Office: IND
FXUS63 KIND 090946
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
546 AM EDT Wed Jul 9 2025
.KEY MESSAGES...
- Scattered storms today with best chances across the southeast
half of central Indiana
- Generally very warm/humid through this weekend...greatest rain/
storm chances on Saturday...not as humid Sunday
&&
.SHORT TERM (Today and Tonight)...
Issued at 245 AM EDT Wed Jul 9 2025
Remnant pockets of showers continue to drift across the northern
Wabash Valley southwest into eastern Illinois in tandem with an
upper level wave and a weak surface front. The airmass remained dry
below 10kft over much of the region with mid level clouds
increasing. 06Z temperatures ranged from the upper 60s to the mid
70s.
The aforementioned upper wave and surface boundary will track across
the region today and provide at least the opportunity for scattered
convective development with a moist and unstable airmass across
central Indiana. As this shifts off to the east this evening... weak
high pressure will expand into the area with slightly drier air.
Cannot rule out scattered showers continuing to develop across the
northwest half of the forecast area through much of the morning but
the current ACARS sounding at KIND highlights the problems in the
lower levels of the atmosphere that will likely limit broader
convective development over the next several hours. Mainly...the air
remains dry up into the 600-500mb layer with negligent instability.
Much of the better forcing aloft is displaced to the north across
lower Michigan as well. Will maintain low pops through late morning
but most locations will remain dry due to the extenuating factors
above.
Low level moisture will improve this afternoon along and ahead of
the front as it moves into the forecast area and this will aid in
MLCAPES peaking at near 2000 j/kg. But the forcing aloft will remain
weak with little to near shear as well. This will likely keep
convection in a scattered and disorganized state focused especially
across the southeast half of the forecast area ahead of the
boundary. Once again as has been the case for the last several
days...primary threats from convection this afternoon will be brief
and localized heavy rainfall and cloud to ground lightning.
Convection will linger into the evening across eastern counties
before departing to the east as weak high pressure expands south
from the western Great Lakes. Despite dry air advecting in
overnight...potential for patchy fog will exist in the predawn hours
Thursday as winds lighten to near calm levels and skies clear.
Temps...low level thermals support mid 80s across the forecast area
today. With the arrival of a slightly drier airmass tonight...lows
will fall into the mid and upper 60s.
&&
.LONG TERM (Thursday through Tuesday)...
Issued at 245 AM EDT Wed Jul 9 2025
Overall typical midsummer weather is expected through the long term
as generally very warm and humid conditions with scattered diurnally-
driven convection...surround a couple rather brief less humid and
mainly rain-free periods. Synoptically, North America will be more
trough dominant, although only along the Canadian border and
north...while any attempts of the southern subtropical ridge to
regain momentum is suppressed to the southwestern CONUS through at
least this weekend. In between these features, weak zonal flow will
carry embedded small weaknesses into the Midwest through Saturday...
before light southwest flow tries to quietly build the ridge towards
Indiana, bringing a marginally-hot set-up around next Monday and
onward.
This will all translate to more early mornings usually starting in
the upper 60s/lower 70s, with higher humidity capping diurnal
spreads up to around 85-90F. Maximum afternoon heat indices usually
in the upper 80s to mid-90s...may approach 100F on Saturday, and
again at the end of the long term. Widely scattered afternoon/
evening showers and thunderstorms will be the rule most days...while
occasional modest wind shear may promote a few stronger storms. Best
opportunity for greater coverage of rain/storms will be around the
Saturday period when a more amplified northern wave should drag a
weak cold front across the region. Milder and less humid conditions
will hopefully accompany subtle drops in heights/H850 temperatures/
precipitable water both at the start of the long term and then
through the latter half of the weekend, when several northern zones
may observe a tandem of overnights dropping into the mid-60s.
Indianapolis' normal max/min will maintain the year's peak values
through July 22...85/67.
&&
.AVIATION (12Z TAF Issuance)...
Issued at 546 AM EDT Wed Jul 9 2025
Impacts:
- Brief visibility restrictions this morning in showers and storms,
mainly at KHUF and KLAF
- Scattered thunderstorms continue for this afternoon
- Fog possible predawn Thursday
Discussion:
An area of convection has developed over the northern Wabash Valley
early this morning and is likely to impact KLAF and possibly KHUF as
well over the next few hours. Additional scattered storms are
expected as the day progresses as an upper level wave and weak
frontal boundary move into the region. Convection will shift east of
the terminals by this evening with clouds diminishing as drier air
advects into the region from the northwest.
Winds will be light through the forecast period...gradually
transitioning to W/NW this evening. Patchy fog is likely to develop
late tonight and early Thursday.
&&
.IND WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
SHORT TERM...Ryan
LONG TERM...AGM
AVIATION...Ryan
Office: IWX
FXUS63 KIWX 091032
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
632 AM EDT Wed Jul 9 2025
.KEY MESSAGES...
- Becoming hot and humid Friday and Saturday. Highs in the upper 80s
with heat indices in the low to mid 90s.
- Chances abound for mainly afternoon and evening showers and
thunderstorms through early next week.
- Severe storms are not expected.
&&
.DISCUSSION...
Issued at 258 AM EDT Wed Jul 9 2025
Incredibly stable mid level (700mb-500mb) lapse rates in the
order of 4.7 to 5.0 C/Kg were over northern Indiana and
surrounding areas. Scattered showers and a few storms have
survived the night in the base of the upper level trof that was
moving through the Upper Great Lakes region. Scattered showers
and storms will become more numerous by late this afternoon with
daytime heating. Severe storms are not expected, but locally
heavy rainfall and wind gusts up to 40 mph will be possible.
There should be a short break in the activity Thursday with
somewhat more stable air, slightly lower dew points and weak
subsidence.
An upper level trof topping the subtropical ridge extension was
over the southwest CONUS will phase with another wave moving
east across southern Canada. These merging systems will bring a
good chance for showers and storms Friday. Given the stable
conditions, heavy rainfall is not expected. After Friday,
numerous chances for showers and storms will persist through the
middle of next week given the environment of high precipitable
water values and deep moisture.
&&
.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 630 AM EDT Wed Jul 9 2025
A lead mid/upper level trough will continue to track across
northern Indiana this morning and appears to have an MCV feature
associated with it. Showers have increased in coverage over the
past hour or two across west central Indiana along the southern
periphery of this feature. Eastward track of this vort max
could provide a brief window of shower potential mid morning
through midday at KFWA. Some brief vsby restrictions are
possible at KSBN early this morning as departure of greater
coverage mid cloud deck could allow for some patchy fog to
develop through 13Z.
A larger scale upper trough will settle across the Great Lakes
today allowing a cool front to drop southeast across the region.
This should allow for scattered thunderstorm development this
afternoon across northern Indiana with best chances at KFWA
given frontal progression. Rain showers should diminish this
evening as frontal boundary becomes more diffuse. Guidance does
depict some potential of some patchy shallow fog just in wake of
this sfc trough where near surface vertical moisture profiles
may be a bit more supportive before drier air works in from the
west. Did include MVFR vsby mention at KFWA with the 12Z TAFs to
give some indication of this potential late this period.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Beach Hazards Statement from 4 PM CDT this afternoon through
late tonight for INZ103.
OH...None.
MI...Beach Hazards Statement from 5 PM EDT this afternoon through
late tonight for MIZ177-277.
MARINE...None.
&&
$$
DISCUSSION...Skipper
AVIATION...Marsili
