507
FGUS76 KSGX 042243
ESFSGX

Hydrologic Forecast for Extreme Southwestern California
National Weather Service San Diego CA
343 PM PDT Thu Sep 4 2025

...Flash Flood Potential Index for Extreme Southwestern California...

.SYNOPSIS...
Thunderstorm coverage over the San Diego and Riverside county
mountains this afternoon will diminish by sunset. Thunderstorms
are expected again for the mountains, locally into the deserts,
Friday afternoon. The greatest coverage is expected on the San
Diego and Riverside county mountains. HREF 90th percentile hourly
rainfall has peak hourly rainfall around 0.80 inches for Friday
afternoon. Isolated flash flooding is possible, mainly for the
mountains.

$$

CAZ056-058-051315-
Riverside County Mountains-San Diego County Mountains-
Including the cities of Idyllwild-Pine Cove, Julian,
and Pine Valley
343 PM PDT Thu Sep 4 2025

.TONIGHT...Low...the risk of flash flooding is minimal.
.FRIDAY...Moderate...thunderstorms are expected to develop and
isolated flash flooding is possible.
.SATURDAY...Low...the risk of flash flooding is minimal.

$$

CAZ055-060-051315-
San Bernardino County Mountains-Apple and Lucerne Valleys-
Including the cities of Crestline, Lake Arrowhead, Big Bear City,
Big Bear Lake, Running Springs, Wrightwood, Victorville,
Hesperia, Apple Valley, and Lucerne Valley
343 PM PDT Thu Sep 4 2025

.TONIGHT...Low...the risk of flash flooding is minimal.
.FRIDAY...Low...the risk of flash flooding is minimal.
.SATURDAY...Low...the risk of flash flooding is minimal.

$$

CAZ061-062-065-051315-
Coachella Valley-San Diego County Deserts-
San Gorgonio Pass near Banning-
Including the cities of Indio, Palm Springs, Cathedral City,
Palm Desert, Palm Desert Country, La Quinta, Coachella,
and Borrego Springs
343 PM PDT Thu Sep 4 2025

.TONIGHT...Low...the risk of flash flooding is minimal.
.FRIDAY...Low...the risk of flash flooding is minimal.
.SATURDAY...Low...the risk of flash flooding is minimal.

$$

CAZ048-051315-
San Bernardino and Riverside County Valleys-The Inland Empire-
Including the cities of Riverside, San Bernardino, Ontario,
Moreno Valley, Fontana, Rancho Cucamonga, and Corona
343 PM PDT Thu Sep 4 2025

.TONIGHT...None...no flash flooding is expected.
.FRIDAY...Low...the risk of flash flooding is minimal.
.SATURDAY...None...no flash flooding is expected.

$$

CAZ050-051315-
San Diego County Valleys-
Including the cities of Escondido, El Cajon, San Marcos, La Mesa,
Santee, and Poway
343 PM PDT Thu Sep 4 2025

.TONIGHT...None...no flash flooding is expected.
.FRIDAY...None...no flash flooding is expected.
.SATURDAY...None...no flash flooding is expected.

$$

CAZ043-057-552-554-051315-
San Diego County Coastal Areas-Santa Ana Mountains and Foothills-
Orange County Coastal Areas-Orange County Inland Areas-
Including the cities of Oceanside, Vista, Carlsbad, Encinitas,
Chula Vista, National City, San Diego, Huntington Beach,
Costa Mesa, Newport Beach, Laguna Beach, San Clemente, Santa Ana,
Anaheim, Garden Grove, Irvine, Orange, Fullerton,
and Mission Viejo
343 PM PDT Thu Sep 4 2025

.TONIGHT...None...no flash flooding is expected.
.FRIDAY...None...no flash flooding is expected.
.SATURDAY...None...no flash flooding is expected.

$$