155
FXUS63 KIND 151334
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
934 AM EDT Sat Jun 15 2024

.KEY MESSAGES...

- Dry weather with seasonable temperatures today

- Hot and humid trend starts Sunday...increasing confidence in
  potentially hazardous heat into next week

- Low chance for a few showers or storms Monday and Tuesday

&&

.FORECAST UPDATE...
Issued at 934 AM EDT Sat Jun 15 2024

Forecast is on track this morning. High pressure will continue to
bring dry conditions, with dewpoints mainly in the 50s (some 40s
will occur east).

Cirrus will move in at times, mainly north, but overall skies will
remain sunny to mostly sunny today. Seasonable temperatures still
look good for highs today.

&&

.SHORT TERM (Today and Tonight)...
Issued at 300 AM EDT Sat Jun 15 2024

Largely clear skies present across central Indiana early this
morning...with just some thin cirrus cresting the approaching ridge
and drifting across the region. 06Z temperatures were comfortable in
the 60s.

Quiet weather will continue through tonight with high pressure
passing by to the north across the Great Lakes and an expanding
upper ridge combining to maintain dry conditions and mostly clear
skies. While it will be warm across the forecast area today...it
will be seasonable as subsidence remains across much of the Ohio
Valley. This will be the last day however before the long discussed
transition to hotter and more humid air beginning Sunday and
continuing through the upcoming week.

Light and variable winds this morning will veer to an easterly
direction by daybreak...then to southeast throughout much of today
as the center of the aforementioned high pressure over the Great
Lakes shifts east. A deeper area of subsidence will shift around the
base of the high and into the region from the east this afternoon
which should largely mitigate any diurnal cu. This will also keep
dewpoints  and RH values low throughout the day. Mixing levels
peaking at near 6kft this afternoon and a modest surface pressure
gradient should be sufficient to generate periodic gusts to near
20mph during peak heating.

Cirrus will continue to periodically drift overtop of the ridge
aloft but should see even that diminish as the ridge axis centers
across the Ohio Valley tonight. Surface flow will remain from the
southeast tonight with the onset of a deeper plume of more humid air
set to arrive during the day Sunday as return flow develops behind
the departing high. More on this and the heat and humidity upcoming
in the Long Term section below.

Temps...a cooler start this morning and slightly lower low level
thermals supports highs generally in the low to mid 80s over much of
the forecast area...with warmest temps potentially into the upper
80s in the lower Wabash Valley. Lows tonight will range from the
upper 50s east to mid 60s west.

&&

.LONG TERM (Sunday through Friday)...
Issued at 300 AM EDT Sat Jun 15 2024

Saturday night through Next Week

**Increasing confidence in an extended period of very hot and humid
conditions Sunday through much of next week**

The main story in the extended period will be the very hot
temperatures building across much of the eastern CONUS Sunday and
persisting through next week. Upper ridging initially centered over
the Great Lakes region Saturday night is expected to amplify and
become centered over the Northeast by early next week. At the
surface, high pressure should gradually shift east before settling
near or just off the Northeast coast supporting southerly flow back
across the Ohio Valley. Increasing heights aloft combined with
return flow will result in temperatures quickly warming up into the
90s at the beginning of the long term period. In addition, look for
humidity to be on the rise which raises concern for dangerous heat
indices near or above 100F by Monday.

Most guidance shows upper ridging remaining the dominant influence
through much of the period though the ridge may begin to flatten
late next week as a few troughs traverse far northern portions of
the Great Lakes or Canada. Unfortunately, there appears to be little
relief from the heat during this period and overnight lows are only
expected to fall into the 70s. The extended stretch of heat this
early in the season is abnormal so make sure to stay hydrated and
take frequent breaks in air conditioning if you are outdoors.

Increasing moisture from southerly flow combined with daytime
heating supports at least low end chances for showers and storms
most days. The strongest subsidence from the upper ridge/surface
high should be focused further east of the area suggesting capping
should not be an issue. Some models show ridging breaking down late
next week allowing for a system to move in, but diverging model
solutions leads to low confidence for this scenario.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 548 AM EDT Sat Jun 15 2024

Impacts:

- None

Discussion:

High pressure over the Great Lakes will serve as the dominant
feature through tonight with mainly clear skies and just periodic
cirrus drifting through the region overtop of the expanding upper
level ridge. Winds will become southeast later this morning and
remain there through early Sunday.


&&

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

$$

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