Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 101950

Area Forecast Discussion
National Weather Service Gray ME
350 PM EDT Sat Jun 10 2023

A weak area of high pressure will cross the region on Sunday
into Monday with any showers being less numerous. A frontal
system will bring widespread showers and thunderstorms to the
region on Tuesday. An upper level low will then cross the region
during the mid to late week period. This will bring plenty of
clouds and showers through the duration.


Instability will allow for more showers and a few thunderstorms
for the rest of this afternoon and early this evening with
daytime heating. Otherwise, expect the precipitation to end as
well roll into sunset this evening.

The latest HREF solution and recent satellite imagery continues
to show some fog out over the Gulf of Maine. The coverage is
much less than yesterday due to a slightly drier westerly
gradient just above the sea breeze circulation. Nevertheless,
some of this fog may make a run for the coastline overnight.
Patchy radiation fog may develop as well over some of the
interior valleys as temperatures fall towards the dew point
levels. Temperatures will fall into the 40s in the north to the
lower 50s in the south.


An upper level low will continue to exit through the Canadian
Maritimes on Sunday with a weak ridge of high pressure entering
New England. Sunday will be the pick of the week for drier air
and milder temperatures. Nevertheless, there will be some pop up
isolated showers as the atmosphere destabilizes during the day.
Any precipitation would be brief however.

With some sunshine and H8 temperatures around +10C it will be
warmer than the last several days. High temperatures will reach
the 70s in most areas. The exceptions will be southernmost New
Hampshire which may take a run at the lower 80s and the Midcoast
region which will struggle to climb above the 60s.

Clouds will increase, thicken and lower Sunday night ahead of an
area of low pressure that will pass by to our northwest. The
cloud cover will allow for a milder night with relatively
similar temperatures across the region and overnight lows in the


Overview: Damp conditions in, damp conditions out. There is
more detail to the forecast than that, but overall theme will
revolve around unsettled conditions beginning Monday into
tuesday with a strong disturbance. This will trend into yet
another upper low blocking pattern to prolong unsettled and
showers weather through the region. Guidance hints at a warmer
week than observed prior, but believe there is more room for a
cooler outcome under low pressure through the week.

Details: Monday morning will offer a brief window of dry
conditions for much of the CWA. Southerly flow will allow warm
temperatures to again reach over the region, but clouds will be
on the increase. Temperatures will be trickier into the
afternoon as a sea breeze looks to move inland. This will have
the potential to rapidly cool coastal locations and interior
portions where the southerly flow helps advect marine air
inland. Thus, daytime highs for communities along the coast and
particularly the Midcoast may come in late morning.

Shower coverage increases through the day across NH and then
into ME. Good consensus amid det runs of NAM, CMC, and GFS pin
the timing of most widespread rain during the evening into
overnight hours, exiting into central Maine Tues morning. Have
molded rain chances to follow this progression at this time.
Certainly room to modify when the heaviest rain may pass as the
front slowly loses some fgen passing overhead.

PWATs are forecast to push above 75% climo of 1.19”, and amid
the extra forcing can expect at least a period of mdt rain
during its passage. LLJ is weak however, and not sure how much
enhancement over the western mtns will be attained. That said,
WPC and NBM QPF maxes in upslope region from the Whites into
Maine amid the onshore flow. This isn’t good news due to the
week’s worth of showers and downpours leading into the event. In
conclusion, agree with WPC’s inclusion of the area in a
Marginal Risk ERO for day 4. Additional excessive rainfall
threat could also be made for southern NH where some isolated
locations received 2 to 5 inches of rain in some slow moving to
nearly stationary showers Friday afternoon. However, expect
heaviest rates to be progressive for much of the event.

Fog development over the waters is possible, and that could
also advect along the coast Mon afternoon into the overnight
hours. Have brought this into the forecast, but left it most
consistent over the coastal waters. Overnight temperatures will
be quite mild where marine air didn’t already intrude. Some
locations in southern NH may only bottom in the mid 60s.

Another round of convection will be possible in NH Tuesday.
This comes as low pres approaches from the west and some cloud
breaks help to build instability late morning and through the
afternoon. Shear profiles will be improving through the day as
instability builds. Some question on the existence on a mid
level warm layer to cap off some of the deeper CAPE potential,
but can’t rule out some of these storms being stronger should
lapse rates improve.

Through mid-week, another upper low is set to push into the
region. It will broaden into late week as another wave dives out
of the northern Great Lakes. This will only serve to reinforce
the broad area of low pressure overhead. Guidance is convinced
daily highs settle the the 70s through the period, but it is
expected to be damp and abundantly cloudy. Have gone slightly
lower on daytime highs considering this, but it should still be
warmer than the previous week where southerly flow was directed
well away from the region.


Short Term...Patchy fog will develop along the coastline again
tonight from the marine layer. This may allow for IFR conditions
later tonight in restrictions at KPSM, KPWM and KRKD. Some
radiation fog may develop inland as well tonight, otherwise
expect VFR conditions. A few scattered showers on Sunday may
lead to localized, brief MVFR conditions. Patchy fog to develop
once again Sunday night.

Long Term...VFR ceilings will trend to IFR Monday evening. This
may be in combination with incoming front from the west, as
well as coastal marine stratus or fog off the Gulf of Maine.
Thus, some coastal ME locations may transition to IFR quicker
than interior locations. IFR continues overnight into Tues amid
RA and BR. LLWS will be possible as well. TS will be possible in
southern NH Tuesday afternoon. Some improvement to MVFR is
likely into Wed


Short Term...A weak west to southwesterly gradient will continue
tonight before becoming onshore on Sunday into Sunday night.
Winds will be light however. Fog will expand over the coastal
waters tonight into Sunday morning with lowering visibilities.

Long Term...Winds and seas are forecast to remain below SCA
criteria through Thursday. There may be some visibility
restrictions through the period in the way of heavy rain and fog
Monday night into Tuesday as a front lifts through the region.
Fog may continue through Tuesday as onshore flow remains. Upper
low pressure will near the coast from the west through midweek.




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