Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
833 PM EDT Fri Jun 5 2026
Day 1
Valid 01Z Sat Jun 06 2026 - 12Z Sat Jun 06 2026
...THERE ARE SLIGHT RISKS OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
EASTERN NEBRASKA/KANSAS INTO THE MID-MISSISSIPPI VALLEY AS WELL AS
MUCH OF TEXAS/SOUTHERN OKLAHOMA...
01Z Update: Much of Texas remains in a SLGT risk as convection is
ongoing across a good portion of the state with central and north
Texas likely to be the focal point overnight. HREF probs remain
high (40-70%) for >3" potential across the I-35 corridor where
low-level confluent flow is shaping up to maintain an active
evening between San Antonio up through Georgetown. Further north,
we'll see the introduction of a LLJ help play a role, along with
remnant outflows from convection to increase heavy rain prospects
across western Rolling Plains up through southwestern OK where
convection is already running rampant. There is way too much going
on to deviate from the previous SLGT risk inherited in these zones,
so the SLGT was maintained to account for everything ongoing, and
expected to continue for several more hours.
Over the Central Plains and Midwest, yet another shortwave will
eject out of the High Plains with a focused convergence axis
situated from southeastern NE through southern IA. This area will
have some overlap from the previous period of heavy rainfall, so
soils in some parts may be either compromised, or relatively close
leading to a greater threat for flash flooding compared to normal.
Neighborhood >2" probabilities are steady 40-70% across the
aforementioned corridor with even a bullseye of ~80% located across
southeastern NE. The potential for training convection will be
greatest in that area in particular as low to mid-level flow backs
for a period as the shortwave approaches. Look for cell motions to
slow and provide a period of prolonged heavy rain potential
overnight before we finally see everything shift eastward.
Considering the nature of the setup and consistency in guidance,
the SLGT from previous forecast(s) were maintained.
Elsewhere over the Upper Midwest and Great Lakes, a quick-moving
disturbance migrating east-southeast from the Northern Plains
continues to plague portions of northern WI into the U.P. of
Michigan this evening leading to some sporadic flash flood concerns
near the southern shores of Lake Superior. Prospects for flash
flooding remain lower compared to other areas of the CONUS, but the
threat is right within the lower threshold for a MRGL risk when
assessing the prob fields at both FFG exceedance and 3-hr QPF >2".
Both were right within the bounds of convergence considering a
MRGL risk, so opted to add the risk given the already issued flash
flood warning that materialized recently with rain continuing.
Kleebauer
Day 1 threat area:
www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
400 AM EDT Sat Jun 6 2026
Day 1
Valid 12Z Sat Jun 06 2026 - 12Z Sun Jun 07 2026
...THERE ARE SLIGHT RISKS OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
SOUTHERN PLAINS, OHIO VALLEY, UPPER TEXAS COAST, AND CENTRAL GULF
COAST...
...Southern Plains...
A plume of deep tropical moisture will surge northward across the
Southern Plains on Saturday. The low level jet advecting this
moisture north will run into an area of enhanced lift due to a
nearby upper level shortwave, which will be lifting northeast to
rejoin the jet. The result will be a series of rounds of storms
moving north-northeast across portions of north Texas, eastern
Oklahoma and western Arkansas. Highly efficient warm rain processes
will dominate due to the present of such abundant amounts of
moisture, with PWATs close to 2 inches. For eastern
Oklahoma/western Arkansas, the rain will persist for much of the
day in the form of training lines of storms. Back into Texas, the
threat will be mostly overnight tonight due to persistent storms
associated with an MCS that will drift east across far north Texas
and southern Oklahoma. An internal higher-end Slight was introduced
from southwest of the Metroplex through it, and continuing into
much of eastern Oklahoma and western Arkansas for the combination
of two areas of persistent heavy rain. Overall changes from
inherited were minimal.
...Ohio Valley...
A very-slow moving cold front drifting south across the
Midwest/Ohio Valley on Saturday will be the animus for multiple
rounds of storms which will track east-southeast from Indiana east
to the central Appalachians. A new Slight Risk area was introduced
with this update. In the upper levels, a shortwave may help the
storms become stronger for the first part of the period before
shifting off to the east. The front will form the leading nose of a
plume of deep Gulf moisture tracking northward up the Mississippi
Valley. The front will "shear" the moisture eastward in a narrow
corridor, along which the storms will form and move. Stronger and
more persistent storms from Indiana to western Ohio will become
somewhat less strong and less organized into the Mountains of
western Pennsylvania and West Virginia, but those areas will have
lower FFG thresholds, allowing the two areas to combine into one
Slight Risk area for somewhat different reasons. Uplift along the
western face of the Appalachians may also locally enhance rainfall
rates.
...Upper Texas Coast...
