textproduct: San Diego

SYNOPSIS

The final round of rain, snow, and gusty winds will be Thursday, with the main cold front moving through the area late Thursday morning through the early evening. There is a slight chance of thunderstorms Thursday afternoon and evening. Showers will diminish overnight Thursday with gusty winds diminishing by Friday morning. Frost is possible Friday and Saturday mornings. Dry conditions looking like they will prevail through the weekend. Chances of precipitation increase again mid-next week.

DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE

SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Key Points:

*Gusty and potentially damaging west winds along the mountain crests and adjacent desert slopes Thursday into Friday morning. Gusty westerly winds expected for the coast and valleys during the day Thursday.

*3-8 inches of additional snow expected Thursday into Friday morning. Additional snow plus strong winds may result in blowing snow and limited visibility. Snow levels as low as 3500 to 4000 ft Thursday may result in light accumulations through the Cajon Pass.

*Light to moderate rain is expected Thursday. Ponding of water on roads and minor street flooding in urban areas possible. Thunderstorms may bring locally heavy rain, stronger winds, and small hail.

At 1 PM a few isolated showers were moving across the coastal basin. Any lingering showers this afternoon will produce light rain, with hourly rates less than 0.10" per hour. Winds are still gusting over the mountains and into the deserts. Gusts this afternoon are mainly 35-55 mph. A lull in the winds is expected overnight, but winds are still expected to increase again Thursday peaking in the afternoon and evening, continuing into early Friday morning. For the mountain ridges and desert mountain slopes peak gusts of 60 to 70 mph, potentially up to 75 mph in wind prone locations are expected. Wind gusts in the deserts will be 45 to 65 mph with the strongest winds near the mountain foothills. For the coast and valleys, peak gusts of 30 to 45 mph are expected. Winds for the coast and valleys are expected to peak with the passage of the cold front. The front will start to move through Orange County/San Bernardino County mid- morning, reaching San Diego county by the early afternoon.

Light to moderate precipitation is expected Thursday with the heaviest precipitation expected with the frontal passage or where any thunderstorms develop. For the coast and valleys and additional 0.25 to 0.50" of rain are possible with 0.10" or less in the deserts. Snow levels for through Thursday are expected to be 3500- 5000 ft with an additional 3 to 8 inches of snow expected across area mountains. Current forecast has a 60% chance of accumulating snow on I-15 at the summit of the Cajon Pass.

Dry conditions are expected by Friday, with diminishing winds. Dry conditions will prevail through the weekend. Conditions may be cold enough Friday and Saturday morning for patchy frost to develop in the valleys and High Desert. High temperatures will warm each day for Friday through Monday with high temperatures on Monday around 5 degrees above average. Shower chances begin to increase again Monday evening into Tuesday, with the highest chances of precipitation currently Wednesday.

AVIATION... 181730Z

SCT-BKN clouds 3,000-6,000 feet MSL through the period mainly west of the mountains. Low clouds will begin to drop after 17z Thursday as another system makes its way across the area. Strong westerly winds continue through this evening around 20- 25 kts along the coast and in the valleys with some higher gusts 30- 40 kts and locally higher in mountains and areas of deserts before easing around 02-04Z. Mountains will be obscured at times throughout the day. Winds will begin to pickup again ahead of the next system moving from the northwest to the southeast after 17-19Z.

MARINE

Winds have weakened behind the line of storms that moved through this morning. Winds are still creating hazardous conditions for small craft through this afternoon, calming briefly overnight, and will redevelop ahead of the next system Thursday. Conditions will improve Friday.

BEACHES

High surf of 5 to 9 feet is expected, with sets as high as 11 feet, highest in San Diego County today. Dangerous swimming and surfing conditions and localized beach erosion can be expected. 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 from 9 AM Thursday to 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.