Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
801 PM EDT Thu Oct 15 2026

Day 1
Valid 01Z Fri Oct 16 2026 - 12Z Fri Oct 16 2026

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF WEST TEXAS...

01Z Update: Updates to the Day 1 ERO were mainly to trim the
western portions of the outlook areas across TX -- areas now west
of the front and (thus) quite a bit more stable following the
FROPA. Elsewhere, based on the latest observational trends
(radar/satellite/mesoanalysis), along with the trends in recent
HRRR runs and with the 18Z HREF and REFS QPF exceedance
probabilities, have removed a large portion of the Marginal Risk
area across the MOKSAROK, the Mid MS Valley, and parts of the
western OH Valley.

Hurley

Previous discussion...

The setup for Thursday into early Friday morning continues to trend
towards a very active period across portions of the Southern Plains
as a cold front drives south with the aid of a strengthening
surface ridge emanating out Canada. Complex longwave evolution
will generate quite a strong surface response with high pressure
nosing out of western Canada, eventually strengthening into a 1040+
mb high centering over Montana by later this afternoon. This will
finally push the front bisecting the Plains through the Ohio Valley
southward creating a focused area of low-level convergence as it
interacts with rich theta_E air positioned over the Southern Plains
of OK/TX. Current surface analysis maintains our ridge across the
Lower Mississippi Valley with a prevailing south to southwest fetch
out of the adjacent Gulf, leading to a fairly pronounced deep
layer moisture source across much of the Lone Star state and the
eastern half of OK. PWATs centered over west TX up through OK
remain very much elevated with the 00z RAOB's out of both KOUN and
KMAF indicating PWAT anomalies encroaching on +2 to +3 standard
deviations when accounting for climatology. This is also well above
the 90th percentile with the NAEFS outputs signaling closer to the
upper 97-99th percentile when adjusting for seasonal climo, so the
environmental conditioning is more than favorable for prospects of
heavy rainfall in any convective regimes.

Streaming mid- level vorticity within the western flank of our
ridge over the Southeast CONUS will continue for at least another
24 hours before the general pattern, both at the surface and aloft,
finally shifts and the threat for significant convective coverage
and associated impacts diminishes across the region. Classic low-
level convergence regime with the front will allow for the standard
continuation of convection over the Southern Plains the first part
of Thursday with the eventual decay in the magnitude for a short
time late-morning into the afternoon. By the mid to late-afternoon
time frame, we'll begin seeing our front take a dive south as it
begins feeling the pressure gradient pattern building over the
Plains and Northern Rockies thanks to our maturing high out of the
Canadian Prairies. By the following evening (Thursday night), the
nocturnal LLJ will respond ahead of the approaching boundary
leading to enhanced low to mid-level convergence from the eastern
Permian Basin down through the adjacent Concho Valley, into the Big
Bend and Lower Trans Pecos. The further south the setup, the more
prolonged the heavy convective regime will last creating a
cumulative effect of all the heavy rain occurring during the
period.

A noteworthy precipitation gradient can be seen within the ensemble
means with heavy QPF signatures over the Big Bend to Lower Trans
Pecos with a gradient decline as you move northward. Areal average
QPF between 3-5" with locally higher amounts are anticipated along
and south of I-10, mainly east of the Davis Mountains with the
maxima centered over the Lower Pecos River basin between Sanderson
to north of Del Rio. 00z HREF/REFS neighborhood probabilities
continue to pinpoint 70-100% exceedance probs for >3" with even a
pocket of 50-80% for >5" positioned over Terrell county in the Big
Bend up through portions of the Lower Concho Valley. This is the
area where the convective pattern will linger the longest before
the eventual frontal progression pushes the front through the area,
but it's also the area with the greatest instability and deep layer
moisture presence when assessing raw PWAT indices being forecast.

Considering such a robust signal, the previous MDT risk forecast is
still very much in play with only minor modifications to the risk
itself from the previous issuance. Continuity and the enhanced
probabilities maintain a favorable prospect for widespread flash
flooding across the aforementioned areas with even a threat for
areas north around the central Concho Valley, including the San
Angelo area and surrounds. The SLGT risk extends further north into
southern OK with the initial convective threat carrying over from
the morning hours and some overlap in the afternoon on initiation
before the front finally pushes through the air and dry air
advection in wake of the front puts an end to the threat. DFW metro
will be right on the edge of seeing more appreciable rainfall, but
current progs are the worst stays just outside the metroplex this
period. Will be something to monitor moving forward, but the area
remains in the MRGL encompassing the outskirts of the main axis of
heavier precip and associated SLGT risk.

