Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
429 PM EDT Thu Oct 22 2026
Day 2
Valid 12Z Fri Oct 23 2026 - 12Z Sat Oct 24 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR THE SACRAMENTO
MOUNTAINS SOUTH THROUGH THE EL PASO METRO...

...21Z update...

...NM and southern CO...

Model agreement remains good concerning the track and timing of a
mid to upper-level trough axis moving east across the Southwest
through Saturday morning. As the main energy over Arizona/Utah from
Thursday night lifts northeastward, the trough is reinforced on
Friday over California/Nevada/Arizona, resulting in the formation
of a new closed low. The net result downstream is only a minor
eastward push of heights into New Mexico and Colorado which will be
a hindrance for forcing. However, precipitable water values are
forecast to remain anomalous (2 to 4+ standardized anomalies from
the 12Z GFS) from far western Texas into central/eastern New Mexico
and southeastern Colorado including a middle and upper level
connection to moisture related to remnant tropical systems west of
the central Mexican coast.

The mean steering flow will be from the SSW, ranging from 20 to 40
kt and 850-700 mb winds remain fairly strong at 15 to 30+ kt.
Therefore, while individual cells should remain progressive, there
will be high potential for repeating and training of heavy rain.
The 12Z HREF/REFS showed that the probabilities for 0.5 to 1.0+
in/hr rainfall ramp up in the 18-21Z time frame and diminish after
06Z Saturday. Total rainfall of 1 to 2 inches is likely across
portions of central/eastern New Mexico into southern Colorado for
the 24 hour period with localized totals between 2 to 3 inches.

Thinking from the previous shift remains valid (see below),
including the higher potential for higher rates/instability across
far western Texas into southern New Mexico despite the QPF signal
in the models lowering the existing Slight Risk area.

...East Coast of Florida...

A Marginal Risk remains in place across southeastern Florida but
was expanded northward to include Cape Canaveral where similar
potential for slow moving cells will exist. Some of the 12Z model
guidance showed the potential for higher instability farther north
with 500 to 1000 J/kg in place at times throughout the 24 hour
period near the Cape Canaveral region. While precipitable water
values are lower into the Space Coast (at or less than 1 inch),
there are some modest probabilities for 3, 5 and 8 inches over the
24 hour period ending Saturday morning near or just offshore of the
coast according to the 12Z HREF/REFS.

Otto

...previous discussion follows...

...NM and southern CO...
Scattered convection is expected to develop across portions of NM
into southern CO downstream of a mid to upper level trough
tracking eastward from CA into AZ. In the broader evolution of the
system, day 2 (Friday) appears to represent a relative minimum in
convective coverage and overall intensity compared to more active
periods expected on both Thursday and Saturday. Nonetheless, PWs
will remain anomalous and collocated with 500-1500 J/kg of CAPE.
This environment will support scattered convection capable of
locally high rainfall rates and an isolated flash flood threat.
While the latest QPF guidance remains modest and generally
supportive of a Marginal risk, the presence of better instability
over southern NM could yield an uptick in convective rainfall as we
get more into the high res model timeframe. Considering the
hydrologic vulnerability, the inherited Slight risk was maintained
across the terrain and burn scars of the Sacramento Mountains into
adjacent urban corridors.

...Southeast FL...
A setup similar to day 1 will persist across southeast FL, where
low level northeasterly flow and coastal convergence could focus
slow moving cells along the immediate coast. The heavy rainfall
threat remains conditional, with a possibility the heaviest cores
remain just offshore. Model differences also introduce some
uncertainty regarding the moisture profile, with the GFS showing
notably higher PW values than the ECMWF. Given the lingering
uncertainty with these details the inherited Marginal risk was left
unchanged.

Chenard


Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt