FOUS30 KWBC 250759
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
359 AM EDT Thu Jun 25 2026

Day 1
Valid 12Z Thu Jun 25 2026 - 12Z Fri Jun 26 2026

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL IS IN EFFECT
OVER SOUTHEAST KANSAS INTO SOUTHWEST MISSOURI...

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

Active period on tap for Thursday as the overall longwave pattern
across the Western and Central U.S. will finally shift towards a
more zonal mid and upper level structure allowing for the next
disturbance that enters the Plains to migrate more west to east,
inducing a repeated convective regime for later this afternoon and
evening. MCS from overnight will translate southeast through
western KS, eventually making headway towards the KS/OK state line
during the morning hours. This disturbance will act as an initial
shortwave disturbance providing local forcing for the afternoon
with isolated to scattered thunderstorms to materialize across
southwestern KS into north-central OK. By the afternoon hours, a
potent shortwave will begin moving eastward across KS as the mean
flow aloft shifts to more prevailing westerlies creating a flow
running parallel to a slow-moving front bisecting the southern half
of KS into MO. Surface cyclogenesis over the High Plains will
accompany the shortwave trough with the low expected to ride east
along the thermal gradient setup over the quasi-stationary front in
the region. Guidance has been slowly pushing this boundary south of
I-70 over the last succession of runs with the CAMs even taking
that step that's been noted via previous forecasts. The global
deterministic models on the 00z run this evening are now also in
the southern camp for the positioning of the front which is going
to play a pivotal role in exactly where the heaviest rainfall will
occur. NAEFS PWAT anomalies remain within the +1 to +2 standard
deviation outputs as PWAT values will likely resonate within the
bounds of 1.7-2.1" across much of central and eastern KS into the
southern two-thirds of MO into the western Ohio Valley.

The thermodynamic posture for this evening will be seen as
reputable for heavy convective cores as regional theta_E's remain
elevated across the Central and Southern Plains to Mid-Mississippi
Valley with the core of greatest SBCAPE positioned along and south
of US54 in southeastern KS to southwest MO. It is this area where
HREF probabilities for rates >1"/hr are most noteworthy with modest
probabilities (20-35%) for upwards to 2"/hr plausible in these
stronger cell cores. The heaviest rain will materialize late
afternoon and evening with the heaviest rainfall likely to coincide
with the genesis of the nocturnal LLJ as strengthened low-level
convergence and intensifying isentropic ascent across the area
downstream of the surface low over the Plains will create a period
of widespread heavy rainfall over that area of southern KS into
southwestern MO. HREF blended mean QPF is bullish on an axis of
2-4" areal average QPF with pockets of 6+ inches being depicted in
the HREFpmm, a guide to the 90th percentile type outcomes possible
in the setup. Flow running parallel to the boundary only adds for
the potential of back-building until the surface low and attendant
shortwave can finally eject eastward into the Mid-Mississippi
Valley which can be noted in the hourly composite radar forecasts
via various CAMs. Elevated antecedent soil moisture and lingering
hydrologic concerns across southeast KS into southern MO only add
to the heightened risk of flash flooding as the area will likely
struggle to maintain any additional rainfall, especially
significant totals over 2". In coordination with the local Wichita,
KS and Springfield, MO WFO's, a targeted Moderate Risk was added
to the latest D1 period with the focus highlighting that US54
corridor and 50-100 miles on either side, including the city of
Wichita where models are consistent in some of the heavier totals
near or into the urban center.

Will be monitoring the frontal alignment through the course of the
D1 as this will be the ultimate factor on where the heaviest precip
will occur later in the period. Additional heavy rainfall threat
will occur away from the primary areas referenced above with
locally significant rainfall poised to impact areas of eastern KS
over into southern and central MO to the Mississippi River area
near St. Louis. The trajectory of the shortwave and frontal
alignment will play a role in the path of where the heaviest
rainfall will occur and the prospect for another complex developing
will also be a factor on who gets the more significant impacts for
flash flooding. The SLGT risk expands east through the areas above
with a high-end SLGT forecast into the St. Louis metro as heavy
rain is forecast to enter the region by the end of the D1 period.

