Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 082317 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 617 PM EST Fri Dec 8 2017 .SYNOPSIS... High pressure will move to our east overnight. Low pressure will develop off the Mid-Atlantic coast on Saturday and track toward Nova Scotia Saturday night. The low will lift north through the Maritimes on Sunday. && .NEAR TERM /THROUGH SATURDAY/...
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6:17 pm update...The biggest forecast challenges tonight will be the cloud cover and temperatures. There is another batch of clouds at around 5k ft agl moving back across far northern Maine, while mostly higher clouds stream across the Downeast Region. Some adjustments were made to the sky grids this evening based on the latest satellite trends. Also made some adjustments to the hourly temperatures this evening, but will not make and changes to the forecast lows overnight as forecast confidence on cloud cover late tonight is low, and hopefully will be able to get a better idea later this evening. Previous discussion... Colder tonight with increasing clouds and snow arriving across the Downeast by Saturday afternoon. Latest satl imagery showed clouds hanging on across the region especially across central and downeast areas. This cloudiness was due to an upper disturbance moving across the region in the sw flow aloft. Further n and w, clouds starting to break up. At the sfc, high pres was starting to ridge into the region and forecast to slide to the e overnight. The model soundings including the GFS/RAP and NAM showed clearing trend overnight even into the downeast region as that cloudiness slides further s. This will allow for a colder night than the previous night. A light wind aid in the cooling especially w/the clearing. We are talking teens across the northern 1/2 of the CWA while central and downeast areas will see low to mid 20s. Clouds will be on the increase during the day on Saturday as low pres off the Carolina coast moves ne. It looks like the latest suite of guidance including the ECMWF/GFS/NAM and Canadian GEM coming in line w/precip arriving into the Downeast region including the coast. It does look like blyr temps will be cold enough for precip to be in the form of snow event to the coast at the onset, but some gradual warming as noted by the GFS and ECMWF will allow for a mix of rain/snow holding down on amounts. Decided on a blend apch w/this event and brought 60-80% pops into the central and downeast areas by late afternoon. Attm, brought 1-2 inches of new snow by early Saturday evening away from the coast w/an around an inch along the immediate coast. The highest snowfall will come Saturday night into early Sunday.
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&& .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... Winter Storm Watches in effect for north-central areas down into the interior Downeast not including the coast. Later shifts can assess this further if colder air holds in longer, then the coast may need a headline. Low pressure developing off the East Coast on Saturday will quickly move north spreading snow over the area during the midday and afternoon. Snow will move into the Downeast region around midday Saturday then progress north reaching northern areas Saturday evening. Forecast guidance has come into good agreement on the duration and intensity of this storm with a moderate snowfall expected throughout much of our area. The highest amounts will likely be across east central and interior eastern Downeast areas where 7 or more inches may fall. Amounts will gradually decrease to the north and west, and toward the coast where snow will mix with rain. Most of the snow will fall during the evening and through the midnight hours Saturday night with snow gradually tapering off to snow showers late Saturday night into Sunday morning as the low lifts away through the Maritimes. Spotty light snow will likely persist over the north on Sunday with precipitation ending Downeast. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Sunday night will be mainly dry across the region. A weak shortwave sliding to the south may bring some snow showers across the area late Sunday night into Monday morning. Monday afternoon should be mainly sunny. Our focus then turns to another fast moving storm system approaching from the great lakes and likely to bring another round of significant snow to the area. Clouds will increase and thicken Monday night and snow will spread across the area from southwest to northeast Tuesday morning. Snow will likely change to rain Downeast. This is a very fast moving storm and a dry intrusion may end precipitation Downeast late Tuesday afternoon and across the north Tuesday evening. Colder air will quickly follow on Wednesday with snow showers across the north. Thursday will be dry and very wintry and cold before we focus on yet another low pressure system possibly moving in with snow on Friday. && .AVIATION /23Z FRIDAY THROUGH WEDNESDAY/... NEAR TERM: VFR into early Saturday for all terminals and then conditions dropping to MVFR by the afternoon especially KBGR and KBHB. SHORT TERM: MVFR conditions will drop to IFR from south to north Saturday afternoon as snow spreads north across the area. IFR to LIFR conditions in low clouds and snow are expected Saturday night. Conditions will gradually improve to VFR Downeast on Sunday and MVFR across the north. VFR conditions are likely Sunday night into Monday evening with conditions dropping to MVFR then IFR late Monday night into Tuesday as a new storm moves in. && .MARINE... NEAR TERM: Conditions will continue to improve overnight into early Saturday as ridge from high pres moves across the waters. Winds will gradually increase by Saturday afternoon out of the NE w/sustained speeds of 15-20 kts. Seas will gradually build on Saturday. SHORT TERM: A SCA will likely be needed Saturday afternoon through Saturday night for northeast winds gusting up to 30 kt as low pressure approaches Nova Scotia. A SCA will likely be needed again for westerlies Sunday afternoon through Monday. This storm system will have a large southerly fetch to its south and a wave train of seas up to 10 feet will reach our waters very late Saturday night into Sunday morning. Winds and seas should diminish and subside on Tuesday. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...Winter Storm Watch from Saturday afternoon through Sunday afternoon for MEZ005-006-011-031-032. Winter Storm Watch from Saturday afternoon through Sunday morning for MEZ015>017. MARINE...None. && $$ Near Term...CB/Hewitt Short Term...Bloomer Long Term...Bloomer Aviation...CB/Hewitt/Bloomer Marine...CB/Hewitt/Bloomer

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