FOUS30 KWBC 240729
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
329 AM EDT Sat Oct 24 2026

Day 1
Valid 12Z Sat Oct 24 2026 - 12Z Sun Oct 25 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
WEST TEXAS, NEW MEXICO, AND COLORADO...

...West Texas to the Southern/Central High Plains...

An upper level low will split off from the main upper trough over
the southwestern U.S. early this morning. This feature will create
favorable conditions downstream for scattered to widespread
convection to develop from West Texas and New Mexico into the
southern and central High Plains, and convection will likely be
enhanced in coverage and intensity by an upper level shortwave
lifting north across the region this afternoon and evening.
Additionally, a strengthening south-southeasterly jet ahead of the
system will increase moisture transport into the region, and
instability will combine with this anomalous moisture to create a
heavy rainfall threat.

A Slight Risk of excessive rainfall was maintained for much of
eastern New Mexico and southeastern Colorado and portions of West
Texas and western Kansas. This area is expected to see the highest
rainfall totals ranging from 1.5-3 inches, with higher amounts
expected in portions of northeastern New Mexico and southeastern
Colorado where the HREF and REFS show 50-75% chance of exceeding 3
inches in 24 hours. Rainfall rates in this region may reach 1-1.5
inches per hour, rivaling flash flood guidance, and could lead to
scattered instances of flash flooding. Thankfully, the heaviest
rainfall today should be displaced to the east of where the
heaviest rain fell yesterday, but portions of north-central New
Mexico and south-central Colorado have been included in the Slight
Risk area to account for an elevated flash flood threat where
locally heavy rain may fall over already saturated soils.

The Slight Risk area also extends south into southeastern New
Mexico and West Texas where the environment will be favorable for
strong, organized convection later today. This area will see the
highest CAPE and wind shear values this afternoon, and the
vertically veering wind profile will be conducive for supercell
development. Any supercells that develop will be capable of
producing locally heavy rainfall that could cause flash flooding.
These cells should be fairly quick-moving, which should help to
somewhat limit the flash flood risk. The surrounding Marginal Risk
area was expanded in West Texas to account for the potential
eastward progression of convection this evening and for an upward
trend in hi-res model QPF in this area.

...Four Corners region...

A Marginal Risk of excessive rainfall extends back into the Four
Corners region and includes portions of eastern and southern Utah
and northern Arizona where convection in the vicinity of the upper
low may result in isolated instances of flash flooding. Convection
in this area should be fairly slow moving, and although snow levels
will be dropping, they should remain high enough to allow for
heavy rainfall. Models show some instability developing across Utah
and Arizona during the afternoon hours, and there should be enough
moisture to support widely scattered convection. Given the
preceding days of heavy rainfall leading up to Saturday, the region
may be more sensitive to additional heavy rainfall.

...East Coast of Florida...

A mid/upper-level low will slowly move south over the Atlantic
parallel to the Florida East Coast, which will generate scattered
convection over the Atlantic that will migrate onshore with strong
northeasterly flow on the northern and western sides of the
circulation. A plume of anomalous moisture with PWATs of 1.3-1.5
inches will be aimed onshore by the low circulation and gradually
shift down the coast throughout the day. The moist and unstable air
mass will allow for heavy rainfall rates to develop and coastal
convergence will focus rainfall over the urban I-95 corridor, which
has been highlighted with a Marginal Risk of excessive rainfall.
Isolated instances of flash flooding will be possible, especially
in urban, low-lying, and poor drainage areas.

Dolan
 

Day 2
Valid 12Z Sun Oct 25 2026 - 12Z Mon Oct 26 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE CENTRAL AND SOUTHERN HIGH PLAINS AND SOUTHEAST FLORIDA...

...Central and Southern High Plains...

