Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
905 PM EDT Sat Jul 11 2026

Day 1
Valid 01Z Sun Jul 12 2026 - 12Z Sun Jul 12 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
ARIZONA AND THE SOUTHERN PLAINS TO THE CENTRAL APPALACHIANS...

0100Z Update -- Shifted the northern extent of the Slight and
Marginal Risk areas farther south over the Ohio Valley. As drier
air continues to advect across the region, activity should continue
to diminish across the much of the remainder of the upper Ohio
Valley overnight. However, farther south there remains a good
signal for organized activity and a potentially higher-end flash
flood threat across portions of the lower and Ohio and Tennessee
valleys. Deepening moisture (PWs ~2 in) interacting with a slow-
moving shortwave may produce locally heavy rainfall amounts of 2
inches or more. Raising the risk for flash flooding, especially
over portions of Kentucky into the southern Appalachians, are the
wet antecedent conditions reflected by low FFGs. Refer to WPC MPD
#680 for additional information regarding the near-term heavy rain
and flash flooding threat across this area. A notable threat also
remains from the Mid-South back into central Oklahoma and far
south-central Kansas where moisture is expected to deepen over the
next few hours along a slow-moving boundary, supporting heavy
rates, with slow-moving/backbuilding storms raising the threat for
heavy accumulations and flash flooding. Refer to WPC MPD #679 for
more detail on the near-term threat.

The Marginal Risk extending along the upper Texas and Louisiana
coast was removed. However, a small portion was left in place
across southern Texas and along the Rio Grande, where convection is
expected to continue for a few more hours.

Outlook areas over the Southwest were left largely unchanged.

Pereira

1600Z Update -- Main change to the Day 1 ERO was to expand the
Marginal Risk to include much of the western and central Gulf
Coast. Deep-layer bulk shear values do remain low (<20kts), however
weak mid-level perturbations (including a H5 vort across South TX)
and weak, broad cyclonic flow along the coast will allow for more
organized storm clusters within such a favorable thermodynamic
profile (mixed layer CAPEs between 2000-3000 J/Kg and PWs of
2.0-2.3 inches).

Hurley

Previous discussion...

...OK into the OH and TN valleys...
An active convective regime is anticipated ahead of a
southeastward moving shortwave trough axis extending from MO to OH.
At 12z this morning, an initial round of convection will be
ongoing from southern IL into portions of KY and TN. Model guidance
supports a transition toward a primarily forward propagating
convective mode this morning, which should place the overall flash
flood risk on a declining trend, though localized upwind
propagation may keep an isolated threat going.

By this afternoon, the primary MCV/shortwave will shift over IL
and IN, interacting with a southward moving frontal boundary to
trigger scattered redevelopment across portions of IL, IN and WV.
Within this zone, PW values near or just under 2" will overlap with
CAPE of 1000-2000 J/kg. While widespread convective organization
is not anticipated, slow cell motions and localized mergers near
the frontal zone will support heavy rainfall rates capable of
producing localized pockets of 2-3" of rain. This is supported by
the 00z HREF and REFS, which both show FFG exceedance
probabilities of 15-40%.

A more organized, and potentially higher end, flash flood threat
is expected to evolve later this afternoon into tonight across
portions of KY and TN. Convection should develop to the south-
southeast of the main shortwave/MCV, likely focusing along remnant
outflow boundaries and instability gradients left behind by the
morning activity. Global deterministic and AI models favor a heavy
rainfall axis focused primarily from KY into northeast TN,
whereas high res models (including the RRFS/REFS) suggest the core
threat may track further south into TN. Given the strong westerly
low level moisture transport south of the MCV, the environment
will be favorable for backbuilding and training convective clusters
tonight. This environment, combined with PWs hovering around 2",
suggests that many HREF members may be underdoing the
afternoon/nocturnal threat. Do expect to see a swath of heavy
rainfall materialize somewhere across the KY/TN corridor, where an
axis of locally higher end flash flood impacts is possible. A
higher end Slight risk is maintained, with a MDT risk upgrade not
out of the question if we gain spatial model convergence and more
confidence on exact convective mode.

