Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
900 PM EDT Mon Jun 8 2026
Day 1
Valid 01Z Tue Jun 09 2026 - 12Z Tue Jun 09 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
CENTRAL PLAINS INTO THE OZARKS AND FROM PARTS OF THE UPPER MIDWEST
TO THE LOWER OHIO AND WESTERN TENNESSEE VALLEYS...
For the 01Z Update, removed the southern portion of the Slight Risk
that extended into the Southeast. Showers and storms continue to
fall across portions of northern Alabama, Georgia, and eastern
Tennessee and they may present some additional isolated issues
given the wet antecedent conditions. However, rates have generally
been on the decrease across this region, and lacking any strong
forcing and low level inflow, coverage and rates are expected to
continue to diminish with the loss of daytime heating.
Maintained the Slight Risk farther to the north, extending from
western Tennessee to central Wisconsin. Benefiting from stronger
forcing associated with a well-defined shortwave and sufficient
southwesterly low level inflow, storms are expected to persist
further into the evening within this area, with pockets of heavy
amounts expected. Both the HREF/REFS show higher probabilities for
additional accumulations of 2 inches over across portions of
southern Illinois/Indiana, as well as central Wisconsin.
The heaviest amounts of the evening and overnight may occur across
central into eastern Kansas. Supported by strengthening low level
inflow, a complex now developing over north-central Kansas is
expected to further organize as it moves east-southeast across
eastern Kansas into Missouri overnight. This will followed by the
storms now drifting east across northeastern Colorado, taking a
similar track across Kansas, resulting in a stripe of heavy
accumulations overnight. Recent runs of the HRRR and HREF are in
generally good agreement, presenting a signal for 3+ inch amounts
extending from portions of north-central into eastern Kansas.
Pereira
Day 1 threat area:
www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
418 AM EDT Tue Jun 9 2026
Day 1
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, OHIO AND TENNESSEE VALLEYS, AND SOUTHERN
APPALACHIANS...
.Northern Plains...
A potent upper level trough will push across the northern Rockies
into the Plains today and spur cyclogenesis over the northern
Plains. Low pressure will strengthen over the region with a cold
front extending to the southwest and a warm front extending to the
east. Southerly winds ahead of the trough will direct warm, moist,
unstable air into the northern Plains, with PWAT values expected to
exceed 1.5 inches and MUCAPE expected to rise above 3000 J/kg.
Increasing mid/low level winds on the leading edge of the trough
will create a highly sheared environment that is conducive for
supercell development this afternoon. By this evening, an
intensifying low level jet oriented parallel to the surface cold
front will support upscale convective growth into a linear MCS.
Deep convection within supercells and eventually the more organized
MCS will be able to tap into the atmospheric moisture to produce
very intense rainfall rates in excess of 2 inches per hour.
Relatively fast storm motion will be a limiting factor to the flash
flood risk, but rainfall rates will be enough to overwhelm FFGs
and cause flash flooding, especially if heavy rain occurs in urban
environments. A Slight Risk of excessive rainfall remains in effect
for the heaviest convective activity expected over central and
eastern North Dakota and northwestern Minnesota. A broader Marginal
Risk area extends into the Midwest where convection may focus
along a surface boundary extending from the northern Plains cyclone
tonight.
.Ohio and Tennessee Valleys and southern Appalachians...
An upper level trough will lift northeast across the Midwest and
Great Lakes region today accompanied by a surface low over the
Great Lakes and a slow-moving warm front extending south into the
Ohio and Tennessee Valleys. The air mass in place across these
regions will be anomalously moist with PWAT values around 2 inches,
2-2.5 standard deviations above normal for this time of year.
There will also be sufficient synoptic forcing and instability to
support scattered to potentially widespread convection from the
Great Lakes to the Interior Southeast. Convection will be ongoing
at the start of the period and should translate east throughout the
day as the system progresses. High moisture content in the
atmosphere will support chances for locally heavy rainfall, and
more intense rainfall may be possible over the Ohio and Tennessee
Valleys where convection will be enhanced by a couple quick-moving
mid-level waves rounding the top of the ridge positioned over the
Gulf. The first wave will pass over the region early in the period,
resulting in a burst of more intense convection this morning. The
second wave will pass over this area tonight into early Wednesday
morning and will have the potential for back-building storms along
a surface boundary extending into the lower Ohio Valley from the
northern Plains cyclone. Hi-res guidance suggests rainfall rates of
2-3 inches will be possible in stronger cells, and most hi-res
CAMs are showing a swath of rainfall totals of 3-5 inches, with
locally higher amounts, across portions of Kentucky and maybe
southern Indiana as well. The HREF and RRFS are both showing
relatively high probabilities (50-70% and 40-50% respectively) of
24 hr totals exceeding 5 inches in this area. Enhanced convection
will also be possible, but to a lesser extent, under the upper
waves over Tennessee and in upslope areas of the southern
Appalachians. Some areas may be more susceptible to heavy rain
today after recent heavy rains over the past few days. A Slight
Risk of excessive rainfall covers the area of enhanced convection
over the Ohio and Tennessee Valleys and southern Appalachians and
a Marginal Risk area extends north through the Great Lakes.
