Area Forecast Discussion
Issued by NWS San Diego, CA
FXUS66 KSGX 271124
Area Forecast Discussion
National Weather Service San Diego CA
324 AM PST Mon Feb 27 2017
Through tonight...a low pressure system from the northwest will
bring periods of precipitation...with precipitation heavy at times
in San Diego County from late morning through early evening.
There will be strong gusty west winds in the mountains into
Tuesday morning. Slightly warmer for Tuesday. Then dry with a
warming trend for Wednesday through Friday with periods of weak
offshore flow. A little cooler for next weekend.
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
A trough of low pressure moving southward along the California
coast will draw moisture northward into far southern California
from a plume of subtropical moisture directed into northern Baja.
Lighter precipitation early this morning may intensify for late
this morning through early this evening with the most significant
rainfall across northern Baja extending northward into southern
and central San Diego County and possibly into western Riverside
County. Showers will decrease from the northwest late tonight and
end early Tuesday.
Greatest rainfall totals north of the border are expected across
southern and central San Diego County. Through tonight...rainfall
across central and southern San Diego County is expected to range
from around one inch near the coast to 2 to 3 inches in the
mountains with amounts decreasing towards the northwest.
Urban and small stream flooding is expected across portions of the
coastal...valley...and mountains areas below 5000 feet in San
Diego County with isolated flash flooding possible. The rainfall
could cause a rise in the San Diego River sufficient to flood low
water crossings through Fashion Valley for late this evening
through late tonight.
Snow levels near 4000 feet early this morning...will rise to 5000
to 5500 feet for this afternoon...then decrease to 3500 to 4000
feet late tonight. A few inches of snowfall early this morning...
with total snowfall of 3 to 6 inches through late evening...with
isolated snowfall to 8 inches on the highest peaks.
Strengthening onshore flow will bring strong gusty west winds
in the mountains and the northern Coachella Valley into Tuesday
morning. Strongest winds are expected through late tonight with
west winds 25 to 35 mph with gusts to 55 mph...and with isolated
gusts to 65 mph at times in the most wind-prone areas. Strongest
winds are expected near mountain ridge tops onto the desert slopes
of the mountains and in the northern Coachella Valley below the
San Gorgonio Pass. The strongest gusts through 3 AM were 63 mph
at Whitewater in the northern Coachella Valley...and 62 mph at
Volcan Mountain in the San Diego County Mountains.
Continued cool today...then drying and slight warming for Tuesday.
For Wednesday through Friday...high pressure aloft off the
California coast and surface high pressure over the Great Basin
will bring dry weather with a warming trend with periods of weak
offshore flow. A little cooler with weak onshore flow for next
week with a return of coastal low clouds fog possible Saturday
night into Sunday morning.
271000Z...Cigs 800-4000 feet msl vis 3-5sm with occasional rain this
morning mainly San Diego County. Persistent rain heavy at times late
morning through afternoon with obscured terrain mainly south of a
line from KSNA to KRAL through 02-04Z this evening. Strong winds
along ridge tops and desert slopes creating mod-stg up/down drafts
and llws over and east of the mountains. Desert areas to have SCT-
BKN clouds with bases 4000-8000 feet MSL and vis mostly unrestricted.
Strong northwest winds will develop tonight and continue into
Tuesday morning, creating conditions hazardous to small craft.
Following that, no additional hazardous marine weather is expected
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
CA...Winter Weather Advisory from 8 AM this morning to 10 PM PST this
evening for Riverside County Mountains-San Diego County
Wind Advisory until 10 AM PST Tuesday for Riverside County
Mountains-San Bernardino County Mountains-San Diego County
Mountains-San Gorgonio Pass Near Banning.
Flash Flood Watch from 8 AM PST this morning through this
evening for San Diego County Coastal Areas-San Diego County
Mountains-San Diego County Valleys.
PZ...Small Craft Advisory for winds from 9 PM this evening to 9 AM
PST Tuesday for Waters from San Mateo point to the Mexican
Border Extending 30 to 60 nm out including San Clemente