Further west, isolated to scattered flash flooding is also expected
across portions of central OK into AR. Low level flow will become
convergent on the southwestern flank of the broader convective
regime. Slow cell motions near a boundary will pose a threat over
OK, while enhanced northerly flow on the western periphery of the
MCV/shortwave will converge with the broad south-southwesterly
inflow to promote some backbuilding/training threat over parts AR.

...Mid-Atlantic...
A localized flash flood threat is forecast across portions of the
Mid-Atlantic. While low level flow will be northerly, one or two
low level convergence axes are projected to setup across the
region, potentially acting as a focus for convection. Despite the
northerly flow, ample moisture and instability will remain in
place. Convective cells will generally track from north to south,
but localized repeating cells will be possible along the trough
axis. The strongest signal for localized 3" totals with the HREF
resides along the coastal plain from NJ southward into southeast
VA where convergence is enhanced. Because FFG values are generally
higher here compared to inland locations, think the overall flash
flood risk should stay isolated, though localized urban and low
lying flood impacts are expected.

...AZ and NM...
The persistent terrain driven pattern continues across the
Southwest, with convection developing over the higher elevations
before propagating southwestward into a pooling instability axis
over the lower deserts of southern AZ. Instability and moisture
profiles should be a bit higher today relative to the past few
days, leading to a corresponding increase in the overall flash
flood risk. Both the 00z HREF and REFS depict greater convective
coverage and higher localized rainfall totals. While fast
southwestward storm propagation and cell speeds may act as a
limiting factor, the moisture/instability footprint should be
sufficient to promote some cell mergers and localized 1-2"/hr
rainfall, justifying the maintenance of the Slight risk.

A Marginal risk has been added to portions of eastern NM. This area
received locally heavy rain yesterday, and the model QPF signal is
a bit stronger today within an environment characterized by
slightly higher moisture and instability. Convection should remain
isolated to scattered, with the primary flash flood threat focused
over recent burn scars, particularly across the Sacramento
Mountains.

...TX...
A Marginal risk was added to portions of the TX Hill Country, where
PWs are forecast to climb above 2". Isolated to scattered
convection is expected within a broad southerly low level flow
regime. While most cells will remain transient and produce only
brief downpours, any cells that establish mesoscale organization
could briefly train or backbuild into the low level inflow.
Guidance suggests a weak MCV currently south of the Rio Grande
that may track northward towards the region later today, which
could provide an additional focus for ascent. The risk area aligns
closely with the HREF and REFS 1" EAS probabilities of 10-20%
(signaling organization potential), and 3" neighborhood
probabilities exceeding 40%. Global deterministic and AI suites
also show a distinct convective focus over this corridor.

Chenard


Day 2
Valid 12Z Sun Jul 12 2026 - 12Z Mon Jul 13 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM PORTIONS OF
EASTERN KENTUCKY AND TENNESSEE INTO THE CAROLINAS..

2000Z Update: Only minor tweaks made to the Day 2 ERO based on the
latest (12Z) guidance suite. We did trim back a little bit of the
Marginal Risk across central AR, northern MS, and along the OH
River based on the latest trends. Especially with the CAMs,
including the HREF probabilistic suite, which collectively
indicate more pronounced post-MCV stability and drying over these
areas.

Otherwise, one area we will need to continue to monitor the need
for a Slight Risk on the current Day 2 period will be the central
Gulf Coast, specifically southern LA. Both the 12Z HREF and REFS
have >5" 24hr probabilities above 50% across the southern LA Gulf
Coast. This ahead (south) of an elongated H5 vort lobe and
associated W-E surface front that will be pressing south towards
the Gulf Coast. Thermodynamically, the airmass will remain primed
for areas of excessive rainfall, with mixed layer CAPEs between
1500-2500 J/Kg and PWs 2.1-2.3" remaining optimal in terms of
rainfall efficiency. However, working against an upgrade for a
slight would be the extensive swamps/marshes within this region,
along with 0-6km bulk shear values remaining under 20kts,
indicative of intense sub-hourly rainfall rates that should quickly
become outflow dominated. For now we've continued with the Marginal
Risk.