Dolan
Day 1 threat area:
www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
418 AM EDT Tue Jun 9 2026
Day 2
Valid 12Z Wed Jun 10 2026 - 12Z Thu Jun 11 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR NORTHEASTERN
KANSAS, SOUTHEASTERN NEBRASKA, NORTHERN MISSOURI, AND SOUTHERN IOWA...
.Midwest and central Plains...
On Wednesday, the northern Plains cyclone will move into south-
central Canada and push a trailing cold front across the Midwest.
Showers and storms will be ongoing Wednesday morning ahead of the
system over northern Minnesota, then another round of convection is
expected across the Midwest and central Plains Wednesday afternoon
and evening ahead of and along the cold front. Deep southerly flow
ahead of the system will increase PWAT values to 1.5-2 inches,
with the higher values focused between northern Missouri and
southern Wisconsin. Instability should increase through the
afternoon as daytime heating kicks in, but the best instability
(3000-4000 J/kg) looks like it will focus from eastern Kansas and
southeastern Nebraska into northern Missouri and southern Iowa,
where there is a Slight Risk of excessive rainfall. This area will
likely experience a period of enhanced convection Wednesday night
as a frontal wave develops at the intersection of the cold front
and a dryline. A secondary wave of moisture and instability will
surge into the central Plains as a low level jet strengthens
Wednesday night, which should support efficient rainfall rates,
potentially exceeding 2 inches per hour, that could lead to
scattered instances of flash flooding. There is still some
uncertainty regarding rainfall totals within the Slight Risk area.
If the frontal wave is more progressive, the risk of flash
flooding may be limited. A broader Marginal Risk area surrounds the
Slight Risk and extends up through the Midwest where strong
convection could result in at least isolated instances of flash
flooding.
.Tennessee Valley and southern Appalachians...
Convection should be ongoing across portions of the Tennessee
Valley and southern Appalachians at the start of the period. A
quick-moving upper level wave will round the top of the ridge
positioned over the Gulf and support a period of enhanced
convection late Tuesday night into Wednesday morning. Anomalous
moisture and sufficient instability will be in place to support
efficient rainfall rates, and slow storm motions will contribute to
high rainfall totals. There will also be some potential for back-
building storms along a surface boundary extending from the
northern Plains/southern Canada cyclone into the Tennessee Valley,
mainly focusing over Kentucky. Showers and storms will also be
enhanced by upslope flow along the southern Appalachians.
Convection should start to weaken Wednesday morning and wane by
Wednesday afternoon, but there will at least be enough rainfall
over saturated soils to continue a Marginal Risk of excessive
rainfall into Wednesday morning.
.Interior Northeast...
A Marginal Risk of excessive rainfall was introduced for portions
of the Interior Northeast. An upper level trough will cross over
the Great Lakes into southeastern Canada accompanied by a surface
low pressure system that will bring precipitation chances to much
of the Northeast. The warm sector of this system will be
characterized by an anomalously moist air mass with PWAT values up
to 2 inches. There should be enough moisture and synoptic forcing
to support locally heavy rainfall in stronger convection near the
low pressure center over southeastern Canada and the Interior
Northeast. Rainfall totals and flash flood potential may also be
increased by terrain and upslope flow Wednesday afternoon.
Dolan
Day 2 threat area:
www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
418 AM EDT Tue Jun 9 2026
Day 3
Valid 12Z Thu Jun 11 2026 - 12Z Fri Jun 12 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM NORTHEASTERN
MISSOURI THROUGH EASTERN IOWA AND NORTHERN ILLINOIS TO SOUTHERN
WISCONSIN...
The frontal wave that developed over the central Plains Wednesday
night will progress northeast and intensify as a strong upper
trough swings into the northern and central Plains Thursday
morning. A strong low level jet will increase moisture and
instability across the central Plains Wednesday night, and this air
mass will expand towards the Upper Midwest as southerly winds surge
ahead of the surface frontal boundary. A large swath of high PWAT
values above 2 inches will stretch from the southern Plains to the
Midwest, which will support a broad area of convection capable of
producing locally heavy rainfall. A wave of deeper convection will
accompany the strong frontal wave as it progresses, resulting in
high rainfall totals over an area from northeastern Missouri
through eastern Iowa, northern Illinois, and southern Wisconsin.
