FOUS30 KWBC 230804
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
404 AM EDT Fri Oct 23 2026

Day 1
Valid 12Z Fri Oct 23 2026 - 12Z Sat Oct 24 2026

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

...New Mexico, Colorado, West Texas...

An upper level trough moving into the southwestern U.S. will
generate instability downstream over portions of New Mexico,
Colorado, and West Texas where scattered convection will develop
today. Model guidance shows a corridor of elevated instability over
this region this afternoon and evening, with the highest values
concentrated over far West Texas and southern/central New Mexico.
Deep southwesterly flow ahead of the trough will bring anomalous
moisture into the region, with PWATs reaching 2-3 standard
deviations above normal. Soils in portions of southwestern Colorado
and northwestern New Mexico have been somewhat saturated following
a period of heavy rainfall yesterday evening and last night. These
areas may see isolated convection again today, but the heaviest
totals will likely be displaced to the east as the upper trough
progresses.

Today will feature a relative lull in precipitation as compared to
Thursday and Saturday, mostly due to energy splitting off from the
main upper trough, but there should be enough instability and
moisture to support locally heavy rainfall rates and isolated to
widely scattered instances of flash flooding. Hi-res model
guidance suggests rainfall rates in the most intense cells may
reach 1-1.5 inches per hour and the highest totals may materialize
in northern New Mexico north and east of Albuquerque where terrain
will help to focus convection. The most vulnerable areas to flash
flooding will be steep terrain, burn scars, and urban areas, and
the inherited Slight Risk was maintained from far West Texas into
southern/central New Mexico that covers the Sacramento Mountains
and adjacent urban areas and burn scars. A broader Marginal Risk
area surrounds the Slight and includes much of New Mexico and
southern Colorado.

Dolan


Day 2
Valid 12Z Sat Oct 24 2026 - 12Z Sun Oct 25 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM WEST TEXAS
THROUGH EASTERN NEW MEXICO INTO SOUTHERN COLORADO AND FAR WESTERN
KANSAS...

...West Texas through southern Colorado and far western Kansas...

An upper level low will become cut off from the main upper trough
over the southwestern U.S., which will result in another day of
downstream convection from West Texas/New Mexico into the southern
and central High Plains. Widespread convection will develop across
this broad region on Saturday and will likely be enhanced in
coverage and intensity by an upper level shortwave ejecting into
the Plains ahead of the low. A strengthening mid/upper-level jet
ahead of the system will increase moisture transport into the
region and maintain anomalously high PWATs and instability. These
ingredients will support heavy rainfall, and deep unidirectional
southerly flow will support training/back-building storms from
eastern New Mexico into southeastern Colorado and far western
Kansas.

Global models show a broad area of 1-3 inch precipitation
totals across this region, and locally higher amounts are expected
with any training/repeat convection. Hi-res guidance suggests
rainfall rates may reach 1-2 inches per hour, which would rival
flash flood guidance. A Slight Risk of excessive rainfall covers
these area from West Texas through eastern New Mexico and into
southeastern Colorado and far western Kansas where heavy rainfall
may lead to scattered instances of flash flooding. A Marginal Risk
area surrounds the Slight and extends a bit further into the
central Plains where convection could produce locally heavy
rainfall but will be more progressive, resulting in a lower flash
flood threat.

...Four Corners region...

