Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
335 PM EST Fri Nov 13 2026

Day 1
Valid 16Z Fri Nov 13 2026 - 12Z Sat Nov 14 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF NORTHERN/CENTRAL CALIFORNIA...

A progressive cold front moving through northern and central
California this morning/afternoon will likely generate scattered
to organized thunderstorms. Heavy rainfall leading to isolated
instances of flash flooding is possible, especially for urban
areas like San Francisco and Sacramento. Precipitable water values around
1" and most unstable cape values peaking around 500J/Kg by late
this afternoon/early evening may produce 0.25-0.5" rain rates. Hires
guidance have anywhere between 1-3" of 24 hour QPF ending at 12z on
Saturday morning. The marginal risk area (at least 5% chance) is
consistent with Colorado State University's Machine Learning
Product first guess field, which highlights much of
northern/central California with 5-15% probabilities of excessive
rainfall ending at 12z tomorrow morning.

Kebede


Day 2
Valid 12Z Sat Nov 14 2026 - 12Z Sun Nov 15 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS NORTHWEST
WASHINGTON STATE IN THE AREA OF THE OLYMPIC PENINSULA AS WELL AS
NORTH-CENTRAL TEXAS...

...2030z update...

North-Central Texas

Global and CAM models have begun to resolve upper-level trough
phasing spread and converge on a location for heavy convective
rainfall on Saturday. A mid-level trough responsible for the day 1
marginal will cut across the Rockies while phasing with a southern
stream disturbance tonight. Surface cyclogenesis is likely to
occur tomorrow night followed by convective initiation. Storms will
propagate from eastern portions of the Texas panhandle through
northern-central parts of the state Saturday night.

Instability of about 100-400 J/Kg MU/ML CAPE paired with 1-1.25"
precipitable water values through central Texas could yield
efficient rain rates. Relative soil moisture is fairly dry so some
of this rain may be more beneficial. RRFS 40km neighborhood
probability of 24 hr QPF exceeding 1-3" is over 5%, which is
consistent with WPC's marginal risk (at least 5% chance) area.

Kebede

...Previous Discussion...

00Z guidance continues to show the arrival of another round of
moderate to heavy rainfall across portions of northwest Washington
and the Olympic peninsula on Saturday. The two-day rainfall total
may be enough to result in isolated flash- and areal-flooding.
Rainfall forecasts of an additional 1 inch to 3 inches, with
locally higher amounts, are expected through Saturday night or
early Sunday morning. Much of the rainfall is expected to occur in
a 12-hr window before the passage of a cold front late in the
forecast period. This could send some of the river banks
overflowing and cause some local flood concerns, some of which
could be flashy. Still felt there was no fundamental changes needed
with the latest forecast.

Bann


Day 3
Valid 12Z Sun Nov 15 2026 - 12Z Mon Nov 16 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF COASTAL TEXAS/LOUISIANA SUNDAY...

Storms from Saturday are expected to continue their southeastward
track through eastern/coastal Texas on Sunday. The inherited
marginal risk (at least 5% chance) of excessive rainfall area
pulled back closer to the Texas/Louisiana coast for Sunday based on
the latest global guidance trends. The greatest exceedance
probabilities continue to be along the coast with maximum QPF
values staying just offshore.

Kebede

...Previous Discussion...

Only minor adjustments to the Marginal Risk over eastern Texas and
western Louisiana were made this outlook cycle given continued
model signals for potentially excessive rainfall near the Gulf
coast. There was little resolution to the question whether the
heaviest rainfall stays off-shore or if makes its way inland. Consensus
of the preferred guidance still indicates the heaviest amounts are
likely to center near the upper Texas/southwestern Louisiana
coasts, Some models are showing amounts that would warrant an
upgrade along the coast as northern stream energy overtakes a
leading southern stream wave. That would provide providing the
necessary lift to support scattered convection. However, with
limited instability would likely temper rates to the north. However,
due to uncertainty regarding whether the heaviest rainfall will
develop offshore, held off from upgrading to a Slight Risk once
again.

Bann


Day 4 and Day 5

Valid 12Z Mon Nov 16 2026 - 12Z Wed Nov 18 2026

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

An upper-trough and accompanying cold front will progress eastward
from the West Coast into the Interior West Monday-Tuesday.
Increasing moisture along and with the frontal passage will lead to
scattered showers and thunderstorms across the Desert Southwest.
However, limited instability and modest moisture should keep rates
low and the progressive nature of the system passage should limit
rain totals overall.

Roth/Putnam


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