Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1159 AM EDT Sat Jun 13 2026

Day 1
Valid 16Z Sat Jun 13 2026 - 12Z Sun Jun 14 2026

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR SOUTHWESTERN
MISSOURI...

...Southern Plains, Mid-Mississippi Valley, western Ohio Valley...

Maintained the Moderate Risk area for southwestern Missouri and
adjoining areas with a continued signal for heavy rain this
afternoon/evening and early overnight hours. A broader Slight Risk
outline extends from the eastern half of Oklahoma northeastward to
the far western Ohio Valley.

At 15Z, a cold front extended from the Upper Midwest back to the
central Plains and will continue to push southeastward today. In
addition, a warm front extended from southeastern Nebraska across
southern Missouri into the Tennessee Valley. Southerly flow from
Texas and the Gulf will continue to supply warm/moist air to the
region as dew points in the 60s/low 70s are common across the warm
sector along with precipitable water values of 1.75-2.00 inches.
Morning convection over central/southern MO (near and east of the
warm front) will continue eastward this afternoon, allowing for
some clearing to the west. By 00Z, cold front from the northeast
will push into southeastern KS with an increase in the LLJ and an
expected convective expansion into the Moderate Risk area. 40+kt
850mb southwesterly flow along/ahead of the surface cold front
should favor sufficient growth with heavy rain rates of 2-3 inches
per hour, especially where any training occurs if the cold front
slows. 12Z CAMs still show potential for a fairly widespread 1-3"
of rain and embedded 6+" totals over southwestern MO and far
northeastern OK per some members. HREF mean signal has been
consistent since 00Z and little change to the outlook area was
made. The topography of the Ozarks across southern Missouri
supports a heightened flash flooding threat as the mountains
quickly funnel the heaviest rains into narrow valleys, worsening
the impacts of any flooding that develops there. Will note the
AI guidance from the ECMWF and GFS (though lower res at 0.25 deg)
showed a QPF max over either eastern KS or northeastern OK rather
than into MO, but their D1 skill is generally not as good as the
traditional CAM guidance.

A much larger Marginal Risk area exists from the southern Rockies
all the way to the southwestern Great Lakes in the broad warm
sector ahead of the front, with expected coverage isolated.

...Central/Eastern Florida...

Trimmed the Marginal Risk area to remove the western portion of
the peninsula. Westerly flow, though light, should favor
convergence inland and over eastern areas. Moisture levels remain
higher than climo -- near 2" -- and coupled with slow-moving cells
may favor local flash flooding especially in urban areas. 12Z HREF
neighborhood probabilities for at least 3 inches per hour are
10-40% (a little higher in the 06Z REFS) and 1-h FFG values are
generally 3-4 inches per hour. Farther north into
eastern/southeastern SC/NC inland from the coast, combination of
sea breezes and incoming front to the north could support isolated
heavier rain and very localized flash flooding should any
convection remain slow-moving, though the coverage is likely less
than the 5% threshold for a Marginal Risk outline.
Fracasso/Wegman


Day 2
Valid 12Z Sat Jun 13 2026 - 12Z Sun Jun 14 2026

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
EASTERN KANSAS AND SOUTHWEST MISSOURI...

...Central Plains to Mid-Mississippi Valley...

20Z Update: In coordination with the local WFO's across eastern
Kansas into Missouri, a Moderate Risk was issued for the D2 period
with emphasis across eastern Kansas into southwestern Missouri.
Deep moist environment will preclude the arrival of a prominent
shortwave ejecting into the Central Plains, making headway into the
mid-Mississippi Valley on Saturday afternoon and evening.
Instability gradient will be present across northern MO into Iowa
as a cold front begins to slowly press south with the guide of a
potent shortwave trough dropping out of Canada. This is the making
of an increasingly convergent low to mid-level setup within a very
favorable environment across the nation's mid-section.