Kleebauer


Day 2
Valid 12Z Fri Oct 16 2026 - 12Z Sat Oct 17 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF CENTRAL AND SOUTHERN FLORIDA...

Flow across the region will become more southerly ahead of an
amplifying trough moving into the easterly U.S. This will support
increasing moisture, with PWs climbing to at or above 2 inches (or
around 2 std dev above normal) across much of central and southern
Florida on Friday. This will support efficient rain-producing
storms, with slow storm motion raising the threat for localized
heavy accumulations. The Marginal Risk highlights the area where
the HREF and REFS both generally show higher (greater than 50
percent) probabilities for accumulations exceeding 3 inches.

Pereira


Day 3
Valid 12Z Sat Oct 17 2026 - 12Z Sun Oct 18 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ALONG PORTIONS
OF THE FLORIDA EAST COAST...

20Z Update...

No changes were made to the previous outlook.

Pereira

Previous discussion...

Cold front will be pushing through the Florida Peninsula by Friday
night and maintaining slow progression southward through Saturday
with a bit of a frictional convergence regime along the east coast.
Surface ridging to the north coupled with the front will allow for
prevailing east to northeast flow off the nearby Atlantic with
focused convergence along the front as it motions south. Current
progs are for the front to be aligned between Melbourne and West
Palm Beach by Saturday afternoon which should coincide with the
diurnal max instability. As of now, the signal shows convection
confined right along the coast with little progression inland, so
the threat for any heavy rainfall is along that immediate coastal
plain. That said, that's the main population center with urban
sprawl up and down this area of the state, and with the environment
conducive for locally 2-3"/hr within any convective cores, imagine
isolated totals of 4-6" are very much plausible in this scenario.
It's a tricky setup with low areal coverage of heavy rain potential
given the expected proxy to the coast. Considering the marginal
signal within the global deterministic and ensemble bias
correction, the previous MRGL risk was maintained with no
adjustment.

Kleebauer


Day 4 and Day 5

Valid 12Z Sun Oct 18 2026 - 12Z Tue Oct 20 2026

...MARGINAL RISKS OF EXCESSIVE RAINFALL EXIST FOR THE GOLD COAST OF
FLORIDA SUNDAY & PORTIONS OF THE EAST COAST MONDAY...

2000Z Update: Only minor changes made to the Day 5 outlook. The
Marginal Risk area along the Mid Atlantic Coast is still predicated
on the trends in the AI guidance, especially with the 12Z ECAIFS,
which came in much wetter (low closer to the Mid Atlantic Coast) at
12Z compared to 06Z.

Hurley

Previous discussion..

...FL Gold Coast...
A well defined cold front is expected to press southward, becoming
stationary across Cuba on Monday. Moderate to strong Low level
east northeasterly flow exist near the east coast Florida Sunday,
nearly antiparallel to the flow aloft. Precipitable water values
are forecast to be 1.5-2". Strong boundary layer convergence
maxima likely along the east central coast of Florida, which would
be strongest overnight. This will support potential for locally
heavy rains from well defined rain bands that may train for periods
early Sunday, with isolated runoff issues possible along the east
central coast of Florida, especially in urbanized regions. The
guidance is slowly trending downward with amounts as the front
trends faster due to more of a signal in a low near the East Coast,
so there is a chance that later shifts may be able to drop the
Marginal Risk. Stay tuned.

...Eastern NC/Southeast VA...
The guidance is trending towards an occluded low, which could have
some interior convection, somewhere across the western subtropical
North Atlantic between the Southeast Coast and Bermuda. The 00z
GFS is the farthest east, but the 00z ECMWF/Canadian/UKMET are much
closer to the 12z EC mean/00z GEFS mean in more coastal solutions.
This could allow for heavy rainfall near the NC Outer Banks and
Southeast VA as moisture/instability pivot back to the coast from
the Gulf Stream within its comma head or TROWAL. The 00z UKMET has
the strongest signal while the 00z ECMWF is slightly offshore.
Since the ensemble means indicate more western solutions may have
merit, raised a Marginal Risk as a course of least regret.

Roth


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