Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 151927
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
327 PM EDT Mon Apr 15 2024

.SYNOPSIS...
A weak cold front exits the region this evening. High pressure
gradually builds in Tuesday and Wednesday. A cold front
approaches late in the week bringing another chance for rain
showers late Friday into Saturday.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Cold front and weak 500 MB trough are producing a few scattered
showers, which are mostly over S NH and the coastal plain of ME
at 3 PM. These should shift S and E over the next few hours and
will likely be out of the CWA by 6 PM, although a few mtn
showers will be possible into the first part of the evening.
Upslope mtn clouds will likely hang around through much of the
night, but should see gradual clearing overnight S of the mtns.
Although some areas may decouple, there is enough flow where and
clouds that full rad cooling is not expected, and lows range
from the mid 30s in the mtns to around 40 in the S, but again
some of the more sheltered spots could drop to around 30 if
there’s enough clearing.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Tuesday should start off mainly sunny outside the mtns and
partly sunny in the mtns. It’ll be breezy with WNW winds, and
some gusts to around 25 mph, but it’ll be mixing warm enough air
down to push temps back into the 60s across much of the areas S
of the mtns, and could approach 70 again in S NH. The mountains
will generally top out the 50s, and should see clearing in the
afternoon.

Tuesday night does look like a good rad cooling night with clear
skies and sfc ridge pushing in from the N allowing winds to
slacken. Also with Tds in the upper 20s to mid 30s, this should
allow temps to fall rapidly. Lows will range from the mid to
upper 20s in the mtns to the low to mid 30s in the S. Again
isolated sheltered areas could come in several degrees below
this. Also, uncertain about fog, given the dry air mass, but
could see it some patchy fog in the CT valley.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Broad high pressure and a very dry airmass, characterized by PWATs
around 0.25", will provide plenty of sunshine for Wednesday.
Temperatures should be able to warm into the low 60s for most of the
area, except mid 60s across southern NH. This is slightly above
guidance with how dry the air is. The exception is along the coast
with the northerly flow being light enough to allow for the
seabreeze development to keep things a touch cooler and in the 50s.
Upper ridge builds overhead Wednesday night, and the same airmass
sticks around. This will keep most areas clear or mostly clear, and
with light winds I have blended in some MET/MAV guidance to account
for radiational cooling. NH get some more clouds through the course
of the night so I haven`t gone as low there.

An upper low will open to a wave as it moves across the Great Lakes
on Thursday. This wave will move toward New England, temporarily
weakening the ridge, and perhaps bring some light showers to the
area. The better potential looks to be across NH with a gradual
increase in moisture in the Thurs-Thurs night time frame. That said,
I have actually lowered PoPs during the day Thursday as the GFS
seems to be the outlier in how quickly it increases moisture
and brings the wave across, but I still 20-30% chances later in
the day into Thursday night where there is more agreement among
the models.

Most of Friday looks dry with the ridge still largely in control,
but it will eventually shift east of the region as a low pressure
system moves across the Hudson Bay/Great Lakes regions and sends a
cold front toward New England. Global models have come into slightly
better agreement since this time yesterday with focusing more in the
Friday evening into Saturday window for us to see some rain showers
with the better potential for northern areas. However, there are
hints of a weak southern stream low that could may end up increase
chances farther south as a well. Amounts from ensemble continue to
support amounts around 0.25".

There`s still timing discrepancies with the frontal passage
although sometime on Saturday, and following the front, Sunday
and Monday are looking dry, other than lingering upslope showers
in the mountains.

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
Short Term...There might be some on and off MVFR cigs at KHIE
through this evening in upslope flow, but otherwise VFR is
expected through Monday night.

Long Term...VFR expected at all sites Wednesday through at least
Wednesday night. A weak disturbance may bring a brief period of rain
showers to the area Thursday and Thursday night along with MVFR
ceilings (with more potential in NH). Higher chances for rain
showers and flight restrictions will accompany a cold front in the
late Friday through Saturday timeframe.


&&

.MARINE...
Short Term...Will hold the SCA through 00Z as still seeing
reports of 5-6 feet, but the trend continues downward, so 00Z
might work out well. After that should stay out of SCA
conditions through Tuesday night.

Long Term...Conditions are expected to remain below SCA levels
Wednesday through Friday with high pressure in control.  The high
starts to slide east of the waters on Friday as a cold front
approaches the region with the front looking to cross sometime on
Saturday. It`s possible a weak low pressure precedes the front and
moves into the waters Friday night, and if this occurs, it could
bring a brief period of SCA conditions. Behind the front, W/WNW
winds may gusts in excess of 25 kt Saturday into Saturday night.
Conditions look to improve Sunday into Monday as high pressure
slowly builds into the Northeast U.S.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ150-
     152-154.

&&

$$

NEAR TERM...Cempa
SHORT TERM...Cempa
LONG TERM...Combs


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