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Area Forecast Discussion (AFD)

Issued by Caribou, ME (CAR)

FXUS61 KCAR 191602

Area Forecast Discussion
National Weather Service Caribou ME
1202 PM EDT Sun May 19 2019

A warm front will approach from the southwest today and tonight
and stall across the region on Monday. Low pressure will form
along the front Monday evening and track east into the 
Maritimes on Tuesday.


Update 12:00 PM: Have made adjustments based on latest 
observations. No other changes.

A complex warm front well ahead of a large low tracking into 
the Great Lakes region will lift into our area today. An initial
wave of low pressure will form along the front just to our 
southwest. This will spread rain into western and Downeast 
areas later this morning then some light rain across the north 
this afternoon. The front will continue to lift north into our 
area tonight and the initial low will dissipate. Warm humid air
riding up over the cooler air across our area will bring low 
overcast with some spotty light rain and drizzle overnight. As 
the Great Lakes low lifts into Quebec on Tuesday, a triple point
occlusion will form across our area forming a new secondary low
across the region. This will produce more low overcast with 
rain and drizzle on Monday. Forecast capes are up to 1K J/KG in
southern areas. The triple point low may provide some surface 
convergence focus for convection so have included a chance of 
thunder central and Downeast Monday afternoon and slight chance 
north. The rain should then taper off Monday night as the triple
point low slides east into the Maritimes and a dry intrusion 
aloft lifts across the region. Cooler air following the low will
begin to filter in on westerly winds Monday night as the upper 
low approaches from western Quebec and the surface low moves 
east and away. This will bring a chance of some spotty showers 
across the north late Monday night.


Unsettled weather to continue for this term.

Sfc and upper low are forecast to move across the region on 
Tuesday w/a frontal boundary hanging back across the northern 
areas. Sfc convergence coupled w/the cooling aloft will allow 
precip to develop. Model soundings showed airmass moist up 
through 650 mbs all the way down to the Bangor region. The best 
forcing is shown to be across the northern 1/2 of the CWA, and 
this is where the heaviest concentration of rainfall will be 
situated. Therefore, decided to ramp up the precip chances to 
70-80% for the northern 1/2, and taper the percentages back as 
one heads south due to less forcing. Northern areas could 
easily pick up another 0.25-0.30" of rainfall before the rain 
tapers to showers by Tuesday afternoon. The 00Z ECMWF is by far 
teh wettest of the long range guidance and keeps the rain in 
longer. The 00Z NAM/GFS and Canadian Global start winding things
down a bit quicker as they move the low further east. Attm, 
decided on a blend and carried 30-40% pops into Tuesday night 
across the n and w, while further s, precip chances drop off. 
The reason for this is that a west wind starts taking hold, 
which should lead to some drying.

For Wednesday, the region will still be under some influence
of the low to the east as winds become more northerly. Given
this, decided to carry 20% chance for showers across the n and
w. Central and Downeast should see a mainly drier day.
Temperatures however will still remain below normal for May.


Some drier weather and moderating temperatures are expected for
this term through at least Friday. 

High pres is forecast to start moving toward the region Wednesday
night and move across across the area on Thursday. This high is
shown by the long range guidance including the GFS, Canadian 
and ECMWF to remain across the region right into Friday. This 
would mean a dry stretch of weather w/temperatures gradually 
warming to near normal readings. A quick look into Memorial Day 
weekend shows another system possibly bringing another round of 
rain by Saturday, but not as cool as it has been over the past 
few weeks. We'll have to see how the long range guidance plays
this out as we head into next week.


NEAR TERM: VFR conditions early today will lower to IFR Downeast
around midday in lowering clouds, then lower to MVFR late today
across the north. IFR conditions across the area tonight will 
likely persist through Monday with an improvement to MVFR or 
VFR possible Downeast Monday night. 

SHORT TERM: IFR for the northern terminals early Tuesday w/MVFR
for KBGR and KBHB. There does look to be improvement later in
the day as conditions look like they will go to VFR for KBGR and
KBHB. North of there, MVFR looks like it hangs on longer w/the 
upper low nearby right into Wednesday and the threat for some
showers. The real improvement across the entire aviation area
looks to come on Wednesday evening into Thursday w/VFR


NEAR TERM: Wind and seas will be below SCA today. A few wind
gusts may reach 25 kt tonight and Monday from the SSW and seas
are expected to build to 5 ft over the offshore waters requiring
a SCA for seas from late tonight through Monday night. Humid air
lifting up from the south will likely result in some fog across
the waters late tonight through Monday night. 

SHORT TERM: Could be seeing SCA conditions on Tuesday which
could hold on into Wednesday, as the low pulls away and winds 
turn to the W. Decided to go w/sustained winds of 15-20 kts and 
carry gusts to 25 kts for the outer zones. The intra coastal 
zone looks like it will remain at solid 15 kts through this
period. Seas are expected to hold at 4-5 ft and given the latest
trends of the local wave model, this looks fitting w/the
offshore wind. Conditions should drop off by Wednesday afternoon
as high pres starts moving in from the west.


MARINE...Small Craft Advisory for hazardous seas from 2 AM Monday to 8 
     AM EDT Tuesday for ANZ050-051.



Near Term...Mignone