Area Forecast Discussion
Issued by NWS San Diego, CA

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260
FXUS66 KSGX 230533
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
933 PM PST Sun Jan 22 2017

.SYNOPSIS...
The third and most powerful in the sequence of storms will
continued impact Southern California with periods of heavy rain
showers,possible thunderstorms, mountain snow, and gusty winds
through Monday, diminishing on Tuesday. A building high pressure
ridge will bring dry and warmer weather Wednesday through next
weekend with gusty offshore winds Friday through next Sunday.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

Widespread moderate to heavy rain fell across the CWA this evening
with numerous reports of flash flooding and wind damage from falling
trees. The rainfall over the past 24 hours ending at 7 PM PST ranged
from less than one-quarter inch in southern San Diego County, to
over four inches in parts of Orange County and on the coastal slopes
of the mountains. See RRMSGX or our website for the latest rainfall
totals. Snowfall has not been as impressive yet as snow levels rose
above 6500 FT. The snow levels will begin to fall later tonight, and
scattered showers will continue.

Southerly wind gusts were impressive as well. Numerous reports
exceeded 40 MPH west of the mts. Please see LAXPNSSGX for details.
Expect more heavy showers at times through Mon night with isolated
thunderstorms possible. Showers will taper off but may continue
across San Diego County on Tuesday.

Look for drying on Wed/Thu, but continued cool as a strong high
builds over the Great Basin forcing gusty offshore winds across
SoCal. Warmer by the weekend into early next week with temps back
above average under fair skies.

&&

.AVIATION...
230330Z...West of the mtns...BKN-OVC clouds layered from 1000-12000
ft msl will continue through tonight, with vis mostly unrestricted
except where clouds and terrain intersect. During periods of
rainfall, CIGS could lower to 1000 ft msl or less with vis 1-3SM
even at lower elevations.

In the deserts...clouds layered 5000-15000 ft msl will prevail
through tonight, with periods of BKN cigs around 2000 ft msl and vis
about 2SM during rain showers. Expect higher terrain obscurations at
times.

South to southwest winds 15-20 kt gusting to 30 kt will continue
through Monday. This will produce stg-svr up/downdrafts and LLWS
over and N, NE, and E of the mountains.

&&

.MARINE...
Currently, the San Clemente basin buoy shows combined seas about 13
ft with south winds gusting to 28 kts. Winds become southwesterly
this evening, then westerly late tonight into Monday, but wind
speeds will still be strong and possibly at gale-force strength at
times with rough, large seas continuing. A Gale Warning continues
through Monday night. Winds will diminish on Tuesday with seas very
gradually decreasing on Tuesday as well. By early Wednesday, sea
conditions should no longer be hazardous to small craft.

The storm will also bring heavy rain squalls at times through Monday
afternoon, with a slight chance of thunderstorms Monday morning
through late Monday night. Waterspouts will be possible as well. A
Marine Weather Statement has been issued.

&&

.BEACHES...
Surf of 8-12 ft in San Diego and 6-10 ft in Orange County will
likely continue overnight. Surf this large could damage structures
and produce beach erosion. Early morning high tides will only be
around 5 ft, so anything more serious than minor coastal flooding is
not expected from the large surf.

Swells and surf will likely diminish a little Monday, but high surf
conditions and strong rip currents will persist into Tuesday. It is
not until Wednesday that surf and swell conditions will lower below
high surf thresholds.

In addition, there will be a slight chance of thunderstorms Monday
afternoon and evening at the beaches.

More high surf is expected next Friday as a northwest swell of 9 ft
at 19 seconds moves into the coastal waters and surf zone.


&&

.HYDROLOGY...
The Rainfall this evening tapered off rapidly as it moved south
across San Diego County. This will likley keep the San Diego River
from reaching Flood Stage. So the Flood Warning for the San Diego
River has been cancelled. The San Diego River will still rise
overnight, and depending on the rainfall over the next 24 to 36
hours, could still reach Flood Stage at some point.

Heavy rain did fall on northern San Diego County however, and that
will cause problems for the Santa Margarita River on Camp Pendleton.
The  has forecast Flood Stage there, and a peak flow of 16,900
Crs by 2 AM PST. A Flood Warning has been issued there.

Water is flowing through the San Luis Rey channel and low water
crossings are being impacted upstream. Flood stage is not expected
at Oceanside.

More heavy convective rainfall is likely on Mon/Mon night...but it
will be associated with scattered showers and isolated
thunderstorms, so predicting time and amounts will be more of a
challenge.

Snow levels have risen this evening but will fall back to 4500 feet
by Monday morning. Heavier snow accumulations are likley on Monday.

&&

.SKYWARN...
Skywarn activation is requested for Monday.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Winter Storm Warning until 6 PM PST Monday for Riverside County
     Mountains-San Bernardino County Mountains-San Diego County
     Mountains.

     Flash Flood Watch through Monday evening for Apple and Lucerne
     Valleys-Coachella Valley-Orange County Coastal Areas-Orange
     County Inland Areas-Riverside County Mountains-San
     Bernardino County Mountains-San Bernardino and Riverside
     County Valleys-The Inland Empire-San Diego County Coastal
     Areas-San Diego County Deserts-San Diego County Mountains-
     San Diego County Valleys-San Gorgonio Pass Near Banning-
     Santa Ana Mountains and Foothills.

     Wind Advisory from 6 AM to 6 PM PST Monday for San Diego County
     Deserts-San Gorgonio Pass Near Banning.

     High Wind Warning until 6 PM PST Monday for Apple and Lucerne
     Valleys.

     High Wind Warning until 6 AM PST Monday for Orange County
     Coastal Areas-Orange County Inland Areas-San Bernardino and
     Riverside County Valleys-The Inland Empire-San Diego County
     Coastal Areas-San Diego County Valleys-Santa Ana Mountains
     and Foothills.

     High Surf Warning until 10 PM PST Tuesday for Orange County
     Coastal Areas-San Diego County Coastal Areas.

     Flood Warning for the Santa Margarita River tonight

     Flood Advisory for the Coachella Canal through Tuesday
     afternoon

PZ...Gale Warning until 4 AM PST Tuesday for Coastal Waters from San
     Mateo Point to the Mexican Border and out to 30 nm-Waters
     from San Mateo point to the Mexican Border Extending 30 to
     60 nm out including San Clemente Island.


&&

$$

PUBLIC/HYDROLOGY...JAD
AVIATION/MARINE/BEACHES...PG



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