379
FXUS63 KIND 122206 AAA
AFDIND

Area Forecast Discussion...UPDATED
National Weather Service Indianapolis IN
606 PM EDT Wed Jun 12 2024

.KEY MESSAGES...

- Quiet weather expected through much of the day Thursday, Warming
  trend continues with highs near 90F by Thursday

- Thunderstorms possible Thursday night...with possibly a few
  strong/severe cells north of I-70

- Hot and humid trend starts Sunday

&&

.FORECAST UPDATE...
Issued at 606 PM EDT Wed Jun 12 2024

Latest visible/DCP RGB satellite imagery shows cumulus field within
a narrow band of enhanced moisture just ahead of a cold front. Wake
subsidence behind departing shortwave perturbation is making for a
hostile environment for sustained deep convection, thus the large
"splotches" of cumulus are observed, typical of a strongly capped
environment. There may be a short window for an isolated convective
shower early this evening if the subsidence layer erodes
sufficiently toward the tail end of the diurnal maxima. Coverage
will be minimal if any showers do develop.

There is a cold pool-driven area of convection and attendant MCV over
southern Wisconsin. The downstream environment features modest
instability and shear, and may be supportive of sustenance a bit
longer than CAMs indicate, but the richer moisture/instability axis
is narrow and positions north of our area. So, it appears unlikely
any impact will occur later tonight from remnant MCS other than
high-level cloud debris.

&&

.SHORT TERM (This evening through Thursday)...
Issued at 301 PM EDT Wed Jun 12 2024

Expect quiet weather conditions to persist through the short term
period as surface high pressure remains in control. Latest surface
observations show the aforementioned high near southeastern Indiana
and Kentucky. A weak frontal boundary which moved into far NW
counties this morning has stalled. Earlier thoughts were that
daytime heating over this negligible convergence zone could be
enough to force a few light showers this evening. Confidence remains
very low in this scenario due to weak forcing. Will continue to
keep a dry forecast for this reason, but cannot completely rule out
a few light showers over far NW counties. Plentiful sunshine
combined with increasing southwesterly flow has allowed temperatures
to warm up considerably after a brief cooldown over the past few
days.

Good radiational cooling conditions tonight should allow for
temperatures to fall well into the 60s, possibly upper 50s in a few
spots over far S/SE portions of the area where winds will be nearly
calm. Temperatures will then warm into the upper 80s and possibly
low 90s for some location Thursday with increasing southwesterly
flow and mostly sunny skies. Thankfully dewpoints should remain in
the 50s, but this will likely be the hottest day of the year so far.
Some increase in mid-high clouds may be evident early in the day
from an upper level impulse moving over the northern Great Lakes
Region. Additional clouds are expected towards the evening as a
system approaches. Details on this system will be covered in the
extended period.

&&

.LONG TERM (Thursday night through Wednesday)...
Issued at 301 PM EDT Wed Jun 12 2024

Thursday night through Saturday...

The long term will begin with a conditional strong to severe t-storm
threat as convection expected to initiate late Thursday between the
Iowa/Illinois region matures to the west of central Indiana Thursday
evening...and then most likely slowly collapses while steadily
crossing Indiana in a southeasterly direction up to pre-dawn hours.
The front end of this convective cluster may bring a few marginally
strong/severe storms, focused near the Upper Wabash Valley...
although stronger gusts could make it as far as the I-70 corridor,
especially if storms started earlier Thursday and/or closer to the
CWA.  Otherwise this should be the most organized rainfall of the
forecast period...with most areas picking up 0.10-0.50 inches along
an overall NW/SE gradient, and perhaps isolated areas up to 0.75-
1.00 inches under one or two stronger/slower cells.  No flooding
concerns following recent drier pattern and rather brief window of
possibly steadier rain.

The remainder of this week will be marked by subtle relief from the
broader trend into a more summerlike pattern...as seasonably strong
Canadian surface high pressure following the Thu night wave...
crosses the Great lakes during Friday-Saturday, bringing lower
heights and H850 temperatures.  Corresponding modest northerly flow
will promote afternoon highs closer to the mid to upper 80s both
days, along with dewpoints that should hang in the 50s...providing
more of a June than July feel to start the weekend under ample
sunshine.

Sunday through Wednesday...

The broad subtropical upper ridge, building northward while slowly
crossing the CONUS through Saturday...will then envelope the Midwest
through at least the first several days of next week.  Latest
guidance is continuing to show stagnant upper troughiness settling
over the northwestern CONUS, which will further promote the ridge
building over the eastern half of North America as well as light to
moderate southerly surface flow into Indiana which will also serve
to boost dewpoints to at least moderate levels.  Surface
cyclogenesis expected to occur from the central High Plains to
western Ontario through the early week may help boost this breeze,
albeit while continuing to advect heat and humidity into the Midwest.

At least a few afternoon showers and t-storms will be possible amid
this hot/humid period when precipitable water values will be around
1.50 to 2.00 inches, although little confidence in location and
timing of any such disorganized convection, with little if any
forcing and any boundaries based on previous days` outflow. Bigger
story will be widespread high temperatures 90-95F, especially Sunday
and Monday when H850 temperatures will approach 20 Celsius.  Higher
dewpoints will promote maximum heat indices in the 90s to possibly
around 100F if any showers/scattered clouds could be dodged.  The
normal max/min at Indianapolis through the long term is 82/63.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 606 PM EDT Wed Jun 12 2024

Impacts:

- None.

Discussion:

VFR conditions will continue. Winds may vary slightly during the TAF
period by around 30 degrees or so with the dirunal cycle, but
generally southwesterly. Mixing may be enough for momentum transfer
and gusts up to around 15-20 knots Thursday afternoon.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

UPDATE...BRB
SHORT TERM...Melo
LONG TERM...AGM
AVIATION...BRB