Severe Thunderstorm Warning 3, NWS Indianapolis, IN

612 
WWUS53 KIND 271742
SVSIND

Severe Weather Statement
National Weather Service Indianapolis IN
1242 PM EST Mon Feb 27 2023

INC093-105-271800-
/O.CON.KIND.SV.W.0003.000000T0000Z-230227T1800Z/
Monroe IN-Lawrence IN-
1242 PM EST Mon Feb 27 2023

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 100 PM EST
FOR SOUTHEASTERN MONROE AND NORTHEASTERN LAWRENCE COUNTIES...

At 1242 PM EST, a severe thunderstorm was located near Bedford,
moving northeast at 50 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Expect damage to roofs, siding, and trees.

This severe storm will be near...
  Monroe Reservoir around 1245 PM EST.
  Charles Deam Wilderness around 1250 PM EST.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 400 PM EST for south central
Indiana.

Remain alert for a possible tornado! Tornadoes can develop quickly
from severe thunderstorms. If you spot a tornado go at once into the
basement or small central room in a sturdy structure.

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 3901 8656 3912 8637 3905 8637 3905 8632
      3899 8632 3899 8628 3889 8628 3885 8645
TIME...MOT...LOC 1742Z 234DEG 44KT 3895 8644 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Nield

811 
WWUS53 KIND 271755
SVSIND

Severe Weather Statement
National Weather Service Indianapolis IN
1255 PM EST Mon Feb 27 2023

INC093-105-271805-
/O.EXP.KIND.SV.W.0003.000000T0000Z-230227T1800Z/
Monroe IN-Lawrence IN-
1255 PM EST Mon Feb 27 2023

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN MONROE AND
NORTHEASTERN LAWRENCE COUNTIES WILL EXPIRE AT 100 PM EST...
        
The storm which prompted the warning has weakened below severe
limits, and has exited the warned area. Therefore, the warning will
be allowed to expire.

A Tornado Watch remains in effect until 400 PM EST for south central
Indiana.

LAT...LON 3901 8656 3912 8637 3905 8637 3905 8632
      3899 8632 3899 8628 3889 8628 3885 8645
TIME...MOT...LOC 1755Z 234DEG 44KT 3904 8628 

$$

Nield

Area Forecast Discussion
National Weather Service Indianapolis IN
1229 PM EST Mon Feb 27 2023

.Mesoscale Update...
Issued at 1229 PM EST Mon Feb 27 2023

Convection has increased significantly across the western half of
our CWA. Radar trends show generally a mixture of broken line
segments with a few stronger discrete cells, particularly over
Putnam and Owen counties. These two cells have shown low-topped
supercell characteristics with little in the way of lightning
despite at times decent low-level rotation. The cells will progress
northeastward towards the Indianapolis metro area. Further west,
additional cells have organized into a broken line along the
Illinois / Indiana border. Shear within the 0-1 km layer remains
very strong with about 56 kts according to latest ACARS soundings
out of Indianapolis, along with a backed wind profile at the surface
across the region. Low-level lapse rates continue to steepen
slightly, but increased cloud cover has slowed this trend. Expect
continued development of low-topped supercells with isolated tornado
potential as these cells expand eastward into an environment that
remains conducive for low-level mesocyclone and tornado formation.

Previous Mesoscale Discussion...

Latest satellite imagery shows a variety of interesting features
across Indiana and into Illinois. Starting locally, low stratus
continues to thin across central Indiana with embedded waves,
indicative of a sheared low level environment. As the clearing
progresses, the visible stability of the cloud layer fades. A more
bubbly appearance takes hold in Illinois where surface heating has
steepened lapse rates enough to begin the convective process.

As this region advects eastward, further destabilization appears
likely. Latest ACARS soundings out of Indianapolis show the low-
level inversion beginning to erode away, with gradually steepening
lapse rates aloft. Strong low-level shear with a long looping
hodograph reveal the strongly sheared environment as evident on
satellite. Lapse rates are steepening, but generally remain moist
adiabatic through the column. Further steepening will likely remain
within the lowest few kilometers, thus limiting overall storm depth
and favoring low-topped convection. Only the strongest cells may be
deep enough to allow for charge separation and therefore lightning.
However, enough shear exists in the low levels (50kts 0-1km) and
within the effective cloud layer for low-topped supercells capable
of isolated tornadoes. In fact, this has already been seen near
Champaign Illinois with a reported tornado an hour or so ago.

