FOUS30 KWBC 260735
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
235 AM EST Tue Nov 26 2024

Day 1
Valid 12Z Tue Nov 26 2024 - 12Z Wed Nov 27 2024

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE SOUTHERN SIERRA NEVADA...

A moderately strong atmospheric river will be ongoing this morning
across coastal areas of central to southern CA, portions of the=20
San Joaquin Valley and into the southern Sierra Nevada. Please
consult MPD #1167 for more details.

The axis of subtropical moisture associated with the southern
stream upper-level jet will continue to impact the orographically=20
favored high terrain at least through midday, with a gradual=20
thinning out and weakening of the larger scale IVT axis=20
thereafter. The 00Z HREF guidance suggests weaker forcing overall,=20
with more modest ascent by later in the day and this will lead to a
dampening of the rainfall rates and coverage of rain with time.=20
Nevertheless, some 0.25" to 0.50"/hour rainfall rates at least=20
through this morning should facilitate additional rainfall amounts=20
as high as 2 to 4 inches across the foothills of the southern=20
Sierra Nevada. Lesser amounts will be noted over the coastal ranges
and into areas of the San Joaquin Valley. Given the wet antecedent
conditions, these additional rains are expected to extend the=20
threat for some areas of flooding, and potentially a localized burn
scar flash flooding impact going through the morning hours.=20
However, conditions should improve during the afternoon as the=20
atmospheric river itself weakens substantially and the rainfall=20
rates diminish. The Slight Risk area is maintained for the=20
foothills of the southern Sierra Nevada with just some modest=20
tweaks made to the Marginal Risk area involving the San Joaquin=20
Valley and the coastal ranges.

Orrison

Day 2
Valid 12Z Wed Nov 27 2024 - 12Z Thu Nov 28 2024

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

Orrison


Day 3
Valid 12Z Thu Nov 28 2024 - 12Z Fri Nov 29 2024

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

Orrison

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/94epoints.txt__;!!DZ3fjg!9Y5CVZ9mEFI8BMgUNw8zXLm-HgMpXhUMxEo9pubpHErV=
tKZX6T_v1DyiD4CU_L410b-CtSSYpwWhXlcCPzN_LrmjnrI$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/98epoints.txt__;!!DZ3fjg!9Y5CVZ9mEFI8BMgUNw8zXLm-HgMpXhUMxEo9pubpHErV=
tKZX6T_v1DyiD4CU_L410b-CtSSYpwWhXlcCPzN_6C5d4oU$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/99epoints.txt__;!!DZ3fjg!9Y5CVZ9mEFI8BMgUNw8zXLm-HgMpXhUMxEo9pubpHErV=
tKZX6T_v1DyiD4CU_L410b-CtSSYpwWhXlcCPzN_p5vX0LM$=20

=3D =3D =3D
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