IND issues Area Forecast Discussion (AFD) at Feb 26, 2:50 PM EST091
FXUS63 KIND 261950
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
250 PM EST Wed Feb 26 2025
.KEY MESSAGES...
- Scattered light showers likely this afternoon and evening with
a few thunderstorms across south-central IN
- Additional showers possible Thursday afternoon
- Breezy conditions at times late this week, particularly Friday,
when frequent gusts of 35-45 MPH are likely and locally higher
gusts will be possible
- A brief weekend cooldown will be followed by rebounding
temperatures next week, as well as potential for heavy rainfall
and possibly few strong storms by Tuesday into Tuesday night
&&
.SHORT TERM (This evening through Thursday)...
Issued at 250 PM EST Wed Feb 26 2025
Rest of Today:
The warm front is now well north of central Indiana,
placing the entire forecast area within the warm sector. This warm
sector has broad SW flow of 8-12kt with modest moisture advection
attached. This moisture advection has induce isolated convective
showers/thunderstorms this afternoon, and weak stratiform rain over
northern portions of the forecast area, but most places should
remain dry through the next few hours.
Temperatures have been a challenging forecast today with clouds and
increases in moisture combating with modest WAA. Most of southern
central Indiana should still reach the mid to upper 60s this
afternoon, but there is some uncertainty along the I-70 corridor and
northward. This area should see a modest temperature gradient due to
greater cloud depth. Generally near 60 is expected along the I-70
corridor, but this could increase by a few degrees if the greater
cloud deck lifts northward before 4PM.
A cold front will slowly push eastward this afternoon and evening
leading to greater lift and coverage of showers. These showers will
likely have isolated thunderstorms embedded within them, especially
as they reach south central Indiana. Current observations show 250-
500 J/kg of CAPE over this area, and this should only increase as
low level theta-e advection destabilized the lower troposphere. These
thunderstorms should remain subsevere given the lack of substantial
instability and fairly unorganized development. With that said,
there is enough speed shear through the lowest 3km for an isolated
organized cell to form, and potentially isolated strong wind gusts.
Tonight and Tomorrow:
The cold front begins shifting east this evening allowing
precipitation to taper off. Behind the front, a well mixed boundary
layer is expected leading to occasional wind gusts. Between wind
gusts and broken cloud cover, diurnal cooling will be much weaker,
with overnight lows in the low 40s to upper 30s. Quiet weather is
then expected through the rest of the overnight period. Most
guidance shows increasing subsidence behind the front and lingering
moisture resulting in a low stratus deck by late tonight. This would
normally limit diurnal cooling, but cold air advection will help
cool temperatures into the mid-upper 30s.
Tomorrow will be much windier with dry warm advection pushing in
from the west ahead of a southward diving trough. This should create
deep PBLs and encouraging mixing into a 20-25kt LLJ in the
afternoon. As the trough dives south tomorrow evening, additional
showers will be possible. Although instability will be less than
today, weak low level instability will be possible in far eastern
central Indiana leading to a low chance of isolated thunder.
&&
.LONG TERM (Thursday night through Wednesday)...
Issued at 250 PM EST Wed Feb 26 2025
The large scale synoptic situation through the first half of the
weekend will be dominated by an amplified western ridge pattern.
While this will allow a cooldown for the weekend, with highs
dropping back into the 30s to low 40s and lows in the upper teens to
20s, first, a fairly strong clipper-type system will push through
the Great Lakes Friday into Saturday. As is typical, the majority of
moisture and precipitation with the system will be along and north
of the surface low track, and model profiles support a dry forecast,
but a strong pressure gradient and fairly deep mixing in the PBL
will promote strong, gusty winds on Friday.
Depending upon the depth of the mixed layer, which may be up to 5kft
or so, flow aloft of 45-50KT could potentially be tapped into and
mixed down. Average winds through the mixed layer look to approach
40KT at their peak, so frequent gusts in the 35-45 MPH range appear
likely with locally higher gusts possible. Flow throughout the mixed
layer will be largely unidirectional, which could enhance momentum
transfer and set the stage for isolated gusts approaching 50KT. Will
continue to message this concern and monitor evolving guidance for
potential wind headlines.
The weekend will turn sharply cooler in the wake of this system, as
a modestly strong Canadian surface high passes through the region,
with a warmup again next work week as the pattern deamplifies and
becomes more progressive.
Guidance suite has come more in line with a potentially very strong
low pressure system somewhere in the Midwest into the Ohio/Tennessee
valleys going into mid week next week, which could place severe
weather on the table in that time frame somewhere within that very
broad region, primarily Tuesday into Tuesday night given current
timing. The threat as it exists at this point would be more likely
to be to our south, as is well depicted by CIPS analogs,
experimental CSU machine learning guidance, and the SPC day 8
outlook, but this is a concern that will merit monitoring in the
coming days.
Even if a severe threat did not materialize locally, significant
rainfall would be on the table. Current WPC QPF shows a widespread 1-
3 inches of rainfall across the state, which could easily take
portions of the main stem rivers back into at least minor flood.
Hints of this are beginning to show up in some of the hydrologic
ensemble guidance.
&&
.AVIATION (18Z TAF Issuance)...
Issued at 1256 PM EST Wed Feb 26 2025
Impacts:
- Light Rain showers possible over the next several hours. TSRA
possible at KIND and KBMG this evening
- Winds will switch to southwest by mid afternoon, occasional
gusts between 20-25 knots possible during the day.
- MVFR ceilings possible late tonight into Thursday morning
Discussion:
A warm front has moved through the terminals this morning quickly
followed by a cold front in the afternoon/evening. Scattered
showers and isolated thunderstorms will develop along and ahead
of the cold front. Light winds will shift to southwesterly over
the next few hours, and increase in magnitude with occasional
gusts between 20-25 knots possible this afternoon.
MVFR ceilings may develop late tonight into early Thursday
morning, but should raise and scattered throughout the day on
Thursday.
&&
.IND WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
SHORT TERM...Updike
LONG TERM...Nield
AVIATION...Updike
Source:
IND issues Area Forecast Discussion (AFD) at Feb 26, 2:50 PM EST---------------
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