Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 170141

Area Forecast Discussion
National Weather Service Gray ME
941 PM EDT Sun Jun 16 2024

High pressure will move off the New England coastline tonight,
allowing for continued mild temperatures and low humidity. A warm
front will move into the region Monday followed by a stretch of very
hot and humid conditions through the week. A weak cold front will
slowly cross through the region on Thursday and Friday.


9:30PM Update...Clouds continue to stream over the region with
cloud heights mostly remaining above 10K at this time. Removed
any mention of a shower for tonight as low levels are extremely
dry. Also trending sky cover up a bit due to thickening mid-
level clouds.

6:15PM Update...No real updates needed with the forecast with a
quiet Sunday evening expected to continue as some high clouds
stream over the region. Expect another cool and dry night,
overall limited if any tweaks to the forecast with this update.

High pressure over the Gulf of Maine will slide southeast
tonight while a warm front approaches from the west towards
Monday morning. A relatively cool and dry airmass in place will
allow for temperatures to drop quickly after sunset while
increasing clouds with the approaching front will keep
temperatures from dropping as low as last night. Lows will
generally be in the 50s. The approaching warm front may bring
enough forcing for isolated showers towards Monday morning
across the mountains toward central Maine.


A warm front lifting through the area will maintain slight
chances for showers across the north with much of the area
seeing mostly cloudy skies to start the day. Cloud cover will
thin from SW to NE through the day leading partly to mostly
sunny skies in the afternoon. The leading edge of a warm and
humid airmass will push into New Hampshire by early afternoon
and with clearing skies... highs across New Hampshire will
climb into the low to mid 80s. High temperatures will drop off
into the low 70s across eastern zones where cloud cover will
linger the longest.

Warm air advection will continue into Monday night as high
pressure anchors southeast of the Gulf of Maine. Lows Monday
night will be in the 60s.


The extended portion of the forecast starts right off the bat
with increased temperatures and humidity values on Tuesday.
Models continue to suggest a large and highly anomalous upper
level ridge will build over the Northeast this week. A 600 DM
500 MB high is rare for this part of the country, especially
considering it is mid June. H8 temperatures near +18C and nearly
full sunshine will allow for widespread 90s with a few
communities in southern New Hampshire approaching 100 degrees.
Along the coast, cooler temperatures can be expected as winds
become onshore during the day.

Wednesday will be a similar day as the H5 high remains parked over
the New England coastline. A warm start, nearly full sunshine and H8
temperatures climbing to +20C, expect even warmer temperatures.
Afternoon temperatures will likely approach if not exceed 100
degrees across some interior locations. The atmosphere will once
again be modified along and near the coastline where southerly winds
bring in cooler temperatures.
This inland penetration of this coastal front will not be
significant however. A few miles inland and away from the coast will
be extremely hot, hazy and humid. Surface dew points will climb into
the 65 to 70 degree range.

12Z operational models and ensemble solutions remain with some
disagreement with the timing of a passage of a cold front either
late Thursday or Thursday night into Friday morning. This has some
impact on forecast highs. In general, with a possible delay in the
passage of the cold front, the day may be relatively cloud free, at
least over central and southern portions of the forecast. Mainly
sunny skies and some compressional warming ahead of this weak and
broad front may very well lead to the hottest day of the week with
readings above 100 degrees across portions of southwest interior
Maine and southern New Hampshire. The coast may be cooler once again
due to a sea breeze, but high surface dew points will remain in
place in all locations.

Record high temperatures during the Tuesday through Thursday period
may be in jeopardy as shown in the climate section below.
Even Friday will be in the 90s across the interior despite
additional cloud cover and scattered showers and thunderstorms with
the weak and broad frontal system that will be slowly crossing New
England. Overnight lows will be mild as well during the three day
stretch which will exacerbate heat related issues.

Note the summit of MWN may reach 70 degrees during the period.

Confidence in the heat wave continues to increase as we head into
the week across the interior. Exactly how hot it reaches remains the
question. Any clouds from decaying MCSs to our west for example
would impact the forecast highs. As mentioned above, onshore winds
along the coast may keep things cooler. Will also be monitoring for
any potential development of coastal fog during this period as well
as inland radiation fog at night and during the morning hours.
However, at this time the gradient flow appears to have a sufficient
westerly component to prevent much in the way of maritime moisture
from entering the region. Coolest readings, albeit still very warm,
will be along the Midcoast region where winds will be onshore.

High pressure nosing into our region from Quebec Province will lead
to diminishing heat over the upcoming weekend. Surface winds will
switch to a cooler easterly flow. However, despite a 10 to 15 degree
drop in daytime highs, it will still be very warm over in New
Hampshire and along the Maine border with readings in the 80s.

It will turn mostly cloudy with scattered showers and thunderstorms
over the weekend. Low pressure will track out of the Plains Saturday
and Sunday leading to the precipitation.


Short Term...VFR likely prevails tonight through Monday night.
Clouds increase tonight into Monday morning while cigs look to
remain above MVFR thresholds. South winds increase through
Monday with gusts 15-20 kts along the coastal plain Monday

Long Term...Mainly VFR conditions through Wednesday followed by more
showers and thunderstorms with a cold frontal passage by late
Thursday into Friday. Areas of IFR conditions are possible as well
during the night time period with patchy valley fog.


Short Term...High pressure slides SE of the Gulf of Maine
tonight and remains centered just SE of the waters through
Monday night. South winds will increase Monday with gusts around
20 kts Monday afternoon. There may be a few gusts to 25 kts
Monday afternoon, while a stable boundary layer should limit
the potential for stronger gusts. Persistent S flow will lead
to seas building 4-5 feet Monday afternoon and there is
potential an SCA may be needed late Monday into Monday night.

Long Term...Winds and seas will primarily be out of the south during
the extended portion of the forecast and below SCA thresholds.
Highest wind gusts likely will be during the afternoon hours as the
sea breeze attempts to form.


Record breaking high temperatures and warm overnight low
temperatures are likely Tuesday through Friday of next week.

Here are the records...

Concord-98, 1995
Augusta-98, 1995
Portland- 94, 1995

Concord-98, 1993
Augusta-95, 1953
Portland-93, 2020


NH...Excessive Heat Watch from Wednesday afternoon through Thursday
     evening for NHZ008-012-013-015.



NEAR TERM...Dumont/Schroeter
SHORT TERM...Schroeter
LONG TERM...Cannon