AWUS01 KWNH 272107
FFGMPD
OHZ000-KYZ000-MIZ000-INZ000-ILZ000-280300-
Mesoscale Precipitation Discussion 0864
NWS Weather Prediction Center College Park MD
506 PM EDT Mon Jul 27 2026
Areas affected...Much of Indiana...Northeast & Eastern
Illinois...Southwest Ohio...Far Northern Kentucky...
Concerning...Heavy rainfall...Flash flooding possible
Valid 272105Z - 280300Z
SUMMARY...Intense, locally repeating thunderstorms capable of
2.5"/hr rates may result in multiple stripes of 2-4" totals in 1-3
hours resulting in possible localized incidents of flash flooding,
particularly across urban centers where there will be limited
infiltration.
DISCUSSION...A complex, vigorous and highly dynamic environment
across the Great Lakes is spreading south into the Ohio Valley
with very deep moisture/unstable environment to support
strong/highly efficient rainfall production. However, given
strong deep layer flow, the speed will likely limit overall totals
with exception of incidents of repeating/training which are
probable locally across a broadening zone from W OH to E IL.
Aloft a strong shortwave at the nose of a splitting upper-level
jet can be seen with rapid WV leading ahead of rapid/broadening
warming in WV across WI into northern LP of MI. This split
downstream has allow for solid divergence aloft and upscale growth
of initial supercells near Milwaukee and Chicago this afternoon,
into a progressive bow in north-central IND with an upstream
elongated long updraft from SE WI across Lake Michigan.
Here the upstream edge of outflow boundary can be seen from a
surface low near ISW in central WI due south along, just east of
I-39 into northern IL. A surface pressure trof well ahead of the
surface cold front is helping to provide slightly enhanced
confluence at the trailing end of a broad west-southwesterly very
moist and very unstable inflow where surface Tds are in the upper
70s, low 80s and MLCAPEs are up to 5000 J/kg. This ascends
orthogonally to the outflow boundary supporting the trailing broad
updraft in SE WI but also newer development along the flank of the
exiting bow echo across the western suburbs of Chicago at this
time. Scattered TCU and weak CBs are intersecting and
reinvigorating surface based convection along the outflow. Hourly
rates of 2.5-3"/hr are probable given broad updrafts that are
rotating, providing the extra flux convergence from super-cell
influences. It is along this upstream edge, the greatest potential
of training will exist given unidirectional steering flow
generally parallel to the N-S outflow boundary. Depending on
further expansion/destabilization, streaks of 2-4" are possible
mainly in E IL and along the IND line. This is in line with
recent RRFS and WoFS solutions, with the latter suggesting 90th
percentile range may even locally reach 6", which seems to be a
bound for worse case solution given current trends.
Further east...the progressive bow echo will help to produce a
quick sub-hourly 1-1.5" higher near the cyclonic rotor of the bow,
but RAP analysis still shows some remaining pockets of
conditionally unstable air and with reduced upstream development,
perhaps further elevated advection of higher theta-E air to
support additional upstream development filing in before the main
upper-level trof swings through. This is more in line with recent
HRRR and ARW solutions with slightly reduced totals but localized
random intersections up to 2-3". Proximity to urban centers where
limited infiltration and higher run-off given the shear rates
resulting in the highest potential for localized FF across central
IND into SW Ohio later this evening.
All in all, the broadening of the split flow and current trends do
not provide high confidence, but a few incidents of flash flooding
(as described above) remain possible through this evening.
Gallina
...Please see
https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!DZ3fjg!4oYYttlfZLP3JT869MGLLBZz8nkclrS4uRkQLDhbGDONfOx5S96nw_r-8hqfe-Y5MyUvVfmIQBG7q2PxOhZH9fzlWXU$ for graphic product...
ATTN...WFO...ILN...ILX...IND...IWX...LMK...LOT...
ATTN...RFC...MSR...TIR...NWC...
LAT...LON 42378797 42248716 41908654 41398595 40818518
39898415 38878434 38408545 38568699 38898789
39808829 40588852 41358865 41788865 42138842
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--- scorpsmtpd
* Origin: capitolcityonline.net * KY, USA (1:2320/107)