Topsham, Maine 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

495
FXUS61 KGYX 050128
AFDGYX

Area Forecast Discussion...Corrected.
National Weather Service Gray ME
928 PM EDT Mon Aug 4 2025

.SYNOPSIS...
A weak cold front will push into northern New England overnight.
It will bring a chance for an isolated shower for parts of
central Maine, but mostly it will help to push smoke back
towards the Connecticut River. Temperatures will be cooler
Tuesday into Wednesday before the front starts to lift back
north. Conditions will be mainly dry and a return to hot weather
is possible for the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
6PM Update...Hazy and smoky skies continue, with no changes made
to the forecast. Did refresh temperatures to match most recent
observations.

Previously...
Hazy, smoky skies continue today as a cold front slowly moves
south across ME this evening. The front will be responsible for
a few showers towards the Midcoast this evening, as well as a
wind shift for the area around midnight.

The northeast winds will help push the greater concentrations of
near surface smoke west overnight, but skies tomorrow will
likely still have a milky appearance based on hires vertically
integrated smoke guidance.

Mixed outcome of temperatures tonight, likely derived from
passing cloud cover from the front. Points to the north that see
clouds this afternoon likely clear out more readily as the front
sags south. Likewise for points to the south, while clear now,
will see increasing cloud cast as the front approaches and goes
overhead. Some uncertainty how thick this will be, but enough to
prevent good radiational cooling like we had last night.
Forecast lows end up in the lower 60s across the south and coast,
with low to mid 50s in the mountains.

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
Main focus Tuesday will be afternoon shower development. CAMs
and HREF guidance continue to develop showers across mostly
western NH. QPF has continued to increase, although it is
resolving in hotspots rather than a more widespread footprint.
This tells us that the precipitation will be showery, and very
localized. With little synoptic dynamics in the region under
high pressure, shower initiation will likely be from the
terrain, and closely hug where lift is generated. Comparing to
SBCAPE plots, this keeps the shower coverage isolated to
scattered across mainly the western half of NH.

PWATs and mean RH values through the column aren`t impressive,
and thus precip efficiency will suffer. However, showers that
develop won`t have much steering flow for shower movement. So
showers may be stationary or redevelop over higher terrain
features through the early evening. That said, given dry
antecedent conditions, the flash flooding threat is low.

With the loss of daytime heating, showers dwindle and cut off
for the night. Expect similar overnight temperatures in the mid
50s to around 60 as clouds linger in the region.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Key Message: Fairly quiet extended forecast until next weekend
when a return to hot temps looks possible.

Impacts: Continued dry weather will start to expand the area of
abnormally dry weather on the drought monitor. By next weekend
there is a signal for a return to well above normal temps.

Forecast Details: Pretty quiet stretch of weather relatively
speaking...with no strong ensemble signals thru about the end of
the week. I did opt for adding some smoke/haze wording to the
forecast at the beginning of the period on Wed...as model
guidance continues to keep this current air mass lingering
across NH. There is some potential that it gets entrained again
ahead of the next front and expands in coverage back across the
forecast area late week...but that is a more low confidence
forecast and not included in the grids at this time.

Over the weekend into early next week there are growing signals
for heights and temps to be approaching or exceeding the 99th
percentile. That would point towards temps well above normal.
The NBM already has high temps in the low 90s...which seems
reasonable given the long range.

&&

.AVIATION /22Z MONDAY THROUGH SATURDAY/...
Short Term...VFR with HZ continuing to impact vis today through
tonight. A cold front will bring a wind shift and BKN skies
overnight, as well as some SHRA to AUG/RKD this
afternoon/evening. Another night of valley fog possible for HIE
and LEB. SHRA develop for SW NH, and less so towards the Whites
and northern NH Tuesday afternoon. These subside in the evening
as high pressure remains overhead.

Long Term...Largely VFR conditions expected in the extended.
Will have to deal with some valley fog especially midweek before
southwest return flow develops. I do not anticipate smoke/haze
to reduce VIS to MVFR...but it will hover around 6SM at times
especially across NH terminals.

&&

.MARINE...
Short Term...A cold front passes south over the waters tonight.
This will bring a wind shift to the northeast by Tuesday
morning. Conditions will remain below SCA through Tuesday night
as broad high pressure controls the region.


Long Term...Winds and seas are expected to remain below SCA
thresholds. Midweek high pressure will promote sea breezes on
most days until southwest return flow begins to dominate.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Air Quality Alert until 11 PM EDT this evening for MEZ007>009-
     012>014-018>028-033.
NH...Air Quality Alert until 11 PM EDT this evening for NHZ001>015.
MARINE...None.

&&

$$

NEAR TERM...Cornwell/Palmer
SHORT TERM...Cornwell
LONG TERM...Legro