Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
358 PM 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...

...21Z update...

...Central and Southern High Plains...

The 12Z models showed good agreement on the movement of the upper
low to track northeastward from the central High Plains on
Monday, and an upper trough axis forecast to advance through AZ/NM.
The upper trough will be associated with a a 70-90 kt upper level
jet streak which will bring favorable diffluence and divergence
aloft over the southern High Plains between 18-00Z, coinciding with
peak daytime heating and 1 to 3 standardized anomalies of
precipitable water. Brief training/repeating of thunderstorms will
be possible among MLCAPE values of roughly 500-1500 J/kg,
supporting hourly rainfall of 1-2 inches.

...Southeast Florida...

The Marginal Risk was maintained for southeastern FL given the
continued potential for isolated excessive rainfall. While the
model signal for high QPF has fluctuated over the past 24 hours and
the latest models do not indicate very high rainfall totals (40 km
neighborhood probabilities from the 12Z HREF/REFS are ~30 percent
or less for 2+ inches/24 hr), limited potential remains for mainly
urban flash flood impacts across the urban southeastern corridor.

Otto

...previous discussion follows...

...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