In coordination with HGX/Houston, TX forecast office, a Slight Risk
upgrade was introduced with this update. Extreme amounts of
moisture will be in place throughout the atmosphere of southeast
Texas Saturday afternoon. PWATs between 2 and 2.25 inches are 3
sigma above normal for this time of year, an impressive threshold
to meet for June. With peak heating this afternoon, scattered
showers and thunderstorms are expected to form, likely 20-50 miles
inland from the coast. Cold pools from Friday's storms and new ones
from the storms that form Saturday afternoon will likely drive new
storm development along the I-10 corridor from southwest of Houston
to the TX/LA border near Beaumont. With plenty of new moisture
streaming north off the Gulf, the storms will have no trouble
reforming and training over the same areas for the duration of the
long afternoon. Nightfall should end the storms in the area due to
lack of other forcing and the loss of instability. Friday's storms
have knocked down FFGs in this region significantly, and with good
capability of efficient warm rain processes, urban concerns in
Houston, and slow storm movement were all reasons contributing to
the Slight Risk upgrade.
...Central Gulf Coast...
Few changes were needed to the Slight Risk area from New Orleans
east to Pensacola. A strong front is in place across the eastern
Gulf, characterized by very dry air to its east, rather than any
significant temperature gradient. The dry air is 2 sigma below
normal over portions of central Florida...under 1 inch PWATs.
Meanwhile to the west from Louisiana through Texas, an abnormally
moist air mass will be streaming north to the west of the high
pressure area characterized by the dry air. Over much of Louisiana,
PWATs will be over 2.25 inches or 3 sigma above normal. The front
makes up the gradient between these extremely contrasting air
masses. Through the day, the front will push east as the moist air
mass gradually gains ground. However, the front will be the forcing
along which numerous showers and thunderstorms pushing north out of
the Gulf will form along. The front will be slow to move, allowing
repeating rounds of storms to impact the central Gulf Coast. FFGs
are high, about 4 inches/hour, but the repeating rounds of storms
should rather quickly bring those numbers down, allowing for widely
scattered instances of flash flooding to develop where the rains
are most persistent by late afternoon. Nightfall should see a
decrease in shower and storm activity, ending the flooding threat.
Wegman
Day 1 threat area:
www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
400 AM EDT Sat Jun 6 2026
Day 2
Valid 12Z Sun Jun 07 2026 - 12Z Mon Jun 08 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF THE
MID-MISSISSIPPI VALLEY, OZARKS, AND THE WESTERN TENNESSEE
VALLEY...
A pair of forcings will work cause renewed rounds of showers and
storms across much of the Mississippi Valley on Sunday into Sunday
night. A slow moving but still potent upper level low will track
northeastward up the Plains and into the Midwest by late Sunday
night. Meanwhile a strong front oriented north-south will allow for
shower and thunderstorm development further east across portions of
the South. For the Mid-Mississippi Valley and Ozarks, the shortwave
will be the primary forcing. Deep tropical moisture characterized
by PWATs on either side of 2 inches will advect northward up the
Mississippi Valley. The shortwave will provide the forcing for
storms to form, along with the topography of the Ozarks. Many of
these areas, especially from far eastern Oklahoma, northwestern
Arkansas, and southwest Missouri have seen repeated rounds of heavy
rain in recent days, so FFGs are lower in this area. Thus, a
higher-end Slight was introduced for this area depicting an even
greater threat for flash flooding, as the topography of the Ozarks
works to increase the severity of any flooding. FFGs are also lower
from northern Missouri into Iowa. Storms forming in these areas
will be closer to the nose of the low level jet, though the upper
level shortwave should still be the primary forcing.
The Slight Risk area was expanded north up the Mississippi Valley
into southern and eastern Iowa and western Illinois with this
update.
For portions of the western Tennessee Valley, including western
Tennessee far northeastern Mississippi, and especially northern
Alabama, the aforementioned north-south oriented front will be the
primary forcing for the first half of the day. The front will more
rapidly retreat east across Georgia by Sunday night, leaving any
forcing to weak upper level shortwaves. Thus, most of the storms
will be during the afternoon and evening during peak heating and
when the front is closer. FFGs are lower across northern Alabama
from recent heavy rainfall, around 2.5 in/hour, which due to PWATs
occasionally over 2 inches, should be easily attainable by the
strongest storms expected Sunday afternoon. Thus, the Slight Risk
was expanded southeast for these reasons.
Wegman
Day 2 threat area:
www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
400 AM EDT Sat Jun 6 2026
Day 3
Valid 12Z Mon Jun 08 2026 - 12Z Tue Jun 09 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
MID-MISSISSIPPI, LOWER OHIO, AND WESTERN TENNESSEE VALLEYS...
On Monday, the excessive rainfall risk translates a bit further
north and east into the Mid-Mississippi, lower Ohio, and western
Tennessee Valleys. A strong front over the Great Lakes will retreat
northeastward as the plume of anomalously deep moisture from the
Gulf surges northeastward to replace the drier air mass in place
over the Northeast. A slow-moving negatively tilted trough will
also promote upper divergence and lift throughout the atmosphere
over the Slight Risk area throughout the period. PWATs around 2
inches will be 3 sigma above normal for this time of year across
the region, so many of the storms that form will consist of highly
efficient warm rain processes, which will promote heavy rainfall.
