FOUS30 KWBC 220945
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
545 AM EDT Mon Jun 22 2026

Day 1 Valid 12Z Mon Jun 22 2026 - 12Z Tue Jun 23 2026

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL IN EFFECT FROM
NORTHERN ARKANSAS TO WESTERN TENNESSEE AND FAR NORTHWEST MISSISSIPPI...

0930Z Update...

A Moderate Risk was added for northern AR to western TN and far
northwest MS after assessing radar trends and latest HRRR/RRFS
guidance. A mature MSC moving across eastern OK has an eastward
extending wing of nearly stationary thunderstorms along an outflow
boundary across northern AR into western TN and well south of the
synoptic cold front to the north. The southward push of this
outflow boundary is expected to compete with increasing southerly
flow ahead of the MCS and strong mesovortex located in northeast
OK. This all leads to an expected axis of heavy rain (hourly rates
up to 3" and totals up to 6" are possible) through northern AR and
into parts of western TN and northwest MS. This is just north of
Little Rock, AR, but does include Jonesboro, AR and Memphis, TN.
Coverage of flash flooding as well as potentially localized
significant impacts prompted the upgrade to a Moderate Risk prior
to the start of this day 1 forecast period (12Z Monday). This event
is expected to begin diminishing by around 17Z as the MCS clears
the region and weakens, but this still provides potential for
around 6-hrs of intense rainfall rates and flash flood impacts.

Snell

Previous Discussion...

...Southern Plains to Tennessee Valley...

Current WV satellite and UA analysis depicts a potent mid-level
shortwave sliding southeast through the Central and Southern High
Plains with eyes likely downstream into the Lower Mississippi
Valley and southwestern Tennessee Valley as we move through the
morning and afternoon Monday. Favorable boundary layer instability
presence across much of the Southern Plains into the Southeastern
CONUS will benefit periods of heavy rainfall during the period with
a likely impact beginning early in the forecast period with a
secondary batch likely to ensue the following evening. At the
surface, surface wave will be located across OK in conjunction
with an organized area of thunderstorms migrating southeast through
the region overnight. A bit further east into the Ozarks and
eastern OK, a slow-moving cold front will shift through the region
overnight with increasing convergence likely to occur between the complex/surface wave and the front as it heads into central OK.
Instability maximum over eastern OK into AR on the order of
2000-3000 J/kg MUCAPE will aid in the necessary component to
initiate more thunderstorm activity as the convergence regime
materializes with likely a long stretch of heavy convection
orienting from south-central OK back into southwest TN by sunrise.
PWAT anomalies between +1 to +2 deviations off the latest NAEFS
indicate a deep moist convective environment situated over the area
ahead of the front with the combination of both favorable
instability and 2+ inch PWATs set to provide effective warm rain
processes capable of producing efficient heavy rainfall that can
spur flash flood capabilities.

Recent 00z HREF outputs are pretty aggressive with scattered areas
of 2-3" of precipitation anticipated in the means across the
ArkLaTex through central and southern AR into southwest TN and
western MS. A good portion of this rainfall is likely to occur in
the first half of the period as the expected QLCS development will
encroach the area and provide significant rainfall over the above
locations. The disturbance over OK is forecast to utilize the
positioning of the front as a focal point for the wave as model
guidance agrees on the surface wave riding eastward along the front
as it begins to enter eastern OK, eventually making headway into
the Lower Tennessee Valley and MS Delta. Indications are for a
small corridor between northeast AR through southwest TN into the
Mississippi Delta to see a training episode materialize in the
morning with neighborhood probs for >3" highlighting that zone with
50-70% probabilities. Some of the deterministic is very bullish
within this general area noting totals of 4-6" in an isolated
coverage with 2-4" more representative of an areal average. This
expands back into central and southern AR as the complex of
organized thunderstorms will likely slide south through Little Rock
and surrounding areas creating a busy morning for flash flood
prospects. This will likely expand into OK as the front location
will be the main factor on where heavy precipitation would occur.
In this case, the entire area is within a broad SLGT risk with a
higher-end SLGT forecast across the above area between eastern OK
into southwest TN and northern MS.

