Flash Flood Warning issued December 24 at 10:12AM PST until December 24 at 12:45PM PST by NWS San Diego CA

At 1012 AM PST, While a brief lull in rainfall rates has occurred in
the last hour or so, between 4 and 6 inches of rain have fallen and
we have received numerous reports of flash flooding and mud/debris
over roadways, including I-15 through the Cajon Pass. The current
lull in heavy rainfall will be short lived as the main band of heavy
rainfall will move into the area over the next 1 to 2 hours.
Additional rainfall amounts of 2 to 5 inches are possible in the
warned area. Flash flooding is ongoing or expected to begin shortly.

HAZARD…Life threatening flash flooding. Heavy rain producing
flash flooding.

SOURCE…Radar.

IMPACT…Life threatening flash flooding of creeks and streams,
urban areas, highways, streets and underpasses.

Some locations that will experience flash flooding include…
San Bernardino, Fontana, Rialto, Hesperia, I-15 Through The Cajon
Pass, northern Rancho Cucamonga, Devore, Silverwood Lake Rec Area,
Hwy 18 Between San Bernardino And Crestline and Muscoy.
Turn around, don’t drown when encountering flooded roads. Most flood
deaths occur in vehicles.