Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 162349 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 649 PM EST Thu Nov 16 2017 .SYNOPSIS... Low pressure will track northeast through the Gulf of Maine this evening, then move into the Canadian Maritimes overnight and into Friday. High pressure will build in for Saturday, following by another low pressure system for Sunday. && .NEAR TERM /THROUGH FRIDAY/...
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6 PM Update: Based on latest sounding info here at KCAR, both the 12z and 18z dtmnstc models runs were running about 1.5 deg C to warm at 925mb, with latest radiosonde data indicating about +1 deg C at this lvl compared to GFS +2.5 deg C. The obsvd 925 mb temp is more comparable to slightly cooler 12z ECMWF/CANGEM models. Latest radar ref imagery is showing a solid bright band extending from KCAR to KMLT, then wrapping back SE toward Eastport. Based on spotter info about 7 miles N of Caribou which also indicates rn, it`s likely that the radar beam is over shooting the top of the bright band AOA 4000ft MSL. Still though, it would not take much cooling to result in a chgovr to all sn ovr NE ptns of the FA, so we did bring the chgovr forward in tm by 2 to 3 hrs ovr this area, resulting all sn at KCAR by arnd 06z (1am) at KCAR rather than 08-09z (3 to 4am). The column of air arnd + 1 deg C xtnded to about 3500 ft abv ground in sounding, so initial cooling working downward in the atmos beginning late this eve will begin in the 925 to 840mb layer, then work downward below 925mb by late tngt as the upper low intensifies and reaches the lon of Ern ME. Total snfl was increased by an inch from the prev fcst ovr the N Cntrl ridges and NE, with best sn rates xpctd in the 4 am to 7 am tm frame when deformation banding develops ovr the NE and moves Nwrd into far N cntrl ptns of the FA. Orgnl Disc: A vigorous shortwave in southern New England is moving northeastward in a broader upper trough centered over Quebec. Cyclogenesis occurred this morning in response to this shortwave, a powerful upper jet and a strong baroclinic zone. The deepening low pressure system is currently just south of Cape Cod and will track towards Washington County later tonight and onward into New Brunswick Friday morning. The low will bring rain to most of the area with amounts over a half inch over large portions of the forecast area and some areas could get an inch. Snow will be a factor for locations in northwest Aroostook County this evening before mixing with rain late this evening. However, as the cold upper low moves over the area after midnight, snow will return with a trowal-like structure. As a result, have issued a Winter Weather Advisory for northwest Aroostook County and will be carefully watching northeast Aroostook where rain will change to snow after midnight. At this point, am expecting just 1 to 2 inches with temperatures near 33-34F and have not extended the advisory eastward. However, recent HRRR runs are trending a bit colder with a faster changeover and more intensity along the northeast border of the state. Snow will wrap up early Friday morning in the northeast portion of the forecast area. Northwest winds will then become the primary item of interest as the low continues to deepen in the Canadian Maritimes. Gusts to 40 mph will be possible with some power outages possible. Added patchy blowing snow to areas that are forecast to receive snow overnight into Friday morning. High temperatures will occur Friday morning and temperatures will be falling by mid afternoon. Apparent temperatures will fall into the teens Friday afternoon.
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&& .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... Weak cold advection can be expected for Friday night on the backside of low pressure that will be moving through the Canadian maritime provinces. With a bit of a gradient remaining across the area and at least some lingering stratocumulus clouds, mainly across the north, it doesn`t look like an ideal radiational cooling night. Nevertheless, lows are still expected to be below normal for this time of year. High pressure briefly builds in from the south early Saturday before increasing high and mid clouds will be advancing across by afternoon, ahead of low pressure tracking east from the lower great lakes region. Expect some light overunning precipitation to develop across the western sections by later Saturday afternoon but most of the region should remain dry through the daylight hours Saturday. Expect light overrunning precipitation to overspread the entire area overnight Saturday as the low level warm advection strengthens in advance of intensifying low pressure approaching from the west. Although we could see a brief period of snow or mix across the north and west at the onset, the southerly flow in advance of intensifying low to our west will assure a change to all rain across all areas by daybreak Sunday as temperatures slowly rise overnight. Sunday will be a wet and unseasonably mild autumn day as low pressure tracks just to our west and into Quebec. Expect the steadiest rain early Sunday to then become more showery in nature as the low tracks off to our north during the afternoon. One concern on Sunday is the potential for stronger southwest winds along the down east coast where gust to 40 to 45 mph cant be ruled out as low pressure intensifies to our west. It will be unseasonably mild on Sunday with high temperatures climbing into the low to mid 40s north and upper 40s to lower 50s downeast. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... Strong cold advection commences Sunday evening as low pressure intensifies to our north. A few evening snow showers cant be ruled out Sunday evening but the bigger concern could be freezing of any standing water from Sunday`s rainfall, as temperatures start to tumble below freezing by evening. The work week starts on the blustery and cold side on gusty northwest winds with partly to mostly cloudy skies north, and partly cloudy down east. Highs on Monday across the north not likely to get out of the low to mid 20s, and only to near the freezing mark down east. Monday night will see increasing high clouds in advance of low pressure tracking well off to our northwest across central Canada. Tuesday will see a significant rebound in temperature as strong southwest flow between the low to our northwest and high pressure east of the mid atlantic sends the temperature into the mid to upper 30s north and low to mid 40s downeast. Tuesday night will see a cold front crossing the region with the potential for a few rain or snow showers later Tuesday night. Early indications for the big travel day next Wednesday and Turkey day looks quiet with no significant precipitation expected to hamper travel, although it does turn cooler on Wednesday and for the Thanksgiving day holiday. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... NEAR TERM: FVE will be LIFR to IFR into Friday morning due to low cigs and snow. Other sites will trend to IFR due to cigs and drizzle initially...and then to LIFR at times in snow after midnight for terminals north of HUL. BGR and BHB will improve to VFR in the predawn hours and stay VFR through the day. When snow ends Friday morning north of HUL, conditions will improve to MVFR cigs...and then VFR in the afternoon. Strong gusty northwest winds will affect all terminals on Friday. Gusts may reach 35 to 40 mph at times. SHORT TERM: VFR Friday night through Saturday. Conditions then lower to MVFR and IFR Saturday night and Sunday in lowering clouds and developing precipitation. Sunday night through Tuesday we are expecting VFR conditions to rule. The main concern Monday will be the gusty northwest winds that are expected. && .MARINE... NEAR TERM: Winds and seas will increase later tonight...and reach gale strength on Friday. Left the headline in place without change, but the start time could be postponed by 6 hours to 7am Friday. SHORT TERM: Gale Warnings are up into Friday evening but winds should be diminishing later Friday night through Saturday afternoon. By Sunday we could once again see strong SCA, if not Gale Force conditions in the southwest flow ahead of advancing low pressure to our west. && .CAR WATCHES/WARNINGS/ADVISORIES...
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ME...Winter Weather Advisory until 11 AM EST Friday for MEZ001. MARINE...Gale Warning from 9 AM to 10 PM EST Friday for ANZ050>052.
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