Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 232243
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
643 PM EDT Sat Mar 23 2024

.SYNOPSIS...
A significant late winter or early spring storm will quickly
exit to the east tonight with a period of breezy northwest winds
following the system into Sunday. Heavy snow, sleet, freezing
rain, and rain from the system will continue to result in
difficult travel in the meantime. Much quieter weather is
expected early in the coming week with temperatures moderating
to near seasonal norms. Unsettled weather returns for the middle
and second half of the week, but with quiet low model certainty
with numerous weak waves in play.

&&

.NEAR TERM /UNTIL 7 AM SUNDAY MORNING/...
Update...Low pressure over Long Island New York this evening
will continue to track towards southeastern Massachusetts and
into the Gulf of Maine tonight. This will allow a large area of
heavy precipitation to cross western Maine and New Hampshire
through the evening hours. The area of snow will expand
southwards during this process and the mixed precipitation will
enter portions of coastal York County and perhaps far southeastern
New Hampshire once again.

The latest HRRR has remains a little faster with the
precipitation exiting the western half of the forecast area
tonight, while snow and mix remains over eastern and northern
portions of the forecast area.

Have made slight adjustments to the forecast package this
evening in terms of timing of the precipitation type changes.
Have also issued a few Flood Advisories for roadside ponding in
areas of rain or mixed rain and freezing rain over southeastern
New Hampshire and the Portland area.

Some power outages expected due to the weight of the ice on
trees tonight.

Prev Disc...
Latest RAP13 surface pressure analysis this afternoon shows the
center of low pressure located near Atlantic City, NJ with
stratiform precipitation stretching well to the northeast within
a region of favorable jet dynamics. Precipitation types range
from moderate to heavy snow from Laconia through Fryeburg to
Lewiston and Augusta/Waterville with a mixture of wintry
precipitation south of this line. Temperatures have risen to
above freezing in extreme southern NH along with the immediate
coast of southwestern ME, which has allowed for a transition to
mainly plain rain. Correlation coefficient from KGYX 88-D does
show this mixing line continuing to move inland as warmer, above
freezing air moves in between 2500-5000 ft AGL. Hazardous travel
conditions will persist through the remainder of the day,
especially away from the immediate coast and extreme
southeastern NH.

Deepening low pressure will quickly move northeastwards over New
England before arriving over western Nova Scotia by daybreak on
Sunday. This system will continue bring periods of moderate to
heavy precipitation to the region through around midnight,
before quickly ending from west to east later tonight. Latest
hi-res guidance shows increasing h850 FGEN forcing arriving over
the next couple of hours and continuing through this evening as
the stronger LLJ arrives and WAA increases aloft. The placement
of the strongest forcing looks to setup over the western ME
foothills and mountains. The WPC Snowband Probability Tracker
(SPT) shows the potential for snowfall rates of between 1-2"/hr
across these regions with dangerous travel conditions. The
snowfall forecast has not changed too significantly across
these areas with generally between 1-2 feet of snow expected and
little in the way of sleet or freezing rain.

A wintry mix is expected to persist across the Lakes Region of
NH and ME and extending towards the interior coastal plain with
storm total snowfall of between 6-12" and ice accretions between
a tenth to three tenths of an inch. Sleet amounts up to 1" are
also possible.

Closer to the coast and in southeastern NH, rain mixed with
sleet will continue through this evening with temperatures into
the middle 30s before temperatures cool to at or below freezing
late this evening as precipitation begins to end. Ice amounts up
to around a tenth of an inch are possible with perhaps an
additional inch of snow and a few tenths of an inch of sleet.
Periods of moderate to heavy rain through this evening could
result in some minor nuisance flooding as well, especially where
snow/ice is clogging storm drains.

Precipitation ends from west to east overnight with most areas
becoming dry by 2am or so. Low temperatures tonight will range
from the teens across the north to the lower and middle 20s
south. Northerly winds will increase overnight, which could
result in some blowing snow.

