Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 221615
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
1215 PM EDT Sat Jul 22 2017

.SYNOPSIS...
A cold front will drop southward across the forecast area today
with just a slight chance of a shower or thunderstorm.
Temperatures will remain very warm. High pressure will settle
over the region Sunday into Sunday night. Low pressure will
approach from the southwest later Sunday night and for Monday
and will deliver cooler temperatures and the likelihood of rain.
Conditions will improve Tuesday and Wednesday as high pressure
moves in.

&&

.NEAR TERM /UNTIL 8 PM THIS EVENING/...

1212 PM...minor ESTF update to reflect the current mesonet in
near term grids.

Prev disc...
900 AM...The cold front extends from the mid Maine coast
westward through central New Hampshire into upstate New York.
This boundary will only inch southward today and will provide
the focus for widely scattered convection. Based on satellite
trends...I adjusted cloud cover grids to reflect the dense high
and patchy mid cloud traversing much of the forecast area along
and to the south of the boundary. The latest mesonet was also
ingested into near term grids for this ESTF update.

Prev disc...
7 AM Update...Very little change to the going forecast. Continue
to expect some mid and high clouds from time to time this
morning, but it should remain dry. Isolated showers and perhaps
a tstm still a possibility this afternoon but vast majority of
locales will remain dry.

Previously...

A relatively weak cold front will push southward across the CWA
today into this evening. Moisture and forcing for ascent will be
limited so very little precipitation is expected, if any. We
just have a 20 percent chance of a shower or isolated
thunderstorm across central and a few southern zones. Most
everyone will remain dry. Otherwise, temperatures will be quite
warm again with highs well into the 80s at most locations, with
a few 90 degrees readings possible in the far south.

&&

.SHORT TERM /8 PM THIS EVENING THROUGH 6 PM SUNDAY/...
High pressure will settle into the region in the wake of the
cold front tonight. This will bring cooler temperatures, with
lows in the 40s expected in the the far northern zones.

High pressure remains in control on Sunday although WAA aloft
should foster an increase in clouds. Forcing for ascent with the
next short wave trough looks to hold well to our west during the
day so we do expect to remain dry. High temps should be a good
10 degrees cooler than those seen on Saturday.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
The week will begin with a trough in place over the northeast
US. By Sunday night a strong short wave will dive southward
around the main trough. As this moves through widespread rain
will move in from west to east across the area on Monday. At the
surface low pressure will develop south of New England. This
will keep northeasterly flow in place at the lowest levels
helping to keep temperatures lower than normal. Meanwhile the
easterly flow into the mountains will help to ring out moisture.
PWAT values climb to around 1.5 inches which in combination
with the low level jet and saturated conditions should allow
some areas of heavy precipitation across Maine on Monday. Most
of the variability in this system is with the strength of the
offshore low and the placement of the heaviest axis of
precipitation.

Showers will continue Monday night and into Tuesday especially
in the mountains as the low moves out. The upper level trough
will remain in place through Wednesday keeping the high
temperatures once again in the upper 60s for Tuesday.

By Wednesday surface high pressure begins to build in as the
upper level trough moves out. Temperatures will begin to
increase once again reaching the mid to upper 70s region wide. A
cold front will approach on Wednesday night and cross the
region Thursday. A region of fairly steep lapse rates in
combination with mid afternoon timing will mean thunderstorms
are likely and have added straight thunder wording for the
daytime hours.

&&

.AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
Short Term...VFR today outside of some early morning valley fog.
VFR conditions continue tonight and Sunday with river valley
stratus and fog once again likely late tonight.

Long Term... Sunday night will see most of the area move into
MVFR or IFR Fog as log pressure develops. Monday will have
widespread showers and rain with some thunderstorms possible.
IFR conditions may persist throughout the day especially along
the coast. Conditions will improve on Tuesday with mostly
mountain shower activity and increasing ceilings to the south.
High pressure builds back in for Wednesday.

&&

.MARINE...
Short Term /through Sunday/...A cold front will drop southward
across the waters late today and tonight. Northerly wind gusts
may briefly reach 25 kt tonight into early Sunday but the
probability is a bit low to issue a SCA at this time.

Long Term... A low will develop south of New England late Sunday
night into Monday. This will bring increasing easterly winds to
the waters with small craft conditions likely during the day on
Monday. A strong low level jet may result in a few gusts to
near 30kts especially in regions of heavy rain. High pressure
will move in for Wednesday with subsiding winds and seas.

&&

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

&&

$$

ES



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