textproduct: San Diego

SYNOPSIS

The next round of rain, snow, and gusty winds is moving in from the northwest this afternoon, with the cold front and band of precipitation moving from northwest to southeast through this evening. There is a slight chance of thunderstorms with this band. Showers and winds will diminish overnight. Patchy frost and fog likely in the Inland Empire late tonight or early Friday morning. Fair, dry and warmer weather is expected over the weekend, and will likely persist through much of next week.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

At this time...The frontal boundary and associated band of organized showers are moving into Orange, Riverside and San Bernardino Counties from the northwest. The showers are weakening as they move southeast but additional bands of showers are following the main frontal band. Chances for a tstm or two can't be eliminated but the probability of occurrence is quite low. The main band of showers should move off to the southeast of San Diego County by about 10 pm and the last post-frontal band should have moved off to the southeast by about 2 am Friday. A few showers could linger through about 8 am Friday. Additional precipitation amounts will range from about 0.2 inch to about 0.5 inch in the coastal areas and valleys, 1 to 1.5 inch in the mountains, and from a trace to 0.15 inch in the deserts. Periods of moderate to heavy rainfall could produce minor localized flooding.

In the San Bernardino and Riverside County mtns, snow could accumulate as low as 4500 ft and totals could reach 1-8 inches from 5000 up to 7000 ft. The highest peaks could get 8-12 inches. In the San Diego County mtns, snow amounts could range from a dusting at about 4500 ft to as much as 3 inches at the peaks. A combination of wind and snow will make driving unsafe, and unnecessary travel should be avoided.

Winds will strengthen from the southwest as the front approaches and maintain strength as the winds become west and northwest after frontal passage. Wind gusts of 35-45 mph are expected in the coastal areas and gusts of 45-65 mph are expected in the mountains and deserts. Winds will gradually weaken late tonight into Friday morning.

High temps today are unlikely to exceed 60 degrees, even in the inland valleys. As skies begin to clear late tonight, cold air pooling could produce some frost in portions of the inland valleys and coastal areas early Friday morning.

Fair and dry, but cool weather starts Friday, with some variable high clouds. Weak offshore flow over the weekend will boost the drying and warming trend as high pressure aloft amplifies a little. Temperatures in the 60s Saturday will be followed by lots of 70s Sunday at lower elevations. A weak and stationary ridge appears to be taking shape over California next week. Current guidance shows that high pressure aloft is likely to control our weather through the middle of next week. This could allow a return of marine layer coastal low clouds during the nights and mornings. Monday and Tuesday will likely be the warmest days, with temps in the upper 70s at low elevations west of the mtns and in the low to mid 80s in the lower deserts. Some ensemble members are indicating chances for precipitation next Wednesday but

AVIATION

191730Z...SCT-BKN low clouds from 2,000-7,000 ft MSL ahead of the approaching cold front from the coast to the mtns, bringing a band of RA/+RA. The main precip band will move from the northwest to the southeast through the coastal basin beginning around 18Z today to 05Z Fri. Southwest winds will increase ahead of the band, gusting 25- 35 kts through the coastal basin, 35-45 kts widespread for the mtns and deserts, and 50-65 kts along desert slopes. A few hours of MVFR cigs/vis are expected for the coasts/valleys as the band of rain moves over the area. Mtns will be shrouded in snow (mainly above 5 kft MSL) with these storms, reducing VIS to 0-2SM at times. SCT SHRA is expected to continue over SD County overnight and dissipate by Friday morning.

General VFR conditions expected behind the main band outside of the mtns. Winds shift to westerly and weaken through the coastal basin this evening, but will remain strong in the mtns and deserts through Friday morning.

MARINE

Strong southwest winds today in front of the cold front will gust up to 30 knots with steep 8-11 foot seas, producing hazardous conditions for small craft. Winds will remain strong and shift to northwesterly in the late afternoon, then weaken overnight into early Friday. Steep seas will subside by late Friday morning.

BEACHES

High surf of 5 to 8 feet is expected with sets as high as 9 feet with the highest surf expected for San Diego County. Surf will diminish by Friday afternoon. Dangerous swimming and surfing conditions and localized beach erosion can be expected until then. A High Surf Advisory is in effect through Friday and contains more details.

SKYWARN

Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions.

SGX WATCHES/WARNINGS/ADVISORIES

CA...High Surf Advisory until 10 PM PST Friday for Orange County Coastal Areas-San Diego County Coastal Areas.

Wind Advisory until 2 AM PST Friday 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.

Winter Storm Warning until 9 AM PST Friday for Riverside County Mountains-San Bernardino County Mountains.

Winter Weather Advisory until 9 AM PST Friday for San Diego County Mountains.

Wind Advisory until 9 AM PST Friday for Apple and Lucerne Valleys-Coachella Valley-San Diego County Deserts-San Gorgonio Pass near Banning.

PZ...Small Craft Advisory until 10 AM PST Friday for Coastal Waters from San Mateo Point to the Mexican Border and out to 10 nm- Waters from San Mateo Point to the Mexican Border Extending 10 to 60 nm out including San Clemente Island.