Instability across eastern KS into MO will be quite robust with
model forecast MUCAPE along and east of I-35 into the 3500-5000
J/kg range by the time we reach peak diurnal heating. Coupled with
a deep moisture pool in the column, any convective development will
comprise of significant rainfall rates as noted via elevated hourly
and 3-hourly prob fields within the latest 12z HREF. Deterministic
output from various CAMs indicate rates between 2-3"/hr with likely
higher intra-hour rates exceeding 4" at times, especially as you
get further south into southeastern KS and southern MO where
instability will be maximized. QPF forecasts are consistent for
2-4" totals across the area south of Topeka down into the
Joplin/Springfield region of southwestern MO. Kansas City at this
time on the edge of the potential with a split in guidance on where
the heaviest precip will reside for the northern and northeast
periphery of any established maxima. Considering such a close
proximity to the max, and the D2 error in convective forecasting
still a concern, there's potential that the urban center can get
into some of the heavy precip as it materializes on Saturday
evening. With a Flood Watch issued over the metro and surrounds,
decided to include the city in the MDT risk to maintain consistent
messaging and signaling a heightened threat compared to normal.

A high-end SLGT is forecast for much of the remainder of Missouri
not encompassed within the MDT risk. There could very well be an
initial round of thunderstorms in the morning across southern MO in
conjunction to the shortwave moving across the area as referenced
in the D1 update. Any rainfall occurring would be a priming
scenario for what would transpire later as the cold front to the
north begins pushing south with a strong low-level convergence
pattern taking shape over the mid-Mississippi Valley. The area of
greatest concern, outside the MDT risk, is likely across
northeastern MO where recent rainfall over the past 72hrs have led
to significant flash flooding over portions of the area allowing
for highly compromised soils and swollen streams and creek beds
located in the area. Local FFG's in the 1/3/6 hour thresholds
continue to run much lower than normal with most of the thresholds
between 1-2" for either temporal range meaning any heavy convection
will be susceptible to flash flood prospects. As of now, the saving
grace for areas north of I-70 will be a majority of the precip will
be due to the frontal progression and any convection should be more
progressive in the grand scheme. This typically negates significant
flooding prospects as rainfall will only last for so long before it
moves away and we see a de-escalation of hydrologic impacts. In any
case, the threat is still elevated across much of the mid-
Mississippi Valley, so the period will bear watching for any short
term upgrade potential if trends allow.

...Midwest...

20Z Update: A strong cold front will migrate through the region
allowing for convective initiation over the Central Midwest into
the western Great Lakes, overlapping areas that have been hit
recently with periods of heavy rainfall. The highest potential is
across southern and eastern IA into northern IL where significant
rains have impacted area FFG's considerably over the past 72hrs
meaning chances for flash flooding are easier to attain.
Progressive nature of precip is the reason this area is just
outside the more significant rainfall prospects, however
environmental conditions are still favorable over the area with
deep moisture pooled as far north as I-80 for the setup. As the
front moves out of the area, drier air will advect into the region
in its wake ending the threat for the rest of the forecast period.
Widespread 1-3" with local to 4" is forecast in this area of the
CONUS, certainly enough to cause scattered flash flood threats as
the pattern evolves when you couple with the lower FFG's in place.
A broad SLGT risk is forecast for the potential.

Kleebauer


Day 3
Valid 12Z Sun Jun 14 2026 - 12Z Mon Jun 15 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
TEXAS AND THE LOWER MISSISSIPPI VALLEY...

20Z Update: Little changes were necessary for the D3 period as
guidance remained fairly consistent on the premise of heavy
rainfall across the Southern Plains to Lower Mississippi Valley on
Sunday. The SLGT risk across west TX was pushed further west into
southeastern NM to reflect the latest QPF increase from 12z
guidance. Overall synoptic pattern remains favorable heavy rain
across much of the area south of I-40 with the heaviest rain likely
to occur over the Lower Mississippi Valley given the approach of
the cold front to the north and a very moisture rich environment
thanks to advection of Gulf air. Will be monitoring closely for any
targeted upgrades, but will likely have to see how the previous
period's convection evolves before doing so.

Kleebauer

...Southern Rockies, Texas to Southeast...

