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Area Forecast Discussion (AFD)

Issued by Caribou, ME (CAR)

FXUS61 KCAR 191021

Area Forecast Discussion
National Weather Service Caribou ME
521 AM EST Tue Feb 19 2019

Canadian high pressure will build across the region today and
crest over the area Wednesday. Low pressure from the Great 
Lakes will approach Wednesday night then cross the area  

The high will bring generally clear skies as there's very little
low level moisture for cu and stratocu. The only exception could
be the Saint John Valley where moisture advection from the St
Lawrence and upslope could generate some clouds and even a
flurry. While ingredients such as strong cold air advection,
trajectory and upslope favor a flurry in the Saint John Valley,
the air is so dry and low level mixing is so strong that 
confidence is too low to include pops in the forecast. Wind 
chills are really the primary issue today with the Wind Chill 
Advisory in place for northern zones until 10 am. Subzero wind 
chills are expected for the entire area through much of the day.
Highs today will again be far below normal with readings in the
low teens north and upper teens to lower 20s in the southern 
half of the area. Winds are the challenge for tonight's 
forecast. If the winds went calm with the building ridge and 
cold air mass, readings less than minus 20F would be possible in
Aroostook County. However, the ridge axis will stay west all 
night and maintain steady northwest winds. A deep low northwest 
of Newfoundland will help maintain a decent pressure gradient 
over the forecast area much of the night. Do not expect another 
round of Wind Chill Advisories for tonight, but it'll still be 
cold. Subzero readings are anticipated in northern zones and low
single digits further south. 

High pressure will cross the region Wednesday with 
mostly/partly sunny skies. Low pressure tracking east from the 
Great Lakes will approach New England Wednesday night with a
secondary low possibly starting to develop along the New England
coast. Clouds will increase early Wednesday night, with snow 
developing overnight. The remnants of the primary low will 
cross the region Thursday, while the potential secondary low 
crosses the Gulf of Maine. Generally expect precipitation in the
form of snow Thursday. However, dependent on the strength of 
the secondary low, enough warmer air could reach the Downeast 
coast to allow the snow to mix with rain there. However, a 
stronger secondary low across the Gulf of Maine would limit the 
amount of warm air and allow precipitation to remain mostly in 
the form of snow even along the Downeast coast. Generally expect
total snow accumulations of 4 to 5 inches across much of the 
region through Thursday, though amounts along the Downeast coast
will be dependent on the potential mix with rain. The low will 
exit across the Maritimes Thursday night with snow tapering to 
snow showers across the north and mountains with decreasing 
clouds Downeast. Temperatures will be at below normal levels 
Wednesday. Near normal level temperatures are expected Thursday.

High pressure should cross the region Friday into Saturday, 
with generally partly cloudy/mostly clear skies. Could also have
a slight chance of snow showers across the north and mountains 
Saturday. Low pressure will approach from the Great Lakes 
Sunday, with a secondary low again possibly developing across 
the Gulf of Maine. The lows should cross the region Sunday
night through early Monday, then exit across the Maritimes later
Monday. Expect accumulating snow to develop across the region
Sunday then persist through early Monday. Dependent on the 
strength and track of the potential secondary low, the snow 
could transition to a wintry mix Downeast later Sunday. The 
snow will taper to snow showers later Monday in the wake of the 
exiting low. Near normal, to slightly above normal, level 
temperatures are expected Friday through Monday.

NEAR TERM: VFR conditions with gusty NW winds are forecast. 
Some gusts to 25 kts can be expected north of HUL and 
GNR, especially at sites such as MLT, GNR and FVE. LLWS is 
forecast north of HUL early this morning with over 35 kts at 
2000ft. A few afternoon snowshowers with tempo IFR vis cannot be
ruled out at FVE, and possibly HUL. 

SHORT TERM: VFR conditions are expected Wednesday. Conditions 
will lower to MVFR/IFR levels Wednesday night. IFR/LIFR 
conditions are expected Thursday. Conditions will then improve 
to VFR/MVFR levels later Thursday night. Occasional MVFR 
conditions are possible across the north and mountains Friday, 
with VFR conditions Downeast. VFR conditions are expected across
the entire region Saturday.

NEAR TERM: The Small Craft Advisory will remain in place through
the forecast period. The Freezing Spray Advisory will end at 1
PM, but will likely need to be reinstated for tonight.

SHORT TERM: A Small Craft Advisory is in effect through 
Wednesday morning. Conditions should briefly fall below small 
craft advisory levels later Wednesday through early Wednesday 
night. Small craft advisory conditions are then expected later
Wednesday night through Thursday night. Light freezing spray is
expected Wednesday morning. Visibilities will lower in 
developing snow Wednesday night, with a snow/rain mix expected

ME...Wind Chill Advisory until 10 AM EST this morning for 
MARINE...Small Craft Advisory until noon EST Wednesday for ANZ050>052.
     Freezing Spray Advisory until 1 PM EST this afternoon for 



Near Term...MCW
Short Term...Norcross
Long Term...Norcross