As the complex of thunderstorms begins to peter off in the
afternoon, another round of convection will spawn in-of the
ArkLaTex into the eastern Red River area between OK/TX the
following evening as a nocturnal LLJ develops after 23z with
increasing convergence along the back edge of the front located in
the area. There's still some discrepancy on the exact placement of
the front, however there's enough consensus on the second round of
convection to warrant attention to the prospects of flash flood
potential into that area of the ArkLaTex to perhaps as far west as
the I-35 corridor in southern OK towards the DFW metro. As of now,
thunderstorm development is likely with training potential
increasingly favored in the area as storm development will likely
anchor to the front as mid-level flow aligns parallel to the
boundary with surface convergence maximized along the front. A
slow-moving axis of thunderstorms is a more textbook way for
greater flash flood potential, especially in speaking in spatial
terms as there will likely be a large area encompassed within this
second round of convective development over that referenced
corridor. If this were to make headway into I-20, this would likely
result in numerous flash floods given the environment in place
with rates between 2-3"/hr at peak intensity likely to occur. As of
now, placed the region within the broad high-end SLGT forecast,
but will have to monitor the CAMs closely over the course of the D1
to see if a targeted upgrade may be necessary for this band of
heavy rainfall potential.

...Central Appalachians to Northeast U.S...

Surface low currently analyzed over the western Ohio Valley will
gradually lift to the east-northeast with an expectation for the
low center to exit off the northern Mid Atlantic coast, dragging a
cold front through the Mid Atlantic and Ohio Valley and lifting a
warm front ahead of the disturbance. The current indications are
for convection to spawn over the eastern Ohio Valley by the early-
afternoon as mid-level ascent and increased surface forcing aided
by the cold front and area of low pressure will trigger convective
initiation just upstream of the terrain in WV and western PA. This
area of thunderstorms will migrate eastward, entering a favorable
environment within a modest warm sector as you move east of the
Appalachian front. Shear profiles across the Mid Atlantic are
anticipated to be greatest north of the Mason Dixon, however shear
magnitudes are still capable for enabling stronger mid-level
mesocyclones to materialize and hold as far south as I-66 leading
to prospects for heavier thunderstorms to hold across the urban
corridor extending from northern VA up through NYC and western LI.

HREF probs for >1" are pretty high for both the neighborhood and
EAS fields meaning there's a consensus for areas of heavy rainfall
to impact much of the Mid Atlantic with the most pronounced
signatures into the Central Appalachians and the urban centers,
both are which are susceptible to flash flood concerns. Antecedent
soil moisture is dry, so the initial burst of rainfall will be
beneficial to those areas not tied completely by urban
infrastructure, however, there's a sufficient signal in the QPF
means to maintain the previous SLGT risk inherited for the region
as 00z CAMs maintained their depictions on a multi-round cycle of
convection moving into the area with pockets of 2-3+" forecast
across portions of the aforementioned areas.

...New England...

Shortwave ahead of an approaching disturbance from the southwest
will enter the region by late-morning into the afternoon with
scattered to widespread showers with isolated pockets of thunder
for the initial wave of precipitation during the period. A second
wave of precipitation with higher convective potential will enter
the area by the second half of the afternoon and evening with
heavier rain threat poised to impact portions of central and
northern New England with southern New England likely to see more
of a benefit from the approaching surface low and associated
warm/cold front evolution. Areas of northern and central New
England are forecast to see the most rainfall of the setup, however
the instability gradient will likely be better situated south of
the region as boundary layer theta_E's are likely just below the
necessary magnitude to embrace a heavier convective footprint.
Still, local pockets of >1"/hr are plausible over New England,
north of I-90 with a greater potential for 1-2"/hr closer to the
interstate and points southeast. Antecedent soils in southern New
England are very dry currently with the watershed running well-
below normal which should curb a more pronounced flash flood
prospect with generally isolated flash flood signals in more
urbanized settings. With that, the MRGL risk inherited remains
forecast for much of New England.

