Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1159 AM EDT Sat Jun 6 2026
Day 1
Valid 16Z 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 Saturday. The low level jet advecting this moisture
north will run into an area of enhanced lift due to a nearby
lingering upper-low, 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/northwest Texas, Oklahoma, and
western Arkansas. Highly efficient warm rain processes will
dominate due to the presence of such abundant amounts of moisture,
with PWATs close to 2 inches. For eastern Oklahoma/western
Arkansas, rainfall is already ongoing and will persist for much of
the day in the form of training lines of storms. To the west,
another round of storms is expected to develop with daytime heating
along the eastern periphery of the upper-low, with the expectation
that repeated rounds of storm development and storm
clustering/merging cold pools may eventually lead to a more
organized convective system that will progress slowly to the east-
southeast through the evening and overnight hours. An internal
higher- end Slight covers 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.
The latest convection allowing guidance (CAMs) show peak rain
rates reaching upwards of 2-3 inches per hour with locally heavy
totals into the 5-6+ inch range, more than sufficient for at least
scattered instances of flash flooding despite some locally drier
antecedent conditions.
...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 within the Slight
Risk area roughly from central Indiana east to the central
Appalachians. 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. There is some
uncertainty as to how persistent an ongoing complex of storms
moving into central Ohio will be as they progress east-
southeastward through the afternoon. However, even if storms do not
maintain quite the same strength/organization as they move into
the Mountains of western Pennsylvania and West Virginia, these
areas have lower FFG thresholds and the risk for scattered flash
flooding will remain a concern. Uplift along the western face of
the Appalachians may also locally enhance rainfall rates. Another
round of storms is expected along the boundary further west within
the Slight Risk over central Indiana where the CAMS/HREF suggest
heavier totals into the 3-5 inch range are possible. Additional
storms are also forecast to develop further west along the boundary
stretching through central Illinois and along the Iowa/Missouri
border. However, these storms are forecast to remain more
scattered/less organized with generally lower rain totals in the
CAMS, keeping the flash flood threat more isolated compared to
further east.
...Upper Texas Coast...
A Slight Risk remains in effect for the greater Houston area/Upper
Texas Gulf Coast. 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 east into southwestern
Louisiana. 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.
...Central Gulf Coast...
No 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 scattered instances of flash flooding to develop where the
rains are most persistent by late afternoon, particularly for urban
areas. HREF probabilities for rainfall exceeding 5 inches are also
moderate to high (45-70%), with low end probabilities (~15%) of
exceeding 8 inches. Storms are also expected west along and just to
the north of the I-10 corridor between the Slight Risks covering
southeastern and far southwestern Louisiana. However, more
persistent forcing/greater storm coverage to the east and lower
FFGs to the west suggest there will be a relatively more isolated
threat in between. Similar to the Upper Texas Coast, nightfall
should see a decrease in shower and storm activity, ending the
flooding threat.
Putnam/Wegman
Day 1 threat area:
www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1159 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
1159 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
