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Area Forecast Discussion (AFD)

Issued by Caribou, ME (CAR)

FXUS61 KCAR 212205

Area Forecast Discussion
National Weather Service Caribou ME
605 PM EDT Sun Apr 21 2019

A cold front will cross the area tonight and stall before
reaching the coast. Low pressure will cross the Gulf of Maine 
Monday night into Tuesday.


Update 6:00 PM: Have adjusted temperature, wind, and dew points
based on latest observations. Also have extended the Small 
Craft Advisory for Seas out to 00Z Tuesday.

A warm and humid air mass is in place over the region. A
decaying vertically stacked low in the Mid-Atlantic region will
continue to fill. An associated occlusion along the warm
conveyor belt will continue to bring some showers this evening 
and slowly shift eastward tonight. The risk of showers along
this boundary will continue in the Downeast region tonight into
Monday. Meanwhile, the cold front will enter northern Aroostook
County this evening. This front is weak without any
precipitation, but will bring lower dewpoints and temperatures
for Monday over most of the area, especially the north. The 
challenge for tonight's forecast will be the distribution of fog
and low clouds given the very moist air mass in place. The only
real detriment to fog formation will be high and mid clouds 
minimizing radiational cooling. Towards the coast, the frontal 
inversion remained in place all day with stratus and fog. The 
stratus and fog will certainly push northward in the southerly 
flow ahead of the cold front. How far northward will depend on 
the amount of clearing. If fog does form in northern zones ahead
of the cold front, it will probably linger into daybreak since 
the cold air advection behind the front is so weak. Northern 
zones will have some sun on Monday. Highs will be in the mid to 
upper 50s for most of the area. Low pressure reforming off the 
Mid-Atlantic coast will bring a renewed push of precip northward
towards the coast Monday afternoon, but amounts should be 


Low pressure will track across the Gulf of Maine to Nova Scotia,
with high pressure ridged to the north, Monday night into
Tuesday. The better rain chances Monday night into Tuesday will
occur across Downeast areas, with lesser chances to the north
nearer high pressure. However, uncertainty still exists 
regarding the northern extent of the rain and rain totals. The
low will exit across the Maritimes Tuesday night, while low
pressure tracking east across Quebec province draws a 
cold/occluded front toward the region. Rain chances will 
increase later Tuesday night in advance of the low and 
cold/occluded front. The low will cross the region Wednesday 
with rain. Temperatures will be at near normal, to slightly 
below normal, levels Tuesday/Wednesday.


The surface and upper low will exit across the Maritimes 
Wednesday night through early Thursday. The rain will taper to
showers Wednesday night. Colder air in the wake of the low 
could allow the rain showers to mix with, or transition to, 
snow showers across mostly the north and mountains later 
Wednesday night. Could still have a slight chance of rain/snow 
showers across the north and mountains early Thursday. 
Otherwise, high pressure will build across the region Thursday 
with partly/mostly cloudy skies north, partly cloudy Downeast. 
Surface/upper level low pressure will cross the region Friday 
with rain, which could mix with snow across the north and 
mountains Friday night. The system will exit across the 
Maritimes Saturday, with showers persisting across the forecast 
area. The showers will be mostly in the form of rain, though 
could be mixed with snow across the north and mountains early. 
High pressure should build across the region later Saturday 
night into Sunday. However, a disturbance later Sunday could 
bring a slight chance of rain/snow showers north with a slight 
chance of rain showers Downeast. Near normal, to slightly below 
normal, level temperatures are expected Thursday through Sunday.


NEAR TERM: IFR to LIFR cigs will persist towards the coast into
Monday afternoon. That includes BGR and even as far north as 
GNR and MLT. Further north, fog and low clouds stand a high 
chance of reforming after sunset this evening unless thicker 
high clouds prevent radiational cooling. These northern sites 
will be VFR through most of Monday, but from BGR southward, to 
include BHB, IFR cigs remain more likely.

SHORT TERM: MVFR/IFR conditions are expected Downeast Monday 
night into Tuesday, with VFR/MVFR conditions across northern 
areas. VFR/MVFR conditions are expected across the region 
Tuesday night. IFR/LIFR conditions are expected Wednesday, with 
VFR/MVFR conditions Wednesday night. Occasional MVFR conditions 
are possible across the north and mountains Thursday, Otherwise,
VFR conditions are expected Thursday. Conditions will lower to 
IFR/LIFR levels Friday.


NEAR TERM: Will leave the Small Craft Advisory for Hazardous
Seas in place, but will not extend further into Monday at this
time as forecast seas will be decreasing, but may linger above 
criteria. Stability with humid air over the cold waters 
continues, which means light winds and areas of fog through 

SHORT TERM: Small craft advisory conditions are expected Monday
night through Tuesday night. Conditions are expected to be 
below small craft advisory levels Wednesday. Visibilities will 
be reduced in occasional rain and fog Monday night into


Southern rivers and streams look like they have crested and look
like they will remain below flood stage and remain within their
banks. Decision was to remove MEZ011,015,31-32 from the Flood 
Watch since additional rainfall will be minimal to cause and 
substantial rises. The Flood Watch will remain up for the 
northern zones since some snowmelt and runoff will continue due 
to the mild temps. 

Areal Flood Warning to remain in place for eastern Aroostook 
County due to smaller streams spilling out of their banks and
road closures. 

River Flood Warning for MATM1 and points north, remain in 
place until further notice. Aroostook River looks like it is 
ice free. Additional snowmelt and any rainfall will lead to 
further increases on the St. John and Fish River. River Flood 
Warnings are in place for these two rivers. The Big Black River 
looks to be ice affected as it keeps spiking above 12.0 ft, 
which is flood stage. 

Some more rain is expected by later Tuesday night into Wednesday
but QPF not expected to really impact the main stem rivers with
any sharp rises.


ME...Flood Watch through Monday evening for MEZ001>006-010.
MARINE...Small Craft Advisory for hazardous seas until 8 PM EDT Monday 
     for ANZ050-051.



Near Term...Mignone