Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
904 PM EDT Sun Oct 25 2026
Day 1
Valid 01Z Mon Oct 26 2026 - 12Z Mon Oct 26 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE CENTRAL AND SOUTHERN HIGH PLAINS...
...01Z update...
...Southern High Plains into the Central Plains...
Overall, not much change from the previous outlook, with a Slight
Risk maintained from Far West Texas to southeastern Kansas. Expect
the greater threat for organized heavy rain through the near-term
to focus from northeastern New Mexico through the Panhandle Region
into southwestern Kansas. Favorable upper jet and mid-level forcing
interacting with persistent southerly low-level inflow/moisture
advection will continue to support moderate to heavy rain along
this axis, with training storms raising the threat for heavy
amounts and flash flooding. Both the HREF and REFS show high
neighborhood probabilities for additional amounts of 1-2 inches
across this area through the remainder of the evening into the
overnight.
Farther to the south across southeastern New Mexico and Far West
Texas, activity is expected to be generally less organized. But
given the greater sensitivity and low FFGs across this area, along
with the potential for some additional localized 1-2 inch amounts,
the Slight Risk was maintained.
The latest HRRR, HREF, and REFS did suggest the threat for heavy
rain and flash flooding would be confined farther west than the
previous Marginal Risk suggested, so the eastern extent of the
Marginal Risk was pulled a little farther west with this update.
...Florida...
Onshore flow continues to produce isolated to scattered showers
along the eastern shores. While an isolated concern can not be
ruled out, these showers are fairly progressive and are moving
into a more stable airmass centered over the peninsula. With latest
guidance also not indicating a notable signal for anything beyond
isolated heavy amounts, the Slight Risk was removed but a Marginal
Risk maintained along the coast.
Pereira
Day 1 threat area:
www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
414 AM EDT Mon Oct 26 2026
Day 1
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...
An upper low/trough will push across the north-Central U.S. today
accompanied by a surface low pressure system with a trailing cold
front extending back across the central Plains and a dryline
extending across the southern High Plains. Scattered showers and
thunderstorms are expected along this boundary, and additional
storms are expected to develop this afternoon and evening as upper
level dynamics come into play. A southwesterly upper level jet
ahead of the system will place portions of the central and southern
Plains in the favorable right entrance region, and an upper level
shortwave is expected to move north into the region.
A moist (PWATs 1.25-1.5 inches) and unstable (MUCAPE 500-1500
J/kg) air mass will be in place across the central and southern
High Plains, which should support some strong/deep convection with
heavy rainfall rates. The HREF and REFS show modest probabilities
(~30%) of rainfall rates exceeding 1 inch per hour from West Texas
to the Texas Panhandle, but low probabilities (less than 20%) of
rainfall rates exceeding 2 inches per hour. It will be difficult
for these rates to exceed hourly FFGs for much of the area, but
they could exceed FFGs in areas where soils are saturated from
recent heavy rainfall from eastern New Mexico into the Texas
Panhandle. Fortunately, the heaviest rainfall totals (1-2 inches,
locally higher up to 3-4 inches) are expected to be displaced to
the east of recent heavy rains, which will help limit the threat of
flash flooding. A Marginal Risk of excessive rainfall is in effect
for much of the central and southern High Plains where locally
heavy rainfall will be possible with storms this afternoon and
evening, and isolated instances of flash flooding may be possible.
Further north, widespread precipitation is expected over the
northern Plains in the vicinity of the surface low pressure system,
but with little instability, rainfall rates should remain moderate
at best. Model guidance is showing rainfall rates and totals
remaining well below current FFGs for the area, so there will be
little to no flash flood risk for this area.
...Southeast Florida...
A mid/upper level low will stall southeast of the Florida
Peninsula, resulting in northeasterly onshore flow along the
Florida East Coast. Moisture wrapping around the low circulation
will surge across Southeast Florida, raising PWATs to 1.5-2 inches
between Palm Beach and the Florida Keys. The best instability will
also be focused along the Southeast Florida coast and over the
adjacent Atlantic waters where MUCAPE will likely reach 700-1000
J/kg this afternoon and evening. This environment will support
scattered showers and storms with locally heavy rainfall that will
originate over the Atlantic then migrate over the Southeast Florida
coast. Model guidance has been showing a southward trend with the
low, which may result in the heaviest rainfall remaining south of
Florida with only isolated to widely scattered showers in Southeast
Florida. With any showers that do move onshore, convergence along
the coast will focus the heaviest rainfall totals over the I-95
urban corridor, an area that has received several rounds of locally
heavy rainfall over the past couple of days. Given recent heavy
rainfall in this area and the sensitivities of the urban areas,
isolated instances of flash flooding may be possible with heavier
showers and storms, so there is a Marginal Risk of excessive
rainfall for Southeast Florida.