...Southeast U.S...

Remnants of a complex currently migrating out of the Lower
Mississippi Valley and adjacent Mississippi Delta will wander
southeastward overnight with sights onto southern AL and southern
GA by Thursday morning and afternoon, respectively. CAMs continue
to depict a round of convection firing late this morning and
afternoon in proximity to the mid-level vorticity responsible for
the previous convective episode. The disturbance will become a
mechanism for targeted low- level convergence in a zone of
favorable boundary layer moisture and instability. Signals for
locally heavy rainfall of 2+ inches are noted in the deterministic
CAMs with the HREF blended mean QPF between 12z Thursday to 00z
Friday showing pockets of 1.5-2" located from the MS coastal areas
through the I-10 corridor towards Tallahassee, back up into
southern GA, as far east as Savannah/Brunswick in this latest
cycle. This is coincident with the 500mb vorticity trajectory of
our mid- level impulse generated from the previous period of
thunderstorms which provides a better target point for heavy
rainfall compared to just your standard pulse convection regime we
see in the summer. Modest HREF neighborhood probs of 20-40% exist
for localized totals >3" across the aforementioned areas, enough to
account for potential isolated flash flood concerns, mainly within
more urbanized/developed areas across the Southeast. As a result,
maintained the previous MRGL risk with just some minor adjustments
to account for QPF trends.

...Interior West...

Multiple shortwaves and elevated moisture presence across the
Interior Mountain West will likely lead to another afternoon and
early evening of scattered convection with localized flash flood
concerns today. The threat remains low-end for the time being
given the current QPF outputs, however this could still provide
some isolated flash flood prospects in those terrain focused zones
across UT/CO, as well as any heavy rain encounters in the favored
slot canyon areas littered over western CO into UT. The previous
MRGL risk was generally maintained outside a few minor adjustments
on the western edge.

...Northeast...

A potent shortwave trough located over the Northern Great Lakes
into the neighboring Ontario Province will allow for a focused area
of ascent downstream of the mean trough as the Northeastern U.S.
nestles squarely into the LER of a modest 110kt jet ejecting
eastward across the Great Lakes. Sufficient deep layer moisture and
added shear with the incoming disturbance will aid in maintenance
of an area of quick-moving convection across NY state through
central and northern New England later this afternoon. High
probabilities for >1" and low probs for 2" indicates a general
pattern of 1-2" with perhaps a few pockets exceeding 2" in the
setup over the Hudson Valley into VT/NH, enough to warrant at least
a low to modest threat of localized flash flood concerns,
especially given some of the more saturated soils located over the
region as noted via the latest NASA SPoRT 0-10cm soil moisture
percentiles >90%. The previous MRGL risk was generally maintained
with only some minor adjustments a touch further east to align with
trends in guidance.

Kleebauer


Day 2
Valid 12Z Fri Jun 26 2026 - 12Z Sat Jun 27 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN EFFECT OVER
PORTIONS OF THE MID-MISSISSIPPI AND OHIO VALLEYS...

...Mid-Mississippi and Ohio Valley's...

Shortwave ejecting out Missouri Friday morning will continue to
progress through the Ohio Valley the rest of the D2 time frame.
Quasi-stationary front will remain positioned along and just north
of the Ohio River leading to an emphasis on convection within
proximity of the boundary. The 00z HREF does not go beyond the 00z
Saturday hour, however, the 12hr period between 12z Fri - 00z Sat
is very much indicating some significant rainfall in-of that area
of the Mississippi/Ohio River confluence and surrounds. HREF
neighborhood probabilities for at least 3" in that 12hr period are
solidly between 30-60%, a signal that usually correlates to heavy
rainfall with rates sufficient for flash flood prospects.
Thermodynamically and kinematically, this setup is one that favors
locally significant rains with most guidance in agreement on areas
of 2+ inches during the back end of D1 heading through D2. The
threat will continue to extend east through southern IN and OH with
the eastward advancement likely to extend as far as western PA down
through the Central Appalachian front in PA/MD/WV. Current
indications are for the heaviest rain to likely focus west of I-79
in WV, so the SLGT risk remains situated closer to the OH/WV/KY
border and points west with a MRGL further east. A high-end SLGT is
forecast over the confluence area of the Mississippi/Ohio rivers
and surrounds, which includes: southern IL/IN, eastern MO, and
western KY where consensus for 2-4" has grown over the course of
the last 24hrs.

...Montana...

A potent shortwave trough will migrate through the interior
Northwest U.S. leading to a regionally amplified setup capable of
producing locally heavy rainfall across central and eastern MT.
Steering flow will be pretty fast overall, so any convective
activity will likely be moving relatively quickly with the flow to
the east-northeast after genesis. That said, environment for mature
mesocyclones and stronger convective cores will be capable for
periods of heavy rainfall during any of these thunderstorms as they
migrate through the High Plains of MT. Rates between 1-1.5"/hr will
be plausible at peak intensity leading to pockets of 1-2" of rain
falling in a short window as storms traverse over the area. The
previous MRGL risk was maintained to account for the threat.

...Northern ME...

Shortwave trough moving through Quebec will pivot across northern
ME as we move into Friday afternoon. Sufficient buoyancy and mid-
level forcing brought upon by the disturbance and boundary layer
priming in the afternoon will lead to a round of thunderstorms
capable of producing locally enhanced rainfall that could impact
more sensitive areas of northwest ME. As of now, the prospects for
locally 1-2" of rainfall have increased the past succession of runs
from NWP with some deterministic outputs pointing to a quick inch
or more over the northern Appalachian area of western ME advancing
into interior Aroostook county in northern ME. The previous MRGL
risk was maintained for the threat as guidance still favors the
potential.

Kleebauer


Day 3
Valid 12Z Sat Jun 27 2026 - 12Z Sun Jun 28 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN EFFECT OVER
PORTIONS OF THE OHIO VALLEY...

...Ohio Valley...

Longwave pattern begins to pivot toward a more amplified western
trough with a ridge rapidly materializing across the Southeastern
U.S. as we step through the weekend. A broad upper trough will be
positioned over the Pacific Northwest through the interior with a
succession of strong mid-level shortwaves ripping through the lead
side of the mean trough. There's growing support for a mid-level
shortwave to eject out of the Central Plains on Saturday morning
and migrate east-southeast through the Mid-Mississippi Valley,
eventually making headway into the central and southern Ohio Valley
by Saturday afternoon as it moves around the northern periphery of
the ridge building to the south. Heavy rainfall from the previous
period will act as a primer for any additional rainfall leading to
a heightened threat for flash flooding in those terrain locations
in eastern KY up into WV. CSU First Guess Fields have the region
firmly in the MRGL risk just given the signal, however the
antecedent ground conditions will favor a tick up in the forecast
risk with a SLGT risk in place across the aforementioned area.
Hardest hit locations with convection Saturday afternoon and
evening will likely see 1-2", locally higher during the threat
which would be sufficient for at least scattered flash flood
prospects for the D3. The previous forecast was generally
maintained with the SLGT risk extended a bit further north up the
I-79 corridor towards Morgantown, WV.

...Northern Plains...

Robust upper trough will be positioned over the Pacific Northwest
and the interior with falling heights and an ejection of several
stronger shortwaves pivoting around the primary upper circulation.
A period of strong to severe thunderstorms are forecast in-of the
High Plains of MT and ND as a robust shortwave makes an appearance
by late-Saturday afternoon through the evening. Ample shear and
moisture anomalies creeping above the 90th percentile up over the
Northern Plains will be sufficient in locally enhanced rainfall
rates, especially in any supercell cores and multi-cell mergers
that transpire once the LLJ kicks in after 00z. A broad MRGL risk
is in effect for the threat up across the area with a potential for
a targeted upgrade in future updates once the CAM signals come into
their temporal windows.

Kleebauer


Day 4 and Day 5

Valid 12Z Sun Jun 28 2026 - 12Z Tue Jun 30 2026

...The probability of rainfall exceeding flash flood guidance
values is less than 5 percent...

Oravec


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



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