IND issues Area Forecast Discussion (AFD) at Mar 22, 6:29 AM EDT171
FXUS63 KIND 221029
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
629 AM EDT Sat Mar 22 2025
.KEY MESSAGES...
- Breezy today with seasonably cool temperatures
- More widespread rain for Sunday and Sunday night
- Temperatures hovering around normal for much of the upcoming week
- Daily chances for showers Tuesday through next weekend
&&
.SHORT TERM (Today and tonight)...
Issued at 312 AM EDT Sat Mar 22 2025
A weakening line of showers continues to progress east across the
forecast area early this morning ahead of a cold front. Wind gusts
were at 45-50mph as the line moved into the Wabash Valley between 05
and 06Z but has weakened since then. Temperatures remained steady
or had risen slightly with a narrow axis of warm advection
immediately ahead of the boundary. 06Z temps ranged from the mid 40s
to the lower 50s.
The passage of the aforementioned front with the scattered showers
and stronger wind gusts accompanying it remain the primary focus for
the next few hours. After that...high pressure returns to the region
providing a pleasant but seasonably cool Saturday before clouds and
rain approaches prior to daybreak Sunday as low pressure tracks into
the Missouri Valley.
The showers have diminished in coverage and should continue to
do so as they move east into a progressively drier airmass.
However...the sounding profiles ahead of the showers continue to
show near dry adiabatic flow through 700mb with steep lapse
rates...and that has led to relatively efficient momentum transfer
of stronger boundary layer flow to the surface. Velocity scans off
of both KIND and TIDS radars currently continue to show 35-40kt
winds in the lowest 1000ft AGL. Expect gusts briefly peak at 40-50
mph in spots as the remnants of the showers shift east across the
forecast area over the next couple hours.
Dewpoints come up rapidly in wake of the showers which will disrupt
momentum transfer of stronger winds aloft with much weaker lapse
rates. Gusts will continue near 30mph at times through daybreak as
skies clear from the west behind the front. Lower stratus may linger
across the northeast half of the forecast area through a good
portion of the morning but even here expect clearing skies by midday
as the influence of the surface ridge increases.
The approach of the ridge this afternoon will allow the pressure
gradient to relax and surface winds to slowly diminish by late day
before becoming light and variable this evening. Mid and high clouds
will increase from the southwest tonight as a cold front moves into
the Missouri Valley. Despite dry air initially and low level flow
from the southeast...an axis of deeper moisture in tandem with
strengthening isentropic lift will aid in the expansion of rain into
the southwest half of the forecast area in the predawn hours
Sunday...serving as a prelude to more widespread rainfall later in
the day on Sunday as the front moves into the region.
Temps...temperatures will slide back into the upper 30s and lower
40s by daybreak behind the cold front. Low level thermals support
a cooler afternoon versus Friday...with highs ranging from the upper
40s over northern counties to the mid 50s in the south. Lows tonight
will fall into the 30s but as the clouds increase after midnight...
expect temperatures to slowly rise towards daybreak in response to
increasing warm advection.
&&
.LONG TERM (Sunday through Friday)...
Issued at 312 AM EDT Sat Mar 22 2025
Near normal conditions for mid to late March expected over the next
week with periodic chances for rainfall. Increasing confidence in a
warm up back to above normal temperatures towards next weekend.
This weekend...
