Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
424 PM EDT Wed Oct 14 2026
Day 1
Valid 16Z Wed Oct 14 2026 - 12Z Thu Oct 15 2026
...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF OKLAHOMA INTO THE RED RIVER VALLEY OF TEXAS...
...16Z Update...
The prior forecast reasoning remains on track with the approach of
the upper low and analyzed cold front through northern Oklahoma
into the Texas Panhandle. An anomalously moist environment is in
place along and ahead of the front with plentiful Gulf moisture and
influence from Simon in the Pacific leading to PWATs near/at or
even past record breaking levels for the month of October. The 2.23
in PWAT value indicated by the 12Z OUN sounding is the highest
recorded for October during the period of record. Storms overnight
which continue this morning have already lead to several inches of
rainfall, particularly from central Oklahoma west-southwest into
the southeastern Texas Panhandle where areal average estimated
rainfall totals per MRMS data are in the 3 to 4" range (locally
6-8" to the west of Oklahoma City). Expect a lull in activity as
the overnight low-level jet continues to wind down and before
renewed surface heating leads to higher instability later this
afternoon. The latest surface observations indicate an outflow
boundary through southern Oklahoma which leads to some uncertainty
with the northward extent of the threat, though expect most of this
region to recover as storms wind down into the early afternoon in
combination with daytime heating, as well as when the low-level
flow ramps up again into the overnight hours helping to draw higher
theta-e air back further north ahead of the approaching dry
line/Pacific front. There is some uncertainty with westward extent
when combining the HREF/RRFS deterministic amounts and ensemble
probabilities, with the RRFS favoring a bit more of a southwesterly
axis in terms of additional rainfall which makes sense given the
airmass may not fully recover as far north as the observed west-
southwesterly axis overnight. However, there is growing concern of
potentially higher impact flash flooding over portions of central
Oklahoma around the greater Oklahoma City metropolitan area and
just to the west along I-40. The best overlap in the high-res
guidance for higher rainfall totals is through this region
(moderate to high HREF and RRFS probabilities of >5"), and some of
the heaviest rainfall overnight into this morning was observed in
the I-40 vicinity just to the west of Oklahoma City (estimates of
over 8").
Putnam
...Previous Discussion...
Current upper level setup is shifting into a classic longwave
pattern suitable for widespread convective impacts and heavy rain
potential from southwest TX up through the Plains, arcing back into
the Mid-Mississippi and Ohio Valleys. Deep upper low (ULL)
positioned over the interior west will slowly pivot eastward,
maintaining a persistent diffluent pattern centered downstream of
the Rockies leading to multiple rounds of convection and flash
flood prospects over the Central and Southern Plains. At the
surface, multiple surface lows are analyzed over the CO Front Range
back into the Four Corners with another set of weaker lows aligned
within a quasi-stationary front extending from the Plains into the
Ohio Valley. The whole setup is in flux with the slow evolution of
the longwave trough over the west, but we'll finally see some
progression of the frontal waves, and front in general, as we move
into the second half of the D1 period as another key component in
the setup makes its presence known further north.
WV satellite over the Northern CONUS into Canada notes a digging
shortwave trough migrating southeast out of the Canadian Prairies
that will continue to dig south and strengthen as it merges with a
mid-level vorticity maxima streaming northeast out of the Plains
involved in the current convective regime this evening. The
shortwave to the north will amplify and create a pronounced
meridional regime that will act as a pivotal piece to the surface
reflection as a surface high will slide south out of western Canada
and strengthen rapidly thanks to the general upper level
amplification. This will take our "stalemate" currently analyzed
over the Plains and give it the push necessary to finally press the
quasi-stationary front southward, turning the front into a textbook
cold front on the leading edge of the surface ridge to the north.
This combined with convergent flow around the western periphery of
a ridge centered over the Lower Mississippi Valley will lead to a
significant rainfall threat across portions of Southern Plains,
especially into OK and the Red River basin between OK/TX.
