Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 251310 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 910 AM EDT Tue Oct 25 2016 .SYNOPSIS... Low pressure northeast of the area will slowly move east toward the open Atlantic through Wednesday. Canadian high pressure will then cross the region Thursday. Low Pressure from the midwest will approach Thursday night...cross the Downeast coast by late Friday... then exit across the Maritimes Saturday. && .NEAR TERM /THROUGH TONIGHT/...
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9:10 AM Update...Cloud cover has decreased along Downeast coast where skies have been mostly clear from Downsloping. Otherwise, no major changes this hour with only very light patchy rain and snow showers over central and northern areas. Orgnl Disc: An area of sn shwrs is slowly movg ESE out of NE ME into N Cntrl NB prov very erly this morn with a mid lvl vort max. Most near term models indicate isold to sct sn shwr cvrg for msly Nrn ptns of the FA for the remainder of the morn before another mid lvl vort max swinging Swrd from Ern QB potentially brings more numerous rn/sn shwrs this aftn across the NE, where we increase PoPs to the likely range. Fcst hrly sim radar ref from latest hrly HRRR model runs back this scenario. Despite sig abv fzg temps xpctd this aftn, heavier shwrs could result in enough cooling for lgt brief accumulation. Otherwise, sct shwrs will become all sn this eve as sfc-BL temps cool closer to fzg. Based on projected aftn 925-850mb temps being about a deg C less than ystdy aftn, fcst aftn hi temps across the FA should be at least 2 deg F than ystdy, and perhaps even a little cooler if cld cvr prevents much in the way of any brief sunshine. This same difference in 925-850 mb temps will likely result in ovrngt lows of a couple deg F cooler than this current erly AM. Winds will be brisk again tdy as they turn from the NW, but not quite as strong as ystdy, with winds diminishing to less than 10 mph tngt.
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... A cold upper trough remains in place on Wednesday with snow showers continuing. An inverted trough will extend over the state from a low well east of Nova Scotia. An unstable layer up towards H700 will be in place to enable the snow showers. Boundary layer temps lead to a northward movement of the rain/snow line during the day, but the air aloft is sufficiently cold to maintain snow showers all day in northern zones. Will have to keep a close eye on whether the inverted trough becomes more focused on a particular region as such a development could produce heavier snow showers. The upper trough finally pulls out Wednesday night with snow showers ending. Cold high pressure builds from northern Quebec and should set up conditions for the coldest night of the season. Have gone with widespread readings in the teens for northern zones and mostly mid 20s for Bangor and the Down East region. The high will generate sunshine for Thursday with highs just short of 40F in the Saint John Valley and mid 40s for Bangor and Ellsworth. Clouds increase late Thursday in advance of the season`s first winter storm. Low pressure will track from the Western Great Lakes region and redevelop by late night in the Gulf of Maine. An upper level trough associated with the low will develop a negative tilt and the surface low will deepen by late Friday night. As always with early season winter storms, boundary layer temperatures and elevation will be key issues. As this point, it appears that a pretty strong onshore ESE flow will ensure boundary layer warmth for Bangor and all of the Down East region. The troubles could start as far south as a line from Dexter towards southern Aroostook County. It`s conceivable that 2-3 inches of snow could fall towards Dover-Foxcroft, Greenville and Millinocket by daybreak Friday. && .LONG TERM /FRIDAY THROUGH MONDAY/... The upper low will cut off over Maine and the surface low will continue to deepen Friday as it moves across the Gulf of Maine towards the Bay of Fundy. The surface track will minimize warm air advection northward. The upper low will promote instability aloft and bring good potential for heavier precip rates. This means that boundary layer issues often associated with these early season storms could be negated and snow could remain the dominant P-type. As a result, have made significant adjustments to the previous forecast in keeping snow in northern zones all day. Elevation will remain a big factor and the heaviest snows would likely be in the Katahdin region and higher terrain in Piscataquis County. Warning level snows are possible. Used ECMWF surface temps in the grids as other guidance looked too warm. The snow will gradually wind down Friday night as the upper low moves east of the state and the heavier precip rates end. This means a transition back towards rain with temperatures in the mid to upper 30s. There will be no real cold air advection behind this low. Generally warmer temperatures and cloudy conditions will follow Saturday into Monday. Temperatures will be in the 30s at night and in the upper 40s to near 50F during the day...which will melt the snow. There is another shortwave that will cross the area but timing is very uncertain with solutions ranging from Saturday night to Monday. The one certainty is that this system will be rain. && .AVIATION /13Z TUESDAY THROUGH SATURDAY/... NEAR TERM: Msly MVFR clgs and vsbys with intermittent sn and rn shwrs tdy and msly sn shwrs tngt can be xpctd across Nrn TAF sites with brief IFR clgs/vsbys possible with heavier sn shwrs. Otherwise low VFR clgs for Downeast sites, with brief MVFR clgs possible attms. SHORT TERM: MVFR cigs with tempo IFR conditions in snow showers will prevail Wednesday morning. Conditions will lift to VFR in the afternoon and persist until Thursday night when the trend will be towards IFR cigs for all sites...and LIFR/VLIFR vis in snow north of a line from GNR to HUL. This will continue all of Friday and into Friday night. LLWS is possible. Conditions will improve Saturday to a prevailing condition of MVFR cigs. && .MARINE... NEAR TERM: Will cont the SCA ovr our outer MZs tdy and tngt msly due to winds, but also marginal wv hts with cont`d llvl cold advcn NW winds. Primary wv pds will be msly in the 5 to 6 sec range, typical of short fetch off-shore wind directions. Kept close to WW3 wv guidance for fcst wv hts for this ptn of the fcst. SHORT TERM: SCA conditions may still exist early Wednesday morning, but winds and seas will quickly diminish during the morning. The next big event will be the potential for the season`s second gale event beginning Thursday night and going into Friday night. SCA conditions will follow the gale and last into Saturday evening. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...Small Craft Advisory until 4 AM EDT Wednesday for ANZ050-051. && $$ Near Term...VJN/MCB Short Term...MCW Long Term...MCW Aviation...VJN/MCW Marine...VJN/MCW is the U.S. government's official web portal to all federal, state and local government web resources and services.