Scientific Forecaster Discussion
fxus61 kcar 151635
Area forecast discussion
National Weather Service Caribou ME
1235 PM EDT sun Sep 15 2019
a cold front will exit the area this morning. Canadian high
pressure will gradually build eastward towards the area into
Wednesday, crest over the region Wednesday, and move south of
the state Thursday into Friday.
Near term /through tonight/...
1235 PM update: the only chg this update was to raise high temps
a deg or two f ovr ptns of the forecast area based on trends shown in
midday sfc obs, which indicated hrly temps near or just abv prev
fcst hi temps. Thinking is that increasing SC cld cvr with the
apch of the upper trof later this aftn should cap temps from
rising past 2 PM EDT.
Orgnl disc: temps have stayed up all night in the 50s and lower
60s as the SSW wind has brought some weak warm air advection to the region and
clouds. Radar showed some showers moving across eastern
Aroostook County ahead of the cold front. That cold front is
expected to slide across the region by this afternoon. The 00z
upper air showed an upper disturbance to accompany the front W/a 30 kt
jet streak noted at 700 mbs. This feature will help to trigger
some showers this afternoon mainly across the north and west.
Otherwise, winds turning to the west will allow for some drying
and the latest rap and NAM sounding indicate this drying trend.
Temps will rebound W/the returning sunshine for afternoon
reading to top out in the mid 60s north to upper 60s to near 70
for central and downeast areas.
The scattered showers across the northern areas, especially near
the northern border are expected to diminish by 9 PM or so as
the upper trof swings through the region. Some cold air advection W/this trof
and partial clearing will allow for temps to drop back into the
low/mid 40s for the northern 1/2 of the cwa, while central and
downeast areas will see upper 40s to around 50. Some low lying
sites could experience some fog given the wet ground, partial
clearing and a light west wind.
Short term /Monday through Tuesday night/...
for Monday, a cool northerly flow and plentiful 925/850 moisture
will ensure mostly cloudy skies through the day and limit highs
to the lower 60s for most of the area. Downsloping wont be a
factor with this wind flow. Cant rule out a few sprinkles,
but no measurable precip can be expected. A trough approaching
the Saint John valley late in the day will decay and keep the
area dry Monday night, but cloud cover will remain during the
night. As a result, pushed lows up a bit towards model guidance.
The clouds linger Tuesday and high temps will be several degrees
lower with some locations unable to crack 60f. The clouds break
up Tuesday evening from north to south and set the stage for
potentially the coolest night of the season to date. Have
introduced patchy frost in the forecast for the northern half of
the area with the expectation that well move towards areas of
frost or widespread frost in subsequent forecasts. Fog in
valleys and over lakes/rivers can also be expected.
Long term /Wednesday through Saturday/...
cool Canadian high pressure remains draped over the area on
Wednesday with highs still only in the lower 60s...even with
clear skies. Another night of frost and valley fog seems
probable Wednesday night. An powerful upper level ridge will
push towards the area Thursday into Friday and bring a return to
Summer-like conditions for the equinox. Temperatures will warm
on Thursday towards the upper 60s. High clouds spilling over the
ridge will likely affect the area later Thursday into Thursday
night with a marked increase on the low temp forecast on
Thursday night. Subsidence associated with the building upper
ridge and warm southwest winds will likely push Friday and
Saturday highs towards the upper 70s or even 80f. Leaned towards
the warmer raw model guidance and MOS for these days and then
adjusted up. The bias-corrected guidance will have to be avoided
on these days. Would have gone higher but for the threat of
weak fronts moving on the periphery of the upper ridge into the
Aviation /14z Sunday through Thursday/...
near term: looking for conditions to improve to VFR by mid to
late morning for all the terminals. Kfve will take a bit longer
to improve to VFR as LIFR/IFR conditions are holding on this
morning W/some fog.
Tonight...conditions will be VFR tonight. The exception to this
will be the far northern terminals, such as kfve could see MVFR
cigs as some moisture gets pulled down from Canada.
Monday into Tuesday...MVFR cigs will likely affect all
sites...most consistently north of gnr and hul.
Tuesday night into Thursday...VFR outside of patchy shallow fog
near term: winds and seas will remain below Small Craft Advisory right into
tonight. South-southwest winds will veer to the west later today and continue
into tonight. Sustained winds of 10-15 kts W/seas 3-4 ft should
Short term: winds may gust towards 20 kt on Tuesday and again
later Thursday. Long period south swell from Humberto may start
to affect the waters by Friday.