Area Forecast Discussion
Issued by NWS Portland, ME

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953
FXUS61 KGYX 250638
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
238 AM EDT Thu Apr 25 2019

.SYNOPSIS...
Weak high pressure will build in from the west today. Another
low pressure system will move through the region this weekend,
with rain arriving on Friday. Rain on Friday and early Saturday
will cause water levels to rise on area lakes and rivers with
more flooding possible. Another system will pass south of the
region late Sunday with high pressure following early next week.

&&

.NEAR TERM /THROUGH TODAY/...
At 06z...a 1002 millibar low was centered south of Nova Scotia.
A 1015 millibar high was centered over upstate New York. GOES
water vapor imagery showed an upper low over New Brunswick. NWS
Doppler Radar showed a few sprinkles vicinity of the Kennebec
Valley...otherwise dry conditions across the forecast area at
moment. The upper low will exit the region by morning. Other
then some lingering low clouds across northern and eastern
sections this morning...a mainly sunny day as the high over
upstate New York builds into New England. Highs today will range
from the mid 50s to mid 60s...but it`ll be chillier along the
coast as the light synoptic flow turns onshore by afternoon.

&&

.SHORT TERM /TONIGHT THROUGH 6 PM FRIDAY/...
The high retreats offshore by late today and well offshore
tonight. Meanwhile upstream...northern and southern stream
energy begins to phase and carves out a trough to our west. At
the surface...developing low pressure tracks from the
Mississippi valley to the lower Great Lakes by Friday morning.
In advance of this system...clouds will spread quickly north
and east across the forecast area tonight with light rain
arriving over far southern and western New Hampshire by morning.
Lows tonight will range from the mid 30s to mid 40s. On
Friday...the upper trough goes negative tilt and rain overspreads
the remainder of the forecast area and may become heavy at
times during the afternoon. Clouds...precipitation and onshore
flow will limit high temperatures to the upper 40s and lower
50s.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
00Z model suite in relatively good agreement depicting a
negatively tilted upper level trough over the Great Lakes region
Friday night. Strong jet dynamics will allow for cyclogenesis
over the region as a surface area of low pressure intensifies
and enters Canada. This will bring rain to the region, aided by
a moisture and rather strong low level southerly flow.

Rainfall totals will range from an inch along and near coastal
areas, to two inches in the foothills and mountains Friday night
into early Saturday morning. Additional runoff will occur with
snowmelt as temperatures top out in the 40s across the
mountains.

The upper level support will then cross our forecast area
Saturday afternoon triggering more scattered showers, mainly in
the north and mountains. More rain will return for the end of
the weekend as a fast moving weather disturbance passes south of
New England later on Sunday. Some of this precipitation may mix
with snow in the north with cooler temperatures arriving Sunday
night.

High pressure and cool temperatures will occur on Monday.
However, yet another system will race east, embedded in a fast
upper level flow. This will allow for rain and snow showers on
Tuesday.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
Short Term /Through Friday/...Areas of MVFR across mountain and
eastern Maine sections...improving to VFR throughout by midday.
MVFR with areas of IFR develops from SW to NE aft 12z Friday in
cigs...rain...and fog.

Long Term...IFR and localized LIFR conditions are possible
Friday night in rain and fog as low pressure approaches the
region. Improving conditions Saturday. Areas of MVFR conditions
reappear Sunday as more rain enters the region. Some snow may
mix in over the far north with this system.

&&

.MARINE...
Short Term /Through Friday/...Winds and seas remain below SCA
through tonight as high pressure builds across the waters.
Strengthening onshore flow Friday ahead of low pressure should
bring SCA conditions mainly outside the bays.

Long Term...SCAs will likely be required Friday night as the
southerly gradient continues to tighten with time. There may
also be a few brief gusts to gale force during this period.
Gusty winds to also return from the west around the departing
system on Saturday.

&&

.HYDROLOGY...
Although a few rivers still have Flood Warnings for ongoing
flooding, the trend will continue to have these levels recede
at least until rain arrives again. Although our focus tends to
be on rivers with gauge points for reference, there are also
many lakes which are full or spilling out of their banks as
well. The interior of western Maine and the northern half of New
Hampshire remains water logged and prone to additional flooding
when rain arrives again.

An analysis of the remaining snow cover across the area shows
that there still remains a good deal of snow in the White
Mountains, but areas west and northwest of there have cleared
up. Thus additional runoff from snow melt here is rather
limited. To the east, though, across northwest Maine there
remains some snow left to melt. This will add to flows in the
Kennebec, Androscoggin, and possibly the Saco Rivers through the
weekend.

With rain beginning on Friday and being possibly heavy Friday
night into early Saturday, we anticipate more flooding on area
rivers and lakes. This will most likely begin on Saturday and
would last into next week. The heaviest rainfall is expected
over interior western Maine which is also where conditions
remain water logged and some snow remains left to be melted.
Thus the biggest threat for new river flooding this weekend will
be in the Kennebec and Androscoggin river sheds and possibly
the Saco as well. In addition to high river levels, lake levels
have also been reported as quite high and could see flooding
along their banks this weekend as well.

&&

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

&&

$$
NEAR TERM...Schwibs
SHORT TERM...Schwibs
LONG TERM...Cannon



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