NWS Forecast Discussion

For Fremont, NH

440
FXUS61 KGYX 211531
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
1131 AM EDT Sat Jul 21 2018

.SYNOPSIS...
High pressure will remain overhead through today providing the
region with fair weather. Low pressure will move northward off
the Mid Atlantic coast Saturday night and Sunday and bring rain
to northern New England, possibly heavy at times Sunday morning.
Thereafter, a tropical air mass will remain in place through
mid week with scattered tropical showers and thunderstorms each
day.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1130 am Update: All the fog has burned off. No changes needed to
forecast at this time.

630 AM Update...Have updated the forecast for the next few hours
mainly for minor adjustments. Have added more dense fog through
12z based on latest observations and satellite imagery. Have
issued a special weather statement where dense fog is most
widespread - mainly from Portland northward to Augusta and
eastward to the mid coast. This should burn off over the next 2
hours or so. Otherwise, little change to the going forecast.

Previously...

Deep layer high pressure ridging will remain in place over
eastern New England today allowing for another day of dry, fair
weather. Onshore flow will keep the coast in the 70s while
interior locations reach and exceed the 80 degree mark.
Otherwise, early morning fog, locally dense will burn off an
hour or two after sunrise.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
Tropical moisture begins to stream in tonight as a short wave
lifts northward along the Mid Atlantic coast. Onshore flow in
the low levels will bring low stratus and fog to coastal
locations starting in the evening, then spreading inland
overnight. As low pressure moves northward along with an
increasing low level jet, showers (possibly heavy along with
embedded thunder) will move into southernmost zones after
midnight. This activity will spread northward late at night
through Sunday morning to the rest of the forecast area.

While the best forcing for ascent with this system should move
northwestward into western NY, moist and weakly confluent deep
layer meridional flow across northern New England should allow
for n-s training showers with embedded storms for much of
Sunday morning. At this time the most likely area for the
heaviest precipitation looks to be across the eastern half of NH
into adjacent southern ME. This is where 1-2" of rain will be
possible with locally heavier amounts. A lot of the region has
been in drought so far this summer so will forgo any sort of
flash flood watch. However, localized flash flooding will be
possible. The precipitation should become a little more
scattered Sunday afternoon.

The severe weather threat on Sunday looks low. However, with
very moist air mass in place, any substantial surface heating
will result in weak to possibly moderate SBCAPE in the midst of
moderate low level shear. This could possibly result in an
isolated tornado or a few wind damage reports. Again, this is a
low probability scenario, but non-zero.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
The deterministic model solutions are now in decent agreement on
the long wave pattern through next weekend...lending increasing
confidence to latter portions of the forecast. We begin the
period with a western Atlantic ridge and an upper trough/closed
low over the eastern third of the CONUS. The ridge will briefly
build westward into northern New England early in the period
before weakening. Meanwhile...the upper ridge initially over the
western two thirds of the CONUS will weaken with shortwave energy
eventually carving out a broad upper trough stretching from the
northern plains to the northeast CONUS by the end of the period.
We begin the period with the offshore high transporting warm and
increasingly humid air northward into the region. Daytime heating
and a series of passing weak shortwave impulses will produce
scattered convection accompanied by tropical downpours at times.
There`ll be little change in sensible weather until a slow-moving
cold front crosses the area Friday and early Saturday accompanied
by more widespread showers and thunderstorms. Behind this front
we should finally see some relief from the heat and humidity.

&&

.AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
Short Term...VFR conditions through this afternoon. IFR to LIFR
conditions develop on the coast this evening then spread inland
overnight...mainly low clouds and fog. Showers are expected to
arrive across southern NH after midnight tonight and expand to
the rest of NH and ME by early Sunday morning. Low conditions in
showers and possibly thunder are expected during the day on
Sunday.

Long Term...

Mon - Wed...Areas of MVFR in shra/tsra...with lcl IFR in
nighttime fog.

&&

.MARINE...
Short Term...Seas will gradually build later tonight and Sunday
due to a developing onshore wind. A SCA may need needed for the
ocean waters.

Long Term...

Mon - Wed...SCA`s are psb...especially outside the bays.

&&

.HYDROLOGY...
Some smaller rivers and streams may need to be monitored Sunday
as heavy rains and scattered thunderstorms produce 1-2 inches
of rain with some higher amounts possible.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Beach Hazards Statement until 8 PM EDT this evening for MEZ027-
     028.
NH...None.
MARINE...None.

&&

$$

NWS GYX Office Area Forecast Discussion