One main question remains, namely regarding convective evolution as
we head into the afternoon. Surface forcing remains nebulous, but a
strong vort max aloft is beginning to overspread Illinois from the
west as the surface low occludes. This feature can be seen on
satellite as an area of eastward moving mid-level clouds, near the
center of the surface low. Sufficient lift aloft combined with
height falls and further surface insolation should allow continued
environmental destabilization. The greatest threat for convective
potential therefore lies along and ahead of the path of this upper-
level vort max. Given satellite trends, that would place the
northern half of our CWA at greatest risk. With the nebulous surface
forcing, convection may remain discrete or organize into small line
segments centered along convective rolls / areas of differential
surface heating.

&&

.Forecast Update...
Issued at 942 AM EST Mon Feb 27 2023

- A WIND ADVISORY remains in effect
- Rain and Wind Today

Surface analysis late this morning shows deep and strengthening low
pressure centered over south Central IA. This low was influencing
the flow across the region, with moderate southeast winds in place
across Central Indiana within the cyclonic flow. Satellite showed
the classic comma cloud configuration, with a dry slot punching into
the flow from the southwest across MO and western IL. This will
become important this afternoon. Meanwhile radar showed a band of
rain showers over western Indiana, ahead of the dry slot, poised to
push across the state within the flow. The cold front with this
system was poorly defined, but is likely across eastern MO, as STL
temps were in the lower 60s and temps in Central MO were in the
lower 50s.

Models suggest that the low pressure system to the northwest will
Make progress to Lake Michigan today. This will keep the sharp
pressure gradient and across Central Indiana and allow for the
arrival of the dry sector this afternoon.  Within the flow aloft, a
strong LLJ continues to be present, with 850mb winds near 50 knots
across Central Indiana through the day. Latest ACARS soundings at
IND show those strong winds even lower than 850mb.Thus after the mid
day passing of the rain showers, some better mixing and heating will
be possible within this dry sector in the wake of the rain. With the
strong winds aloft, this may result in gusty winds to 40-50 mph.
Thus the ongoing wind advisory continues to appear reasonable. Will
continue to keep pops rather high for the next 1-4 hours as the
showers ahead of the dry punch push across Indiana, but pops will be
lessened from west to east this afternoon.  Given the possible
mixing and heating will continue to trend highs around 60 that will
be touched briefly this afternoon.

&&

.Short Term...(Today and tonight)
Issued at 301 AM EST Mon Feb 27 2023

A strong midlevel shortwave trough within the southern stream will
impact central Indiana today with strong gradient winds, and a
conditional risk of convectively-enhanced damaging wind gusts. There
are some uncertainties with regards to convective evolution that
will be highlighted in the meteorological analysis below.

Early this morning, an intense 100-120-knot 500-mb speed max at the
base of the aforementioned shortwave over the Ozarks region, and
quickly moving toward the Ohio Valley. Models generally agree on
slight weakening/occluding through the morning. Nevertheless, very
intense DCVA and focused area of forcing for ascent will arrive in
Indiana by mid-morning and progress quickly across the state.
Preceding this, strong isentropic ascent and moisture advection is
ongoing and regional radar mosaic shows increasing warm advection-
driven rain from Iowa through Illinois into Kentucky. This should
expand and move northeastward across central Indiana early this
morning in tandem with strongest isentropic ascent in the 290-295-K
layer. A small positive area from most unstable parcels could
support a few lightning strikes within this warm frontal rain band.

It is unclear whether the primary convective wind threat (if any)
for our area will evolve out of (1) the ongoing forced QLCS at the
leading edge of intense vort max now entering the Ozarks, or (2)
wake environment that becomes slightly more buoyant with diabatic
surface heating into the afternoon.