...Front Range and Central High Plains...

Defined theta_E ridge positioned over the Central to Southern High
Plains will lead to an axis of relatively unstable boundary layer
conditions conducive for convective generation in tandem with
passing shortwaves ejecting out of the Rockies. HREF blended mean
QPF depicts a smattering of elevated precipitation outputs with
1-2" totals littered across the High Plains from eastern WY and
western SD down through KS/CO and portions of southwest TX. Some of
the areas noted for potential impact have been hit recently, so
local FFG's are lower than normal for the time frame meaning a bit
easier chance at exceeding the FFG markers in place and creating
isolated flash flood concerns. Threat is lower end compared to what
has transpired in the past few days, but it is the beginning of
what will be an active northwesterly flow pattern that could spawn
multiple MCS's across the High Plains. The previous MRGL risk
inherited was maintained with an extension north into the Badlands
of SD and neighboring eastern WY.

...Northern Plains...

Potent shortwave dropping out of western Canada will aid in
regional amplification of the flow out ahead of the trough with
increased ascent located within the diffluent area downstream into
eastern MT and northern ND. Sufficient mid-level forcing and
instability over the region will allow for scattered convection to
materialize during peak diurnal destabilization, generating pockets
of heavy rainfall during the late-morning into the early evening
before instability wanes. Modest probs (30-50%) for >2" of rain
exist within the latest 00z HREF neighborhood fields across the
area of northeastern MT into the northern tier of ND with low end
probabilities for >3" as some CAMs spawn supercells in-of the
Northern High Plains. Previous MRGL was carried over into this
update, but did expand the risk into MT to account for the heavy
QPF distribution in the CAMs bleeding over into the area with
similar FFG markers situated in the area.

Kleebauer
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/10)

FOUS30 KWBC 240729
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
329 AM EDT Wed Jun 24 2026

Day 1 Valid 12Z Wed Jun 24 2026 - 12Z Thu Jun 25 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN EFFECT FROM THE
CENTRAL HIGH PLAINS THROUGH THE MID-SOUTH TO THE CENTRAL GULF COAST...

...Central High Plains...

The period will maintain a relatively stagnant upper pattern with a
broad northern trough and stout mid and upper ridge axis centered
over northern Mexico into the Southwest U.S. The setup is conducive
for yet another active evening as pronounced shortwave will eject
out of the Rockies and migrate southeastward into the Central
Plains after 00z Thursday. Initiation of thunderstorms over the
WY/CO Front Range will occur after sunset with more convective
activity firing downstream into western NE and northwest KS as we
head through the evening. Ample shear and mid-level ascent plus a
well-defined theta_E ridge positioned within a quasi-stationary
front bisecting the High Plains will act as both a focal point for
convection, as well as the driver for aiding in intensification of
any mesocyclone development after initiation. All models from hi-
res CAMs suites to globals have some type of convective mode
forming over the Central High Plains Wednesday evening allowing for
high confidence in areas of not only severe weather, but
accompanying heavy rainfall thanks to elevated PWAT's centered over
the Central and Southern High Plains.

HREF neighborhood probs for >2" are high (50-80%) across the
corridor centered over northeastern CO, southwestern NE, and
northwest KS, the inflection point of both cell initiation and
expected forward propagation area of any convection as cell mergers
occur and grow upscale. Some of these areas will have been hit
pretty hard the prior evening leading to lower FFG's as recovery
time for soils will be limited (<24hrs). In this case, the SLGT
risk inherited is sufficient with a high-end SLGT risk forecast
over that tri-state zone between CO/NE/KS as models continue to
forecast heavy convection over that area with run-to-run
consistency. The SLGT will extend through the rest of western KS
and much of the CO Front Range with the expectation of cell motions
moving through the area the back-end of the D1 period.

...Southern Plains to Central Gulf Coast...

