Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 161757 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 157 PM EDT Mon Apr 16 2018 .SYNOPSIS... Low pressure will approach from the Great Lakes today and tonight then slowly cross the area Tuesday into Tuesday night. The low will exit into the Maritimes on Wednesday. && .NEAR TERM /THROUGH TONIGHT/...
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Update... Have issued a Winter Weather Advisory through 8 PM across northern portions of the forecast area with this update. Have extended the Winter Weather Advisory across central and interior Downeast portions of the forecast area through 6 PM. Have cancelled the Winter Weather Advisory along the Downeast coast where temperatures have warmed above freezing. A mix of freezing rain, sleet and rain will persist across much of the forecast area this afternoon, with rain along the Downeast coast in advance of an approaching occluded front. Winds will begin to increase across Downeast areas this afternoon, where a Wind Advisory is in effect starting this afternoon. High temperatures today will range from the lower to mid 30s north, to the mid to upper 30s interior Downeast with upper 30s along the Downeast coast. Have also updated the forecast to adjust for current conditions along with afternoon precipitation chances/types. Previous Discussion... A strong sfc high centered in northern Quebec continues to drain cold and dry air into far northern Maine early this morning with single degree dew points in the far north. The high will weaken over the next 24 hours and elongate with centers just east of Hudson Bay and south of the Newfoundland coast by late tonight. An elongated area of low pressure extends from the lower Great Lakes Region to the central Appalachians early this morning. The low will deepen today and by tonight with the main low center expected to be over Georgian Bay with a secondary low to lift into the northern CT River Valley tonight. An occlusion will lift north across the Downeast region late tonight. Many weather issues in the near term. The first is the precipitation that will lift north and east today. It will be fighting dry air in far northern Maine toward the Saint John Valley. Any snow Downeast will likely quickly change to sleet this morning before transitioning to rain in the afternoon. As the sleet changes to rain there could be a period of freezing rain, especially from Bangor north and west. The winter weather advisories were expanded to include Washington County and central Penobscot County where there is high enough confidence that there will be enough sleet and freezing rain during the morning to cause some slick spots on the roads. Will keep the advisories going until noon, but there is the concern if the cold air hangs in that they might need to be extended into at least the first half of the afternoon, and worst case into this evening. To the north, the precipitation will have a hard time getting going from Caribou north until this afternoon, and have trimmed back the PoPs/QPF quite a bit for this morning. Although air temps will likely hoover around freezing this afternoon, the high sun angle should allow for most roads to just be wet as they warm up a bit before the onset. Of course, this will need to be monitored closely, and it is still possible that advisories could need to be extended further north later this morning. Sleet and any pockets of freezing rain from the central highlands north to the Saint John Valley will gradually transition to rain tonight, but with temperatures to remain near freezing. There will be some concern that with the loss of daytime heating that there could be slick spots well into the night, especially in the Saint John Valley and in the valleys of the north woods. When one looks at the model soundings there is a deep layer above freezing from 850-700H, so confidence is high that there will not be significant snowfall, but a prolonged period of sleet with some freezing rain remains possible in the north tonight. Downeast, temps will slowly rise and it will be all rain tonight, although some local pockets of sleet or freezing rain could persist into early evening well inland. The next concern is the wind. The models have a 50 to 60 kt jet aimed right along the coast later this afternoon ahead of the main jet that affects the region tonight. The current wind advisory along the coast looks very reasonable, but with the possibility of some mixing of the stronger wind aloft, a decent gradient, and wet soils due to the rain will expand the advisory into southern Penobscot County, interior Hancock County, and central Washington County where wind gusts to 45 mph are expected from very late in the afternoon through at least the first half of tonight. Isolated to scatterd power outages are possible.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY/... Low pressure, both surface and aloft, will be centered just to our west on Tuesday. A dry intrusion circulating into the low from the south will taper rain off to spotty showers across the area by midday and the sky may brighten at times. Showers may increase again across western areas late in the day into Tuesday night in response to the upper low working into the area. Some low level convection is possible late Tuesday afternoon as the upper low moves in with colder air aloft moving in over the warm intrusion in the low levels. Low pressure, both surface and aloft, will be over our region Wednesday bringing overcast skies and showers. The showers should taper off Wednesday night as the low moves away and a weak surface high moves over. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Our attention on Thursday turns to a second wave of low pressure sliding off the Mid-Atlantic coast, and then projected to track to our south Thursday night. Boundary layer temperatures are expected to be cold enough to support snow over central and northern areas with rain likely Downeast. Precipitation output, however, is expected to be light with this system, possibly giving a couple inches of snow over the north with perhaps a band of moderate snow across some parts of the central highlands Thursday night into early Friday. Precipitation will taper off late Friday into Friday night as the low moves away. A large high pressure system is then expected to build in over during the weekend bringing a return of partial sunshine late Saturday, clear skies Saturday night and a sunny milder day on Sunday. Mild and dry weather look likely for much of next week. && .AVIATION /18Z MONDAY THROUGH SATURDAY/...
