Tornadoes and Hail in Indiana, March 31, 2023

Area Forecast Discussion...UPDATED
National Weather Service Indianapolis IN
842 PM EDT Fri Mar 31 2023

.Mesoscale Update...
Issued at 842 PM EDT Fri Mar 31 2023

Deep closed low is currently located over eastern Nebraska and is
moving eastward now. Intense DCVA and associated strong forcing will
primarily track over the northern portion of the area into the
southern Great Lakes and this should be where a more
intense/widespread wind threat should evolve, from the line of
convection in northwest Illinois. Further south, trailing more
positively tilted vort maxima and still appreciable midlevel height
falls will likely still be sufficient for linear evolution with
time. Another factor favoring at least a quasi-linear trend is
veered low level flow and generally straight hodographs supporting
splits and cell mergers which have been observed over western
Illinois the last hour or two.

0-3-km shear vector orientation is more parallel to these
southernmost segments that will impact much of central Indiana into
the evening, somewhat limiting the QLCS mesovortex/tornado threat
some. Nevertheless, any embedded mesocyclones or localized surges
and resultant line reorientations will need to be watched closely
for tornado potential. Even if shear vector orientations aren't
optimal, the magnitude of shear is particularly high and can
compensate.

Latest ACARS from IND shows a trend toward stronger ascent with
cool/moist PBL below capping EML deepening as CIN decreases. Near-
term model guidance continues to show a fairly narrow corridor of
enhance instability and little/no inhibition ahead of the QLCS. In
fact, thermodynamic profiles may be quite favorable for deep
coupling with stronger momentum aloft, and strong winds (locally
significant). Wind damage continues to be the main threat.

&&

.Mesoscale Update...
Issued at 646 PM EDT Fri Mar 31 2023

Latest ACARs soundings and the 21Z HRRR 0 hour forecast soundings
are both showing that the previously mentioned cap at 850mb is
eroding away with only a minor bump noted at 2235Z. Parcels are
still not surface based, but this won't stop any ongoing storms that
move into the area. Thoughts from earlier this afternoon are still
in line with the main timeframe for severe weather being from 9PM to
12AM.

Latest radar imagery shows a line that has become to congeal across
western Illinois into Missouri with widespread severe weather being
reported along the line.  With Indiana well within the exit region
of the jet and a strong push of southwesterly flow behind the line,
there shouldn't be any problem keeping this complex together as it
arrives into Indiana. Models are maintaining the thought that the
thermodynamic profiles will be favorable by the time of storm
arrival.

Relevant portions of previous discussions below....

A sounding from Purdue in Lafayette showed at around 545PM the cap
that was advertised earlier remains in place with good shear.
Instability remains generally locked above the cap.  Latest ACARs
soundings over IND show a similar profile.  Expectations are that
this will erode between 6PM and 8PM with the severe threat rapidly
ramping up afterwards.

Expect additional discussions through the evening.

&&

.Short Term...(This evening through Saturday)
Issued at 301 PM EDT Fri Mar 31 2023

***SEVERE WEATHER EXPECTED TONIGHT***

- Central Indiana now under a MODERATE RISK for severe weather.
- Main Severe Threat tonight will be damaging straight line winds to
  70 mph
- Showers/Storms Possible late this afternoon
- WIND ADVISORY 800 PM - Sat 500 PM

Surface analysis this afternoon shows deep low pressure in place
over western IA. This was providing a quick southwest flow in place
across Indiana and the Ohio Valley. Dew points have crept into the
lower 50s. THe initial moisture plume as shown by GOES16 has now
shifted farther east of Indiana and the rest of the afternoon should
be spent within the warm and somewhat dry sector. Radar mosaics show
convection developing upstream in two areas. Severe storms were
developing over N MO and IA, and also over Arkansas and MO. The
storms over Arkansas and MO will be the storms of concern for
Central Indiana tonight. Water vapor imagery shows negatively tilted
upper low over NB. This low was providing diffluent flow aloft over
the Mississippi Valley where storm development was currently ongoing.