Hurley

Previous discussion..

...Southeast Quarter of the Country...
A Slight risk has been introduced stretching from KY and TN
eastward into southern VA and the Carolinas. A well defined
shortwave/low over the KY/TN vicinity will interact with a slow
moving backdoor front to focus organized convection. High res
guidance, including the RRFS, FV3 and 3km NAM, indicates a
concentrated axis of convection capable of producing localized
totals exceeding 3". While the global GFS and ECMWF are less
pronounced with their QPF swaths the GEM regional and UKMET are
more in line with the high res guidance. The AIFS and AIGFS also
depict a corridor of enhanced QPF that generally matches the Slight
risk placement. Beneath the closed low over KY and TN, convection
may be less organized, but slow moving. Given PWs near 2" and the
possibility of saturated soils from day 1 rainfall, a flash flood
risk should continue. Across the central and eastern Carolinas PWs
over 2" combined with low level southerly moisture transport and
backdoor frontal convergence should create an environment for high
rainfall rate driven flash flood potential.

Surrounding the Slight risk, a broad Marginal encompasses eastern
NM, TX and much of the Southeast. A southward advancing cold front,
the aforementioned mid level shortwave/low, and upper jet support
will provide the necessary synoptic forcing for scattered
convection. PWs over 2" and CAPE of 2000-3000 J/kg where daytime
heating is maximized, will support heavy rainfall rates. Some
mesoscale uncertainty exists with the track and strength of the
shortwave and frontal positions. An embedded Slight risk or two
may be needed on future updates as confidence increases. Increasing
low level westerly flow along the central Gulf Coast provides a
signature for backbuilding and training, but model divergence on
the exact axis remains. Given the higher regional FFG, did not
want to go with an overly large Slight risk at this time.

...Southwest...
Monsoonal moisture and instability will expand northwestward on
Sunday, necessitating a broader Marginal risk across AZ. While an
embedded Slight risk may eventually be needed, lingering questions
regarding storm coverage and organization keep the risk at
Marginal for now. Current indications suggest that while robust
convection will initiate over the terrain, it will propagate
westward quickly, potentially limiting the threat to isolate
instances of flash flooding.

Chenard


Day 3
Valid 12Z Mon Jul 13 2026 - 12Z Tue Jul 14 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE CENTRAL GULF COAST...

2000Z Update: Very few (subtle) changes made to the previous Day 3
ERO. See discussion below for more on the meteorological
reasoning, which per the latest (12Z) guidance/model trends, has
not changed much.

Hurley

...Central Gulf Coast to the Southeast...
The inherited Slight risk across portions of the central Gulf Coast
has been maintained and expanded both westward into southeast TX
and eastward into the FL Panhandle. A favorable synoptic and
mesoscale setup for training and backbuilding is forecast to align
with coastal areas. Enhanced west to northwesterly low level flow
south of the persistent shortwave/low over the TN/GA vicinity will
converge with southwesterly inflow off the Gulf. This configuration
is conducive for upwind propagation and some training convection.
While some uncertainty remains regarding how far inland the heavier
totals will reach, the moist airmass characterized by PWs around
2.25" will support heavy rainfall rates.

Further west, increasing low level southerly moisture transport
out of the western Gulf will push up the Rio Grande Valley and into
central TX, potentially resulting in convective clusters Monday
night. Future shifts may need to expand the Slight risk even
further into TX depending on how this threat evolves.

A broad Marginal risk remains in place from TN into the Southeast
and southern Mid-Atlantic, Similar to day 2, a lingering
shortwave/low will continue to interact with a backdoor frontal
zone. Model divergence exists regarding the exact positioning of
these features and the available instability footprint by this
time. Given this, and the fact that model QPF signals are a bit
more muted compared to Sunday, we will maintain the Marginal
risk...although an embedded Slight risk upgrade may still
eventually be needed as the mesoscale details clarify.

...Southwest...
A Marginal risk is maintained from southern NM into AZ, southeast
CA and southern NV. Deep monsoonal moisture will continue to push
northwestward with isolated to scattered convection expected TO
result in at least a localized flash food threat.

