Weather Prediction Center issues Mesoscale Precipitation Discussion #539 concerning HEAVY RAINFALL...FLASH FLOODING LIKELY679
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Mesoscale Precipitation Discussion 0539
NWS Weather Prediction Center College Park MD
800 AM EDT Sat Jun 27 2026
Areas affected...Portions of the Middle MS and OH Valley
Concerning...Heavy rainfall...Flash flooding likely
Valid 271200Z - 271800Z
SUMMARY...Regional concerns for flash flooding will continue over
the next several hours going into the early afternoon hours.
Repeating rounds of heavy shower and thunderstorm activity will
support new areas of flash flooding, and locally significant
impacts will be possible.
DISCUSSION...The morning GOES-E IR satellite imagery along with
regional radar data shows an elongated axis of broken shower and
thunderstorm activity impacting areas of southern IL, southern IN,
and multiple areas of central KY. More recently some of this
activity has been edging into western WV as well. All of this
convection is associated with multiple MCVs that are embedded
within the westerly mid-level flow pattern across the Middle MS
and OH Valley region. Much of the region is very moist, with PWs
of 1.8 to 2.2 inches, and generally on the order of 2 to 2.5
standard deviations above normal for late June.
The early morning OSPO ALPW data shows substantial moisture in the
mid and upper-levels of the vertical column and supportive of
tall, skinny CAPE profiles. This is a rather classic warm rain
setup which is likely to result in extremely efficient convection
for high-end rainfall rate potential. Already the ejecting vort
energy is fostering sufficient lift for broken clusters/bands of
convection, but with nearly unidirectional flow through the
column, and upwind propagation vectors very weak and nearly
opposing the deeper layer mean flow, we are going to see an
environment conducive for backbuilding and training convection.
Already some hints of this are noted over areas of far southern IN
down through central KY. The MUCAPE values are on the order of
1000 to 2000 J/kg for much of the region, except for far eastern
KY and western WV where they are more in the 500 to 1000 J/kg
range. This coupled with the level of deep moisture in place and
high WCL depths will support rainfall rates easily into the 2 to 3
inch/hour range, with even some potential for rates higher than
this.
Given the repeating/training nature of the heavy rainfall threat,
some additional totals through 18Z (1PM CDT) may reach 3 to 5
inches, and there are multiple hires model CAMs that support this,
although there is disagreement on the placement. Radar and
satellite trends would favor areas of central KY probably seeing
the best potential for this. But areas farther west across
southeast MO into southern IL and southern IN will also see
separate bands of convection with very heavy rainfall potential.
The threat of flash flooding is increasing, and new areas of flash
flooding are expected over the next several hours. This will
include a threat for locally significant impacts going through
early this afternoon.
Orrison
...Please see www.wpc.ncep.noaa.gov for graphic product...
ATTN...WFO...ILN...ILX...IND...JKL...LMK...LSX...LZK...MEG...
MRX...OHX...PAH...RLX...RNK...SGF...
ATTN...RFC...KRF...MSR...ORN...TIR...NWC...
LAT...LON 38998291 38658107 37608094 36748349 36528527
36338756 36249047 36519181 36969233 37569202
38049091 38378935 38548801 38768543
Source:
Weather Prediction Center issues Mesoscale Precipitation Discussion #539 concerning HEAVY RAINFALL...FLASH FLOODING LIKELY---------------
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