333
FXUS63 KIND 011332
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
932 AM EDT Sat Jun 1 2024

.KEY MESSAGES...

- Showers and isolated thunderstorms Today

- Warming trend going into next week with periodic storm chances

- Long range 8-14 day outlook trending toward below normal
temperatures

&&

.FORECAST UPDATE...
Issued at 932 AM EDT Sat Jun 1 2024

Radar is indicating mainly light showers lifting north across the
lower Wabash Valley in isentropic upglide, displayed on the 305K
surface, and ahead of an upper wave that is currently progressing
east over the Ozarks. Stubborn dry layer seen in Hi-Res soundings
has slowed the eastward progress of the rain shield, so adjusted
to a later timing for PoPs over eastern locales.

Very weak instability and lightning detection suggests only very
isolated lightning strikes.

The thick cloud cover and rain will limit afternoon temperatures to
the upper 60s and lower 70s.

&&

.SHORT TERM (Today and tonight)...
Issued at 255 AM EDT Sat Jun 1 2024

Although subtle, the upper flow will begin transitioning out of
ridging and into a short wave troughing pattern over the next
several hours. Initially, this will push upper level cloud cover over
the Ohio Valley, but by early morning, broad lift out ahead of a
developing surface low will approach from the southwest.

At first, this lift and push northward of moisture will be mitigated
be an antecedent dry air mass. Currently, dew point depressions are
between 15 and 20 degrees. The lower 3km will slowly saturate
throughout the morning, eventually leading to scattered showers
pushing in from 10AM onwards. This lift will become stronger and
more concentrated later this afternoon within strong isentropic
ascent, leading to numerous showers across the state.

Generally, these showers will lack strong updrafts with
thermodynamic profiles remaining very saturated and nearly moist
adiabatic. There could be pockets of weak instability enough for a few
rumbles of embedded thunder, but most cells should remain lightning
free. Winds within this wave are also weak, but broad 15-20kt 850mb
flow could be mixed down occasionally within these showers. Given
the deep saturation of the thermodynamic profiles, some of these
showers could be fairly efficient rain produces, but most should be
categorized as moderate to light rain.

This low pressure system will begin to occlude later this afternoon
into the evening, and with this occlusion process, could push in a
relatively dry slot on over central Indiana. As this happens, shower
coverage should begin to wane slightly, but lightning coverage may
take a slight upward tick as mid level lapse rates drop. Eventually,
the broad lift will push far enough east, with ensembles means
ending rainfall around 10pm to midnight.

Total rainfall amounts are expected to be around 0.5" for most
areas, with localized amounts upwards of an inch. Increases low
clouds and rain during peak diurnal warming will inhibit temperature
gains today, with highs expected to be in the upper 60s to low 70s.

Confidence is currently low, but saturated soils and decreasing
winds beneath the low late Saturday night into Sunday morning could
lead to dense fog as stratus lowers over portions of southwestern
central Indiana. For now, patchy fog has been mentioned, but this
could be further increased as confidence increases.

&&

.LONG TERM (Sunday through Friday)...
Issued at 255 AM EDT Sat Jun 1 2024

Sunday

By Sunday, the low will become more diffuse as the upper level
forcing is pushed off to the north. This will most likely place a
weak boundary over southern Indiana. With the low less pronounced,
the bulk of the forcing will be gone and the upper stratus deck will
mix out to some degree. Even with minimal forcing, this weak
boundary could be enough for isolated thunderstorm coverage as we
break convective temperatures in the mid to late afternoon.
Outside of this, central Indiana should remain mostly dry. With
sunshine returning, highs should push back into the mid to upper
70s for most locations.

Monday Through Friday.

Forecast confidence quickly begins to fall off next week as the flow
aloft becomes much more stagnant and the pattern becomes more driven
by mesoscale factors that are very uncertain this far out. There
does look to be at least occasional showers and thunderstorms which
will generally be diurnally driven so will focus POPs highest in the
18Z to 00Z timeframe.  Surface flow will generally remain southerly
through the week which will keep temperatures just above normal with
much higher dewpoints of mid to upper 60s. A more deeply wrapped up
low looks likely towards the end of the week which should bring a
relief from the more humid air and warmth. The pattern favors the
potential for a few storm complexes across the Midwest but there is
low confidence that any will impact central Indiana.

Going into the latter portions of the week confidence is increasing
in colder temperatures moving back in with a strong upper level low
across the Great Lakes region bringing northwesterly flow at the
surface and aloft with lower confidence on the track and strength of
the low.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 646 AM EDT Sat Jun 1 2024

Impacts:

- Rain developing this morning

- IFR conditions by mid to late afternoon

- Small risk for embedded thunderstorms

Discussion:

Cirrus continues to steadily overspread central Indiana ahead of low
pressure system. Clouds will continue to thicken and lower this
morning but dry air will remain prevalent through the low levels
this morning.

A deeper surge of moisture advecting into the region from the south
will allow for showers to spread east through the mid and late
morning with widespread rain for the afternoon and evening. Model
soundings and RH progs show lower levels becoming saturated late day
with ceilings likely to dip quickly to MVFR and eventually IFR
within the steadier rainfall. Cannot rule out a few rumbles of
thunder but overall instability is minimal and will not mention at
the terminals. Winds will remain southeast through much of the
forecast period and may become sporadically gusty Saturday afternoon
as the surface wave approaches.

There is a growing concern of patchy dense fog tomorrow morning at
KHUF and KBMG. For now included a 1 hour group of 1mi to showcase
the threat.


&&

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

$$

UPDATE...MK
SHORT TERM...Updike
LONG TERM...White/Updike
AVIATION...Updike