-- Discussion containing changed information from previous version are highlighted. --
944
FXUS63 KIND 161648
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1248 PM EDT Sun Jun 16 2024

.KEY MESSAGES...

- Extended period of hot and humid conditions through next weekend

- Afternoon heat indices approaching 100 this week may be hazardous
to sensitive and vulnerable groups

- Isolated to scattered storms Monday and Tuesday afternoon

&&

.FORECAST UPDATE...
Issued at 957 AM EDT Sun Jun 16 2024

An area of mid cloud on the edge of the warmer air aloft is
currently moving through the western forecast area. These clouds
will continue to push east across the area as the warm air arrives.
Adjusted sky cover as needed, but still expect a lot of sun today.

Winds are still southeast, so the better warm advection won`t arrive
until later today when winds become southerly. Tweaked temperatures
a bit for now but made no significant changes. Will continue to
watch temperatures closely and see if any temperatures will need to
be tweaked down if the warmer air takes longer to arrive than
expected.

&&

.SHORT TERM (Today and tonight)...
Issued at 306 AM EDT Sun Jun 16 2024

Today and Tonight...

The well advertised heat and humidity arrives today as a strong
ridge becomes established across the Southeastern US with surface
high pressure centered around Cape Cod. Southerly to southwest flow
through the atmospheric column will pump in a hot and humid airmass
northward from the Gulf resulting in noticeably rising dew points
through the day. Humidity values may level off during the afternoon
as deep mixing into a dry layer around 1-2km agl offsets strong
moisture advection. Nonetheless, humidity values will be noticeably
higher than the previous few days with dew points possibly reaching
70 by early in the week. Highs today will reach the lower 90s for
most locations with mid 90s possible for portions of southwestern
Indiana.

Continued warm and moist air advection with slightly elevated winds
overnight will work to keep temperatures from falling much during
the overnight hours. Tonight`s lows may not fall below the low to
mid 70s.

&&

.LONG TERM (Monday through Saturday)...
Issued at 306 AM EDT Sun Jun 16 2024

Hot and Humid Much of Next Week...

An extended period of hot and humid conditions persists into next
weekend with daily highs in the 90s and heat indices approaching
100 degrees.

Monday looks to be the hottest day with highs potentially reaching
the mid 90s for much of Central Indiana. With such a hot and humid
and unstable airmass in place, a few pop up storms are not out of
the question on Monday. Forecast soundings show steep low and mid
level lapse rates with sufficient moisture and little capping. Once
convective temperatures are reached mid to late afternoon, expect
isolated to scattered storms to develop. Forcing and shear are
relatively weak, so any storm that does form likely will be slow
moving and short lived. Most locations will likely remain dry, so do
not expect storms to bring much relief to the heat. In fact, any
area that does see a brief storm will likely have very humid
conditions afterwards resulting in higher heat index values. Max
heat indices Monday will likely be in the 98 to 103 degree range.
While this does not meet criteria for a heat advisory locally,
sensitive and vulnerable groups should take the necessary precautions
to avoid the potentially hazardous temperatures.

For Tuesday and somewhat into Wednesday, a plume of deeper moisture
will move north on the back side of the upper high into the area.
This will likely result in an increase in cloud cover. Also, mid
level temperatures will remain cool enough that some isolated to
scattered convection will pop-up, especially west where the deeper
moisture will be. The combination of clouds and convection will keep
temperatures cooler than Monday, but still hot in the upper 80s to
lower 90s. High humidity values will likely result in heat indices
in the mid 90s to near 100 degrees during the afternoon hours.

Lower confidence for high temperatures Tuesday and Wednesday (with
models showing a wide spread in between 25th and 75th percentiles on
temperatures) precludes any issuance of excessive heat products at
this time. However, will still have to keep a close eye on the
cumulative effects of the heat this week.

For Thursday into Friday, the upper high will expand west into the
area, bringing back temperatures in the mid 90s. Dewpoints may be
lower thanks to the moisture plume being pushed west, but it may not
take much to have heat indices to around 100. The upper high may
start to break down on Saturday and beyond, but models differ on
timing and how much it breaks down. For now will continue with highs
in the 90s, but with lower confidence.

&&

.AVIATION (18Z TAF Issuance)...
-- Changed Discussion --
Issued at 1248 PM EDT Sun Jun 16 2024

Impacts:

- None

Discussion:

Few to scattered VFR cumulus and some mid cloud will be around this
afternoon, then high clouds are expected tonight. Additional cumulus
will pop up on Monday. Isolated to scattered convection is possible
Monday afternoon, but odds are too low to mention that far out.

A few wind gusts to around 15kt are possible this afternoon.
-- End Changed Discussion --

&&

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

$$

UPDATE...50
SHORT TERM...CM
LONG TERM...CM
AVIATION...50