00z HREF this evening was noteworthy with regards to more
substantial prospects for flash flooding given the probabilistic
output, as well as the appreciable HREF mean QPF distribution
across the Southern Plains. The frontal progression will make the
area of southwest to central OK as the primary axis for heavy
convection as convergent flow in-of the front, along with PWAT
anomalies bordering and/or exceeding record levels to date will
provide a sufficient environment capable for producing heavy
rainfall with efficient warm rain processes capable for more
significant totals in the region. Latest CAMs and global
deterministic signals are robust with multiple pieces of guidance
now indicating widespread areas of 3-5" of rain with maxima upwards
of 8" according to low-end probabilities within the ensemble for
exceeding the 8 inch threshold (15-25%). The greatest probabilities
for exceeding all three of the 3/5/8 inch thresholds are positioned
over central OK with the OKC metro as a notable data point in the
middle of the elevated prob fields. Considering the alignment of
the front and the multi-round evolution of convection during the
period, this has merit considering the front will likely not be out
of the area until late in the forecast cycle, and perhaps even
bleeding into the new D2 time frame as the fight between the ridge
axis over the Southeast and the strengthening surface high to the
north will clash with the eventual winner being the high over the
north moving into Thursday. LLJ upwards of 40kts is anticipated
over the Southern High Plains into OK which only adds to the setup
as the shear component will allow for merging cells and larger
convective clusters to materialize and hold together for extended
periods before fading as they move northeast with the mean flow.
This will be the main cause for such a widespread significant
rainfall across the region in this period.
Heavy rainfall will also be plausible over the Southern High Plains
of TX, as well as over the Ohio Valley with the former being the
more prominent for heavy rain prospects thanks to deeper moisture
flux and ample instability positioned around the western flank of
the Southeast ridge. The Ohio Valley threat is due to the migration
of mid-level energy out of the Plains within the confines of the
quasi-stationary front which will delineate the more appreciable
deep layer moisture along and south of the boundary with a slow
filtering of drier from the north as a weaker ridge moves over the
Great Lakes. Areas from the TX Big Bend up through the Permian
Basin and Caprock could see localized amounts of 2-4" which would
certainly cause issues within any urbanized zones and areas with
several low-water crossings that are littered over the area. Areas
in the Ohio Valley are generally more in the 1-3" range for totals,
but a few stronger cells over places near the Ohio River may see
locally higher amounts which could result in flash flood potential.
In coordination with the local Norman, OK WFO, a Moderate Risk of
excessive rainfall was added to the new D1 period with emphasis on
areas from southwestern OK and the Red River basin up through
central OK and into the Tulsa metro area. This aligns with the
greatest probabilities for greater than both 3 and 5 inch
thresholds within both the HREF and REFS outputs this evening.
Despite some antecedent drier conditions, the record breaking
environment in terms of PWATs and repeating axis of convection
would be sufficient for locally significant flash flood potential,
especially into the OKC metro where flash flooding concerns are
highest. The SLGT risk from the previous forecast still extends
from southwest TX up through the Mid-Mississippi and Ohio Valleys
with an eastern inflection over the Central Appalachian front in WV
where the threat for 1-2"/hr rainfall in the period has trended up
over the past few model cycles, indicative of the environmental
conditions in place.
Kleebauer
Day 1 threat area:
www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
424 PM EDT Wed Oct 14 2026
Day 2
Valid 12Z Thu Oct 15 2026 - 12Z Fri Oct 16 2026
...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF WEST TEXAS...
...2030Z Update...
