FOUS30 KWBC 080819
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
419 AM EDT Mon Jun 8 2026

Day 1
Valid 12Z Mon Jun 08 2026 - 12Z Tue Jun 09 2026

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE OZARKS...

Convection will be ongoing at the start of the period across the 
Ozarks where a low level jet ahead of a mid-level vortex/wave will 
create favorable convective conditions that will likely lead to 
impactful flash flooding, especially near steep terrain. During the
early morning hours, hi-res CAMs are showing rainfall totals as 
high as 5-8 inches for portions of southeastern Kansas, 
northeastern Oklahoma, southwestern Missouri, and northwestern 
Arkansas where slow, back-building thunderstorms are expected. An 
anomalously moist and unstable air mass is already in place across 
the central U.S., which will support deep convection with highly 
efficient rainfall rates (rates of 2-3 inches per hour are already 
being observed). This region was incorporated in a special update 
Moderate Risk area overnight, and the Moderate Risk will continue 
into the beginning of the Day 1 period this morning. Convection 
should wane and shift southeast later this morning into this 
afternoon as the system becomes dominated by the outflow.

The broader Slight Risk area includes much of the Middle 
Mississippi and Tennessee Valleys where widespread showers and 
thunderstorms are expected in the warm sector of a northern stream 
cyclone today. Much of the convective activity will be driven by 
mesoscale boundaries and remnant MCV activity continuing from the 
overnight period, which will result in variability of the QPE 
across the warm sector. Some convection may be more focused along a
quasi-stationary frontal boundary draped over the Tennessee Valley
and southern Appalachians. Convection will be enhanced by a 
leading upper level shortwave with embedded MCV activity that will 
push east across these regions, and the environment will be 
extremely supportive of heavy rainfall with high moisture (PWAT 
values around 2 inches) and high instability (MUCAPE greater than 
3000 J/kg). Storms are expected to be slow moving due to a lack of 
steering flow, which will allow for locally high rainfall totals. 
Latest CAM guidance suggests rainfall rates up to 2-3 inches per 
hour and totals up to 5-8 inches will be possible over portions of 
the Middle Mississippi and Tennessee Valleys. HREF neighborhood 
probabilities show the highest chances of exceeding 5 inches of 
rainfall in 24 hours (25-45%) will be over an area from southern 
Illinois and Indiana through western Kentucky and Tennessee. These 
areas can expect impacts on the higher end of the Slight Risk 
category. Some of the areas within the Slight Risk received heavy 
rainfall on Sunday, which may increase the risk of flash flooding 
if areas are impacted by additional storms with heavy rainfall 
today. The Slight Risk areas has also been extended north into
central Wisconsin and eastern Iowa where slow-moving storms are
expected to be enhanced by a mid-level low this afternoon.

Outside of the Slight Risk area, a broad Marginal Risk area extends
into the Upper Midwest and central Plains where locally heavy
rainfall may lead to isolated instances of flash flooding. Storms
across much of the Upper Midwest should be fairly progressive,
which will limit flash flood potential, but isolated flooding
concerns will be possible if heavy rainfall impacts any urban
areas. Models continue to also show a potential MCS forming
underneath a potent upper level shortwave moving quickly east
across the central Plains this evening. Though this feature would
be very progressive, deep convection will have the potential to
produce heavy rainfall and isolated flash flooding. This shortwave
may also enhance convection again over the Middle Mississippi
Valley tonight, and there could be a scenario where a targeted
Moderate Risk area is needed. 

Dolan


Day 2
Valid 12Z Tue Jun 09 2026 - 12Z Wed Jun 10 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
NORTHERN PLAINS AND WESTERN KENTUCKY AND TENNESSEE...

On Tuesday, a potent upper level trough will move across the 
northern Rockies and emerge into the northern Plains. This trough 
will spur cyclogenesis over the northern Plains while a low level 
jet increases moisture and instability ahead of the system. The 
environment will be ideal for supercell development Tuesday 
afternoon, and increasing shear over the region will allow storms 
to evolve into an MCS Tuesday evening into Tuesday night. Deep 
convection within these severe storms will be able to tap into 
moisture in the atmosphere (PWAT values 1.5-2 inches) and create 
very heavy rainfall. The quick nature of the MCS should somewhat 
limit the risk of flash flooding, but intense rainfall rates in 
excess of 2 inches per hour will exceed FFGs and could lead to 
impactful flash flooding, especially in urban areas. A Slight Risk 
area has been introduced for much of central and eastern North 
Dakota and northwestern Minnesota. 

Scattered showers and storms are forecast from the southern
Appalachians and Tennessee Valley through the Ohio Valley and Great
Lakes region, which will be supported by an upper level shortwave
lifting northeast across the Ohio Valley and Great Lakes and a slow
moving warm front extending south into the Tennessee Valley and
southern Appalachians. The air mass in place will be anomalously
moist (PWATs around 2 inches) and sufficiently unstable to support
locally heavy rainfall. Available hi-res guidance suggests higher
rainfall totals will be possible across western Kentucky and
Tennessee where convection will continue from the Day 1 period into
Tuesday morning. A mid-level shortwave will be enhancing this 
convection and should allow for efficient rainfall rates over 2 
inches per hour. A Slight Risk area has been introduced to cover 
the elevated flash flood threat over western Kentucky and 
Tennessee. Global models have also been showing locally enhanced 
rainfall totals over portions of the Ohio Valley, but there is 
still a significant amount of uncertainty in the location of these 
higher totals. It is possible the Slight Risk area may need to be 
expanded to the northeast as convective details become more clear 
with additional hi-res guidance available later today.

Dolan


Day 3
Valid 12Z Wed Jun 10 2026 - 12Z Thu Jun 11 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM EASTERN KANSAS
INTO NORTHERN MISSOURI AND SOUTHERN IOWA...

On Wednesday, the northern Plains cyclone will be moving swiftly
east and pushing a cold front across the Midwest. Showers and
thunderstorms are expected ahead of and along the frontal boundary
from the Midwest to the central Plains, which are encompassed by a
Marginal Risk of excessive rainfall. The tail end of the front will
likely hang up on the Rockies and flatten out over the central
Plains, and low pressure is expected to develop over Kansas where a
dryline will intersect the boundary. Models are showing impressive
moisture transport ahead of the frontal boundary Wednesday morning
and a secondary surge Wednesday night as a strong low level jet
brings increasing moisture and instability into the central Plains.
This set up will be conducive for heavy rainfall, and global models
are showing potential for heightened rainfall totals of 2-4 inches
within the Slight Risk area, which may be underdone given the
convective limitations of the models. Locally heavy rainfall may
also be possible over central Wisconsin and could impact areas
highlighted with a Slight Risk on Day 2, which could warrant an
additional Slight Risk upgrade. However, there is much more
uncertainty regarding rainfall totals in Wisconsin, which may be
limited by the progressive nature of the cold front.

Dolan
$$
--- SBBSecho 3.28-Linux
 * Origin: Capitol City Online (618:250/10)