Tonight...

ACARS soundings this afternoon at IND show an inversion remaining in
place within the lower levels. This will keep convective development
from progressing over the next 2-3 hours. However as some clearing
and drier air arrives from the west, heating may allow this
inversion to weaken, allowing a more unstable column aloft to allow
convection. Showers developing over southern IL may be the trigger
for this, and thus we will need to continue some chc pops through
the afternoon and early evening.ight and people should be prepared
to activate their severe weather preparedness plan.

As the squall line exits overnight, some clearing is expected within
the dry slot as forecast soundings show a quickly drying column
overnight as cold air advection begins. Thus will trend toward
decreasing cloudiness overnight, however strong dynamics will remain
present aloft. Furthermore the strong pressure gradient across the
area will allow for the continued wind gusts of 30-40 mph. Thus the
wind advisory will be in effect at that point. We will expect lows
mainly in the lower 40s.

Saturday...

Models continue to suggest strong dynamics will still be pushing
across the Great Lakes on Saturday as an associated upper trough
axis is dragged across Central Indiana. Strong winds will persist
across the area on Saturday as a LLJ of near 50 knots will remain
aloft ahead of the trough axis. Forecast soundings show initially a
dry column in the wake of the cold front. However as convective
temperatures in the mid 40s are reached, forecast soundings show
lower level saturation amid cyclonic flow in place across the
region. This is indicative for convective showers. Thus will include
chance pops by late morning and afternoon. The wind advisory will
remain in place, as the ongoing strong pressure gradient will remain
in place, but will gradually diminish by late afternoon as the low
departs northeast and the gradient weakens.  Expect only minimal
temperature rises to highs in the middle 40s as cold air advection,
and showers will remain in play for the afternoon.

&&

.Long Term...(Saturday night through Friday)
Issued at 305 PM EDT Fri Mar 31 2023

* Temperatures well above normal at times, particularly Monday-
  Wednesday

* Showers and thunderstorms at times early to mid week, with severe
  weather possible Tuesday afternoon - Tuesday night.

The long term period will begin with fast quasi-zonal flow across
the country, with temperatures fairly close to seasonal normals late
in the weekend. At the surface, high pressure traversing the region
Saturday night into Sunday evening will keep the area dry during
this period with ample sunshine Sunday.

As early as late Sunday night, shower chances will be required as
low amplitude disturbances move through the aforementioned fast flow
aloft, along with modest moisture return ahead of a low level
baroclinic zone.

This frontal zone will persist somewhere in the region as the upper
level flow amplifies early in the week, and broad
southerly/southwesterly flow and attendant increasing warmth and
moisture return through the low to mid levels of the troposphere
will allow for continued chances for showers and thunderstorms, with
PoPs increasing significantly Monday night into Tuesday.

Tuesday into Tuesday night, an extremely strong low pressure system
is likely to develop over the central High Plains into the upper
Midwest in response to the aforementioned amplifying flow aloft.
Strong dynamics and good moisture return as the Gulf remains wide
open appear likely to produce a regional severe weather event in the
region well outlined by SPC in the day 4-8 outlook - with the
highest threat at this time looking to be to our west over the lower
Missouri Valley and mid Mississippi Valley Tuesday afternoon. Late
Tuesday into Tuesday night, a severe weather threat is definitely in
the cards across central Indiana. Ample instability and extremely
strong low and deep layer shear values again appear likely across a
broad area in the open warm sector of the low. Pattern recognition
suggests this would most likely take the form for central Indiana of
one or more line segments with all hazards on the table, but cannot
completely rule out any convective mode, depending on degree and
timing of destabilization in the warm sector and other mesoscale
details that are too far out in time to resolve at this point.

Precip/storm threat should come to an end at least briefly Thursday
into Thursday evening as the cold front associated with the strong
low sweeps across the area. Shower chances may return very late in
the period, but are far more uncertain owing to growing model
differences.

