Area Forecast Discussion
Issued by NWS Portland, ME-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KGYX 211349
Area Forecast Discussion
National Weather Service Gray ME
949 AM EDT Fri Apr 21 2017
Low pressure will move slowly east into New England today. The
approaching low and a cool onshore flow will provide rain to the
region through tonight with some wet snow and sleet possible
across the higher terrain near the international border. This
slow moving system will keep cool unsettled conditions across
the area for Saturday. A cold front will cross the region
Sunday. A ridge of high pressure will gradually build in from
the west for Sunday into early next week. Low pressure will
move up the Eastern Seaboard Tuesday and Wednesday.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --950 AM...Minor ESTF update to reflect the current mesonet and
radar trends in near term grids.
6am update...Rain has moved into Maine now but is already
pulling out of the CT river valley. Have lowered pops a bit on
the VT border but added Fog as most airports are reporting some
prev disc...Rain is very slowly making its way into western New
Hampshire this morning in association with a warm front ahead
of a low pressure center over Lake Ontario. The steady rain will
move through fairly quickly in the morning hours but drizzle
low clouds and patchy fog will linger through the afternoon and
into the evening.
Overall this system has been slow to advance and have decreased
the PoP for eastern portions of the area. Have also gone to more
of a widespread drizzle for this afternoon as most guidance
hints and the system falling apart as it finally arrives this
morning leaving us with a generally damp day.
-- End Changed Discussion --
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
The low pressure will move through the St. Lawrence valley
overnight pushing a cold front through northern New England.
This will spark another round of steadier showers through the
first half of tonight. By Saturday Maine and New Hampshire end
up stuck between dueling low centers, one to our north near
Quebec City and one to our south just east of the 40N/70W
benchmark. This leaves us in cool damp weather. For the coast
easterly on shore flow will keep temperatures in the 40s with
fog through the day.
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Low pressure will gradually pull east of the region and through
the Canadian Maritimes by Saturday night. This will allow for a
small and relatively weak area of high pressure to build into
the region on Sunday.
A cold front will begin to drop through the region Sunday night,
weakening as it does so. This system will be relatively moisture
starved to any chance for precipitation will be limited to the
northern mountains. By Monday, the remains of the front will
begin to retreat northward as a warm front. Conditions will
remain dry however, with some sunshine, especially over southern
areas of Maine and New Hampshire.
This sunshine will be short lived however as a cutoff low
pressure system over the southeastern United States begins to
lift northward beginning Tuesday. The models have been
fluctuating on the track and timing of this system as the energy
from this system is just reaching the Pacific northwest this
morning. With the 00Z model suite, The Euro was the weakest
with this system.
In any case, some cloud cover is expected to advance north and
precipitation to enter southern areas by Tuesday morning. As the
upper level support weakens, the system will shear out to the
northeast, allowing for rain to continue across the region on
If followup model runs indicate that this system will remain
more intact and robust, tides will need to be monitored during
the midweek period next week. This will be a period of very
high astronomical tides.
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
Short Term... IFR conditions have already developed along the
coast as onshore flow in advance of the approaching low. IFR to
LIFR will continue through the day today and into Saturday along
the coast. In the interior a slight improvement with widespread
MVFR currently. Brief periods of IFR are possible in the
interior especially this morning as the heavier rain moves in
but overall expect to see consistent MVFR with occasional drops
to IFR in FG throughout the region until Saturday.
Long Term...Some improvement in ceilings and visibilities
expected Saturday evening. Conditions will then improve to MVFR
region wide for Sunday. VFR seems to be the most likely
scenario Monday with deteriorating conditions once again for
Tuesday into Wednesday.
Short Term...Easterly winds will continue through today with
building seas. SCA remains in effect for tonight into Saturday.
Long Term...SCA will likely be needed into Saturday night,
mainly for seas on the outer waters. More tranquil conditions
are expected Sunday into early next week.
MARINE...Small Craft Advisory until 7 AM EDT Saturday for ANZ150>154.