Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
411 AM EDT Wed Jul 15 2026
Day 2
Valid 12Z Thu Jul 16 2026 - 12Z Fri Jul 17 2026

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE EDWARDS PLATEAU, CENTRAL RIO GRANDE VALLEY, AND HILL
COUNTRY...

...Texas...

Convection will continue across the Edwards Plateau and surrounds
for at least one more period as the regional pattern maintains a
persistence in its evolution with yet another round of convection
lingering through the morning from the previous period, and one
last round of nocturnal convection anticipated the evening of
Thursday into early Friday morning. The past few iterations of the
CAMs and global deterministic are coming into better alignment on
how they have the event across TX playing out with a strengthening
signal for heavy rainfall in-of the Central RGV up through the
Concho Valley and slipping into the southeastern Permian Basin.
Ensemble means have exhibited a crescendo in the depicted areal
average QPF leading to generally robust totals bordering between
2-4", locally higher in the hardest hit locations. Considering the
nature of anticipated compromised soils and ongoing flooding across
portions of the RGV and Edwards Plateau, very little additional
rainfall would cause a myriad of problems, including an
exacerbation of any remnant flood waters, especially if impacted by
additional heavy rainfall >1"/hr as noted via the very low FFG's
already in place across the region.

The previous MDT risk was maintained and even expanded a bit
eastward through more of the Hill Country over into the Edwards
Plateau with emphasis on Val Verde county extending up to the
neighboring counties to the north, including the I-10 stretch in
central Crockett county. This is the area of greatest concern for
the setup in D2 leading to a high-end MDT risk forecast centered
over this corridor. Rainfall totals in a narrow tongue could breach
6" locally as asserted by a few of the deterministic outputs which
makes sense considering the incredibly moist environment in place.
This period will be monitored very closely and its susceptible to
larger scale changes as the setup evolves as the handling of the
MCV and the placement of the quasi- stationary front and any
surface trough axis' in the area will be foci for heavy convection.
Heavy rain will enhance life- threatening flash flooding to
portions of the region for yet another period before the setup
finally looks to break heading into D3.

...Southwest U.S into the Great Basin...

Another round of afternoon and evening convection will transpire
across the Southwest CONUS into the Great Basin on Thursday with
the threat carrying into the early morning periods of Friday in
some locations. Models are keen on a more robust moisture advection
pulse and general instability axis across the Desert Southwest on
Thursday with a broad axis of heavy rain prospects from the
southern border all the way north into southern UT. Hi-res ensemble
and several global deterministic outputs remain very bullish on
the threat in and around the slot canyons of southern UT, along the
Mogollon Rim, and down towards the terrain embedded within
Cochise, Santa Cruz, and Pima counties. Areal average of 1-2" is
forecast for the region along the southern border with 1-1.5"
forecast across the Mogollon Rim and southern UT. Considering the
environment maturing closer to 1000-2000 J/kg MUCAPE over much of
AZ into southern UT/NV, instability and anomalous moisture within
the 90-99th percentile of climatology across the region will
produce more widespread heavy rain prospects leading to scattered
flash flood occurrences in those more susceptible locations in the
terrain. There is even some opportunity for thunderstorm genesis
off several outflows that could impact some of the larger urban
corridors within AZ, including the Phoenix metro as the environment
favors this type of potential. A broad SLGT risk was maintained
for much of AZ into southern UT with the eastern extent out towards
the NM/AZ border into the immediate Four Corners, outlining the
mean QPF closer to 0.5" from recent forecast.

...Mid-Mississippi Valley...

Remnant mid-level disturbance will slowly pivot across AR into MO
by Thursday maintaining a consistent posture of targeted mid-level
ascent and favoring greater convective coverage under the weak
circulation. The pattern is less favorable for more widespread
heavy rain prospects, especially those that would warrant more
considerable attention and a higher risk like in previous days.
Nonetheless, the signal is still there for isolated flash flood
potential within portions of the Ozarks up through the mid-
Mississippi region near St. Louis. HREF mean QPF shows a general
max near the IL/MO border near and north of St. Louis. Expecting
this signal to settle somewhere near this area given the favorable
2+ inch PWATs centered over the area. The previous MRGL was
expanded north to match the trends in guidance.

Kleebauer


Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt