July 27-?, 2024 | Severe/MCS Potential

[snowlover2]

Appears we are starting up an active pattern with the possible threat of severe weather and MCS throughout the week.

[Central Illinois]

Hopefully it can get active its been so boring!

[snowlover2]

Not exactly good timing.

[StormfanaticInd]

First mcs now forming in Iowa 👀

[snowlover2]

ILN has one hell of a write up this morning.

Quote

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
644 AM EDT Mon Jul 29 2024

.SYNOPSIS...
An active weather pattern is in store for the region through the
upcoming week, potentially continuing into the upcoming weekend.
Several episodes of showers and storms are expected through
this active and unsettled regime. Seasonably warm and humid
conditions will prevail through the week as well.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Light rain continues to pivot to the NE along an arcing band
draped across the heart of the ILN FA. This is associated with
the trof axis shifting E through the area, which will exit to
the E into the early daytime hours.

A very muggy/humid airmass has settled into the region, and this
is reflected by the expansive low clouds across the region
early this morning, something that is not too typical for this
time of the year. Dewpoint depressions are running on the order
of only a degree or two, with an increasingly-saturated LL
environment filtering into the area.

While a few disorganized/cellular storms are expected in
central/south-central OH and NE KY into early afternoon, the
primary focus for the daytime period will be directed to our NW
as an MCS originating out of IA dives to the SE through IL/IN
into early afternoon. The environment ahead of this feature
(downstream) will be gradually destabilizing into the late
morning/early afternoon period, with SBCAPE ~2000 J/kg in the
immediate downstream environment past the noontime hour.
Although this complex will be outrunning its source forcing, it
should still be largely cold-pool driven, suggesting that
convective maintenance (and intensity) should be maintained
quite awhile. As with many of these scenarios, certain
convective-allowing models tend to "kill" the complexes much
too soon. And, given the ripening LL thermodynamic environment
in EC/SE IN and the Tri-State area into mid afternoon, this may
very well be another one of those cases where the line/clusters
holds itself together to a much greater degree further to the
E/SE (primarily from Fayette Co IN to Pike Co OH and points S of
this line). This maintenance of both organization and intensity
into the ILN FA, even with a slow "downward tick" in both,
would suggest that a semi- cohesive line of storms will move
into EC/SE IN and the Tri- State into N KY around 18z-20z,
bringing with it the potential for gusty winds and torrential
rainfall. Should this scenario unfold, there certainly may be a
few strong storms in the Tri- State mid/late afternoon
(particularly in any SW-NE oriented segment), with the
expectation for a slow weakening trend with SE extent further
into the area (south- central OH and NE KY) by late afternoon.
Will continue to mention this potential in the HWO, with the
greatest potential for a severe storm or two (with damaging
winds being the primary threat) to be focused in far SE IN and N
KY.

Highs today will generally reach into the mid 80s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
The fcst for the short term period doesn`t become any clearer,
or quieter, than is the case for the near term period. The
primary question remains just how much of a cold pool is
maintained with SE extent following the mid/late day remnant
MCS, which will undoubtedly leave a trailing swath of more
stable air in its immediate wake. The mid afternoon decaying MCS
may act to re-orient and re-position several crucial mesoscale
thermodynamic and kinematic boundaries into the evening which
will serve as a focus for renewed storm development near/past
sunset once again.

A more delayed and longer-lived MCS (with stronger cold pool
maintenance) into the ILN FA mid/late afternoon would likely
shift the axis/gradient of instby a bit further to the W across
parts of central IL/IN where robust destabilization will
certainly be underway even by mid afternoon. This pooling of
extremely-rich LL moisture/instby in central IL into wrn IN will
help provide a focus for renewed storm development into the
evening, especially as a convectively-enhanced LLJ helps
increase LL moisture/mass convergence along a NW-SE oriented
boundary stretching from NW IN to parts of N/cntrl KY. Exactly
where this boundary sets up will be crucial, although there
likely will be /some/ overrunning of this boundary (on the cool
side) where elevated convection may sprout even E of the LL
instby pool in central IL/IN. At this time, given the latest
data and pattern recognition, it is likely that another MCS will
develop this evening into the overnight hours, potentially
impacting (or at the very least grazing) the same areas (and
further to the S and W) that were impacted by the mid afternoon
storm activity. The Tri-State, but more specifically N KY into S
IN, will be the primary focus for this activity, although
additional ISO/SCT storms are likely as far N as WC OH intro
central by midnight).

These patterns tend to produce subsequent MCS activity that is
progressively oriented further to the S and W of the previous
MCS. Model guidance, specifically non-CAMs, tend to struggle
with these patterns, showing a pcpn shield/footprint that is
just too far to the N/E. Given this, it is likely that the
greatest organization and severity of the overnight MCS may
just miss the ILN FA to the S and W, impacting to a greater deal
parts of s-cntrl IN into cntrl KY past midnight. But the NE
fringe of this MCS is still expected to move through the Tri-
State in the several hour period around midnight. So certainly
trends will be monitored closely to determine where a slight
shift to the N or S is expected in actuality vs fcst.

