Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 120407 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1107 PM EST Thu Jan 11 2018 .SYNOPSIS...
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A warm front will cross the area overnight. An Arctic front will move into the region late Friday night into Saturday and stall near the coast. Low pressure will track along the stalled front through the Gulf of Maine on Saturday.
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&& .NEAR TERM /THROUGH FRIDAY/... Update... A disturbance will lift north toward the region overnight with increasing rain chances late. Temperatures will slowly warm through the remainder of the night with a south/southwest flow persisting. With warmer increasingly moist air across the snowpack, widespread fog will also develop. Have updated the forecast to adjust for current conditions along with overnight temperatures and rain chances. Previous Discussion... There are four significant issues through tomorrow. First, continued warm and humid air mass will continue streaming into the area with temperatures and dew points reaching as high as the 50s tomorrow. Temperatures will continue rising tonight into Friday morning. The warmest temperatures will be towards the coast. The next issue...due to the warm and humid air...will be fog. As the warm air advects over the cold surfaces and snow tonight, fog is likely to develop and thicken. The fog will continue through Friday ahead of the cold front. At some point, a Dense Fog Advisory may be needed, but will hold off now until it`s more evident where quarter-mile visibilities will occur. The third issue will be rainfall on Friday. The rain will arrive in northern zones late tonight and sag southward as the cold front nears the NW corner of the state. A number of factors suggest rainfall will intensify in the afternoon in the southern half of the forecast area. Anomalously high PWATs, a powerful 80kt LLJ, and elevated instability will converge towards Washington and Hancock counties ahead of a strengthening cold front. The GFS and ECMWF QPF fields seem to be catching on to these developments. Forecast thermodynamic profiles look like something we`d see in June rather than mid-winter with a deep moisture profile to 40K feet, an impressive warm cloud layer over 10K feet and PWATs reaching 1.5 inches. With any elevated convection, precipitation amounts could exceed our forecast locally. The final issue...resulting from the first three...is snowmelt and flooding potential. The combination of snow depth, the potential rainfall, and duration/magnitude of the warm temperatures, fog, and winds all point to a lot of water runoff towards the coast. The recent deep cold and existence of ice in bodies of water near the coast raise concerns about ice break up and movement with the tides. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... The model guidance is in good agreement through the short term period of the forecast. A frontal system will be extended northeast to southwest across the state at the start of the period. There will be several minor low pressure system along the boundary, that will slow the progression of the frontal system. The warmest temperatures will be at the start of the period with temperatures in 40s across the Crown of Maine and 50s elsewhere across the CWA. Rain, changing to mixed precipitation, then to snow Temperatures will fall. A Canadian High will move into Maine by Saturday morning temperatures will be in the teens to mid 20s across northern Maine, low to mid 30s for the Central Highlands, Upper Penobscot Valley, and the Bangor Region. Downeast will be in the mid to upper 40s. These temperatures will continue to fall through the day as the Canadian high builds across the region. Sunday will be cold across the region with highs 5 to 10 degrees across the north, 10 to 15 degrees Southern Aroostook, Central Highlands, Bangor Region, and Upper Penobscot Valley. Upper teens to mid 20s for Downeast. Loaded a blend of the GFS/NAM/ECMWF to smooth out the minor differences in the models. Used NAWAVE4 for seas in the coastal waters. Loaded windgust by factor tool 20%, 26% for the coastal waters. For QPF used WPCGUIDE except RFC for 06Z Sat to better collaboration. && .LONG TERM /MONDAY THROUGH THURSDAY/... The extended models are in good agreement at the start of the period. A Canadian high pressure ridge will be over the local area at the start of the period. A low will be centered over Lake Superior, its associated frontal system will extend south to Kentucky. The Canadian high pressure ridge will slowly move east as the system over Lake Superior deepens and moves east. By early Tuesday morning it will make its way to VT/NH. Tuesday morning it will be into Southern Maine. This system will remain over Maine through Wednesday evening when the cold front finally moves into New Brunswick. The occluded front and upper low will slowly move across the state and will influence the weather through the end of the period. Loaded a blend to smooth out the differences in the models, however the solution leans more towards the GFS solution. Used NAWAVE4 for seas in the coastal waters. Used windgust by factor tool. && .AVIATION /04Z FRIDAY THROUGH TUESDAY/...
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NEAR TERM: Conditions will deteriorate to generally MVFR/IFR levels through the early morning hours, with LIFR/VLIFR conditions late. LLWS will also be an issue with strong SW winds aloft nearing 50 kts and light surface winds. IFR/LIFR, with occasional VLIFR, conditions then persist Friday with fog and low ceilings with rain developing. Rainfall could be heavy by afternoon for sites such as BGR, BHB and Machias. SHORT TERM: IFR conditions all sites in rain and fog at the start of the period. Precipitation type will change over to wintery mix, rain, freezing rain, and sleet then to sleet and snow then to all snow before ending Saturday evening. A Canadian High will build in behind the frontal system with decreasing clouds and improving visibilities from north to south starting late Saturday afternoon. VFR conditions for FVE, CAR, PQI early evening Saturday with a few lingering snowshowers. VFR all sites around midnight Sunday morning. VFR conditions will hold late Monday evening when the next frontal system moves into the state. MVFR conditions Tuesday morning, becoming IFR in snow Tuesday afternoon. Precipitation type will change over to snowshowers Wednesday morning, MVFR with periods of IFR in snowshowers through the end of the period.
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&& .MARINE...
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NEAR TERM: Small craft advisory conditions will persist through Friday morning. Some gusts could then approach gale levels during the afternoon. Due to the stability and the warmth of the air advecting over the water, fog will develop tonight and persist into Friday along with developing rain. SHORT TERM: Gale warning will be in effect at the start of the period. The gale will likely transition to a SCA early Saturday morning as higher pressure builds across the waters. An SCA will likely be require through Sunday morning. The Canadian high pressure ridge will slowly build across the region further diminishing the winds and seas.
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&& .HYDROLOGY... Up to three inches of rain or more is forecast across the Down East region Friday through Sunday. With the increase in temperatures across the region the snow pack has already started to melt. Guidance indicates that there is around 4 inches of water content in the snow pack that can be released. Snow melt along with the rain will cause flooding issues in poor drainage areas, small rivers and streams. Ponding may flood streets...especially with any clogged storm drains. Ice break- up and movements may affect some coastal highways/culverts. Have issued the flood watch in the areas with the most compelling combination of rainfall and sustained mild temperatures before the cold front arrives. With the recent cold snap and ice along the coast, the break up of ice along coast may cause some relatively unusual issues. A bit further inland, there`s still a risk for some ice movement, and will have to monitor carefully if rainfall forecasts increase towards Bangor. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...Winter Storm Watch from Friday evening through late Saturday night for MEZ001>004. Winter Weather Advisory from 7 PM Friday to 1 AM EST Sunday for MEZ005-006-010-011-031-032. Flood Watch from Friday afternoon through Sunday morning for MEZ016-017-029-030. MARINE...Gale Watch from Friday afternoon through Friday evening for ANZ050>052. Small Craft Advisory until noon EST Friday for ANZ050>052. && $$ Near Term...Norcross/MCW Short Term...Norton Long Term...Norton Aviation...Norcross/MCW/Norton Marine...Norcross/MCW/Norton Hydrology...MCW/Norton

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