Dolan
Day 1 threat area:
www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
414 AM EDT Mon Oct 26 2026
Day 2
Valid 12Z Tue Oct 27 2026 - 12Z Wed Oct 28 2026
...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR SOUTHEAST
FLORIDA...
...Southeast Florida...
Low pressure will gradually shift north over the Bahamas on
Tuesday, resulting on another day of northeasterly onshore flow and
increasing moisture across Southeast Florida. PWATs will increase
to around 2 inches by Tuesday afternoon and evening, but
instability may be limited. Global models are showing MUCAPE values
500-900 J/kg along the immediate Southeast Florida Coast, with
little to no instability across the rest of the peninsula.
Scattered showers and storms are expected to form over the
Atlantic, some of which should be able to make it onshore in
Southeast Florida. With high PWATs and modest instability, locally
heavy rainfall may be possible in some showers and storms. Given
recent heavy rainfall in Southeast Florida and the sensitivity of
urban areas, isolated instances of flash flooding may be possible
along the I-95 urban corridor of Southeast Florida and there is a
Marginal Risk of excessive rainfall.
Dolan
Day 2 threat area:
www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
414 AM EDT Mon Oct 26 2026
Day 3
Valid 12Z Wed Oct 28 2026 - 12Z Thu Oct 29 2026
...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR EAST-CENTRAL
AND SOUTHEAST FLORIDA...
A mid/upper low will continue moving north of the Bahamas off the
Florida East Coast. The stream of moisture on the northern side of
the low circulation will shift north along the Florida coast, with
the highest PWATs (around 2 inches) focused between Cape Canaveral
and Fort Lauderdale. Instability will increase as shortwave energy
moves across Central and South Florida, which could support
increased precipitation coverage, but there is some uncertainty in
how much instability will increase. The ECMWF and EC-AIFS are much
more aggressive, increasing MUCAPE to 1000-1500 J/kg, while the
GFS and AI-GFS only increase MUCAPE to 500-700 J/kg. If showers and
storms can tap into the elevated instability, there will be
sufficient moisture to support locally heavy rainfall rates. The
heaviest rainfall totals will once again focus along the coast,
impacting the I-95 urban corridor. Given recent heavy rainfall
along the Florida East Coast and the sensitivities of the urban
areas, isolated instances of flash flooding may be possible and
there is a Marginal Risk of excessive rainfall for portions of
east-Central and Southeast Florida.
Dolan
Day 3 threat area:
www.wpc.ncep.noaa.gov/qpf/99epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
414 AM EDT Mon Oct 26 2026
Day 4 and Day 5
Valid 12Z Thu Oct 29 2026 - 12Z Sat Oct 31 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTH-CENTRAL TEXAS ON THURSDAY AND CENTRAL ARIZONA ON FRIDAY...
..Texas into New Mexico...
A Slight risk has been maintained on day 4 (Thu) across portions
of TX, stretching from the Stockton Plateau through parts of the
western Hill Country and into south-central TX. Overall, not much
change was needed to the inherited risk area. Large scale forcing
for ascent will be driven in part by a strong southern stream upper
jet providing divergence aloft. Embedded shortwave energy will
also eject out of the East Pacific within the deep southwesterly
flow aloft, with some potential moisture and mid level vorticity
contribution from what is currently tropical cyclone Vance. Mid to
upper level moisture sourced from the East Pacific will combine
with a strong southeasterly low level jet bringing moisture out of
the Gulf. This combination will drive PW values well above the
climatological 90th percentile for late October.
The environmental ingredients in place will support an organized
heavy rainfall event. As expected at a day 4 lead time, exact
spatial and temporal details will change some as the event nears.
However, models continue to converge on a solution, and confidence
in a flash flood event continues to increase. The last few runs of
the ECMWF, AIFS, AIGFS and GFS are all clustered fairly well with
a max rainfall axis over south-central TX. The latest model
consensus is for 2-4" of rain, but with some backbuilding/training
probable the potential for at least localized swaths of 6"+ seems
in play. We will continue to closely monitor trends, as locally
significant flood impacts are possible with this event.