The cutoff low will gradually progress northeastward, resulting in
an expanding region of precipitation ahead of the system from West
Texas through the southern and central High Plains. Similar to the
setup on Saturday, anomalous moisture will stream ahead of the
system into the Plains under favorable upper level conditions for
scattered to widespread convection. The best instability should be
focused over New Mexico and Texas, but there should be enough
instability extending into the High Plains to support deeper
convection with locally heavy rainfall.

The highest flash flood threat will likely be located over
portions of northeastern New Mexico, southeast Colorado, western
Kansas, and the Oklahoma and Texas panhandles where there is a
Slight Risk of excessive rainfall. There is still quite a bit of
uncertainty surrounding rainfall totals, but the general consensus
is for the highest amounts over the southern and central High
Plains, and this is also where the REFS is flagging the highest
probabilities for heavy rainfall. The western side of the Slight
Risk area is where there is a chance that the heavy precipitation
footprint may overlap with areas forecast to receive heavy rainfall
on Saturday, which would make the area more susceptible to flash
flooding with any additional rainfall.

The broader Marginal Risk area surrounding the Slight Risk area
was expanded in this forecast cycle to include more of southeastern
New Mexico and West Texas. This region will have the best
ingredients for heavy rainfall (CAPE greater than 1000 J/kg and
PWATs of 1-1.5 inches) but will be slightly displaced from the best
synoptic forcing with the main low. Any convection that develops
in this area will have the potential to produce locally heavy
rainfall. Given vulnerable terrain in southern New Mexico and heavy
rainfall received yesterday and expected today, the expansion of
the Marginal Risk area was justified. Soils over portions of Texas
will not be as saturated, but given the favorable setup could still
see a localized flash flood threat. The Marginal Risk area was
also trimmed on the northern side to remove some of Nebraska and
South Dakota where rainfall rates will be limited due to a lack on
instability and where rain should be more stratiform in nature.

...East Coast of Florida...

The mid/upper level low sliding down the coast will stall
southeast of Miami, which will result in a prolonged period of
moist, onshore flow across Southeast Florida. Showers and storms
will form over the Atlantic and move over the Florida coast, which
will result in heavy rainfall focused along the I-95 corridor. The
heavy rainfall threat will shift south throughout the day, with the
highest rainfall totals expected to accumulate over Southeast
Florida once the system stalls. There is a Marginal Risk of
excessive rainfall for much of the I-95 corridor south of
Jacksonville and a Slight Risk for the I-95 corridor south of
Melbourne. The Slight Risk area was expanded south to include more
of the Miami metro area based on the latest model trends in QPF.
Scattered instances of flash flooding will be possible, especially
in urban, low-lying, and poor drainage areas.

Dolan
 

Day 3
Valid 12Z Mon Oct 26 2026 - 12Z Tue Oct 27 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE CENTRAL AND SOUTHERN HIGH PLAINS AND SOUTHEAST FLORIDA...

...Central and Southern High Plains...

The upper level cutoff low will progress further, tracking across
the north-central U.S. on Monday with a trailing frontal zone
extending back across the central and southern High Plains.
Scattered convection is expected to develop ahead of the system and
will be able to tap into moisture flowing in from the Gulf and
instability in the vicinity of the front. A shortwave is expected
to move across the region on Monday and a strengthening jet along
the frontal boundary will place the southern High Plains in the
right entrance region, both of which should provide additional
support for convective development. Compared to previous days,
model QPF totals are modest, but the ingredients will be in place
for at least a localized heavy rainfall threat. Therefore, the
inherited Marginal Risk area was continued for the central and
southern High Plains.

...Southeast Florida...

Northeasterly onshore flow will continue across Southeast Florida,
but the low pressure system will gradually weaken, resulting in
precipitation tapering off on Monday night. Given heavy rainfall
expected in Southeast Florida on Sunday, a Marginal Risk was
maintained to account for isolated flash flood potential with
locally heavy rain falling over saturated soils.

Dolan
 

Day 4 and Day 5
Valid 12Z Tue Oct 27 2026 - 12Z Thu Oct 29 2026

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Chenard
$$
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