveals forecast lapse rates over 8C/km up to 800mb, and some sites show minimal CAPE, as well. Beyond Monday, models appear to have diverged some in their solutions, with the GFS showing a compact Low passing across southern New Eng and across the Gulf of maine, giving precip to the southern CWA, while the ECMWF and CMC both show a ridge of high pressure. Active weather pattern likely for mid-week, with one or two low pressure systems likely to impact the CWA. Models have fairly divergent solutions at this time, so tough to tease out details at this time. 12z Wed to 12z Thu appear to have the highest chance of being impacted, so did boost POPs in that period, and are in good agreement with GYX grids. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... NEAR TERM: Cdfnt wl move across northern terminals with MVFR possible at PQI, CAR and FVE in light rain. HUL will be the question regarding any rain falling but expect they will see IFR vsby restrictions after 05z. Expect three northern terminals will become VFR after 09z, remaining VFR until closer to end of TAF valid time as mixed precipitation moves in from the south. BGR and BHB will likely be IFR and possibly LIFR after 04z in extensive low-level moisture. BGR may improve to MVFR after 15z with BHB remaining IFR through end of TAF valid time. LLWS can be expected first few hours this evening with 23040 at FL020. SHORT TERM: IFR/MVFR conditions are expected Friday night through Saturday. -FZRA is expected to affect the northern terminals(KFVE,KCAR,KPQI,KHUL) Friday night through early Saturday. Widespread IFR conditions are expected Saturday night in rain and areas of fog. Conditions will improve to VFR behind the cold front. && .MARINE... NEAR TERM: Have used the GFS for sustained winds. For waves: Currently a southerly fetch is developing across the Gulf of Maine and has become the primary wave system. There is also a secondary southeasterly longer period swell system present based on wave spectra from 44027. Expect wave heights to build to around 7 feet this evening then subside Friday as winds diminish. A longer period secondary southeasterly swell system (1-2 feet/12 seconds) will develop Friday Morning. Will use the Near Shore Wave Model to populate wave grids. SHORT TERM: Wind/seas are expected to remain below small craft advisory levels Friday night. Winds/seas will then begin to increase to small craft advisory levels late Saturday and Saturday night. Winds/seas will be at small craft advisory levels on Sunday. && .HYDROLOGY... After collaboration with GYX and intra office collaboration, have issued a flood watch for ice jams for central areas, as well as interior downeast Maine, from Saturday morning into Sunday evening. The combination of above freezing temperatures and a period of rain later Saturday into Saturday night, will result in the potential for ice movement and ice jams. Rainfall amounts are expected to generally range from one-half to three- quarters of an inch across the area. However, the mild temperatures will increase snow melt/run off on area waterways, resulting in possible ice movement and ice jams. However, mainstem rivers are expected to remain below bankfull, outside of any potential ice jam development. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...Flood Watch from Saturday morning through Sunday evening for MEZ010-011-015>017-031-032. MARINE...Small Craft Advisory until 2 AM EST Friday for ANZ050-051. && $$ Near Term...Farrar/Mignone Short Term...Duda Long Term...Kredensor Aviation...Farrar/Mignone/Duda Marine...Farrar/Mignone/Duda Hydrology... is the U.S. government's official web portal to all federal, state and local government web resources and services.