Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1159 AM EDT Sun Oct 25 2026
Day 1
Valid 16Z 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...
...16Z update...
No changes were made with this update and reasoning with previous
discussion looks good. The 12Z HREF members and 12Z RRFS showed
local maxima of 2 to 4+ inches over southeastern Florid and in the
vicinity of the northern TX Panhandle.
...Central and Southern High Plains...
15Z visible satellite imagery showed fairly widespread cloud cover
across the eastern half of NM which will be a short term
hindrance to the development of instability. However, some
forecast thinning of those clouds and daytime heating should allow
for the development of 500-1500 J/kg MLCAPE over central to eastern
NM with locally higher values over south-central NM into far
western TX into the afternoon. The greatest coverage and
probabilities for heavy rain exist across the TX Panhandle where
instability is expected to keep rain rates a bit lower compared to
farther south into southeastern NM and far western TX. However, the
coverage of cells will likely be more scattered to the south
compared to the better synoptic forcing farther north.
...East Coast of Florida...
Both the 12Z HREF and 12Z REFS showed probabilities for mainly 1
to 2 in/hr rates across the eastern FL Peninsula for much of the
period, but these probabilities lower and translate toward the
south with time tonight between 06-12Z. Previous forecast remains
reasonable with no changes made.
Otto
...previous discussion follows...
...Central and Southern High Plains...
An upper level low will track across the Four Corners region and
central Rockies today, while shortwave energy moves north across
the southern and central High Plains ahead of the low. This setup
will bring anomalously moist air into the south-Central U.S.,
tapping into Pacific and Gulf moisture that will fuel scattered to
widespread convection on the leading edge of the system. PWAT
values are expected to rise to 1-1.5 inches (2-4 standard
deviations above normal) from West Texas through the central High
Plains. The highest instability (MUCAPE 1000-1500 J/kg) is expected
to focus across portions of West Texas and New Mexico, which will
likely support intense rainfall rates up to 1-1.5 inches per hour.
Instability will be more limited over the central High Plains, but
modest instability (MUCAPE around 500 J/kg) combined with upper
level shortwave support should allow for some deeper convection
with locally heavy rainfall. Scattered instances of flash flooding
will be possible from West Texas through portions of the southern
and central High Plains, which is highlighted with a Slight Risk of
excessive rainfall for today. Soils are already saturated from
recent heavy rainfall over portions of West Texas and eastern New
Mexico, and increased runoff may heighten flash flooding concerns.
Areas near steep terrain and burn scars will also be vulnerable to
flash flooding.
A broader Marginal Risk area extends further north into the
central Plains where soils are less susceptible to flash flooding
but locally heavy rainfall may result in isolated instances of
flash flooding. Moisture will spread even further north ahead of
the system into the northern Plains, but with little instability to
work with, it will be difficult to get rainfall rates heavy enough
to pose a risk of flash flooding.
...East Coast of Florida...
A mid-level low will gradually move south over the Atlantic
parallel to the Florida Peninsula, then stall offshore of
Southeast Florida by this afternoon. This will result in a
prolonged period of northeasterly onshore flow along the East Coast
of Florida, with an emphasis over Southeast Florida. Moisture
wrapping around the northern side of the low circulation will bring
PWATs across the Peninsula up to 1.5-1.75 inches and up to 1.75-2
inches across Southeast Florida, which will support scattered to
widespread showers and storms that will form over the Atlantic and
migrate over the coast. Coastal convergence will focus the highest
precipitation totals right along the coast, which will create a
risk of isolated instances of flash flooding along the I-95
corridor south of Jacksonville. As the system stalls, precipitation
will target Southeast Florida, which is where the highest rainfall
totals are expected today. Hi-res models show rainfall totals
reaching 1-2 inches across Southeast Florida with locally higher
amounts possible. Given the sensitivity of urban areas of Southeast
Florida, scattered instances of flash flooding will be possible
and there is a Slight Risk of excessive rainfall for much of this
area.
...Pacific Northwest...
A closed upper low will gradually move onshore in the Pacific
Northwest today, accompanied by steady rainfall along a leading
cold front and scattered to numerous post-frontal showers across
western Washington and Oregon. Locally heavy rainfall may be
possible, but given the dry antecedent conditions there is not
expected to be a flood threat with this system.
Dolan
Day 1 threat area:
www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1159 AM EDT Sun Oct 25 2026
Day 2
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 low will push past the Rockies into the Plains,
resulting in surface cyclogenesis over the central/northern Plains.
Scattered showers and storms are expected in the warm sector of
the system over the central and southern High Plains. Similar to
Sunday, anomalous moisture streaming ahead of the system will
spread along the trailing cold front up into the northern Plains,
but the best instability will be limited to the central and
southern High Plains, which is where the highest flash flood risk
is expected. Precipitation totals are forecast to be modest
compared to previous days, but there will likely be a period of
enhanced convection Monday afternoon into Monday evening as an
upper level shortwave moves north into the region. During this
period, the ingredients will be in place to support a threat of at
least isolated instances of flash flooding within the Marginal Risk
area.
Widespread precipitation is also expected over the northern Plains
in the vicinity of the surface low, 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...
Northeasterly onshore flow with high PWATs up to 2 inches will
continue across Southeast Florida as the mid-level low remains
stalled near the Bahamas. Eventually, the low will be absorbed by
another wave moving north over Cuba, then move northeast into the
Atlantic later this week. Meanwhile, the system will become weaker
and less organized and precipitation coverage and intensity should
decrease. Even so, scattered showers will move onshore in Southeast
Florida throughout the day on Monday, and locally heavy rainfall
will be possible. Given heavy rainfall expected on Sunday, a
Marginal Risk area was continued for Southeast Florida where there
could be isolated instances of flash flooding, especially in urban
areas.
Dolan
Day 2 threat area:
www.wpc.ncep.noaa.gov/qpf/98epoints.txt
