Scientific Forecaster Discussion
fxus61 kgyx 180752
Area forecast discussion
National Weather Service Gray ME
352 am EDT sun Aug 18 2019
a warm front will approach from the west today and will lift
north of the region tonight. Hot and humid weather will return
on Monday and Monday night as a weak frontal boundary settles
south through the region. Stalled frontal boundary over southern
New England will be the focus for showers and thunderstorms
late Tuesday and Tuesday night as it lifts back to the north. A
stronger cold front will approach from the west on Wednesday and
will slowly cross the region Wednesday night and Thursday. High
pressure will build in from the west for the end of the week.
Near term /until 6 PM this evening/...
the continued onslaught of weak onshore flow continue this
morning, but there's some gradual changes in store starting
today. The strong line of convection that moved through NH last
evening is well into ern ME, and there are a few sct weaker rain showers
behind this in central ME but these should move out by 10z or so
Today will start off with the low clouds and fog in place, but
in the wake of the wave that moved thru overnight, the weak flow
veers a little more S-SW, and this should help most of the County Warning Area
se more sun today. Given the weak flow, it;ll happen slowly, and
coastal are cloudy until midday to early afternoon, while
inland areas should see some sun mid-late morning. 850 temps
push up to 15-16 c across the srn half of New Hampshire and into SW ME, so
inland areas should see highs in the low-mid 80s, as will the CT
Vly. Coastal areas and central ME will be slower to see
clearing and highs will be in the 70s, but still warmer than
Sat. Tds will be in the mid-uppr 60s, so it'll be humid this
afternoon as well.
Another 500 mb will approach from the west this afternoon, but
will weaken as it moves into New England. Cannot rule out a few
rain showers/thunderstorms and rain in the west developing ahead of the wave, but think
the better chc of convection will be this evening, as we will
subsidence aloft working again any instability thru much of the
Short term /6 PM this evening through 6 PM Monday/...
should see some convection moving into the County Warning Area from the west
this evening. Although instability and thermodynamics look good
this afternoon, the dynamic forcing and weakening of the cap
look like it will come too late in the day to develop any
strong over the County Warning Area. It is possible that strong storms, move
into New Hampshire from the west this evening, but these look to weaken as
they move into cwa, and become slightly elevated convection.
They will continue to weaken as they head east overnight though.
Look for another round of fog and low stratus as this next wave
briefly shifts back onshore just in time for evening.. lows
will be mostly in the mid to upper 60s given the higher tds.
Behind the exiting wave and ahead of the next wave which moves
thru Mon night will see SW flow increase enuf to allow sun in
all areas by mid-late morning. 850 mb temps rise to 16-19c
across the cwa, and this will allow for a hot and humid day
across much of the cwa, with highs generally 85-90, although it
will be cooler in the ME mtns and on the mid-coast, tds will be
in the upper 60s to low 70s, so it will feel worse with
apparent temps rising to 90-95 in many spots, and especially in
interior srn NH, where a heat advisory may be needed.
Instability will be high so cannot rule an isolated airmass thunderstorms and rain
in the afternoon, and the next wave will be approaching form
the NW, so there is a better chc for thunder in the mtns late in
the day, but again think most of any precip will hold off until
evening. Despite high cape, vertical shear not all that
impressive, and good capping will have to be overcome by the
wave which looks like it won't do much until after Max heating
Long term /Monday night through Saturday/...
showers and thunderstorms will gradually end Monday evening with
loss of heating. Expect clearing overnight as weak frontal
boundary settles into southern New England, stalling there by
Tuesday morning. Lows overnight will range through the 60s.
Modest ridging will build into the region from the west on
Tuesday along with lower dew points. Looking for mostly sunny
skies across most of the forecast area. May see enough
instability and moisture in far southern New Hampshire for a
stray afternoon shower or thunderstorm but most of this activity
should remain to the south and west. High on Tuesday will range
from the upper 70s to mid 80s north and mid 80s to near 90 south.
Another in a series of shortwaves will move into southern New
England Tuesday night and will spread showers and some
thunderstorms into southern New Hampshire and adjacent southern
Maine overnight. Models showing some differences in northward
extent or precipitation and amounts with the GFS wetter and
farther north. With pwat's approaching 1.5 to 2 inches in
southern New Hampshire and Maine will be leaning toward the
wetter GFS solution for pops. Lows overnight will range from
the mid 50s north to the mid 60s south.
Rain will shift east out of southern Maine Wednesday morning
with partial clearing from west to east in the afternoon. At
the same time a cold front will approach from the west in the
afternoon. Will see some moderate cape develop over western
zones in the afternoon but narrow band of drier air behind
departing shortwave may inhibit convective development. High
temperatures will generally range through the 80s.
Strong shortwave digging into the northern Great Lakes
Wednesday night will drive a potent cold front toward the
region. Although timing of the front is not ideal...shear
values will rapidly increase Wednesday evening and overnight
and any stronger convective cells would certainly have the
potential to produce wind damage. Low temperatures overnight
will bottom out in the lower to mid 60s.
Cold front will push offshore early Thursday with skies
clearing briefly during the morning hours. Deep upper trough
swinging in from the west will likely produce another round
of showers and thunderstorms as heights crash and lapse rates
steepen considerably in the afternoon. Strong shear will also
create the potential for wind damage with stronger cells...
mainly in northern zones. Highs will range through the 70s
north and lower to mid 80s south.
Much cooler and drier air will stream into the region on a
stiff northwest flow Thursday night. Looking for variable
clouds in the north and mostly clear skies elsewhere.
High pressure will gradually build in from the west Friday
through Saturday with seasonable temps and low humidity.
Aviation /07z Sunday through Thursday/...
short term...again we deal with low clouds and fog this morning.
However, I think inland areas should see VFR by mid morning or
so, with coastal terminals breaking out early this afternoon.
Krkd may get stuck in the marine lyr all day. We'll fall back
into the murk again tonight, but should see faster improvement
to VFR on Monday morning.
Long term...VFR Monday night with areas of IFR/LIFR ceilings and
vsby in morning valley fog. VFR Tuesday. Areas of MVFR ceilings
Tuesday night into Wednesday morning in showers and
thunderstorms. VFR Wednesday with areas of MVFR ceilings/vsby in
afternoon and evening thunderstorms. VFR Thursday.
short term...areas of fog could reduce vis to around mile or
lower at times through tonight, but otherwise winds/seas stay
blo Small Craft Advisory criteria.
Long term...no problems noted.