Focus this weekend will be on Sunday as an area of low pressure and
associated frontal boundary bring widespread rain to the region. An
occluded front extends southeastward from a low moving through the
Northern Plains with a triple point and warm front setting up right
over Central and South Central Indiana. With a 40-50 kt
southwesterly low level jet pumping moisture northward over the warm
front, expect this area to be the focus for potentially heavy rain
development. Forecast soundings suggest the possibility of a a brief
mix of rain and snow on the leading edge due to wet bulb cooling and
such dry antecedent conditions. P-type will quickly transition to
plain rain, so do not expect any issues from snow mixing in. Models
are showing enough elevated instability to produce some isolated
thunder; but will omit it from the official forecast for now as
chances still look slim. There also looks to be some decent shear
and tight gradient that will produce breezy conditions, but all
other severe parameters are expected to remain minuscule for central
Indiana with the severe threat further south of the state for
Sunday. The axis of heaviest rainfall will likely set up along the
warm frontal boundary draped across South Central Indiana where up
to an inch of precipitation could fall. There will likely be a sharp
north to south gradient in QPF, with South Central Indiana and areas
closer to the Ohio River seeing the higher totals due to better
moisture advection and instability. Further north, toward the I-70
corridor, lower amounts of a third of an inch or less are more
likely. Will have to monitor closely where exactly the warm front
sets up as a shift north or south by just a county and significantly
shift where the heavy rain axis sets up.
This pattern also favors a sharper south to north temperature
gradient through the state as well. Expect highs approaching 60 in
Southern Indiana and temperatures struggling to hit 50 across the
north. As mentioned above, if the placement of the warm front shifts
north or south just a little bit, this could have impacts on
temperatures as well.
Next Week...
A general northwest flow pattern sets up for the Great Lakes region
Monday through Thursday, keeping near normal temperatures around and
periodic chances for light precipitation due to weak passing systems
within the upper jet.
Monday looks mainly dry and breezy with gusts of 30-40 mph at times
with near normal temperatures. If mixing heights end up higher than
what models suggest, temperatures could exceed forecast highs while
min RH falls significantly below guidance. Only monitoring that
possibility for fire weather concerns; however with recent wet
weather, fuels likely will remain wet as well despite windy
conditions and low RH values.
The next chance for rain arrives Tuesday as a weak upper level
disturbance drops southeastward from Canada. Overall, light rain is
expected from this system. Since this is a few days out, timing and
track of the subtle feature could easily change, so keeping PoPs
only at chance wording for now. Will increase PoPs accordingly once
track and timing of this system are more solidified. Keeping low
Pops in the forecast Wednesday into Thursday as some guidance is
suggesting additional weak disturbances within the northwest flow
pattern sliding into the region. Confidence remains low on exact
details as these features are so subtle that guidance will likely
struggle to resolve them this far out. Not expecting a washout of a
week whatsoever, but scattered showers are certainly possible almost
each day through mid to late week in this type of pattern.
A slow warm up takes place the latter half of next week as the
pattern begins to shift toward a set up more favorable for much
warmer, above average conditions. The northwest flow pattern
transitions into ridging with the main storm track pushing further
north as well. Increasing PoPs late week as guidance is showing a
system and front likely moving through. Confidence is higher that
Indiana will be on the warmer side of things by then. The pattern
going into the last week of the month and early April does favor
warmer and wetter conditions with increasing chances for
thunderstorms.
&&
.AVIATION (12Z TAF Issuance)...
Issued at 629 AM EDT Sat Mar 22 2025
Impacts:
- MVFR cigs clearing out from west to east through the morning
- Gusts to 25 kts today, diminishing by the evening
Discussion:
Latest satellite imagery shows widespread MVFR stratus on the
backside of a meso low pushing east into Ohio this morning. The back
edge of the clouds is right along the IL/IN state line and will
slowly move eastward over the next several hours. Expect KLAF and
KHUF to clear out within the 11-13z timeframe, then KIND and KBMG
likely clearing out 12z-15z. Mainly VFR cigs expected for the rest
of the period.
Wind gusts earlier this morning were in excess of 40 kts and have
since diminished into the 20-25 kt range at all sites. Expect
sustained winds of 10-16 kts to persist through the late afternoon
hours with periodic gusts of 20-25 kts. High pressure quickly builds
in overhead tonight resulting in winds going calm around and just
after sunset before becoming light and east-southeasterly during the
overnight hours.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Ryan
LONG TERM...CM
AVIATION...CM
Source:
IND issues Area Forecast Discussion (AFD) at Mar 22, 6:29 AM EDT---------------
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