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NEAR TERM: Conditions will lower to IFR levels this afternoon at the Downeast terminals with a wintry mix transitioning to rain. VFR at the northern terminals will lower to MVFR this afternoon in sleet and freezing rain then to IFR tonight in sleet, freezing rain, and rain. LLWS is expected across the entire region tonight. SHORT TERM: IFR conditions in low clouds are expected Tuesday through Wednesday with some possible breaks of MVFR during the midday or afternoon Tuesday. conditions should improve to MVFR Wednesday night then possibly VFR on Thursday as low pressure moves away.
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&& .MARINE...
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NEAR TERM: A Gale Warning is in effect on the waters today through tonight. Wind gusts to 45 knots are expected with the seas building up to 15 feet. Visibilities will be reduced in rain and patchy fog this afternoon through tonight. SHORT TERM: Winds are expected to be below SCA Tuesday through Thursday as low pressure over the area slowly weakens and moves east into the Maritimes. However, a few gusts may reach 25 kt on Wednesday as the low moves away. A SCA may be needed Thursday night or Friday in response to a new low tracking south of the area.
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&& .HYDROLOGY... Rivers will be on the rise this week due to the combination of rain and snowmelt in the north, and rain in the south. Open water flooding appears unlikely given the amount of precipitation that is expected. The main concern will be on the northern rivers, i.e. the Saint John, Aroostook, and Allagash Rivers that still have significant ice. The rising waters levels will cause the ice to break up later this week and could lead to the potential for ice jams, and possible localized ice jam flooding. && .TIDES/COASTAL FLOODING... Minor coastal flooding is possible at the time of high tide around midnight tonight. Minor coastal coastal overwash and minor beach erosion are expected with some small rocks likely to be washed up on coastal roads. Overall looks to be a relatively minor event. This should be the only tidal cycle that a flood threat exists for and we are not expecting any inundation flooding in coastal areas. && .CLIMATE... The low temperature of 12F at Caribou, Maine Sunday morning broke the previous record low of 13F, set in 1981. Caribou has now had the 5th coldest first half of April on record. The high temperature at Houlton Sunday of 31F tied with 1971 for the lowest high temperature on April 15th. && .CAR WATCHES/WARNINGS/ADVISORIES...
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ME...Winter Weather Advisory until 8 PM EDT this evening for MEZ001>006-010. Winter Weather Advisory until 6 PM EDT this evening for MEZ011- 015>017-031-032. Wind Advisory from 5 PM this afternoon to 5 AM EDT Tuesday for MEZ015>017. Wind Advisory until 5 AM EDT Tuesday for MEZ029-030. Coastal Flood Advisory from 10 PM this evening to 2 AM EDT Tuesday for MEZ029-030. MARINE...Gale Warning until 6 AM EDT Tuesday for ANZ050>052.
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&& $$ Near Term...Norcross/CB Short Term...Bloomer Long Term...Bloomer Aviation...Norcross/CB/Bloomer Marine...Norcross/CB/Bloomer Hydrology...CB Tides/Coastal Flooding...CB Climate...CB

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