Portsmouth, New Hampshire 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

249
FXUS61 KGYX 101141
AFDGYX

Area Forecast Discussion...Resent and Corrected.
National Weather Service Gray ME
739 AM EDT Tue Jun 10 2025

.SYNOPSIS...
Conditions become unsettled today  with fog and drizzle this morning
followed by widespread showers and isolated storms. Dry conditions
return this evening and overnight, and then improving conditions are
then expected for the second half of the week, with perhaps yet
another unsettled Saturday in store.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
7 AM Update...Very little change oth going forecast as


4 AM...A warm front will continue to sharpen up well to our
south with overunning moisture continuing to bring clouds,
showers, and drizzle to our area. Knocked off at least 3-5 F
from earlier forecast highs.

1045 PM Update... Minor changes to align with
observations. Isolated showers continue to
stream into the area with patchy drizzle expanding in coverage
as well.

630 PM Update...Just minor changes to
temperature, dewpoint, and sky to align with observations.
Forecast remains in good shape with onshore flow contributing to
moisture advection ahead of the approaching warm front. Low
clouds and some drizzle are working into southern New Hampshire
at this hour and these are continue to be expected to advance
north and eastward overnight. Some broken lines of light showers
are also forming ahead of the main frontal boundary and moving
across the north and up to the Connecticut River Valley. Not
much guidance is latching on to these, but current PoPs are
advertising them well.

Previous Discussion...
Aside from a few light showers or sprinkles, mostly dry conditions
are expected for the rest of today with temperatures falling into
the 50s to low 60s by sunset. Downslope winds north of the White
may gusts 25-35 mph, but these should ease toward sunset. Going
into this evening and tonight, the low levels will saturate
with skies becoming cloudy with fog possible. There will also be
a chance of showers, but I think there will be more drizzle
than showers based on forecast soundings. Temperatures will
generally stay in the 50s overnight.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
Cold front moves across the forecast area this evening with
winds turning westerly and allow fair weather to return tonight
and Wednesday.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Evening update...No significant changes with the latest long
range NBM incorporated. The pattern continues to favor unsettled
weather next week with uncertainty in the global models on
whether or not we will continue a streak of rainy weekends.

Previous Discussion...
Overview: The region will be between weather systems come Wednesday.
Dry but warmer conditions are forecast ahead of advancing upper low
across the northern Great Lakes and southern Canada. As this system
tracks east, shower chances increase mainly across the mountains Wed
evening and Thursday. Follow-up high pressure into late week and the
weekend will play a big role in precipitation chances.

Details: Midweek begins quiet but warm as temperatures rise into the
upper 70s to around 80. While the surface and aloft remains dry in
model profiles, a moist layer in between will be enough to generate
at least some diurnal clouds. These may be thicker towards the
foothills and mountains with some low moisture getting locked
upstream. Have kept shower chances here for the afternoon and the
evening as a pre-frontal trough advances eastward.

Thursday, upper low passes to the north with surface low
bringing a cold front across the forecast area. This again looks
to bring showers to the mountains, with limited extension into
the interior and coast. This front and incoming high pressure
will both play a role in precip chances late week into the
weekend.

High pressure will be passing north of the Great Lakes Friday, with
cold front settling south of the forecast area. Global ensembles and
deterministic runs depict weak disturbances with precip passing
along the slowing front, with northern high suppressing the activity
south. Recent data suggests this activity nudging northward,
potentially bringing another round of showers to at least the
southern half of the forecast area Friday into Saturday. While
initial guidance suggests spotty, non-uniform QPF...the orientation
of the slowing front and systems traveling along the boundary
becomes a focal point for forcing. Will need to monitor its
positioning and persistence for possible greater amounts.

&&

.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
Low conditions continue today and tonight followed by VFR
conditions in the wake of a cold front on Wed. These conditions
last through at least Thursday.

&&

.MARINE...


&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.

&&

$$

SYNOPSIS...
NEAR TERM...Ekster
SHORT TERM...Ekster
LONG TERM...Cornwell
AVIATION...
MARINE...