FOUS30 KWBC 110851
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
451 AM EDT Sat Jul 11 2026

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...

...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  Valid 12Z Tue Jul 14 2026 - 12Z Thu Jul 16 2026

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

...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
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