IND issues Area Forecast Discussion (AFD) at Mar 22, 3:12 AM EDT456
FXUS63 KIND 220712
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
312 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 and into the region, 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
struggling 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 middle and 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 (06Z TAF Issuance)...
Issued at 1228 AM EDT Sat Mar 22 2025
Impacts:
- Brief period of strong wind gusts of 30-40kts with showers through
08Z
- Outside of showers, westerly winds will gust to 30kts overnight,
gradually lowering before diminishing late day
- Brief period of MVFR ceilings possible predawn at KLAF
Discussion:
The immediate impact to aviators early this morning will be with a
narrow line of convective showers moving out of Illinois. Strong wind
gusts have accompanied the leading edge of the showers and will
likely produce a brief period of 30-40kt gusts with locally higher
gusts at all terminals through about 08Z. KHUF will be impacted in
the 05-06Z time period with all other sites after that. Even in the
wake of the showers...winds will remain gusty from the west through
daybreak.
Clouds will linger to start in the morning with the potential for a
brief period of MVFR stratus primarily at KLAF. However as high
pressure builds in from the west...cloud coverage will diminish with
skies largely becoming mostly clear for the rest of the day. Few to
scattered cu may drift across KIND and KLAF into the afternoon.
Winds will remain gusty but steadily drop back into the afternoon
before becoming light and variable by the evening. Clouds will
increase from the west near the end of the forecast period in
advance of the next weather system which will spread rain into the
region by daybreak Sunday.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Ryan
LONG TERM...CM
AVIATION...Ryan
Source:
IND issues Area Forecast Discussion (AFD) at Mar 22, 3:12 AM EDT---------------
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