Chenard


Day 4 and Day 5


...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ALONG PARTS OF THE
CENTRAL GULF COAST ON MONDAY...

2030Z Update...

Daytime guidance did not indicate any need for significant changes,
therefore the update reflects only minor adjustments.

Pereira

Previous Discussion...
...Southeast U.S. into Texas...

Lingering effects from elevated moisture and slowly decaying
quasi-stationary front across the Southeast U.S. will lead to one
last period of elevated convective enhancements from east TX
through the southern half of the Southeastern CONUS. PWAT anomalies
will remain generally seasonal to perhaps upwards of +1 standard
deviations over the region, enough of a threat for heavy rain
prospects in a environment that favors relatively slower cell
motions. Considering the fact some of the Southeast will have
received a formidable amount of rainfall leading into the D4, some
localized flash flood concerns will linger for at least one more
day before finally waning into the D5 where the risk over the
Southeast is void and we settle into a more benign pattern overall.

Further west into the western half of TX, the same story cannot be
said as the pattern will begin shaping up into a much more
favorable flash flood environment thanks to a shift in the mid and
upper level pattern west of the Mississippi. Dominant ridging over
the top into the northern tier of the CONUS will give way to
a broad inverted trough axis migrating westward into the Southern
Plains as we move into the middle of next week leading to weakening
flow aloft and a myriad of smaller mid-level perturbations rotating
under the dominant cyclonic flow. Lowering heights and regional
forcing align to foster a more suitable convective environment
across the western half of TX with an emphasis currently on
west and southwest TX as noted via the multi-model consensus in
both the deterministic and ensemble outputs. Some of the guidance
is incredibly aggressive in their presentations with several inches
of rain in both the D4 and D5 time frames with a general maxima
located over the Lower Trans Pecos over into the neighboring
Edwards Plateau where the pattern would allow for greater low-level
convergence and prospects for organized convective clusters to
sneak out of Mexico (Mexican State of Coahuila). Considering a
solid agreement within the model suite this evening, felt confident
enough to introduce a SLGT risk across southwest TX over into the
Edwards Plateau and portions of the central RGV. This is certainly
an area to monitor closely as significant rainfall potential is
plausible in the current synoptic evolution being depicted.

...Southwest U.S...

The Southwestern U.S. will lie within the western flank of the
broad ridge pattern over the Central and Eastern U.S which will
provide a dominant southerly flow over the region allowing for
continued moisture advection and enhanced surface troughing over AZ
up through the Great Basin. This pattern is a continuation of the
Monsoonal presence out west with a potential for increasing flash
flood prospects as multi-day impacts could spur targeted
opportunities for repetition of areas getting hit by convection in
consecutive periods. This setup remains very stable in terms of the
broad synoptic pattern in place over the western CONUS, however we
will see a persistent moisture plume advect more formidable deep
layer moisture poleward as we move into early-mid next week leading
to PWAT anomalies pushing the 90-99th percentile according to the
NAEFS and 00z ECENS outputs. The strongest anomalies will lie
within the Great Basin up into the Northern Rockies on D4 with some
modification by D5, but still very much entrenched within the upper
bounds of the anomalies, especially over the Northern Rockies and
Interior Northwest. Increased upper troughing migrating from the
west will slide under the ridge across the Northern CONUS leading
to an enhancement for convective potential over a broader scope by
D5 with widespread thunderstorm prospects aligned from the Canadian
border in MT down through the Inter-Mountain West into the
Southwestern deserts. This setup can lead to sneaky significant
rainfall prospects for those in the interior with a more typical
Monsoonal presentation in the convective coverage.

Given the above variables, the MRGL was expanded north and
northwest for D4 into the Great Basin with another MRGL risk added
across the Northern Rockies in the western half of MT and northern
ID. D5 is a broad MRGL risk for much of the Southwest and interior
west, including areas that were omitted from the previous period(s)
MRGL risks. There is potential for targeted SLGT risks to be issued
in future updates as we move closer to the event, so please check
back over the next several days as the pattern becomes much more
active and favorable for flash flood prospects.

Kleebauer


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