&&

.Aviation...(00Z TAF Issuance)
Issued at 646 PM EDT Fri Mar 31 2023

Impacts:
-Southerly wind gusts to 40kts through the TAF period, brief
westerly gusts in excess of 50kts during line of storms.
-MVFR cigs to briefly IFR cigs this evening
-Line of storms expected from 02Z to 05Z, IFR vsbys during rain.
-LLWS through the TAF period.

Discussion:

A line of storms is expected to impact the terminals between 02Z and
05Z with the potential for wind gusts in excess of 50kts.  Gradient
winds outside of storms will gust to around 40kts at times,
especially after 05Z. Vsbys will remain VFR outside of the heavier
rain. Cigs will remain MVFR through 05Z with low VFR conditions
afterwards. LLWS will be a concern with a very strong LLJ even with
surface gusts to 40kts.  Winds will then gradually become more
westerly and eventually northwesterly tomorrow afternoon.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 6 PM EDT Saturday for INZ021-028>031-035>049-
051>057-060>065-067>072.

&&

Mesoscale...BRB
Short Term...Puma
Long Term...Nield
Aviation...White

Hazardous Weather Outlook
National Weather Service Indianapolis IN
319 PM EDT Fri Mar 31 2023

INZ021-028>031-035>049-051>057-060>065-067>072-011930-
Carroll-Warren-Tippecanoe-Clinton-Howard-Fountain-Montgomery-Boone-
Tipton-Hamilton-Madison-Delaware-Randolph-Vermillion-Parke-Putnam-
Hendricks-Marion-Hancock-Henry-Vigo-Clay-Owen-Morgan-Johnson-Shelby-
Rush-Sullivan-Greene-Monroe-Brown-Bartholomew-Decatur-Knox-Daviess-
Martin-Lawrence-Jackson-Jennings-
Including the cities of Delphi, Flora, Williamsport, West Lebanon,
Lafayette, West Lafayette, Frankfort, Kokomo, Attica, Covington,
Veedersburg, Crawfordsville, Lebanon, Zionsville, Tipton, Fishers,
Carmel, Noblesville, Anderson, Muncie, Winchester, Union City,
Farmland, Parker City, Clinton, Fairview Park, Rockville, Montezuma,
Rosedale, Greencastle, Plainfield, Brownsburg, Danville,
Indianapolis, Greenfield, New Castle, Terre Haute, Brazil, Spencer,
Gosport, Martinsville, Mooresville, Greenwood, Franklin,
Shelbyville, Rushville, Sullivan, Carlisle, Shelburn, Farmersburg,
Linton, Bloomfield, Jasonville, Worthington, Bloomington, Nashville,
Columbus, Greensburg, Vincennes, Washington, Loogootee, Shoals,
Bedford, Mitchell, Seymour, and North Vernon
319 PM EDT Fri Mar 31 2023

This hazardous weather outlook is for central Indiana.

.DAY ONE...Through Tonight.

Isolated to scattered thunderstorms are possible through the
afternoon. A few severe storms will be possible during the afternoon
hours.

A line of severe thunderstorms is expected to move through central
Indiana this evening between the hours of 9 PM and midnight. Damaging
winds to 75 mph and the threat of a few brief tornadoes will
accompany this line of storms.

Strong winds gusts up to 50 mph are possible this evening even
outside of thunderstorms.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Strong wind gusts up to 50 mph are likely on Saturday.

There is a chance of thunderstorms Monday afternoon through
Tuesday night. Severe storms are possible during this period,
primarily Tuesday afternoon and Tuesday night.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is expected late this afternoon into tonight.

&&

More information, along with other weather, hydrological and climate
information can be found at http://weather.gov/ind

Special Weather Statement
National Weather Service Indianapolis IN
429 PM EDT Fri Mar 31 2023

INZ067>069-312115-
Daviess IN-Knox IN-Martin IN-
429 PM EDT Fri Mar 31 2023

...A strong thunderstorm will impact portions of central Knox, Martin
and Daviess Counties through 515 PM EDT...