Will just carry a marginal risk into day 5. The risk of flash
flooding over TX will persist as the features responsible for the
day 4 risk shift northward. However the signal becomes a bit more
muted by day 5 and uncertainty on the details become higher. So
will stick with a Marginal for now, but could eventually need an
embedded Slight risk.
...Arizona...
Synoptic scale model agreement is above average for a day 5
forecast with broad troughing progressing into the western United
States. While some timing uncertainty persists regarding
individual embedded shortwaves, the overall environmental
ingredients are coming together to support a robust convective and
heavy rainfall threat centered over AZ on Friday.
Dynamic forcing will be impressive, featuring a very strong
southern stream upper level jet that will place AZ within its
favored left exit region, promoting strong upper level divergence.
Mid level shortwave energy ejecting east will interact with a
rather strong southerly low level jet resulting in impressive low
level moisture transport and PWs across the region. This strong low
level flow should help organize and sustain some training/backbuilding
convective cells. While thermodynamic details carry inherent
uncertainty at this lead time, current model guidance suggests that
corridors of 1000+ J/kg of CAPE are probable. Much of the region
has been anomalously west of late, which has notably increased the
hydrologic sensitivity across the area. While the exact placement
and magnitude of the heaviest rainfall axis remains subject to
adjustments as we get closer, confidence is high enough in an
isolated to scattered flash flood threat to warrant a Slight risk.
Chenard
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
414 AM EDT Mon Oct 26 2026
Day 4 and Day 5
Valid 12Z Thu Oct 29 2026 - 12Z Sat Oct 31 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTH-CENTRAL TEXAS ON THURSDAY AND CENTRAL ARIZONA ON FRIDAY...
..Texas into New Mexico...
A Slight risk has been maintained on day 4 (Thu) across portions
of TX, stretching from the Stockton Plateau through parts of the
western Hill Country and into south-central TX. Overall, not much
change was needed to the inherited risk area. Large scale forcing
for ascent will be driven in part by a strong southern stream upper
jet providing divergence aloft. Embedded shortwave energy will
also eject out of the East Pacific within the deep southwesterly
flow aloft, with some potential moisture and mid level vorticity
contribution from what is currently tropical cyclone Vance. Mid to
upper level moisture sourced from the East Pacific will combine
with a strong southeasterly low level jet bringing moisture out of
the Gulf. This combination will drive PW values well above the
climatological 90th percentile for late October.
The environmental ingredients in place will support an organized
heavy rainfall event. As expected at a day 4 lead time, exact
spatial and temporal details will change some as the event nears.
However, models continue to converge on a solution, and confidence
in a flash flood event continues to increase. The last few runs of
the ECMWF, AIFS, AIGFS and GFS are all clustered fairly well with
a max rainfall axis over south-central TX. The latest model
consensus is for 2-4" of rain, but with some backbuilding/training
probable the potential for at least localized swaths of 6"+ seems
in play. We will continue to closely monitor trends, as locally
significant flood impacts are possible with this event.
Will just carry a marginal risk into day 5. The risk of flash
flooding over TX will persist as the features responsible for the
day 4 risk shift northward. However the signal becomes a bit more
muted by day 5 and uncertainty on the details become higher. So
will stick with a Marginal for now, but could eventually need an
embedded Slight risk.
...Arizona...
Synoptic scale model agreement is above average for a day 5
forecast with broad troughing progressing into the western United
States. While some timing uncertainty persists regarding
individual embedded shortwaves, the overall environmental
ingredients are coming together to support a robust convective and
heavy rainfall threat centered over AZ on Friday.
Dynamic forcing will be impressive, featuring a very strong
southern stream upper level jet that will place AZ within its
favored left exit region, promoting strong upper level divergence.
Mid level shortwave energy ejecting east will interact with a
rather strong southerly low level jet resulting in impressive low
level moisture transport and PWs across the region. This strong low
level flow should help organize and sustain some training/backbuilding
convective cells. While thermodynamic details carry inherent
uncertainty at this lead time, current model guidance suggests that
corridors of 1000+ J/kg of CAPE are probable. Much of the region
has been anomalously west of late, which has notably increased the
hydrologic sensitivity across the area. While the exact placement
and magnitude of the heaviest rainfall axis remains subject to
adjustments as we get closer, confidence is high enough in an
isolated to scattered flash flood threat to warrant a Slight risk.
Chenard
