Area Forecast Discussion
Issued by NWS San Diego, CA
FXUS66 KSGX 272148
Area Forecast Discussion
National Weather Service San Diego CA
148 PM PST Mon Feb 27 2017
Moderate to locally heavy rain will continue across extreme
southwestern California into the evening as a low pressure trough
pulls a deep moist layer inland. The heaviest rainfall potential
exists for San Diego County. Some snow will fall on the higher
mountain peaks to the north as well. Strong westerly winds will
accompany the rain and snow in the higher mountains. Slightly warmer
for Tuesday. Then dry with a warming trend for Wednesday through
Friday with periods of weak offshore flow. A little cooler next
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
...Moderate to heavy rainfall continuing over portions of San Diego
County and far northern Baja CA into the evening...
A flash Flood Watch is in effect through this evening for San Diego
County. Satellite imagery at Noon PST showed good enhancement
continuing over SW Ca and offshore moving NE. NWS radar also showed
cells of moderate intensity continuing well offshore moving east.
Rainfall rates in some of these cells exceed 0.4 inch per hour.
Hires and even the 12Z global models show an additional potential
for one to three more inches before it winds down late evening and
overnight. Given the saturated ground across the county, areas of
minor to moderate flooding will likley be widespread with continued
At 1 PM PST...A flood Advisory was in effect for much of San Diego
County. Flooding is forecast for the San Diego River this evening
and large flows are likely in other rivers and streams across the
County as well. Of particular concern is the Tijuana River Valley
where low-lying areas will likley have flooding.
The large upper-level trough responsible for drawing in the Pacific
moisture today will move east of the area tonight. Atmospheric
heights/thickness will gradually rise as low level winds turn
offshore. It will be fair and slightly warmer on Tuesday, then much
warmer and drier Wednesday through Friday with clear, cool nights.
Another trough will develop over the PacNW next weekend and suppress
heights across SoCal while allowing sfc wind to turn back onshore.
This will push RH higher as marine air returns, along with perhaps
some low clouds and fog to coastal areas by Sunday morning.
272139Z...Coastal and Valley areas: BKN-OVC005-010 through
04Z Tuesday with vis 1-3 miles in rain and fog. After 04Z...BKN-
OVC015-025 with scattered showers ending through 12Z. After
12Z...clearing skies and light winds.
Strong south winds 15-30 kt at KSAN through 01Z.
Mountains: Obscured in clouds/fog/pcpn through 14Z. Strong winds in
the mountains and desert slopes with strong up/down drafts and llws
over and east of the mountains. After 14Z Tuesday...clearing with
Lower Deserts: BKN-OVC020-040 with rain through 06Z. Vis lowering to
2-4 miles in heavier showers and fog. After 06Z...-SHRA with BKN-
OVC030-050 through 14Z.
Strong south to southwest winds 15-30 kt through late afternoon.
Winds shifting northwest this evening and continuing into Tuesday
morning, strongest over the Outer Waters. A Small Craft
Advisory remains in effect through 9 AM Tuesday.
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.
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 until 9 AM PST Tuesday for
Waters from San Mateo point to the Mexican Border
Extending 30 to 60 nm out including San Clemente Island.
Small Craft Advisory until 9 AM PST Tuesday for Coastal Waters
from San Mateo Point to the Mexican Border and out to 30 nm.