Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
423 AM EDT Thu Jul 16 2026

Day 1
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. A MODERATE RISK IS ALSO IN PLACE OVER PORTIONS OF SOUTHERN
ARIZONA...

...Texas...

The persistent convective pattern centered near the Edwards Plateau
and southern Hill Country is expected to enter its final high-
impact phase this period. The high-end Moderate Risk has been
maintained over south-central Texas, centering on a corridor from
Val Verde and Crockett counties eastward into the southern Hill
Country. Extremely compromised soil conditions from multi-day
rainfall and very low flash flood guidance mean any additional
precipitation will exacerbate ongoing flooding. Convection that has
developed early this morning will likely linger past daybreak
around a slow-moving MCV, followed by another anticipated round of
locally heavy nocturnal storms late Thursday night into early
Friday morning. Both the HREF and REFS show robust probabilities
for additional rainfall totals exceeding 3 inches, with localized
narrow bands potentially reaching over 5 inches.

Farther north, the Slight Risk was extended into portions of
Northwest Texas. This expansion is supported by deep moisture
pooling along a low-to-mid level boundary, combined with shortwave
energy lifting northward out of the main system, which will fuel
scattered, high-rate convective cores capable of localized runoff
concerns.

...Southwest into the Great Basin...

No significant changes were made to the risk areas out West for
this update. A prime monsoonal setup remains in place for southern
Arizona, where a Moderate Risk remains in place. PWs are expected
to climb above 2 inches, or exceeding 2 std dev normal, across
portions of southern Arizona. This moisture along with sufficient
instability and upper level support, will likely support terrain-
initiated thunderstorms. Subsequent rain-cooled outflows will drive
additional intense cells into the evening hours, pushing rainfall
rates up 2 inches/hr in some locations. A broader Slight Risk
encompasses much of Arizona, extending north into the slot canyons
of southern Utah and eastward into far western New Mexico.

...Mid Mississippi Valley into the Lower Ohio/Tennessee Valleys
and Southern Appalachians...

The Marginal Risk has been adjusted and expanded father east,
stretching from the Mid Mississippi Valley into portions of the
lower Ohio and Tennessee valleys, as well as the southern
Appalachians. A remnant mid-level shortwave moving into the region
will provide weak ascent. Southwesterly inflow into a downstream
boundary will support deepening moisture (PWs increasing to 1.75-2
inches). Both the HREF and REFS guidance are showing notable
probabilities for localized rainfall totals exceeding 2 inches.
Hourly rainfall rates along the boundary may support isolated flash
flood occurrences, particularly in complex terrain and urban
areas.

Pereira


Day 2
Valid 12Z Fri Jul 17 2026 - 12Z Sat Jul 18 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS MUCH OF WEST
TEXAS, SOUTHERN NEW MEXICO, ARIZONA, AND THE SOUTHERN GREAT
BASIN...

...West Texas into Southern New Mexico...

A transition and decay in the high-impact heavy rain setup across
the Edwards Plateau and southern Hill Country is expected as the
mid-level trough over West Texas weakens and begins to dissolve.
However, despite the trend, lingering elevated moisture beneath the
lower height field will allow for scattered activity, mostly
northwest of the areas most severely impacted earlier in the week.

While the general forecast totals are lower than previous days,
localized heavy rates may result in additional concerns, especially
in areas left vulnerable by prior rounds of heavy rainfall.

In southern New Mexico, storms are expected to develop along and
near the Sacramento Mountains by the afternoon and continue into
the evening before diminishing with the loss of diurnal heating.
Active wildfire burn scars in this region make it particularly
susceptible to rapid runoffs, supporting the continuation of the
Slight Risk.

...Western U.S./Great Basin...

Overall, only minor changes were made to the risk areas in the
West, as a persistent monsoonal pattern remains locked in place.
A robust moisture profile will sustain widespread convective
coverage from southern Arizona north-northeastward into the Great
Basin. Moisture anomalies will remain high, with standardized
anomalies of 2-3 extending all the way from the Southwest to the
northern Rockies.

This moisture, along with with sufficient instability will support
highly efficient rainfall rates. A broad Slight Risk was maintained
from southern Arizona to southern Utah, with complex terrain,
urbanized areas, and other vulnerable areas likely to a be a focus
for the greater runoff concerns across the region.

...Ohio/Tennessee Valleys into the Central and Southern
Appalachians....

A Marginal Risk covering much of the Ohio and Tennessee Valleys
into the central and southern Appalachians was maintained. Storms
developing across this region will be fueled by the same high-PW
airmass noted in the Day 1 period as it spread farther north and
east. These diurnally-driven storms are once again expected to
raise isolated runoff concerns.

...Northern Great Lakes...

