005
FXUS63 KIND 030546
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
146 AM EDT Mon Jun 3 2024

.KEY MESSAGES...

- Potential for patchy fog Monday morning

- Warmer next week with periodic thunderstorm chances.
  The best chances will be Wednesday.

- Below normal temperatures in the 70s late week into the weekend

&&

.FORECAST UPDATE...
Issued at 1016 PM EDT Sun Jun 2 2024

Clouds have diminished substantially over the past few hours and
skies are now mainly clear across the CWA. Some pockets of cloud
cover remain across southeast portions of the CWA, but these will
likewise continue to diminish.

Our primary forecast challenge during the overnight hours will be
fog development and coverage. There are fairly strong signals
within guidance that fog will develop, especially across
southeastern parts of Indiana and near/in the Wabash Valley.
Guidance is in less agreement regarding dense fog but a weak
signal exists here too. We will maintain the mention of patchy fog
for the entirety of the area for now. Dense fog would be most
probable in typically fog-prone locations.

A weakening upstream convective complex across southeast Oklahoma
and northeastern Texas is spreading cirrus north and east.
We are currently expecting this convective debris to thin as it
heads eastward into a region of subsidence associated with weak
ridging. As such, some high cirrus is possible during the
overnight hours but should remain thin and not be much of a
mitigating factor for fog development.

&&

.SHORT TERM (This evening through Monday)...
Issued at 240 PM EDT Sun Jun 2 2024

.Tonight...

The stratus has been slow to depart through early afternoon as Hi-
Res soundings were indicating a deep saturated or near saturated
boundary layer with winds less than 10 knots in that layer. This is
certainly not ideal for the dry air aloft to completely mix down. In
addition, a dissipating low pressure system was moving east across
central Indiana and this and the moist boundary layer have been
responsible for a few light showers and or sprinkles. In addition,
LAPS and SPC mesoanalysis data was showing CAPEs up to 1200 J/kg
over south central sections of central Indiana. So, will keep
thunder chances going for a few more hours. Lack of forcing and
shear along with upper ridging suggests coverage will be 20% or less
and any storm cells that do develop will not last long.

Should see a gradual improvement in sky cover late today and
especially this evening. However, there will be enough moisture in
the boundary layer overnight combined with very light to calm winds
to produce at least patches of low clouds and or fog. Assuming some
low cloud cover and fog, temperatures will not make it any cooler
than the upper 50s and lower 60s. It could get a few degrees cooler
if sky cover and fog are not present.

.Monday...

Winds will shift to the south Monday in the wake of a warm front
lifting northeast. Meanwhile, Hi-Res soundings are showing nice
drying, even in the lower levels. So, should see a good degree of
sunshine by mid morning and perhaps only some passing high clouds
and scattered fair weather diurnal cu. However, would not be shocked
if convection makes it as far east as the upper Wabash Valley late
in the day ahead of an upper wave that will be lifting northeast
across the Ozarks.

Temperatures will be much warmer Monday with the increased sunshine
and southerly low level winds. DESI 25th and 75th percentile spreads
are rather small giving good confidence on highs near the 2m max
temperatures in the middle to upper 80s to be realized.

&&

.LONG TERM (Monday night through Sunday)...
Issued at 240 PM EDT Sun Jun 2 2024

The long range forecast is active through the middle of the week
with cooler weather arriving by the weekend.

Tuesday through Wednesday...

The first round of storm chances arrive on Tuesday ahead of a
weakening upper trough and mid level wave approaching from the south
and west. This system will be in the process of being absorbed by a
much stronger negatively tilted upper trough in Southern Canada and
the Northern Plains. While the best dynamics, forcing, and wind
energy will be further north and west of the region, the potential
is there for mesoscale boundaries and waves within the warm,
unstable environment to be the main forcing for convective
development Tuesday. Unfortunately, this leads to a low confidence
forecast as guidance greatly struggles with resolving these
boundaries and meso to microscale features this far out. How storms
and boundaries evolve and progress on Monday further west will
likely have an effect on what happens Tuesday. For now, expect a
typical humid, warm summer environment with thunderstorms developing
during the day. Widespread severe weather threat looks low at the
moment, but an isolated strong to severe storm cannot be ruled out.

Better forcing for ascent and more widespread convection arrives
Tuesday night into Wednesday as the aforementioned negatively tilted
trough over the Upper Midwest pushes into the Great Lakes region
with a healthy low level jet developing over Indiana. Strongest
upper level flow look to be offset from the stronger low to mid
level winds as the main jet streak and trough axis don`t push into
Indiana until Wednesday night, after the main low level front
already push through. Despite upper level support possibly out of
sync with the strongest low level flow and forcing, widespread
convection still looks likely early Wednesday morning through the
afternoon hours. Instability during the morning hours will likely be
mainly elevated with weak low level lapse rates resulting in low
chances for severe weather despite 25-35 kts of 0-3km shear. Would
not rule out an isolated strong storm especially if a strong
downdraft can punch through the low level inversion, but this set up
looks more like a heavy rainfall threat at the moment. Since this is
a few days out, confidence on exact mesoscale details is still
lower, but confidence on heavy rainfall and thunderstorms occurring
on Wednesday is higher. With the presence of widespread rain,
guidance likely is too high with max temperatures in the 80s, but
the potential is there for highs to reach those levels if there is
clearing behind storms during the late afternoon and evening hours.

Thursday through the weekend...

High confidence in a northwesterly flow pattern setting up across
Indiana Thursday into the weekend. Longer range guidance has been
consistent with showing persist troughing over the Great Lakes and
Northeast CONUS with high pressure setting up over the Plains
states. This pattern features a strong upper jet from the northern
Plains southeastward into the Great Lakes with numerous waves riding
along the jet. While there is high confidence in this pattern
setting up, much lower confidence exists regarding timing,
placement, track of these smaller waves which will bring occasional
chances for showers and storms. The end of the week and into the
weekend will not be wash out by any means; however it will be
difficult to pin point wet periods versus dry periods as that is all
dependent on small mesoscale features, boundaries, and waves which
are nearly impossible to track this far out. This pattern does
support below normal temperatures with highs possibly not getting
out of the 70s some days. For anyone with interests or outdoor plans
this weekend, it is highly recommended to check back daily for
updates on the weather as the forecast will likely change as
confidence rises in timing of rain and storm chances.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 146 AM EDT Mon Jun 3 2024

Impacts:

- Patchy fog after 06z, MVFR and IFR conditions possible

Discussion:

Shallow stratus has dissipated; however, the next challenge is if we
will observe fog develop overnight. There have been a few locations
already report shallow fog development, and the setup appears to be
favorable. A few things that may help to inhibit fog develop are
that the KIND wind profile is suggesting the winds aloft have
increased from the southwest and could be enough friction to prevent
widespread fog development. Still feel that some fog may develop in
the more typical low/bowl like airfields that are more protected.
Otherwise those locations would see occasional reductions bouncing
between one half mile and several miles, and with ground fog that is
common.

Elsewhere winds will turn southerly overnight or just prior to
daybreak. This will help to further inhibit fog development with
mainly VFR conds prevailing right at daybreak. A cirrus shield
should start to arrive from the west midday/afternoon, but no
impacts to flying conditions.

&&

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

$$

UPDATE...Eckhoff
SHORT TERM...MK
LONG TERM...CM
AVIATION...Beach