The primary threat with the late evening/early overnight MCS
locally will be locally heavy rain and isolated flooding once
again, especially if there is any development of training or
backbuilding activity. But... there should be enough forward
propagation locally that will help limit the duration of the
torrential rainfall rates that will undoubtedly coexist with
this complex.

It is important to note here that *if* the afternoon MCS
dissipates before it moves into the local area, the late
evening/early overnight MCS activity would likely be further to
the NE more into the local area and would likely be stronger
and pose more of a severe/damaging wind risk (especially for the
Tri-State). While this is the less likely scenario than the one
discussed above, it is still /very/ plausible in the realm of
possible outcomes.

Storm activity will decrease from NW to SE area-wide into the
predawn hours Tuesday as as the primary low shifts E into SE MI
and further away from the local area into the afternoon hours.
Although a few afternoon SHRA/TSRA are expected E of I-75, a
relative minimum in both LL moisture and instby will be
positioned across the ILN FA through late Tuesday afternoon,
suggesting a somewhat quieter window than was previously
expected.

Highs on Tuesday will range from near 90 degrees in the W to the
mid 80s in central/south-central OH and NE KY where cloud cover
will be more persistent.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Confidence is modestly increasing that much of the area is dry
Tuesday night, with lingering showers and thunderstorms over central
Ohio at the start of the period. Later in the overnight, can`t rule
out some LLJ driven activity across portions of Indiana, southwest
Ohio and northern Kentucky into Wednesday morning. This will likely
be inhibited by a progressive MCS moving through Illinois, Indiana,
and western Kentucky.

Have maintained a similar approach to Wednesday as previous
forecasts with a building ridge supplying warm low-level air leading
to a sizable CAP during the afternoon. The primary concern during
the day would be heat-related concerns as heat indices may reach or
exceed 100 degrees. Can`t rule out isolated to scattered activity
during the late afternoon and evening, but any attempts to break the
CAP likely occurs the northwest of the local area late into the
evening. Steep mid-level lapse rates will supply a large corridor of
strong instability across the lower Great Lakes and Ohio Valley. If
thunderstorms are able to organize, a bowing MCS moving through
northern Indiana into west-central Ohio is plausible for Wednesday
night.

A trough descends into the Midwest and Great Lakes Thursday,
breaking down the ridge over the area. This will provide another
opportunity for thunderstorms and heat related concerns. Height
falls favor thunderstorms which may not allow for temperatures to
reach into the lower 90s. The trough will act to pull higher theta-e
values farther north, place the local area in a more favorable
location for MCS activity.

Friday through Sunday remains quite uncertain. Some operational
guidance is much faster with the trough, pushing drier air into the
region as early as Friday night/Saturday morning. However, there is
modest ensemble support that a slower trough passage may provide
more opportunities for thunderstorms. ECMWF ensemble maintains rain
chances through Sunday, with a much slower solution. A faster moving
through would supply a much drier pattern for the local area.

 

[ak9971]

33 minutes ago, snowlover2 said:

ILN has one hell of a write up this morning.

 

Man you weren't kidding. Great read though, a lot of detail there.

[junior]

Pretty active next few days. Need the rain here.

[StormfanaticInd]

Pretty solid risk today

[StormfanaticInd]

Tomorrow is looking very interesting on the gfs with mcs potential 

[StormfanaticInd]

Looks like storms are starting to develop to my northwest. This could get interesting 

[StormfanaticInd]

Mesoscale Discussion 1729

   NWS Storm Prediction Center Norman OK

   0358 PM CDT Mon Jul 29 2024

 

   Areas affected...eastern Illinois into central Indiana

 

   Concerning...Severe potential...Watch possible 

 

   Valid 292058Z - 292330Z

 

   Probability of Watch Issuance...40 percent

 

   SUMMARY...Thunderstorm development appears probable in the next 1-2

   hours across eastern Illinois and far western Indiana. Watch

   issuance may be needed later this evening if robust supercells

   and/or an organized line can be established.

 

   DISCUSSION...GOES visible imagery shows slowly building cumulus

   along a diffuse trough axis to the south of a weak surface

   low/remnant MCV. Air mass recovery continues to the east of the

   trough axis with temperatures climbing into the low to mid 80s with

   dewpoints climbing well into the 70s. This is promoting a gradual

   expansion of MLCAPE values to the northeast with values ranging from

   500-2000 J/kg from southern lower MI southward into southern IL/IN.

