204
FXUS61 KGYX 291335 AAA
AFDGYX

Area Forecast Discussion...UPDATED
National Weather Service Gray ME
935 AM EDT Sat Jun 29 2024

.SYNOPSIS...
A warm front will approach from the west today as high pressure
drifts away from the area. This front will bring increasing
clouds along with chances for showers and embedded thunder late
this afternoon and tonight. A cold front crosses Sunday bring
scattered strong to severe thunderstorms. High pressure builds
in Monday and Tuesday for fair weather into the middle of next
week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
930 AM update: A few sprinkles have pushed across southern NH
into western ME this morning /even here at the WFO/ as
relatively robust radar returns work against a substantial dry
H8-7 layer on the 12Z GYX raob. Boosted cloud cover base on
morning GOES 16 visible satellite imagery...but other than
these sprinkles...expect cloudy but dry conditions through the
morning with more showers pushing in from the west /now over
central NY/ this afternoon. Remainder of the forecast including
high temperatures look good.

635 AM Update...Latest radar shows healthier returns moving
into western NH with surface obs confirming this precipitation
is reaching the ground. Have therefore increased PoPs across NH
into far western Maine through this morning to account for these
trends. Otherwise have tweaked T/Tds to capture the latest
round of observations.

Previously...

Latest water vapor imagery shows a short wave crossing Minnesota
early this morning with mainly zonal flow across the eastern
Great Lakes into New England. At the surface high pressure
centered east of Cape Cod will drift eastward today while a
warm front approaches from the west. The approaching front will
allow for clouds to thicken and lower through today. Latest
radar shows weak returns over much of New England while ample
dry air aloft around 700 mb noted on the 00Z KGYX sounding and
at the surface is limiting this precipitation to reach the
ground.

Moisture advection will continue through today allowing for the
atmosphere to saturate enough for showers to break out west to
east late this morning into this evening. As has been mentioned
over the past few forecast cycles, deep moisture will become
quite impressive tonight with PWATs climbing to 1.75 to 2.25
inches along with warm cloud depths greater than 12kFT and
increasing elevated instability. These ingredients combined will
favor heavy rainfall rates while forcing for ascent will be weak
while these ingredients are in place. The 00Z HREF maximum
24-hour QPF ending Sunday morning paints much of the area with
less than 1.25 inches while the HREF mean is only around 0.5
inches. The exception here is in the mountains where there could
be localized amounts greater than 1.5 inches. Therefore, the
overall threat for flooding with rainfall today through tonight
is low, while it should be monitored given the heavy rainfall
ingredients. Otherwise, today will feature mostly cloudy skies
with increasing chances for showers west to east with highs in
the 60s and 70s north to south.

Widespread showers with embedded thunder area likely tonight
with increasing humidity bringing the potential for patchy fog.
The warm front and associated forcing will lift northeast of the
area Sunday morning reducing the chances for showers towards day
break. Lows tonight will range from the mid 50s to upper 60s
north to south.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
The 00Z CAM suite is in decent agreement that much of the area
will start off Sunday with little in the way of shower activity
as the forecast area becomes enveloped within the warm sector of
low pressure moving through Quebec. Dewpoints are modeled to
rise into the upper 60s to low 70s through Sunday morning while
breaks in the clouds will allow for surface heating. The 00Z
HREF suggests there will be sufficient destabilization with
mean MU CAPE climbing to 1500-2000 J/kg by early afternoon. All
the while a vort max will be racing across Quebec with a cold
front crossing the region Sunday afternoon. The plume of MU CAPE
will be well placed beneath a corridor of deep layer shear of
40-50 kts, which will be more than sufficient for organized
convection across the area. The 00Z is quiet bullish with
scattered convection with strong rotating updrafts developing
from the Canadian Border through SW New Hampshire with these
storms tracking ESE to the coast. This has resulted in SPC
expanding the Slight Risk across all of Maine and much of New
Hampshire, with just portions of far NW New Hampshire in the
Marginal Risk. The primary threat will be damaging winds while
less than impressive mid level lapse rates will make hail a
secondary threat. Low level winds look to be mainly out of the
SW with mainly straight hodographs limiting the potential for
spin-ups, although some backed flow near the coastal plain
brings a non- zero threat.

In addition to building humidity temperatures will climb into
the low to mid 80s with the added humidity bringing heat
indices close to 90F. Storms look to clear the coast by 00Z
Monday.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
I suppose its safe to say we have worked our way into a typical
summer pattern as 500 MB ridging take residence S of the Mason-
Dixon line, and troughs in north-shifted jet stream. Are
generally flatter and more mobile. We start off a little on the
cool side but the trend will be fore warming to near and above
normal 850 MB temps by mid to late week. The tricky part is what
becomes of the closed low that shifts to our SE late in the
week and whether it acts as a block to allow S_SW flow to
settle, making for another round of hot/humid weather or keep
flow more zonal which will lead to more typical summer wx. As
for chances of shra/tsra, beyond Sunday, we do see some of wave
move to our N around Wed-Thu.

The cold front will push offshore Sunday night with cooler and
drier air moving in at least for Mon- Tue, with highs a little
below normal on Monday, but nice otherwise, and warming back to
near normal on Tuesday. Wed will be warmer still with a bit of
increase in humidity, but should stay dry most of the day.
Wednesday night and Thursday are the next chance of precip, but
theres still a lot of uncertainty with this weaker system.

&&

.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
Short Term...Clouds thicken and lower from west to east today
with conditions dropping to MVFR and then IFR tonight. Scattered
rain showers are likely late this afternoon and overnight with
embedded thunder. Conditions improve Sunday morning before a
cold front brings strong to severe storms tracking WNW to ESE
across the area between 18Z Sunday and 00Z Monday.


Long Term...Mainly VFR Mon-Wed. Also valley fog possible at
KHIE/KLEB Sun and Mon night.

&&

.MARINE...
Short Term...High pressure moves east of the waters today with
increasing southerly flow bringing SCA conditions from this
afternoon through Sunday. A cold front crosses the waters Sunday
evening bringing the threat for strong storms tracking into the
waters.

Long Term...SW winds drop off Sun night, and stay below SCA
levels through mid-week.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 4 PM EDT Sunday for ANZ150>154.

&&

$$

SYNOPSIS...
NEAR TERM...Arnott/Schroeter
SHORT TERM...Schroeter
LONG TERM...
AVIATION...
MARINE...