898
FXUS63 KIND 121724
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
124 PM EDT Wed Jun 12 2024

.KEY MESSAGES...

- Warming trend begins today with highs in the mid 80s, highs near
  90 for Thursday

- Thunderstorms, a few strong or severe, are possible Thursday night

- Hot and humid starting Sunday

&&

.FORECAST UPDATE...
Issued at 956 AM EDT Wed Jun 12 2024

The forecast remains in good shape with only minor adjustments
needed. Expect quiet weather conditions today as surface high
pressure remains in control. There is a low (10%) chance for
an isolated light shower this morning over far NW portions of
central Indiana over the next hour or two due to an approaching
weak frontal boundary. This weak boundary will stall near NW
Indiana which could allow for a few additional light diurnal
showers to develop towards this evening.

Confidence in precipitation is very low given weak forcing and
subtle moisture. Will hold off on any mentionable POPs for later
today, but slight POPs may need to be added in future updates.
Increasing southwesterly flow combined with mostly sunny skies
will warm temperatures into the 80s this afternoon.

&&

.SHORT TERM (Today and tonight)...
Issued at 305 AM EDT Wed Jun 12 2024

Surface analysis shows high pressure directly overhead. Winds
have gone largely calm, and large-scale subsidence along with a
mainly dry column has been eroding cloud cover through the evening.
Additionally, the system responsible for the cloud cover is pulling
away to our northeast. As such, continued clearing and excellent
radiational cooling conditions should prevail through sunrise.
Despite this, temps are running about 10 degrees above where they
were last night since the core of colder air aloft is now to our
east.

With high pressure largely in control, we can expect quiet weather
for the most part. Only a few high clouds may pass by at times and
perhaps some diurnal cumulus may develop by the afternoon.
Otherwise, surface winds become southwesterly as the high shifts
eastward. A tightening surface pressure gradient looks to develop
just to our northwest as a system impinges on the departing high.
This may allow for some higher speeds and occasional gusts from
about Lafayette northwestward. Winds still remain on the lighter
side, regardless...with highest gusts hitting 20mph at most. Warmer
winds from the southwest lead to even higher temperatures today with
most places climbing into the middle 80s.

High-res guidance is hinting at a weak convergent zone developing
across northern Indiana late this afternoon. Additionally, they show
a plume of higher dew points advecting northeastward along this
boundary. Some members show dew points climbing into the lower 60s
across northwestern portions of the area by evening (dew points in
the 50s elsewhere). Model soundings show a dry column above 850mb,
but enough near-surface moisture for limited instability along this
boundary. Interestingly enough, multiple HREF members hint at
isolated showers developing from around Lafayette northward around
22z. Probability of occurrence seems low (10-15 percent), due to
limited forcing and instability...and if any shower develops is
should be fairly shallow and short-lived.

By tonight, expect any showers that manage to form to diminish
quickly after sunset. Diminishing surface winds should retain a
southwesterly component...but may go light and variable south and
east of I-70. High clouds may pass through at times as debris cirrus
from upstream convection drifts southeastward. Warmer lows more
typical of June are expected with values dropping into the low 60s,
with a few areas of upper 50s across our far southeast.

&&

.LONG TERM (Thursday through Tuesday)...
Issued at 305 AM EDT Wed Jun 12 2024

Thursday Through Friday night.

The northwest flow regime will continue aloft through Friday night
which will keep it mostly dry. However, models hint at the potential
for an MCS to move across central Indiana Thursday night. Even if
one doesn`t develop and move through, a cold front will be diving
southeast across the area Thursday night and the combo of lift
associated with that along with models supporting moderate
instability with CAPEs to over 1500 J/kg supports 30+ chance PoPs
Thursday night.

If an MCS would develop, Corfidi vectors favor a southeast moving
complex. Weak surface pressure gradient suggests low level inflow
into the system will be minimal, however 50 knot deep shear and
veering with height to go with the moderate instability supports the
Spc Day2 Marginal and Slight Risks over northern and western parts
of central Indiana with damaging winds and possibly large hail the
main threats.It is too early to diagnose mesoscale details,
including cold pool/shear balance. So, confidence is low on timing
and coverage of convection.

As the surface ridge aligns SW-NE along and south of the Ohio River,
temperatures will gradually warm to near 90 degrees by Thursday.
Meanwhile, potential cold front passage looks like it will result in
Friday being not quite as warm with timing considerations key.
Confidence is trending on the not as warm side.

Saturday Through Wednesday.

The main concern later in the weekend and next week will be the heat
and humidity as an upper ridge builds overhead and then shifts east.
At the same time, southerly low level flow will return to the Ohio
Valley and Great Lakes. The return flow around the high is likely to
result in dew points increasing to the upper 60s and perhaps lower
70s by Monday and with little cloud cover and continued southerly
inflow under the influence of the ridge, temperatures could easily
reach the lower 90s if not Sunday then Monday. With the increased
moisture and instability, can not rule out isolated mainly diurnal
pop ups. Models and ensembles are having problems resolving
northeastward moving upper waves around the back side of the ridge
but there is enough there to at least suggest a few storms can not
be ruled out next week.

This time period will need to the be looked at for potential future
headlines. For now, will broadbrush it in the HWO and keep a weather
story graphic going.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 121 PM EDT Wed Jun 12 2024

Impacts:

- None.

Discussion:

VFR conditions are expected through the TAF period as surface high
pressure remains in control. Look for light south/southwesterly
winds to persist through tonight before increasing on Thursday.

Showers and thunderstorms are possible at all terminals beyond the
end of the TAF period Thursday night. Temporarily poor flying
conditions (MVFR or lower) are possible within any storm.

&&

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

$$

UPDATE...Melo
SHORT TERM...Eckhoff
LONG TERM...MK
AVIATION...Melo