A progressive upper trough digging southeast across central Canada,
will shift a notable jet max south into northern Minnesota. Strong
low level convergence along with favorable upper jet forcing will
support nocturnal storms from the Minnesota Arrowhead eastward into
Upper Michigan. Although fast storm motions will the heavy
accumulation and flash flooding threat, anomalous moisture
supporting heavy rates, along with some potential for brief
training, may raise isolated concerns.

Pereira


Day 3
Valid 12Z Sat Jul 18 2026 - 12Z Sun Jul 19 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM WEST TEXAS AND
SOUTHERN NEW MEXICO TO SOUTHERN UTAH...

...Western U.S....

An expansive monsoonal convective pattern will continue, prompting
the inclusion of a Slight Risk stretching from West Texas and
southern New Mexico northwestward across Arizona and into southern
Utah. Overnight guidance indicated a notable uptick in low level
moisture transport into these region on Saturday. This surge will
act to revitalize the potential for additional rounds of high
rainfall rate convective cores capable of producing flash flooding.

Once again, the combination of anomalous moisture and instability
will support highly efficient rainfall rates within the stronger
storms. The threat of rapid runoff and flash flooding will be
elevated across the complex terrain, normally dry washes, and slot
canyons, as well as over highly sensitive soils and wildfire burn
scars.

...Ohio Valley/Central and Southern Appalachians to the Mid
Atlantic and Northeast...

The core of the high-PW airmass will continue to shift east, with
moisture pooling ahead of a strong cold front dropping south
across the Northeast. Strong synoptic forcing, driven by an
amplifying trough over the Northeast and favorable upper jet
dynamics, will support an axis of organized storms from the upper
Ohio Valley into the Northeast. Given the high PWs and strong
forcing, heavy rainfall rates producing at least localized runoff
concerns are expected. Given the uncertainty regarding where the
axis of heaviest rains will occur, maintained a Marginal Risk for
now. However, a targeted Slight Risk may be introduced in future
updates if confidence increases.

Pereira


Day 4 and Day 5

Valid 12Z Sun Jul 19 2026 - 12Z Tue Jul 21 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE WEST ON DAYS 4 AND 5, THE VIRGINIA TIDEWATER ON DAY 4, AND
PORTIONS OF FLORIDA ON DAYS 4 AND 5...

...Western U.S...

A traditional Monsoonal pattern will continue across the Western
CONUS with scattered to widespread bouts of heavy rainfall across
much of the Desert Southwest up through the Great Basin with an
northern inflection into portions of the Rockies. Ridging will
prevail across the west as we move through the weekend into early
next week with a solidified Monsoonal trough positioned over AZ
down through Mexico. Even at leads, there's a well- defined axis
of elevated instability coupling with PWAT anomalies between +2 and
+3 standard deviations positioned from the Great Basin to points
south with the strongest anomalies situated over NV and UT was
assessing both the ECENS and NAEFS anomaly forecast. QPF maxima
are currently situated within the Mogollon Rim and portions of
southern UT, both of which are the more susceptible areas given the
persistence of heavy rainfall leading in, plus the complex
topography and slot canyon allotment. This is really a seasonal
setup which could likely spur short term upgrades in spots as we
move closer to both the D4 and D5 time frame. Broad MRGL risks
exist for both days in similar locations outlining much of the
aforementioned area(s) above.

...Florida...

Models continue to depict heavy rainfall across the western coast
of FL on D4 (Sunday), spreading further east towards the northern
half of the state on D5 (Monday) thanks to developing mid-level
disturbance over the eastern Gulf. General model consensus is for a
development of heavier rains across the western FL coast with a
northern inflection into the Florida Big Bend thanks to increasing
low-level convergence on the eastern flank of a weak low center
progged off the coast. Ensemble QPF for both periods indicate
multiple inches of rain possible which could enhance further if
there is a greater likelihood of tropical cyclogenesis as noted via
the latest National Hurricane Center T.W.O for a disturbance of
interest (Disturbance 2) at 20% chance for development the next
7-days. This is a period to monitor for the prospects of this being
something more organized which models might not have a great grasp
of yet considering the lead time, and the slow maturation of any
organized low the next 5-7 days. For now, MRGL risks exist on both
D4 and D5 for the threat of heavy rainfall.

...Virginia Tidewater into Northeast North Carolina...

Slow-moving front will make headway through southeastern VA and
northeastern NC by Sunday with a deep moisture pooling anticipated
along and ahead of the front which will likely lead to areas of
heavy thunderstorms prior to fropa. Ensemble consensus lends
credence to a localized QPF maxima positioned somewhere around the
VA Tidewater through the northeastern corner of NC, coincident
with the progged frontal positioning around the time of Sunday
afternoon. PQPF for >1" is between 20-40% across the region which
at D4 is formidable enough to monitor closely. Considering some of
the more appreciable outputs via the global deterministic and bias
corrected ensemble, and in coordination with the local Wakefield,
VA WFO, opted to add a D4 MRGL risk for the threat, highlighting
that Tidewater area down into northeastern NC.

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