135
FXUS63 KIND 121349
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
949 AM EDT Wed Mar 12 2025

.KEY MESSAGES...

- Well above normal temperatures expected this week with breezy
  conditions at times

- Strong to potentially severe storms Friday night into Saturday

- Gusty winds and heavy rain at times Friday night through Sunday

&&

.FORECAST UPDATE...
Issued at 946 AM EDT Wed Mar 12 2025

Minor adjustments made to the forecast with this morning`s update.

Another very warm March day expected across Central Indiana with
highs exceeding the 70 degree mark once again. Main changes to the
forecast were to update dew points, humidity, and winds. Guidance
this week has been underdoing afternoon low level mixing which in
turn leads to observed dew points and relative humidity values much
lower than what short term models would suggest. With a similar
pattern setting up today, have lowered afternoon RH and dew points
toward the NBM5th percentile. Increased wind gusts this afternoon
into the 10-15 mph range with sporadic higher gusts possible. Also
increased highs toward the NBM75th percentile into the mid 70s for
most locations. Main impact from these conditions will be a very
slight fire weather risk as this extended period of dry weather
further drys out the ground and fuels.

Otherwise, enjoy the warm weather through the rest of the week!

&&

.SHORT TERM (Today and tonight)...
Issued at 324 AM EDT Wed Mar 12 2025

Synopsis:

Surface analysis early this morning shows high pressure over the
Great Lakes. A poorly organized area of low pressure was in place
over OK/KS. Extending east from the low was a warm front, stretching
across MO to Southern IL, southern Indiana to southern OH. Light
northeasterly surface flow was in place across most of Central
Indiana. Light south or southwest flow was found near the Ohio
river.  Aloft, water vapor shows mainly zonal flow in place, however
there was a trough in place over the American southwest. GOES16
shows only some high cirrus over central Indiana, streaming within
the flow aloft. Temperatures were well above normal, ranging from
the lower 40s north to the middle 50s south.

Today -

Another pleasant and warm day and mostly clear night is expected
across Central Indiana with above normal temperatures. Models show
zonal flow remaining in place today with little to no forcing aloft.
Forecast soundings and time heights remain dry with unreachable
convective temperatures and a mid level inversion aloft. Thus we
will only expect the continuation of the ongoing passing CI within
the flow aloft. Within the lower levels we can watch for some slight
changes. The models show the warm front lifting north across Central
Indiana today, once again placing most of the forecast area within
the warm sector along with southerly winds expected. Thus will trend
toward a mostly sunny sky today, with highs at or just slightly
above persistence.

Tonight -

Little overall change is expected in the weather this evening as
many of the previously discussed features will remain unchanged.
However, overnight the frontal boundary will settle across Central
Indiana along with weak and  poorly defined lower level flow. Aloft,
an upper low is expected to push into the Tennessee River Valley
from the southern plains. This feature will fail to bring any
precipitation to central Indiana, but may result in an increase in
higher level clouds, particularly across southern parts of Central
Indiana. The weak lower level flow and convergence along the front
may allow for some fog formation late. Forecast soundings agree,
showing some mid and lower level saturation. Furthermore dew point
depressions are suggested to be 1-3F. Thus overall increasing
cloudiness along with lows a bit warmer in the upper 40s and lower
50s are expected.

&&

.LONG TERM (Thursday through Tuesday)...
Issued at 324 AM EDT Wed Mar 12 2025

An active period for central Indiana continues to be expected,
particularly late Friday into Saturday night.

Guidance continues to show a rapidly weakening upper level wave
pushing eastward through Kentucky and Tennessee Thursday. With
nearly all forcing for ascent focused south of the area, any showers
that develop would be instability driven. Forecast profiles look
slightly better than they have in recent days, but still not great
given minimal shear and weak deep layer subsidence. Will temper
blend PoPs slightly, keeping them 20-30 percent max and limited to
the south/southeastern forecast area. Suspect that coverage of any
activity will be very limited as will QPF, particularly given that
high end NBM QPF tops out at maybe a tenth at most in any one spot,
with 50th percentile and below at zero.

Primary focus for the long term period remains on a high-impact
storm system Friday into Saturday night, with concerns for strong
gradient winds, as well as showers and thunderstorms potentially
producing heavy rain/localized flooding and severe weather.

Continue to adjust NBM wind gust numbers up toward high end of the
probabilistic envelope given forecast profiles and blend low bias on
wind gusts, particularly in higher end situations.

Friday will be dry and mostly sunny, allowing for ample mixing,
highs well into the 70s, and southerly winds 15-25 MPH with frequent
gusts of 25-35 MPH and locally higher gusts. Gradient winds will
remain similarly strong overnight, then increase during the day on
Saturday (especially through midday - early afternoon) as steep low
level lapse rates continue and momentum transfer numbers indicate
potential for widespread 40-50 MPH gusts, and perhaps even a few
local gusts of 55-60 MPH - solidly within advisory criteria at least.

Friday night into early Saturday presents a threat for a strongly
forced high shear/low CAPE severe threat, with a plausible if not
likely scenario evolving from initial convection well to our
west/southwest growing upscale into a fast-moving QLCS that then
sweeps northeast across the region overnight, with a significant
damaging wind threat, along with a tornado threat, and a heavy rain
threat given precipitable water values near or above climatological
maximum - though the storm motions of perhaps 60 MPH will help to
mitigate this threat significantly.

A lull in activity appears possible early Saturday, before
development of a potent heavy rain/thunderstorm band Saturday
afternoon ahead of the tail end of the front and broader upper
trough. Though models have held onto at least some concern for our
far east/southeast, the bulk of impacts from this are likely to be
further to our south and east, though shower chances will linger as
long as Sunday morning as the upper trough axis finally sweeps over
the area.

Though a brief cooldown will accompany passage of this system,
temperatures will rapidly return to above normal next week as
another broad upper trough moves into the CONUS upstream.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 651 AM EDT Wed Mar 12 2025

Impacts:

- None

Discussion:

VFR conditions are expected throughout the period.

Mostly clear skies are expected today as a dry frontal boundary
lifts back northward. Winds will be easterly early, becoming
southwesterly through the day at all but LAF. This boundary may
drift back southward tonight, and while LAMP guidance suggests a
slight fog potential near daybreak Thursday along the boundary, this
appears unlikely given the very dry column and plentiful mixing in
recent days which has aided in drying out what ground moisture
remained with several days since measurable rainfall. In addition,
increasing high clouds tonight will work against radiational cooling
for fog formation.


&&

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

$$

UPDATE...CM
SHORT TERM...Puma
LONG TERM...Nield
AVIATION...Nield