Thermal, CA 92274 Weather

Synopsis

Showers and a slight chance of thunderstorms will continue today, with highest thunderstorm chances this afternoon. Showers will end from the northwest late Friday afternoon. Southwest to west winds along the desert slopes of the mountains will gust to 40 to 50 mph through tonight. Dry and warmer for the weekend through Monday, then gradually cooler for next week with a chance of precipitation for late next week. Tides will increase over the weekend, remaining elevated through much of next week.

Discussion

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

At noon, scattered showers were being observed especially north of San Diego County. Rainfall totals over the past 6 hours have seen quite the range with accumulations of 0.01 to 0.10" and up to 0.60 to 1". Highest totals have been observed near mountain foothills and in the mountains. Isolated thunderstorms are expected to continue through the afternoon. Rainfall activity is expected move south more into San Diego County through this afternoon and evening, but will remain scattered in coverage. For this evening and overnight peak rainfall rates of 0.25 to 0.35 inches per hour are expected. An additional 0.25 to 0.75 inch of rain may accumulate in some locations. In addition to periods of rain, gusty winds can be expected over the mountains, locally into the deserts. Peak gusts of 45 to 55 mph are expected through this evening.

High temperatures on Friday will be a few degrees warmer than today for the coast to the mountains with greater warming of 5 to 10 degrees on Saturday. High temperatures on Saturday will be as much as 5 to 10 degrees below average for the mountains. Conditions will continue to warm Sunday and Monday. By Monday, high temperatures in coastal areas will be 5 to 10 degrees above average, with temperatures closer to average further inland.

The flow will turn offshore for the weekend, with periods of north to northeasterly winds in the mornings. Strongest winds will be on the mountain foothills and below passes and canyons. Right now it looks like peak wind gusts will be in the 30 to 45 mph range. Given the unsettled weather quickly turning to offshore flow, marine layer low clouds and fog will largely be absent from the coast into early next week.

Aviation

221830Z...SCT SHRA and ISO TSRA this morning, mostly north of SD County, continuing through around 03z. Cigs down to 1500-2500 feet MSL and vis 3-5SM at times in heavier SHRA/TSRA, otherwise bases will be 3500-4500 feet MSL. Partial obscuration of mountains this morning, but improving vis later today. More SCT SHRA expected after 07z through Friday morning for coastal areas and ISO SHRA inland. SHRA taper off everywhere from north to south during the day Friday. Onshore winds in mountains into deserts 25-30 kts, creating MOD up/downdrafts in lee of ridges.

Marine

A storm system will slowly move through the coastal waters today through Friday. There is a slight chance of thunderstorms today. Any thunderstorm is capable of producing gusty, erratic winds, choppy seas, lightning, briefly heavy rainfall with reduced visibility, and waterspouts. Isolated northwest wind gusts will occasionally exceed 20 knots Friday. No hazardous marine conditions are expected Friday night through Monday.