A cold front pushes down the Southern Plains into Texas on Sunday.
This shunts the heavy rain focus south of Saturday and provides a
strong focus for convective development in a rich Gulf-sourced
moisture environment. PW anomalies are 2 to 3 sigma above normal
across Texas (south of the Panhandle) by that afternoon with 2
sigma anomalies expanding east to Alabama by late Sunday night.
Expansion of the Slight Risk to both North Texas and the Houston
metro areas are warranted given the environment as well as the 00Z
consensus of the UKMET and EC-AIFS for the Houston area, and the
RRFS and RDPS for North Texas. Furthermore, a decent signal for
lasting thunderstorm development is over West Texas in the Permian
Basin into the Concho Valley, so a Slight Risk was raised there as
well.

Additional terrain driven diurnal activity is expected over the
Southern Rockies/Sacramento and Davis Mtns. This activity should
spread southeast through the evening, so the Marginal Risk was
expanded over the southern High Plains.

A surge of moisture up the southern Appalachians Sunday morning
brings enough of a heavy rain threat for a Marginal Risk expansion
up to the westernmost section of Virgina.

...Hampton Roads and Delmarva...

Southwesterly low level flow from the Carolinas bring 2" PW to the
Mid- Atlantic coast Sunday afternoon ahead of a cold frontal
passage that night. Evening thunderstorms should be heavy and slow
enough to warrant a Marginal Risk.

Jackson


Day 4 and Day 5

Valid 12Z Tue Jun 16 2026 - 12Z Thu Jun 18 2026

...A SLIGHT RISK OF EXCESSIVE RAINFALL EXISTS FOR PORTIONS OF THE
SOUTHERN PLAINS, LOWER MISSISSIPPI VALLEY, AND THE SOUTHEAST...

The first half of the medium range will see two particular threats
for flash flooding. First, along the Gulf Coast, a stationary
front will work in tandem with with tropical moisture to develop
thunderstorms capable of torrential downpours both on Day 4
(Tuesday) and Day 5 (Wednesday). There is greater confidence in
Tuesday's flash flood threat given better model agreement in
placement of QPF and the nearby frontal boundary remaining strong
enough to help trigger numerous showers and thunderstorms. PWs
will remain above 2.0" in many cases as well, allowing developing
thunderstorms to contain highly efficient rainfall rates. Soils
will be more saturated in wake of Monday's thunderstorms as well,
making the region more susceptible to flash flooding. The forecast
remains largely on track for Tuesday (Day 4) with only some minor
tweaks to the inherited Marginal and Slight Risks to more closely
resemble the latest WPC QPF. By Wednesday (Day 5) the frontal
boundary will undergo frontolysis and the source of lift at the
surface will weaken. However, ensemble guidance continues to show
ample tropical moisture along the Central Gulf Coast, which at by
Wednesday will have dealt with multiple rounds of Excessive
Rainfall. A Marginal Risk was introduced along the I-10 corridor
from the Houston metro on east to the FL Panhandle to account for
the flash flood potential around the more urbanized communities
along the central Gulf Coast.

Farther north, Wednesday looks like an active day from the Midwest
on east into the OH Valley. A 500mb shortwave trough racing east
towards the Great Lakes late Wednesday will provide healthy upper-
level ascent aloft to foster the development of low pressure.
Meanwhile, a strengthening LLJ will direct anomalous moisture
located over the South northward into the region. NAEFS shows an
impressive IVT for mid-June that surpasses 750 kg/m/s over the
eastern Corn Belt that will provide copious amounts of moisture.
Guidance is not in agreement yet as to which locations are most
favored to witness the heaviest thunderstorm activity. Fast storm
motions should also help to limit residency times of developing
storms. That said, PWs ranging between 1.75-2.0" will be the norm
late Wednesday with storms likely containing efficient rainfall
rates. A Marginal Risk was introduced to account for the localized
flash flood potential on Wednesday from the Middle MS River on east
into the OH Valley.

Mullinax


Day 1 threat area: www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt