380
FXUS61 KGYX 231027
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
627 AM EDT Sun Jun 23 2024

.SYNOPSIS...
A stationary front lifts northward into New Hampshire today as
a warm front. There is a slight to enhanced risk of severe
thunderstorms across the area today, especially in New Hampshire,
with the risk of a few tornadoes and damaging winds being the
primary concerns. A cold front will then cross Sunday night and
Monday with additional unsettled weather before high pressure
builds in by Tuesday, bringing drier conditions. Temperatures
moderate through the middle of the week, with another cold front
bringing showers and storms late Wednesday. High pressure then
builds in late in the week, bringing drier and cooler
conditions.

&&

.NEAR TERM /THROUGH TONIGHT/...
620 AM Update...WAA continues across the region this morning
with elevated convection in the form of scattered heavy showers
with embedded thunder moving northeastward through southeastern
NH as of this writing. Other activity will shortly move into
western NH and likely move across the state into ME over the
next few hours. Heavy downpours will be the main threat. No
changes to the forecast for this afternoon and evening`s
probable severe weather event.

Previously...

Slight risk for severe weather remains in effect for the
forecast area, with an enhanced risk remaining in effect for
most of New Hampshire.

SFC warm front remain well to the south and west of the forecast
area as of 07z early this morning, snaking its way from just
south of Lake Ontario southeastward to Long Island NY and
Southern CT. This front will be a key player in our convective
storms outcome this afternoon.

A southwesterly LLJ continues to increase above the SFC this
morning, and the forcing for ascent aided by upglide up the
elevated frontal surface continues to produce areas of showers
with embedded thunderstorms across the forecast area all the way
west to eastern Lake Ontario. This forcing should continue into
much of the morning meaning occasional batches of showers with
embedded thunder moving eastward across the forecast area from
time to time with locally heavy downpours. This activity will
probably hinder the northward progress of the SFC warm front
some, and probably delay its arrival into our CWA until late
morning or even midday across southernmost NH.

The movement of the warm front will aid in determining how
widespread severe storms will be in our forecast area this
afternoon, as SFC temps will only be in the 60s north of the
frontal boundary and therefore a bit too stable for widespread
severe. CAM consensus is that the front will make to at least a
KLEB-KDAW line by 19z or 20z this afternoon setting the stage
for a fairly impressive severe weather environment near and
south of the front. Across northern NH, the chances for severe
increase as well, but will have to watch how long the
stabilizing effect of showers lasts.

As far as timing of the main activity goes, we thinking we`ll
see storms knocking on the CT River door between 18z and 20z,
continuing to move rapidly eastward thereafter. Linear forcing
will make the potential for widespread wind damage the main
threat with these storms, especially in the ENH risk area.
However, forecast hodographs near and south of the warm front
support a few tornadoes, supercellular or the QLCS variety,
with 0-1 KM SRH values in excess of 200 M^2/S^2 in the midst of
SFC based CAPE possibly approaching or exceeding 2000 J/KG.

The threat for severe weather will diminish with eastward and
northern extent as they depart NH. However, with a strong
southwesterly LLJ in place, a favorable air mass for severe
could be transported to the southern ME coast ahead of the
storms between 22z-00z, allowing for a threat for wind damage
even there.

In conclusion, a fairly robust severe weather day is supported
by the latest guidance. However, for some of the CWA this will
be conditional on sufficient heating to build CAPE, and this
could be hindered by lagging pre-event showers and thunderstorms
and/or slower northward warm frontal progress. Mesoscale
analysis will be key today.

Localized flash flooding will be a possibility with training
storms today.

Storms sweep offshore this evening yielding a pretty mild night
with lows in the 60s. Areas of fog, locally dense will be
possible.

&&

.SHORT TERM /MONDAY/...
Upper level low pressure moves overhead on Monday along with an
attendant SFC low. Cold temperatures aloft working in tandem
with dewpoints in the 60s should support an environment for
late morning and afternoon showers and thunderstorms, some with
gusty winds and hail. The main threat would be from the Midcoast
of ME northward and northwestward to the foothills and
mountains.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Overview...

Tuesday looks mostly dry with dew points still mainly in the
50s, but temperatures rebound into the 80s in most spots, to
near 90 across southern areas. Wednesday turns more humid with
southwesterly flow, and temps warming into the mid 80s to low
90s in most spots. A cold front approaches during the day on
Wednesday, with scattered showers and storms likely late in the
day and into Wednesday night. The front may take into Thursday
morning to fully clear the area, with high pressure building in
by late in the day Thursday.

This area of high pressure builds in from Canada, bringing much
drier and sunnier conditions to the area. Temperatures also
look quite seasonable with the high, with daytime highs in the
upper 70s to mid 80s Thursday and Friday, and lows mainly in the
50s at night. Temperatures and humidity likely begin to
increase again by next weekend and the high moves offshore and
brings a return to the southwesterly flow.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
Short Term...Low cigs, SHRA and fog will likely bring widespread
IFR/LIFR through this morning. Low cigs and reduced vsby will
likely impact KAUG, KRKD for much of the day today with PWM
improving this afternoon. Elsewhere, cigs should lift through
the morning before a cold front brings multiple rounds of TSRA
this afternoon and evening. These storms will bring the threat
of severe weather and flight restrictions are likely at times.
IFR to LIFR is likely tonight in lowering cigs and fog as drier
air does not arrive until Monday. Scattered afternoon showers
and thunderstorms are expected Monday.


Long Term...VFR conditions prevail from Monday night into
Wednesday. Nighttime valley fog will be possible, especially at
LEB and HIE. Showers and storms are then likely late Wednesday
and Wednesday night, with brief restrictions at times. VFR
returns on Thursday and prevails into the weekend.

&&

.MARINE...
Short Term...Southerly flow increases today with winds and seas
bringing SCA conditions by this afternoon. A cold front crosses
tonight with strong thunderstorms possible this evening.
Thunderstorms diminish as the evening progresses while elevated
seas maintain SCA conditions into Monday morning.

Long Term...Lingering seas greater then 5ft are possible into
Monday as a cold front clears the waters, with high pressure
building in for Tuesday. The high shifts east by Wednesday, with
SCA conditions possible in increasing southwesterly flow ahead
of an approaching cold front. The front crosses the waters
Wednesday and into Thursday, high pressure building in behind
the front for late in the week.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory from 5 PM this afternoon to 8 PM EDT
     Monday for ANZ150>152-154.

&&

$$


NEAR TERM...Ekster
SHORT TERM...Ekster
LONG TERM...Clair/Cornwell/Ekster