FOUS30 KWBC 120841
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
441 AM EDT Sun Jul 12 2026

Day 3  Valid 12Z Tue Jul 14 2026 - 12Z Wed Jul 15 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF TEXAS...

...Central TX...
A Slight risk continues over much of central TX, with a setup
similar to day 2. Model guidance forecasts strengthening 850mb
southerly moisture transport interacting with a weak mean flow
regime, keeping the threat of backbuilding and training convective
clusters. There is the potential for at least locally significant
flash flooding from the Edwards Plateau into portions of the TX
Hill country. Higher end Slight risk probabilities are warranted
for this corridor, and future upgrades to a MDT risk are possible.
Notably, the AIFS has been highly persistent over multiple cycles
in indicating a possible higher end event...and the AIFS has a good
track record highlighting organized heavy rainfall events. This
will be multi day threat over this region, and so hydrologic
sensitivity should eventually elevate, increasing the risk for
locally higher end impacts.

...Southeast...
A Marginal risk is maintained across the Southeast as the same
low/shortwave migrates slowly southwestward. Deep moisture will
remain plentiful with PW value over 2". However, uncertainty
exists regarding the position of the instability axis and overall
convective organization, and model QPF signals are a bit more
muted than on days 1 and 2. Nonetheless, because multiple days of
rainfall may start to saturate soils and lower FFG thresholds, an
embedded Slight risk area remains a possibility in future updates.

...Southwest into Northern Rockies...
A Marginal risk stretches from AZ into MT. An expansive plume of
deep moisture, featuring PW values near mid-July climatology
maximums will extend across this corridor. The strongest
instability will be focused at the ends of this axis, across AZ and
MT, with weaker CAPE profiles in between. Cape should still be
sufficient for isolate stronger cells and a localized flash flood threat.

Central and eastern MT will need to be closely monitored for a
potential Slight risk upgrade. An axis of strong instability is
projected across the state, overlapping with increasing easterly
low level moisture transport. While the mean flow is weak at 10-15
kts, cells could potentially grow upscale and forward propagate in
this environment. Given the high rainfall rate potential,
convective trends will be closely monitored.

Chenard
 

Day 4 and Day 5  Valid 12Z Wed Jul 15 2026 - 12Z Fri Jul 17 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF
WEST TEXAS ON DAY 4 AND DAY 5...

...Texas...

An increasing threat for excessive rainfall is becoming more and
more pronounced as we move forward in time as consensus grows on a
prolonged heavy rain setup across portions of west TX with emphasis
on the Edwards Plateau, Big Bend, and parts of Hill Country. Dominant
ridging over the top into the northern tier of the CONUS will give
way to a broad upper trough migrating westward into the Southern
Plains along the southern flank of the ridge as we move into the
middle of the week. The introduction of troughing overhead will
lead 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. ML
guidance has also been suggestive of the same threat with the last
series of runs from both the AIGEFS and EC-AIFS ensemble coming in
very aggressive with their interpretations in current D3-5 QPF
output. This has also led to some correlation of elevated
probabilities within the ensembles, both ML and standard NWP for
24-hr totals each period >2".

01z NBM probabilities for >2" have risen to between 30-50% for the
D4 time frame with coverage extending from the Big Bend down into
Maverick County, a span that includes some major population centers
like Del Rio and Eagle Pass, TX. The 30-40% probs expand eastward
into the neighboring Hill Country as well, an area of interest the
prior D3 period, so there's a greater threat for overlap in this
current pattern. When you begin factoring the cumulative threat of
heavy rainfall, guidance has surely risen the bar in terms of the
potential with incredibly aggressive presentations allotting
several inches of rain for the D3-5 time frames. General maxima
continues to be focused over the Lower Trans Pecos over into the
neighboring Edwards Plateau and down through the central RGV 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 maintain a
SLGT risk on D4 with a high-end SLGT prospect now being factored
into the forecast as we move forward in time. Have also introduced
a SLGT risk across west TX over into the Edwards Plateau and
portions of the central RGV for D5 as the threat lingers into
Thursday before finally beginning to disperse by Friday, beyond the
D5 period. This is certainly an setup to monitor closely as
significant rainfall potential is plausible in the current synoptic
evolution being depicted, and further upgrades are not out of the
question as we move closer to the window of impact.

...Western U.S...

Very little change in the previous forecast with the pattern
repeating on the new D5 leading to general continuity in both the
D4 and D5 convective threat and risk areas. The Western 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 D4, carrying into 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.

With a very stable height field being depicted mid to late week,
the threat for widespread convective activity over a large portion
of the Western CONUS remains favored for a broad MRGL risk at the
current lead. The threat will likely induce some upgrade potential
on a day-to-day basis as we step forward in time and we get a
glimpse at previous period impacts and any overlap in where
activity could occur once again for areas hit previously. This is a
relatively solid signal at range, so the risk was deemed
reasonable as a MRGL with upgrades noteworthy once we get a better
focus on potential inside 72 hrs. D4 and D5 maintained a MRGL risk
in very similar areas with only minor deviations in the orientation
of the risk from D4 to D5.

Kleebauer
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