Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
752 PM EST Tue Feb 10 2026

Day 1
Valid 01Z Wed Feb 11 2026 - 12Z Wed Feb 11 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR THE
TRANSVERSE RANGES OF SOUTHERN CALIFORNIA...

0100 UTC Update: Only minor modifications made to the Marginal Risk
area along the Transverse Ranges, most notably to include more of
the San Gabriels (eastern portions) based on the latest HRRR trends
along with the 18Z HREF and RRFS probabilities of 0.50-1.00"/hr
rainfall rates. The good new from a flash flooding perspective
is the main S-N oriented pre-frontal band, currently moving across
Point Conception (between 00-01Z), will continue on a steady
easterly progress across the Transverse Ranges as per the back
edge of the Warm Conveyor Belt or "limiting streamline" Still, we
did want to include the Bridge and Vista burn scars (2024).

Hurley

Previous discussion below...

A mid-level shortwave trough axis will approach the central and
southern coast of California tonight, bringing an atmospheric
river to the region with origins back to the Hawaiian Islands.
Blended TPW imagery showed precipitable water values this morning
up to 0.9 inches within the nose of the atmospheric river near 33N
125W. Recent RAP forecasts show IVT values peaking in the 500-600
kg/m/s range across Santa Barbara County around 03Z and steadily
advancing east while weakening to about 400 kg/m/s through 12Z.
850 mb winds are forecast to peak in the 40-50 kt range early
tonight across the western Transverse Ranges, oriented largely
perpendicular to the axis of terrain, maximizing upslope lift. 850
mb winds look to weaken through 12Z into the 25-35 kt range through
12Z with limited (< 250 J/kg) instability along coastal areas.

A band of heavy rain is likely to move through southern California
tonight in association with an approaching Pacific cold front. The
00Z and 12Z CAMs show hourly rainfall potential across the
Transverse Ranges in the 0.5 to ~1.0 inch range between roughly 03Z
to 12Z Wednesday with rainfall totals of 1 to 2 inches, isolated
near 3 inches possible. The potential for runoff and isolated flash
flooding appears fairly low but the potential for the overlap of
higher rainfall intensities with sensitive burn scars is enough to
support a Marginal Risk for the Day 1 period, in coordination with
WFO LOX. Beyond 12Z Wednesday, rainfall rates weaken further as IVT
values lower into the Peninsular Ranges with little to no flash
flood threat anticipated for the early Wednesday morning period.

Otto/Bann


Day 2
Valid 12Z Wed Feb 11 2026 - 12Z Thu Feb 12 2026

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

Pereira


Day 3
Valid 12Z Thu Feb 12 2026 - 12Z Fri Feb 13 2026

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

Pereira


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