The limitations for scenario one are preceding instability is meager
at best. In fact, model soundings show pre-squall environment having
a stable isothermal layer in the lower ~1.0-1.5-km, and effective
inflow layer from parcels likely at the top of that layer. If strong
enough instability were present with the expected intense momentum
aloft, we would be more concerned about wind damage potential with
this residual QLCS. We'll monitor the mesoscale environment closely
through the morning to see if a more favorable low-level
thermodynamic environment can evolve ahead of the DCVA driven
rain/convective band.

Immediately in the wake of said band, models show a narrow wedge-
shaped warm sector with veered flow and steeper lapse rates
preceding the residual surface reflection of the Pacific front/cold
front aloft. CAMs show mixed signals on whether additional
convection can form along this ill-defined front/CFA later in the
afternoon, thus the convective severe threat is conditional. Many
CAMs show a signal of more scattered convective elements trailing
the DCVA rain band and increasing as surface-based buoyancy
increases during the afternoon. This would be an odd/atypical
evolution, but cannot physically be discounted assuming wake
destabilization is actually sufficient. In either case, convection
will move fast given mean cloud layer wind at around 60 mph.

Regardless of the above, any convective elements that do occur in
the transient warm sector will have to be monitored closely as they
will occur in an environment where near-ground buoyancy (steep low-
level lapse rates and moisture) overlap with a high degree of
vertical shear. A low probability tornado scenario is conditional on
convective development/evolution, but any convection would markedly
increase localized wind potential aside from gradient-driven wind.

We will continue the Wind Advisory to highlight gradient wind
potential, but this may primarily be focused during the afternoon,
several hours after the advisory start time. We think the greatest
chance of >45 mph wind gusts will be in the more mixed environment
during the afternoon and especially across the southern half of the
area where deep thermodynamic coupling with strong wind fields aloft
will exist. Although this will decrease into the evening, gradient
will still support gusts up to around 30 mph until later tonight. No
spatiotemporal adjustments to the advisory will be made at this
time.

&&

.Long Term...(Tuesday through Sunday)
Issued at 301 AM EST Mon Feb 27 2023

**Near Record Warmth Wednesday
**Strong Storm Late Week To Bring Heavy Rain, Potential Flooding

Tuesday through Wednesday...

Generally fair conditions will be the rule heading into the mid-week
under a rather zonal upper flow.  A quick shot of rather weak
surface high pressure will cross the Midwest Tuesday, with clouds
likely scattering out by mid-late day as a subsidence inversion
weakens.  A deepening upper trough over the western United States
will lead to a rearranging of the pattern over the central US as
Canadian high pressure advances towards the Midwest.  Moderate
southwesterly breezes Wednesday will precede the associated
boundary...with H850 temperatures around 10 Celsius and a fetch of
anomalously warm air off of the Mexican highlands boosting readings
to near record highs.  Probably isolated/scattered showers for at
least a few hours Wednesday evening as the boundary passes and drops
readings by 30 degrees before dawn Thursday.

Thursday through Friday...

At least the southeastern quadrant of cold polar surface high
pressure is expected to build into the Midwest by Thursday...with
noticeably colder air holding back over the Upper Midwest/Great
Lakes.

Focus then turns to the late week with confidence building in a
strong late winter storm impacting the Midwest around the Thursday
night-Friday timeframe.  Much of the western trough's energy is
progged to plunge and cut-off near the Four Corners region by early
Thursday.  Impressive surface cyclogenesis should quickly follow
with the system negatively tilting while crossing the southern
Plains.  Model ensembles continue to favor the surface low tracking
near the Ohio Valley...with a warm frontal occlusion developing
westward near the cut-off H500 low, which would then track near the
southern Midwest.  Heavy precipitation developing near the Ozark
Plateau would quickly overspread Indiana...before at least parts of
the CWA possibly catch portions of the lighter cold-conveyor
precipitation as the 985-mb system departed to the northeast.

Questions surround precipitation type as well as total liquid /
flood potential.  Appreciable snow/icing on the front end of the
system does not appear likely...as long as the overall pattern's
northern stream stays retracted and unconnected to this strong
southern wave, with the polar air, if anything retreating into
Ontario as the event starts in Indiana...which should discourage any
sub-freezing temperatures to start.  Any frozen precipitation would
be much more likely amid the lingering cold conveyor around the
Friday timeframe when decent lift should linger amid a cooling
column.  Recent trends in the H700 track slightly farther north
across the state would lean towards lighter/wetter snow, however.

