Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
237 AM EST Thu Nov 21 2024
Day 2
Valid 12Z Sat Nov 23 2024 - 12Z Sun Nov 24 2024

...THERE IS A MODERATE RISK FOR EXCESSIVE RAINFALL ACROSS PORTIONS
OF NORTHERN CALIFORNIA...

The long duration atmospheric river begins to become more
progressive and wane in intensity Friday as a cold front finally
pushes the moisture axis southward. However still expecting rather
widespread 0.25" per hour rates with this last push of rainfall,
with localized 0.5" per hour amounts likely. These higher rates
should only last for a couple hours during the morning over coastal
areas, but should persist a bit longer in the Sierra Nevada.
Overall expecting 1-3" of additional rain over coastal areas, with
3-6" over the northern Sierra Nevada. Warmer temperatures will keep
snow levels pretty high such that even into the terrain areas,
most of the precipitation is expected to fall as rain (aside from
the highest peaks).

By Friday conditions over much of the area will be saturated, and
this last push of elevated rainfall rates on top of saturated ground
will likely result in a continued flood threat...with additional
landslides likely and a continued risk of burn scar flash flooding.
Only minor changes were made to the inherited ERO areas. A MDT risk
remains for the northern Sierra Nevada where the heavier rainfall
will persist longer into Friday resulting in the aforementioned
higher additional rainfall totals. A flooding risk is likely to be
ongoing over coastal areas as well Friday morning, but should be a
shorter lived threat with the higher rainfall rates coming to an end
quicker...thus will continue to carry a Slight risk here.

Chenard

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