A Marginal Risk of excessive rainfall extends back into the Four
Corners region to include portions of Utah and northern Arizona
where convection in the vicinity of the upper low may result in
isolated instances of flash flooding. Though snow levels will be
dropping, they should remain high enough to allow for heavy
rainfall with slow moving storms. Models show some instability
developing across Utah and Arizona during the afternoon hours, and
there should be enough moisture to support widely scattered
convection with localized heavy rainfall. 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-level low is expected to develop along a weak boundary east
of Florida on Saturday, which will enhance onshore northeasterly
flow along the East Coast and direct a plume of enhanced moisture
(PWATs ~1.5 inches) towards the Florida peninsula. Meanwhile, an
upper level shortwave is expected to drop south into the region,
which will provide upper level support and enhance precipitation
coverage and intensity. Coastal convergence will focus enhanced
precipitation totals right along the East Coast of Florida, which
could cause isolated flash flooding in urban, low-lying, and poor
drainage areas. A Marginal Risk of excessive rainfall encompasses
the Florida East Coast roughly from Jacksonville to Miami, with the
highest threat focusing along the Central Florida East Coast. The
Slight Risk over Southeast Florida was removed in this forecast
cycle due to slower timing of this event. The focus for
precipitation will gradually slide down the Florida East Coast, but
the enhanced threat for Southeast Florida looks to hold off until
Sunday.

Dolan


Day 3
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 upper low over the southeastern U.S. will move northeastward
on Sunday, tracking from the Four Corners region to the central
Rockies. Unstable conditions ahead of the low/trough will allow for
another round of convection from West Texas and New Mexico to the
central Plains. Southerly flow across the south-central U.S. ahead
of the system will bring a plume of Gulf moisture into the
southern and central High Plains, which will provide strong support
for heavy rainfall as PWATs rise to 1.3-1.5 inches. Though the
ingredients look to be a little more conducive to heavy rainfall
than on Saturday, the system will become more progressive, which
may result in lower rainfall totals overall. Models are in very
good agreement on the location of the heaviest rainfall with some
divergence in the total amounts. Most likely rainfall totals will
reach 1-3 inches from northeastern New Mexico to western Kansas,
with locally higher amounts expected within this region.

...Southeast Florida...

The mid-level low developing off the East Coast of Florida will
gradually shift south through the period, with northeasterly flow
directing anomalous moisture into the Florida peninsula on the
northern side of the system. The system should stall southeast of
Miami, which is expected to result in a prolonged period of onshore
flow that could lead to heavy rainfall in Southeast Florida. Global
models are showing PWATs rising up to 1.5-2 inches in east-Central
and Southeast Florida, and convergence along the coast will likely
focus heavier precipitation totals between Cape Canaveral and
Miami. With a slow-moving fire hose of moisture aimed at Southeast
Florida through Sunday and Sunday night, scattered instances of
flash flooding could be a concern for urban, low-lying, and poor
drainage areas, and there is a Slight Risk of excessive rainfall in
effect.

Dolan


Day 4 and Day 5

Valid 12Z Mon Oct 26 2026 - 12Z Wed Oct 28 2026

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

...Central to Southern High Plains...
A Marginal risk was maintained across the southern High Plains
region on Monday. Overall it looks like a less active day than
Sunday, however will still have some shortwave troughing over the
region as well as an upper jet to the north providing some right
entrance region ascent. PW anomalies are a bit lower compared to
previous days, but still around the climatological 90th
percentile, to go along with 500-1500 J/kg of CAPE (highest over
southern NM into west TX). Thus it seems likely that scattered
convection will occur from west TX into southeast NM and portions
of western OK. Global model QPFs are pretty modest, but given the
ingredients would expect to see some locally heavier totals once
we get into the timeframe of the higher res models. Isolated flash
flooding should continue to be a threat.

...Southeast Florida...
Northeasterly low level flow and coastal convergence will continue
to result in convection near and just offshore the southeast FL
coast on Monday and Tuesday. There is some model spread regarding
the magnitude of PWs on these days, which will likely be a
determining factor in whether we see any flash flood threat. The
00z ECMWF is notably higher with moisture and QPF than most other
models, especially on Monday (day 4). Low confidence on these
details at this lead time, but there is certainly a conditional
threat for flash flooding if these higher PWs materialize and cells
anchor along the coastal convergence zone. Given increased spread
by day 5 we will hold off on a Marginal for Tuesday, and continue
to monitor trends.

Chenard


Day 1 threat area: https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Day 2 threat area: https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Day 3 threat area: https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt



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