FFGs across the region will average around 2-2.5 inches, which will
be easily overcome by many of the strongest cells, so long as their
forward speed is kept in check. The Slight Risk area was nudged
west over more of southeastern Missouri with this update, adjusted
for expected heavy rainfall and likely lower FFGs in this region
from the Day 2/Sunday period.
Wegman
Day 3 threat area:
www.wpc.ncep.noaa.gov/qpf/99epoints.txt
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
404 AM EDT Sat Jun 6 2026
The shortwave moving from the Ohio Valley eastward combined with
the hot, humid airmass in place from the broader ridge aloft will
lead to thunderstorms capable of heavy downpours and flash flooding
on Tuesday. A Marginal Risk stretches from Lower Michigan through
parts of the Ohio and Tennessee Valleys in the Day 4/Tue ERO.
Scattered thunderstorms are forecast to shift slightly east into
the Appalachians on Wednesday, but upper-level support should be
lessening. Convection could spark in much the same area of the
eastern third of the U.S. into later week. Florida can also expect
daily, diurnally driven thunderstorms as a surface front settles
there.
An unseasonably strong low pressure system is forecast to push
across the northern Plains Tuesday-Wednesday and into south-central
Canada by Thursday, ahead of the northwestern U.S. trough. Fronts
with the low will help focus convection and plentiful moisture,
instability, and shear will be in place. The Storm Prediction
Center is calling for risks of severe weather in the northern
Plains and Upper Midwest due to this potential. Meanwhile heavy
rainfall/flash flooding also looks to be a concern, and Marginal
Risks in the ERO are shown for this potential in the northern
Plains/Upper Midwest on Day 4/Tuesday, shifting somewhat east and
south on Day 5/Wednesday with the frontal boundary. More storms are
likely in parts of the Plains and Mississippi Valley into the
latter part of the week.
The upper trough in the West and multiple frontal passages will
bring cooler conditions and chances for scattered showers and
thunderstorms in the Pacific Northwest Tuesday-Wednesday. Then as
the trough sets up over the northern Rockies/Plains as the week
progresses, this should yield continued forcing for precipitation
there through much of next week. Moisture levels should be high but
instability should generally be lacking, preventing any
significant flooding threat. Some snow is possible in higher
elevations. Farther south, gusty winds under the upper trough and
very low relative humidity Tuesday could produce conditions
favorable for fire weather per SPC.
The amplifying upper-level ridge building over the central to
eastern U.S. is expected to bring the first significant heat of the
summer by mid- to late next week. The threat should gradually
shift from the central U.S. Tuesday and Wednesday towards the East
Coast by Friday and into next weekend. See WPC's Key Messages for
more. Meanwhile, the upper trough over the western U.S. will lead
to some below average temperatures over the northwestern U.S.
eventually shifting into the northern High Plains and moderating.
Tate
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
404 AM EDT Sat Jun 6 2026
The shortwave moving from the Ohio Valley eastward combined with
the hot, humid airmass in place from the broader ridge aloft will
lead to thunderstorms capable of heavy downpours and flash flooding
on Tuesday. A Marginal Risk stretches from Lower Michigan through
parts of the Ohio and Tennessee Valleys in the Day 4/Tue ERO.
Scattered thunderstorms are forecast to shift slightly east into
the Appalachians on Wednesday, but upper-level support should be
lessening. Convection could spark in much the same area of the
eastern third of the U.S. into later week. Florida can also expect
daily, diurnally driven thunderstorms as a surface front settles
there.
An unseasonably strong low pressure system is forecast to push
across the northern Plains Tuesday-Wednesday and into south-central
Canada by Thursday, ahead of the northwestern U.S. trough. Fronts
with the low will help focus convection and plentiful moisture,
instability, and shear will be in place. The Storm Prediction
Center is calling for risks of severe weather in the northern
Plains and Upper Midwest due to this potential. Meanwhile heavy
rainfall/flash flooding also looks to be a concern, and Marginal
Risks in the ERO are shown for this potential in the northern
Plains/Upper Midwest on Day 4/Tuesday, shifting somewhat east and
south on Day 5/Wednesday with the frontal boundary. More storms are
likely in parts of the Plains and Mississippi Valley into the
latter part of the week.
The upper trough in the West and multiple frontal passages will
bring cooler conditions and chances for scattered showers and
thunderstorms in the Pacific Northwest Tuesday-Wednesday. Then as
the trough sets up over the northern Rockies/Plains as the week
progresses, this should yield continued forcing for precipitation
there through much of next week. Moisture levels should be high but
instability should generally be lacking, preventing any
significant flooding threat. Some snow is possible in higher
elevations. Farther south, gusty winds under the upper trough and
very low relative humidity Tuesday could produce conditions
favorable for fire weather per SPC.
The amplifying upper-level ridge building over the central to
eastern U.S. is expected to bring the first significant heat of the
summer by mid- to late next week. The threat should gradually
shift from the central U.S. Tuesday and Wednesday towards the East
Coast by Friday and into next weekend. See WPC's Key Messages for
more. Meanwhile, the upper trough over the western U.S. will lead
to some below average temperatures over the northwestern U.S.
eventually shifting into the northern High Plains and moderating.
Tate