At 428 PM EDT, Doppler radar was tracking a strong thunderstorm over
mainly rural areas of southeast Knox County, moving east at 70 mph.

HAZARD...Winds in excess of 40 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

This strong thunderstorm will be near...
  Washington around 435 PM EDT.

Other locations in the path of this storm include Shoals.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3854 8737 3852 8736 3851 8738 3869 8747
      3891 8691 3890 8668 3858 8668 3853 8710
      3854 8711 3852 8715 3855 8718 3855 8721
      3854 8722 3854 8725 3853 8726 3851 8730
TIME...MOT...LOC 2028Z 248DEG 61KT 3862 8730

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH

Nield

Special Weather Statement
National Weather Service Indianapolis IN
443 PM EDT Fri Mar 31 2023

INZ053-055-061>064-068>071-312145-
Johnson IN-Daviess IN-Brown IN-Owen IN-Martin IN-Lawrence IN-
Bartholomew IN-Greene IN-Jackson IN-Monroe IN-
443 PM EDT Fri Mar 31 2023

...Strong thunderstorms will impact portions of Monroe, Bartholomew,
Brown, southeastern Owen, Martin, eastern Greene, Lawrence, Jackson
and northeastern Daviess Counties through 545 PM EDT...

At 443 PM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from 11 miles south of Bloomfield to 8 miles
southeast of Shoals. Movement was northeast at 60 mph.

HAZARD...Winds in excess of 40 mph and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
  Bloomington, Brownstown, Seymour and Nashville.

This includes Interstate 65 between mile markers 37 and 79.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3890 8712 3890 8709 3893 8715 3934 8648
      3935 8581 3882 8579 3873 8587 3876 8591
      3878 8620 3876 8628 3869 8631 3869 8668
      3853 8668 3853 8674
TIME...MOT...LOC 2043Z 236DEG 54KT 3887 8700 3859 8667

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...40 MPH

Nield

Special Weather Statement
National Weather Service Indianapolis IN
528 PM EDT Fri Mar 31 2023

INZ071-072-312215-
Jackson IN-Jennings IN-
528 PM EDT Fri Mar 31 2023

...A strong thunderstorm will impact portions of southeastern Jackson
and Jennings Counties through 615 PM EDT...

At 528 PM EDT, Doppler radar was tracking a strong thunderstorm 8
miles north of Scottsburg, or 10 miles south of Seymour, moving east
at 65 mph.

HAZARD...Winds in excess of 40 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

This strong thunderstorm will be near...
  Vernon around 545 PM EDT.

This includes Interstate 65 between mile markers 37 and 47.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3873 8589 3888 8593 3914 8544 3891 8545
      3891 8554 3888 8554 3888 8557 3885 8557
      3885 8561 3883 8561 3882 8563 3883 8565
      3882 8570 3883 8572 3881 8579 3874 8584
      3873 8587
TIME...MOT...LOC 2128Z 250DEG 56KT 3881 8584

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH

Nield

Special Weather Statement
National Weather Service Indianapolis IN
530 PM EDT Fri Mar 31 2023

INZ055-056-062>064-312200-
Johnson IN-Brown IN-Bartholomew IN-Shelby IN-Monroe IN-
530 PM EDT Fri Mar 31 2023

...A strong thunderstorm will impact portions of southwestern Shelby,
southeastern Monroe, southern Johnson, northern Bartholomew and Brown
Counties through 600 PM EDT...

At 530 PM EDT, Doppler radar was tracking a strong thunderstorm near
Bloomington, moving northeast at 60 mph.

HAZARD...Winds in excess of 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

This strong thunderstorm will be near...
  Nashville around 540 PM EDT.

This includes Interstate 65 between mile markers 67 and 90.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3905 8639 3920 8651 3934 8628 3934 8625
      3936 8625 3954 8595 3925 8569 3924 8569
TIME...MOT...LOC 2130Z 240DEG 54KT 3918 8640

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

Nield