A targeted Moderate Risk has been introduced for portions of west
Texas from just east of Big Bend along the Rio Grande and across
the Stockton Plateau to the Pecos River Valley and north to just
past the I-10 corridor. As previously noted, this region will see a
more favorable set up for longer duration, heavy rainfall as the
progression of the cold front slows and becomes more ENE to WSW
oriented ahead of a surface wave compared to the faster eastward
progression of the front to the north, preserving the warm sector
through most of the day 2 period. An axis of higher Gulf moisture
and instability as well as stronger southerly low-level flow will
be in place through the day and into the evening/early overnight
hours, intersecting the front as it pushes southward towards the
I-10 corridor. Storms are expected to initiate both along/ahead of
the front and within the instability axis Thursday afternoon and
last through the cold front passage, not expected until at least
the early hours of Friday morning. The anomalously high moisture
will support efficient downpours with these storms, with rainfall
rates of 2"+ per hour possible. The latest deterministic hi-res
guidance shows the potential for locally heavy totals as much as
6-7", and HREF/RRFS guidance both show high probabilities (70-90%)
of totals exceeding 3" and at least moderate (40-60%) probabilities
of totals exceeding 5". One caveat to the overall threat will be
the speed of the cold front. If the front happens to be faster than
currently progged, this would limit the duration of the heavy
rainfall and thus flash flood threat. However, felt there was
enough consistency in the forecast and confidence from the latest
12Z guidance for the upgrade.
The Slight Risk northeastward through Texas to south-central
Oklahoma was also adjusted a bit to the southeast based on the 12Z
hi-res guidance. Otherwise, minimal other changes were needed to
the inherited outlook other than trimming some of the northern
extent of the Marginal Risk through the Midwest based on the latest
forecast frontal position through the day 2 period.
Putnam
...Previous Discussion...
Complex upper level evolution across the northern half of the CONUS
will lead to our first strong cold front of the season being
propelled rapidly to the south Thursday evening as diurnal mixing
ceases near sunset and the front faces little resistance on its
push southward. The upper level setup over the Southeast CONUS will
still be in position to provide a continued draw of rich theta_E
air out of the Gulf into the Southern Plains ahead of the front
meaning the convergence signature and prospects for heavy rainfall
will continue for those along and ahead of the front.
The greatest potential for heavy rain will exist over the Southern
High Plains into southwestern TX as they will be the last places to
see the frontal passage at any point in the forecast period with
areas of the Big Bend and Lower Trans Pecos likely to not see the
front until perhaps after the D2 time frame. General instability
maximum and PWAT anomalies up near +3 standard deviations correlate
to heavy thunderstorm prospects over the Southern High Plains with
a corridor of significant rainfall potential from the Western
Rolling Hills of TX, through the Permian Basin and Concho Valley,
down into the Big Bend area and over into the terrain of southwest
TX. Some added isentropic ascent will lead to prolonged periods of
heavy rain, even after the front passes until a more robust dry air
advection regime takes shape beyond the current D3.
Ensembles continue to trend towards an area of appreciable rainfall,
especially south of the Pecos River in west TX where the greatest
instability axis is located, along with substantially high PWATs
running between 1.5-2", a signal that would easily encroach on the
95-99th percentile according to the latest NAEFS and ECENS
climatological percentiles. Forecast total remain prolific for this
area of the CONUS with guidance inferring on a broad area of at
least 2-4", locally higher, across portions of west TX with the max
focused over the Stockton Plateau towards the RGV within the Big
Bend. This setup resembles some of the more prominent heavy rain
depictions for west TX as the combination of pre-frontal convection
and then prolonged isentropically forced precipitation will
account for a cumulative effect, leading to such a robust QPF
depiction.
This is trending towards a formidable setup for this area of the
CONUS with a high- end SLGT remaining the forecast over the above
areas. There is a potential for an upgrade in the risk further as
the the progged cold front will play a significant role in the
potential, thus will need to evaluate any timing differences in the
latitudinal push of the front itself. For now, a pretty high
likelihood of at least scattered flash flood prospects within the
Stockton Plateau to Big Bend area with outside chances for more
appreciable flash flooding in the areas of both Midland/Odessa over
into San Angelo. The previous SLGT was adjusted a bit further
north to encompass southern OK to account for lingering flash flood
chances beyond the main impacts from the now D1.
Kleebauer
Day 2 threat area:
www.wpc.ncep.noaa.gov/qpf/98epoints.txt
