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Area Forecast Discussion (AFD)

Issued by Caribou, ME (CAR)

                            
000
FXUS61 KCAR 210656
AFDCAR

Area Forecast Discussion
National Weather Service Caribou ME
156 AM EST Thu Feb 21 2019

.SYNOPSIS...
Low pressure from the Great Lakes will approach tonight and cross 
the area on Thursday. High pressure will build in from the west on 
Friday then crest south of the area Saturday.
&&

.NEAR TERM /THROUGH TODAY/...
130AM Update: Snow is rapidly approaching the forecast area and
will cover the entire forecast area by 4-5am. For Bangor,
Downeast, and Piscataquis County, the bulk of the snow will fall
by 7am. Three to four inches will accumulate in those areas by
that time. A review of 00Z guidance and our current analysis 
still indicates the previously advertised 4 to 6 inches across 
the area. Remote NW Aroostook may fall a bit short of that 
threshold while Washington County is most likely to have any 
6-inch reports when the event is over.

Previous discussion:
High pressure siting just offshore of New England with sfc low ovr 
ern SD. High pressure wl scoot to the east tonight as upr low shifts 
parent low into the Great Lakes ovrngt. This wl set the stage for 
upglide and light snow mvg into the CWA around midnight. 

Shield of cirrus currently affecting Downeast areas but is still clr 
acrs the north and St. John Vly. Will take into the evng for clds to 
mv in acrs the far north with temps dropping quickly for the first 2-
3 hrs this evng bfr lvlg off and beginning to rise aft 06z. 

Snow wl continue thru the bulk of the mrng hrs bfr tapering off in 
the aftn fm SW to NE. Rain wl mix with and eventually chg to rain 
acrs the coast around noon. Question centers arnd whether snow 
growth lyr can hold onto moisture by late mrng-early aftn acrs the 
south and whether patchy drizzle or patchy freezing drizzle wl lkly 
be falling at the end of the event as main pcpn exits into New 
Brunswick. For the time being hv gone with rain/snow with only minor 
accums aft 18z. 

Nrn zones wl hold onto snow the longest as moisture wraps in bhnd 
parent low. 24-hr QPF amnts fm all guidance thru 00z Fri averages 
btwn 0.25-0.35" with a consistent 3-5 inches of snow areawide.
&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...
Low pressure will be exiting through the Maritimes Thursday night as 
high pressure begins to build in from the west. Some light snow 
showers or flurries may be across the north Thursday night, mainly 
early, otherwise the north will remain mostly cloudy with Downeast 
becoming mostly clear. A band of moisture across the north will keep 
the sky partly to mostly cloudy north on Friday with Downeast mostly 
sunny. High pressure building in, and cresting just south of the 
area, will then bring a clear to partly cloudy and cold night Friday 
night. High pressure will slide south of the region Saturday as some 
moisture wrapping in behind the high, over a ridge crossing the 
east, and ahead of low pressure in the Plains begins to move across 
the north. This will bring a mostly cloudy sky across the north 
Saturday morning and over the rest of the area during the midday and 
afternoon. Saturday should remain mostly dry although some very 
light patchy snow may begin to stray into northwestern areas toward 
the end of the day as moisture thickens up over the north. Tranquil 
conditions can be expected with high pressure nearby to the
south.
&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Our focus later in the weekend will be on a very large storm system 
lifting north through the Great Lakes. Snow should spread 
across our area overnight Saturday night as the low lifts into 
the northern Great Lakes pulling ample moisture toward the 
region. Deep low pressure will lift into southwest Ontario on 
Sunday as a weak triple point secondary low begins to form near 
southern New England. The very large low will pull warm air 
northward in the mid and upper levels while the weak secondary 
surface low holds cold air in near the surface. This will result
in precipitation changing to sleet north and freezing rain in 
southern areas. By the end of the day Sunday enough warm air 
should work in to change precipitation over to rain or showers 
across Downeast and central areas while snow and sleet hang on 
over the far north. From there, the forecast becomes less 
certain and will ultimately depend on how quickly the secondary 
low develops and where it tracks. A continuation of snow is 
favored over the north Sunday night with rain possibly going 
back over to wet snow over the higher elevations of central 
areas. Strong northwest winds, and snow showers over the north, 
will follow Monday into Monday night. Tuesday should then be dry
and continued windy. A small system may bring some snow for mid
week next week.
&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
NEAR TERM: VFR tonight will lower to IFR after 07z for Downeast
terminals and eventually LIFR after 09z. Further north VFR gives
way to IFR by 09z.

SHORT TERM: MVFR conditions across the north and VFR conditions
Downeast are likely Thursday night. VFR conditions Downeast and
MVFR to VFR conditions across the north are expected Friday 
into Friday night. Conditions should lower to MVFR across the 
entire area Saturday, then drop to IFR Saturday night through 
Monday as a large storm affects the area. Conditions should 
improve to MVFR then VFR Monday night and be VFR Tuesday. Winds 
will be strong and gusty late in the weekend into early next 
week.
&&

.MARINE...
NEAR TERM: Seas and winds will settle below SCA levels tonight
before increasing to 25 kts and over 5ft by mid-morning Thur.
SCA in effect from 15z Thur-12z Friday. 

SHORT TERM: A SCA will likely be needed Thursday night for 
northwest winds gusting up to 30 kt. Winds should then dip below
SCA Friday into Saturday night as high pressure slides south of
the area. A SCA will likely be needed Sunday for southeast 
winds, possibly increasing to gale. A gale may then be needed 
Sunday night through Monday for strong gusty westerly winds.
&&

.TIDES/COASTAL FLOODING...
A high astronomical tide will occur around noon on Thursday.
16.92 ft MLLW at Cutler and 22.46 ft MLLW at Eastport will
combine with southerly flow and about a half foot of storm surge to
result in minor splashover along the Washington County coast. A
coastal flood statement has been issued from 16z-18z. Lower 
water levels expected along the Hancock County coast given the 
timing of the low pressure system but coastal flood statement 
may need to be issued for this zone as we get closer to Thur
morning.
&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...Winter Weather Advisory until 5 PM EST this afternoon for 
     MEZ001>006-010-011-031-032.
     Winter Weather Advisory until 1 PM EST this afternoon for 
     MEZ015>017-029-030.
MARINE...Small Craft Advisory from 10 AM this morning to 7 AM EST 
     Friday for ANZ050-051.
&&
$$

Near Term...CB/Farrar
Short Term...Bloomer
Long Term...Bloomer
Aviation...CB/Farrar/Bloomer
Marine...CB/Farrar/Bloomer
Tides/Coastal Flooding...