The pattern across the Southern Plains to Central Gulf Coast will
remain a complicated scenario that will come down to the
positioning of a quasi-stationary front oriented over the OK to the
Lower Mississippi Valley, as well as the handling of multiple MCV's
and their general locations that will dictate where heavy rain
prospects would unfold for the D1. Models have struggled with the
overall handling of the MCV currently migrating through AR/LA with
the 02z HRRR offering the best handle on the timing and magnitude
of precipitation accompanying the complex. You can see the northern
inflection in the MCV over western AR will act as a region of
localized convergence with cells maintaining very slow motions with
the current storms orienting northwest to southeast to the west of
Little Rock. Further south, the line is more progressive within the
complex with a bit of a bowing segment ejecting eastward across the
AR/LA state line with the heaviest precip focused over northern LA.
Indications for the trajectory of the complex point to a continued
eastward progression, followed by a turn to the east-southeast as
it moves into MS, eventually making headway towards southern AL.
This is in part to the general mid-level steering flow, as well as
the defined theta_E gradient oriented in the same northwest to
southeast alignment. Typical forward propagation centers over these
distinct gradient alignments and this should be no different with
a majority of guidance signaling the complex's motion into that
area of the Southeast. In this case, this would open the door to
enhanced low-level convergence within proximity of the disturbance
and well within an environment conducive for scattered to
widespread thunderstorm activity boasting potential for 2-3"/hr
rates given the depth of moisture within the column, especially
over southern MS.

Upwind back over northern LA, secondary formation of convection
along the persistent quasi-stationary front is anticipated over the
early portion of D1 thanks to regional focus of low-level
convergence left behind by our complex vacating to the east-
southeast. Cell motion vectors within the latest CAMs for the
period between 10-15z Wednesday are incredibly light leading to
very slow cell propagations for hours prior to the dissipation of
the threat. This area has already been hit several times in the
past week with local FFG's running very low with widespread ground
saturation noted by the latest discussions from the local WFO's.
This will prolong the threat for flash flooding through the morning
before we finally see the threat dwindle in part to the ridge
further west finally building back overhead and shifting the front
further north before dying off by early Thursday morning. In this
case, the SLGT risk forecast will be maintained with the highest
threat for flash flooding likely over the AR/LA border into southern MS.

...Western U.S...

Anomalous mid and upper level moisture will be advected over the
Southwestern U.S. through today as prevailing southwesterly flow
around the western flank of the ridge over northern Mexico will
help usher in warm, moist Pacific airmass centered off Baja. The
addition of elevated moisture into the region coupled with intense
heating across the Desert Southwest will lead to increased boundary
layer instability and the ability to generate afternoon convection
for the first time in a while over the deserts of southern CA into
the Great Basin by later this afternoon. Models are not too
enthused by sense of magnitude, however with PWAT anomalies pushing
+2 to +3 standard deviations across the area by the afternoon
period, it stands to reason that some of the convection could be
sufficient in causing localized flash flood prospects over those
more prone areas like slot canyons in the interior and flashier
portions of southern CA. A MRGL risk remains the forecast for the
low- end threat with emphasis on the terrain in AZ, deserts of
southern CA, and slot canyon areas within NV/UT/AZ.

...Midwest...

Despite the addition of a risk in the area, a non-zero potential
for flash flooding exists over portions of southern WI into
northern IL with the best threat likely within the urban corridor
surrounding both Milwaukee and Chicago and its adjacent suburbs.
Localized totals between 1-2" are plausible, especially in
proximity to the warm front that exists ahead of a surface low
migrating southeast through the Upper Midwest over the period. The
frontal positioning will be the focus for the heavier rainfall
threat as added low-level convergence will act as a focus for any
convection in the area, offering a short term training concern as
we move through the late-morning and afternoon. The threat is very
isolated in nature with a few CAMs signaling more robust outputs,
but not enough consensus to draw a definitive location for the
threat. In coordination with the local offices in the area, decided
to maintain a nil ERO posture, but make note of a low-end, <5%
threat for flash flooding at some point in the front half of the D1.

Kleebauer
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/10)

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
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/10)