Area Forecast Discussion
Issued by NWS Portland, ME

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
287
FXUS61 KGYX 171050
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
650 AM EDT Mon Jul 17 2017

.SYNOPSIS...
Bermuda high pressure over the western Atlantic will reinforce a
warm and humid air mass over New England through much of the
week. A weak upper level disturbance will slowly track across
northern New England today and Tuesday, triggering showers and
thunderstorms mainly in the afternoons. Humid conditions
continue with increasing heat Wednesday and Thursday. A cold
front will trigger showers and thunderstorms on Thursday before
it crosses New England Thursday night. Expect less humid
conditions behind the cold front through the weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Update...
Have updated the grids based on current surface observations and
satellite data. Fog continues across much of the region. There
is patchy dense fog which triggered the issuance of two Special
Weather Statements. Otherwise, visibilities have not been
consistently low in many areas, increasing and decreasing at
times. In any case, the fog will begin to lift over the next
hour or so.

Convection over northern New York will shift east. There still
remains a threat of a few storms producing strong gusty winds,
hail and locally heavy downpours. Will continue to monitor.

Minor adjustments made for temperatures, current cloud cover and
dew points. Pops modified to slow down the increasing morning
chances for showers in the mountains.

Prev Disc... Dense fog in many locations will lift this
morning. This may slow down portions of the early morning
commute. Will monitor how widespread the fog becomes. A dense
fog advisory may be required for portions of the forecast area
this morning.

An upper level trough will approach from the west today. This
will increase low and mid level lapse rates over the region,
destabilizing the atmosphere. CAPE values increase rapidly today
in the absence of much of a cap, mainly away from the
coastline. Scattered showers and thunderstorms will erupt. A few
of the storms may contain gusty winds and small hail.
Precipitable water values will be on the increase again, and a
few of the storms may contain locally very heavy downpours.

Most areas will top out between 75 and 85 degrees for highs. It
will be cooler along the Midcoast as the fog lurks near the
coast much of the day.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
Any ongoing strong convection should weaken after sunset this
evening. Scattered showers and thunderstorms will persist
however. The least likely region to receive a thunderstorm will
once again be the coast, in a region of relatively stable air.
Fog will form again, especially along and near the coastline
where visibilities could drop to a quarter mile in some areas.

The upper level trough will gradually exit the region on
Tuesday. However, there will still be scattered showers and a
few thunderstorms. Once again the convection will mainly be away
from the coastline. 70s for daytime highs will be widespread in
Maine with lower 80s over portions of New Hampshire.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Decaying upper trough moves east Tuesday night, with any
lingering showers dissipating during the evening hours. Any weak
surface frontal boundary associated with the passage of this
trough will be imperceptible in the temperature, dewpoint, or
wind fields as the warm, humid air remains in the area,
intensifying a bit as the week goes on. The best day of the
workweek looks to be Wednesday, as weak subsidence in the wake
of the trough suppresses afternoon convection and temperatures
warm into the 80s areawide.

Another trough approaches from the west on Thursday, with the
heat and humidity reaching its peak ahead of it. Based on model
forecast 850MB temperatures, parts of the area could see 90
degrees on Thursday. This heat and humidity will fuel showers
and thunderstorms Thursday afternoon, aided by lift ahead of the
approaching trough. This trough heads off to the east Thursday
night, with a cold front bringing a slight change in air mass
for Friday. Cooler and less humid conditions are expected on
Friday, though there will again be a chance of afternoon showers
mainly in the north and east beneath a lingering upper trough.

Continental high pressure crosses the area on Saturday,
providing a good amount of sunshine along with less humid though
still seasonably warm conditions. The next trough approaching
the area may begin to affect the region as early as Sunday with
another chance of rain.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
Short Term...Early morning IFR/LIFR ceilings and visibilities in fog
improving to VFR conditions through the morning. There will be a
few showers and thunderstorms this afternoon, mainly over New
Hampshire reducing conditions briefly to IFR.

LIFR conditions tonight in developing dense fog, slowly
improving on Tuesday.

Long Term...Expect VFR conditions and light winds Wednesday and
Thursday with a sea breeze near the coast. Showers and
thunderstorms are likely Thursday afternoon, especially away
from the immediate coast. These will diminish Thursday night,
with another round of showers possible in the north on Friday.

&&

.MARINE...
Short Term...Winds and seas expected to remain below SCA
thresholds with generally a light gradient over the coastal
waters.

Long Term...A light southerly flow continues through Thursday. A
cold front will cross the Gulf of Maine early Friday but winds
will again be fairly light behind it.

&&

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

&&

$$
NEAR TERM...Cannon
SHORT TERM...Cannon
LONG TERM...Kimble



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.