Precipitation amounts have most recently trended to less extreme,
yet still heavy totals...with latest guidance suggesting a 1-3 inch
gradient from northeast to southwest across the CWA...which appears
reasonable given moderate/heavy rainfall rates probably contained to
a 12-hour period.  Greatest potential for heavy rain/flooding will
likely lie towards southwest counties where forcing aloft would best
match with a longer duration of precipitable water near 1.25 inches.
 While River and Areal flood potential will be reassessed in future
updates...ensemble river forecasts so far show minor flooding likely
for at least lower portions of the White River, while minor flooding
will likely continue along middle/lower portions of the Wabash.
Temperatures will trend from slightly above normal Thursday to
slight below normal by Friday night.

Saturday through Sunday...

Quiet weather should return for the weekend as broad yet rather weak
high pressure builds across the central CONUS under a very broad
zonal ridge.  A dry column and adequate subsidence will promote dry
conditions.  Near normal chill is expected between light/moderate
west-northwesterly winds and H850 temperatures near negative 5
Celsius.

&&

.Aviation...(18Z TAF Issuance)
Issued at 1145 AM EST Mon Feb 27 2023

Impacts:

* Strong winds with scattered thunderstorms through 20Z-21Z
* MVFR ceilings this afternoon and tonight.
* Strong wind gusts throughout the day, peaking near 40 knots

Discussion:

The TAF sites will remain under the influence of the dry sector of
the passing low pressure system for the first few hours of the TAF
period. This will result in some gusty winds this afternoon as a
strong LLJ will have the potential to mix toward the surface given
diurnal heating. Forecast soundings showing some instability have
also allowed for scattered shower/thunderstorm development. Given
the uncertainty for precise timing due to the scattered nature of
the storms have used VCSH/VCTS for the first few hours of the TAF
period.

The cold front associated with the passing low will pass across the
TAF sites late this afternoon, ending the thunderstorm threat.
However the strong pressure gradient will remain across the area,
allowing for continued gusty winds. Gusts may reach 40 knts.

Forecast soundings and time heights suggest trapped lower level
moisture overnight. This will lead to continued MVFR Cigs overnight
and into Tuesday morning. As the low pressure system pulls away,
gusts will diminish overnight as the pressure gradient weakens.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 7 PM EST this evening for INZ021-028>031-
035>049-051>057-060>065-067>072.

&&

Mesoscale...Eckhoff
Update...Puma
Short Term...BRB
Long Term...AGM
Aviation...Puma

Hazardous Weather Outlook
National Weather Service Indianapolis IN
1038 AM EST Mon Feb 27 2023

INZ021-028>031-035>049-051>057-060>065-067>072-281545-
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
1038 AM EST Mon Feb 27 2023

This hazardous weather outlook is for central Indiana.

.DAY ONE...Today and Tonight.

Strong wind gusts up to 50 mph are likely today, especially during
the afternoon.

A few severe storms with damaging wind gusts are possible from late
morning through afternoon. An Isolated Tornado cannot be ruled out.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Snow is possible for part of the area on Friday.

.SPOTTER INFORMATION STATEMENT...

Spotter reports may be needed this afternoon.

&&

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
1147 AM EST Mon Feb 27 2023

INZ028-271715-
Warren IN-
1147 AM EST Mon Feb 27 2023

...A strong thunderstorm will impact portions of northwestern Warren
County through 1215 PM EST...

At 1147 AM EST, Doppler radar was tracking a strong thunderstorm near
Hoopeston, or 13 miles southeast of Milford, moving northeast at 40
mph.

HAZARD...Wind gusts up to 50 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.

This storm will remain over mainly rural areas of northwestern Warren
County, including the following locations... Tab.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Tornado Watch remains in effect until 400 PM EST for west central
Indiana.

&&

LAT...LON 4048 8752 4047 8725 4036 8753
TIME...MOT...LOC 1647Z 234DEG 35KT 4044 8759

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...50 MPH

50