   The expectation is for thunderstorm development in the next couple

   of hours along the trough axis as the air mass continues to

   destabilize. 30-45 knot northwesterly mid-level winds on the

   southern periphery of the MCV combined with northerly surface winds

   are supporting effective bulk shear values near 40-50 knots nearly

   orthogonal to the trough axis. This may support a few initially

   discrete cells with an attendant large hail threat. With time

   upscale growth into an organized MCS appears likely given weaker

   wind shear near the low, which will favor thunderstorm clustering

   before storms propagate southward along the buoyancy gradient into

   the better deep-layer wind shear. As such, the potential for severe

   winds may increase later this evening across eastern IL into central

   and southern IN, and possibly into the lower OH River Valley.

   Convective trends will be monitored, and watch issuance may be

   needed to address this concern.

Edited July 29 by StormfanaticInd

[snowlover2]

Got a few cells moving into west Ohio.

[junior]

48 minutes ago, snowlover2 said:

Got a few cells moving into west Ohio.

Weak little cells but they sure are loud. 

[StormfanaticInd]

Looks like the strongest storms are going to be in Ohio 

[snowlover2]

Certainly some good thunder.

[snowlover2]

Quote

Special Weather Statement
National Weather Service Wilmington OH
816 PM EDT Mon Jul 29 2024

OHZ061-062-300045-
Montgomery OH-Greene OH-
816 PM EDT Mon Jul 29 2024

...A STRONG THUNDERSTORM WILL IMPACT PORTIONS OF GREENE AND
SOUTHEASTERN MONTGOMERY COUNTIES THROUGH 845 PM EDT...

At 815 PM EDT, a strong thunderstorm was located over Kettering,
moving east at 30 mph.

HAZARD...Wind gusts up to 40 mph, pea size hail, frequent
         cloud-to-ground lightning, and very heavy rain.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Hail may cause minor damage to
         vegetation. Lightning can cause serious injury or death.
         Visibility will be poor and hydroplaning is possible.

Locations impacted include...
Dayton, Kettering, Beavercreek, Fairborn, Xenia, Miamisburg,
Vandalia, Bellbrook, Moraine, Oakwood, Wright-Patterson Afb, West
Carrollton, Cedarville, Jamestown, Wilberforce, Riverside, New
Jasper, Spring Valley, Centerville, and Paintersville.

This includes I-75 in Ohio between mile markers 46 and 59.

If outdoors, consider seeking shelter inside a sturdy building.

Motorists should slow down and use extra caution.

When thunder roars, go indoors! Do not stay in the open or seek
shelter under trees when lightning threatens.

To report hazardous weather conditions, go to our website at
weather.gov/iln and submit your report via social media, when you can
do so safely.

&&

LAT...LON 3984 8420 3972 8367 3956 8377 3958 8411
      3968 8430
TIME...MOT...LOC 0015Z 292DEG 26KT 3971 8412

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

 

[snowlover2]

Tornado warning in EC IN near New Castle.

[StormfanaticInd]

Warnings are starting pop up now. 

[StormfanaticInd]

Tornado warning 

[Chinook]

wow, I didn't think a lot would develop. Now, tornado warning, as mentioned, inconveniently halfway between IND and ILN radars

[snowlover2]

Another tornado warning SE of Springfield IL.

[snowlover2]

Quote

  URGENT - IMMEDIATE BROADCAST REQUESTED
   Severe Thunderstorm Watch Number 562
   NWS Storm Prediction Center Norman OK
   850 PM EDT Mon Jul 29 2024

   The NWS Storm Prediction Center has issued a

   * Severe Thunderstorm Watch for portions of 
     Central Illinois
     Central and Southern Indiana
     Northern Kentucky

   * Effective this Monday night and Tuesday morning from 850 PM
     until 400 AM EDT.

   * Primary threats include...
     Scattered damaging wind gusts to 70 mph possible
     Isolated large hail events to 1.5 inches in diameter possible
     A tornado or two possible

   SUMMARY...Thunderstorms will continue to develop this evening in a
   moist and unstable air mass across much of central Illinois and
   Indiana.  Those storms will track southeastward across the watch
   area.  Locally damaging wind gusts are the main concern.

   The severe thunderstorm watch area is approximately along and 75
   statute miles north and south of a line from 50 miles southwest of
   Decatur IL to 45 miles northeast of Louisville KY. For a complete
   depiction of the watch see the associated watch outline update
   (WOUS64 KWNS WOU2).

   PRECAUTIONARY/PREPAREDNESS ACTIONS...

   REMEMBER...A Severe Thunderstorm Watch means conditions are
   favorable for severe thunderstorms in and close to the watch area.
   Persons in these areas should be on the lookout for threatening
   weather conditions and listen for later statements and possible
   warnings. Severe thunderstorms can and occasionally do produce
   tornadoes.

   &&

   OTHER WATCH INFORMATION...CONTINUE...WW 561...

   AVIATION...A few severe thunderstorms with hail surface and aloft to
   1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
   few cumulonimbi with maximum tops to 500. Mean storm motion vector
   29030.

   ...Hart

 

[snowlover2]

Tornado warning for Richmond IN.

[snowlover2]

New tornado warning just west of Oxford OH.

[snowlover2]

Pretty strong rotation near Cambridge City IN.