Area Forecast Discussion
Issued by NWS Caribou, ME
FXUS61 KCAR 300404
Area Forecast Discussion
National Weather Service Caribou ME
1204 AM EDT Thu Mar 30 2017
High pressure will build down from Eastern Canada tonight and
Thursday and crest over the area Thursday night...then move
east Friday. Low pressure will track off the Mid-Atlantic coast
Friday night and pass south of the Gulf of Maine on Saturday.
.NEAR TERM /THROUGH THURSDAY/...
12:04 AM Update...Flurry and isolated snow shower activity has
continued to diminish over the past 2 hours as an upper trough
in New Brunswick continues to move east. Satellite pictures
indicate quite a bit of cloud cover across the CWA, which will
be slow to erode overnight, especially across the Crown of
Maine. Better chance of breaks in the clouds across the Downeast
region over the next several hours as some drier air works into
the area from the south. The ongoing forecast has a good handle
on the situation and only very minor edits to the forecast
based on the midnight observations and the latest satellite and
Orgnl Disc: Any lingering snow showers across the area early
this evening will dissipate as an upper level shortwave trough
slides east into the Maritimes. High pressure will gradually
build down from Eastern Canada tonight and Thursday. This will
bring gradually clearing skies. Thursday will then be mostly
sunny with afternoon temps just a couple degrees short of late
March normals for the season. The gradient behind departing low
pressure will bring a gusty northwesterly breeze on Thursday.
Winds will diminish a bit late in the day as the gradient eases.
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
A surface ridge of high pressure moving over the region, with an
upper ridge moving in from the west, will act to bring mostly
clear skies and calm winds to the CWA Thu night into Fri. Clouds
will increase from west to east Fri aftn and eve as the next
system approaches. This system manifests itself at the upper
levels as a cut-off eating into and flattening out the ridge,
with sfc low moving from the Ohio Valley across the Mid-Atlantic
and then south of Long Island between Fri AM and Sat Am. Sig
disagreement between NAM/ECMWF and GFS/CMC on the layout of the
precip shield and POPs. The former shows an upr trof north of
the cut-off, inducing more robust POPs to extend north of the
sfc low thanks to a stronger mid-lvl - 700mb - trof north of the
sfc low. The latter pairing both show the sfc low going further
south, and don`t show a significant 500mb or 700mb trof north
of the sfc low, keeping precip contained around the sfc feature
and largely out of our CWA. The POPs and QPF were made to show a
general lean toward the NAM/ECMWF solution, but don`t jump
fully in with that pair in terms of the rather high POPs and
QPF. POPs were generally capped at high-end likely, with storm
total QPF generally 0.25-0.50 inches for central and Downeast
areas. Temps expected to complicate snow totals, with many areas
switching to rain, at least for a time, during the day Sat.
Between the temps and track disagreement, definitely plenty of a
chance for someone to get fooled on this system.
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Continuing with a lean toward the ECMWF from the short term,
current forecast thinking is that any lingering precip departs
quickly Sat night. The GFS, with delayed passage of an upr trof,
would keep some light snow shwrs across the CWA into the day
Sunday. Sun night into Tue AM look to be clear with sfc and upr
ridging. Model disagreement returns mid-week with the reverse
of the weekend scenario - the GFS takes a forecasted low further
north, while the ECMWF keeps it to the south. For now, kept POPs
pretty low given the disagreement.
.AVIATION /04Z THURSDAY THROUGH MONDAY/...
NEAR TERM: Mostly VFR overnight, but pockets of high end MVFR
will persist. VFR conditions are expected across the area on
SHORT TERM: VFR conditions expected Thu night through Fri. Mid-
lvl clouds move in Fri eve, with MVFR and IFR CIGs and vsbys
sweeping in from west to east with arrival of snow Fri night.
KPQI to KFVE may have a chance to keep higher vsbys and possibly
higher CIGs depending on the track of the low pressure. Patchy
MVFR and IFR cigs could linger Sat night with any lingering snow
shwrs, but clearing to VFR for all places expected Sun into Mon.
NEAR TERM: A SCA will be up tonight through Thursday for gusty
northwest winds gusting up to 30 kt across the offshore waters
and 25 kt over the intracoastal waters as high pressure builds
down from the north.
SHORT TERM: Seas are expected to remain below SCA levels through
the short term. Wind gusts will be borderline for offshore zones
at the start of the period, but then decrease by Fri AM. Wind
directions and speeds Fri night into Sat will be highly
dependent on the track of the low pressure system.
MARINE...Small Craft Advisory until 8 PM EDT Thursday for ANZ050>052.