Area Forecast Discussion
Issued by NWS Portland, ME

Home | Current Version | Previous Version | Text Only | 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
000
FXUS61 KGYX 191439 AAA
AFDGYX

Area Forecast Discussion...UPDATED
National Weather Service Gray ME
939 AM EST Thu Jan 19 2017

.SYNOPSIS...
High pressure will build in for the remainder of the week, with
above normal temperatures expected into Monday. A storm system may
affect the region beginning Sunday night and continuing into early
next week. Gusty winds and mixed precipitation will be associated
with this system, primarily Monday into Tuesday. An upper level
trough may keep unsettled conditions over the region later next
week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Update...A few minor tweaks to bring forecast in line with latest
observational trends. Some lingering snow continues over the
Penobscot Bay region...but will quickly come to an end as s/wv
trof passes E of the region. A few upslope snow showers are
possible in NW flow behind it given the abundant low level
moisture remaining. S/wv ridging quickly moves in late this
afternoon and evening.

Previous discussion...A short wave will move through the region
this morning. As of 3 am widespread snow was falling across Maine
with freezing drizzle in portions of New Hampshire. The snow will
move through and out of the region in the next few hours with
clouds lingering through the day time. Low level moisture will
remain through the day. The short wave should be just enough to
cut off the drizzle by mid morning but some isolated pockets may
continue through the day.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
High pressure begins to build in from the southwest tonight. Warm
air advection aloft will begin overnight. This will create a
surface inversion trapping the residual moisture near the
surface. Low clouds and fog will develop overnight especially in
the mountain valleys. Have increased cloud cover and temperatures
above the mostly clear guidance to account for this. Friday
temperatures will begin to warm up but low clouds will remain
especially in the mountains.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Upcoming hazards: A complex weather system may affect the region
early next week. Potential hazards include heavy rain, mixed
precipitation and wind.

A ridge of high pressure will remain just to our west, over New
York State extending south through the Mid Atlantic region Friday
night into Saturday morning. Nevertheless, warm air advection
cloudiness will spill over the ridge and into Maine and New
Hampshire.

Colder air will then seep into the region in association with a
backdoor cold front Saturday afternoon and Saturday night. There
may be pockets of light snow, but any precipitation will likely be
on the light side with little in the way of dynamics in the
atmosphere and a limited moisture supply. This colder air will
continue to advect southwards on Sunday, setting the stage for a
mixed precipitation event next week.

00Z model runs have trended colder with the initial surge of
precipitation on Monday. During this period, a large and anomalousarea
of low pressure will track northeast to the Mid Atlantic region.
With cold air in place and the wet bulbing effect, snow will break
out across the region as a conveyor belt of strong easterly winds
develops over the region. This pattern will allow warm air to
overwhelm the coastline and portions of southern New Hampshire to
change the precipitation over to rain.

Although warming will continue aloft and limit the amount of
snowfall Monday night, enough cold air will remain in the lower
levels to allow for the whole gambit of mixed precipitation. Sleet
and freezing rain will be possible over the interior with mainly
rain falling along the coast. This mixed precipitation will
retreat to the far north on Tuesday with rain falling in most
other areas.

There will be strong gusty winds Monday into Tuesday, especially
along and near the coastline. Expect areas of heavy rain as well
which may lead to rises on area rivers, potentially producing ice
jam issues.

Any precipitation will become light on Wednesday and change to
snow as the system pulls into the Canadian Maritimes. Do not
expect full time clearing as much weaker upper level low pressure
systems will remain overhead and to our west during the mid/late
week timeframe.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
Short Term...Low level moisture will remain trapped under a
developing surface inversion as warm air tries to move in aloft.
This will keep ceilings at or below MVFR through Friday night.
Thursday evening IFR in FZFG is expected for the mountain valley
locations including HIE and LEB. Expect an improvement to MVFR for
the day Friday before IFR Fog returns again Friday night.

Long Term...Mainly VFR conditions over the weekend. Widespread
IFR conditions, with areas of LIFR developing early next week in
association with the large area of low pressure along the Mid
Atlantic coastline. There could be a period of LLWS as a low level
northeasterly flow will dominate for a period on Monday across the
interior.

&&

.MARINE...
Short Term...Winds have decreased by seas remain around 5-7ft so
have continued the Small Craft for Hazardous Seas only. Seas will
continue to subside as high pressure builds into the region
through Friday.

Long Term...An increasing east, northeast gradient will develop on
Sunday. Gale force winds with possible storm force gusts are
possible early next week. The persistent fetch from the east will
allow for large waves to build.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory for hazardous seas until 3 PM EST this
     afternoon for ANZ150-152-154.

&&

$$

NEAR TERM...Legro



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