These areas are highlighted by a Slight Risk of excessive rainfall
to account for enhanced convection capable of producing scattered
instances of flash flooding. A broader Marginal Risk of excessive
rainfall surrounds the Slight and includes much of the Midwest and
portions of the central and southern Plains.
Dolan
Day 3 threat area:
www.wpc.ncep.noaa.gov/qpf/99epoints.txt
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
314 AM EDT Tue Jun 9 2026
A frontal boundary is forecast to stretch across the Interior
Northeast southwestward across the Ohio Valley to Mid-South and
back into the south-central Plains on Friday. The front will focus
moisture and instability for thunderstorm chances along the
boundary. Some locally heavy rain could cause isolated flash
flooding, so a Marginal Risk remains in place for the Day 4/Friday
ERO. By Saturday, the front should clear precipitation out of the
Northeast, but is forecast to stall and meander across the central
U.S. with a west-east orientation. A strengthening low level jet
will increase instability and moisture while a shortwave aloft
helps provide lift in the south-central U.S. where the front sets
up. With the ingredients for heavy rainfall/flash flooding in
place, a Slight Risk will be raised for the
Oklahoma/Kansas/Missouri/Arkansas intersection. Some of these areas
have wet antecedent conditions, or should by that time. This front
is forecast to linger and only gradually press south into early
next week, so additional flood risks are possible especially if
rounds of rain repeat over similar areas. Farther east, scattered
thunderstorms that tend to be diurnally driven are likely in the
Southeast (including Florida) for multiple days. Rain chances may
increase early next week across the Ohio Valley into the Mid-
Atlantic and Northeast, but with plenty of questions in the
details. Elsewhere, the northern Rockies and High Plains could see
some precipitation late Friday into Saturday, dependent on the
evolution of shortwave energy.
The mean upper-level ridge over the eastern U.S. is expected to
bring the first significant heat of the summer into late week, as
temperatures reach 10-15 degrees above average. The heat looks to
reach its peak across the Mid-Atlantic and Northeast on Friday, and
several record highs and record warm minimum temperatures could be
set, before gradually moderating by the weekend. See WPC's Key
Messages for more. Subtropical ridging across the southern tier
will yield hot conditions there as well, generally a few degrees
above already warm averages. The Desert Southwest can expect
temperatures well into the 100s and perhaps over 110, while heat
indices should be over 100 in the southern Plains to Lower
Mississippi Valley. Into early next week, heat and humidity should
ease a bit in parts of the South as the upper trough digs a bit.
But upper ridging behind it will likely stretch warm temperature
across the West Coast, which could be well above average
particularly in the Pacific Northwest.
Tate
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
314 AM EDT Tue Jun 9 2026
A frontal boundary is forecast to stretch across the Interior
Northeast southwestward across the Ohio Valley to Mid-South and
back into the south-central Plains on Friday. The front will focus
moisture and instability for thunderstorm chances along the
boundary. Some locally heavy rain could cause isolated flash
flooding, so a Marginal Risk remains in place for the Day 4/Friday
ERO. By Saturday, the front should clear precipitation out of the
Northeast, but is forecast to stall and meander across the central
U.S. with a west-east orientation. A strengthening low level jet
will increase instability and moisture while a shortwave aloft
helps provide lift in the south-central U.S. where the front sets
up. With the ingredients for heavy rainfall/flash flooding in
place, a Slight Risk will be raised for the
Oklahoma/Kansas/Missouri/Arkansas intersection. Some of these areas
have wet antecedent conditions, or should by that time. This front
is forecast to linger and only gradually press south into early
next week, so additional flood risks are possible especially if
rounds of rain repeat over similar areas. Farther east, scattered
thunderstorms that tend to be diurnally driven are likely in the
Southeast (including Florida) for multiple days. Rain chances may
increase early next week across the Ohio Valley into the Mid-
Atlantic and Northeast, but with plenty of questions in the
details. Elsewhere, the northern Rockies and High Plains could see
some precipitation late Friday into Saturday, dependent on the
evolution of shortwave energy.
The mean upper-level ridge over the eastern U.S. is expected to
bring the first significant heat of the summer into late week, as
temperatures reach 10-15 degrees above average. The heat looks to
reach its peak across the Mid-Atlantic and Northeast on Friday, and
several record highs and record warm minimum temperatures could be
set, before gradually moderating by the weekend. See WPC's Key
Messages for more. Subtropical ridging across the southern tier
will yield hot conditions there as well, generally a few degrees
above already warm averages. The Desert Southwest can expect
temperatures well into the 100s and perhaps over 110, while heat
indices should be over 100 in the southern Plains to Lower
Mississippi Valley. Into early next week, heat and humidity should
ease a bit in parts of the South as the upper trough digs a bit.
But upper ridging behind it will likely stretch warm temperature
across the West Coast, which could be well above average
particularly in the Pacific Northwest.
Tate