&&

.SHORT TERM /7 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
High pressure will build back over New England on Sunday,
bringing a return to tranquil weather conditions under partly
cloudy skies. High temperatures will range from the lower 30s
across the north to upper 30s to near 40 degrees south.
Northerly winds of between 15-25 mph will make it feel a little
colder though and there could be some patchy blowing snow.

Clear skies and lightening winds will allow for cold
temperatures Sunday night. As a result, hedged the forecast
towards MOS guidance, which places lows into the single digits
across the north to teens and low 20s south.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
This forecast discussion will be brief due to ongoing active
weather. An operational blend of models was used with minimal
alteration.

Overall not a ton of hazardous weather potential in the
extended with high pressure dominating through mid-week, before
a front enters the region and lingers through the second half of
the week. After a chilly Sunday night... temperatures are
forecast to trend upward, to around seasonal averages through
mid-week. The second half of the week will remain seasonably
warm and humid, although with lower certainty given a front in
the vicinity and the potential for onshore flow. Periods to
monitor for impactful weather will be for a little bit of
freezing rain Tue into early Wed as cold air hangs on in the
usual CAD spots of the W. Maine mtns and foothills... and again
late in the work week where some system phasing may bring a
more significant dose of rain to the region.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
Short Term...LIFR restrictions will persist through around
03-06Z Sunday before improving to VFR thereafter. Precipitation type
through tonight will range from FZRASNPL at KPWM, KCON, KAUG.
Mainly SN, possibly mixed with PL at times can be expected at
KLEB and KHIE with primarily rain at KMHT, KPSM, and KRKD. There
is a moderate chance for a brief period of FZRAPLSN at KMHT
between 22Z-03Z Sunday before precipitation ends. Snow
character will be dry to near climatological means. A period of
LLWS is likely at KPSM and KRKD as a coastal front develops and
skirts the coastline, mainly between 22Z-04Z. Northerly flow of
15-25 kts and VFR conditions then will prevail on Sunday before
winds diminish Sunday night.

Long Term...VFR expected at all sites on Mon, likely Mon night
as well with mainly light NE wind AOB 20 kts... strongest for
coastal terminals and lighter across the interior. Restrictions
in lowered CIGs are expected to develop on Tue. Confidence is
low for the middle and end of the week, however numerous periods
of restrictions are expected with low CIGs, RA, and BR/FG.

&&

.MARINE...
Short Term...Low pressure will move across the waters tonight
with northerly gales expected through early Sunday, except at
Casco Bay. Seas of 6-10 ft are expected across the outer waters
with 2-5 ft in the bays. SCA conditions will then linger over
the outer waters with northerly winds through at least Sunday
night.


Long Term...Northeast flow prevails over the waters through the
first half of the upcoming week with gusts mainly between 25-30
kts over the outer waters. Winds are expected to be slightly
stronger on Tuesday, bringing 25+ kt winds into the bays... with
a chance for Gales to develop over the very outer waters. A
front crosses around midweek which will bring winds more
westerly or northerly for the balance of the week. Seas
meanwhile are expected to remain elevated between 5 and 10 feet
with a somewhat longer period of 10-12 sec until the mid- week
front crosses and seas begins to gradually diminish.

&&

.HYDROLOGY...
Flood watch remains in place across southeasternmost zones as a
period of heavy rain later this afternoon and evening may cause
urban and small stream flooding.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Winter Storm Warning until 6 AM EDT Sunday for MEZ007>009-
     012>014-018>022-024>028-033.
     Winter Weather Advisory until midnight EDT tonight for MEZ023.
     Flood Watch until midnight EDT tonight for MEZ023.
NH...Winter Storm Warning until 6 AM EDT Sunday for NHZ001>006.
     Winter Weather Advisory until midnight EDT tonight for NHZ012-
     013.
     Flood Watch until midnight EDT tonight for NHZ012>014.
     Winter Storm Warning until 5 AM EDT Sunday for NHZ007>011-015.
MARINE...Gale Warning until noon EDT Sunday for ANZ150.
     Gale Warning from midnight tonight to noon EDT Sunday for
     ANZ151-152-154.
     Small Craft Advisory until 11 AM EDT Sunday for ANZ153.

&&

$$
Cannon/Casey


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