Aviation/marine DISCUSSION BELOW,
Visible satellite at 10 AM was showing a fog bank along the southern Orange County beaches, extending south towards Mission Beach in San Diego County. Lifeguards have reported visibility of 1/8 to 2 miles where the clouds are reaching land. Visibility should improve by later this afternoon but areas of low clouds and fog are expected redevelop overnight into Monday morning. One last day of record breaking temperatures for inland locations can be expected today. By Monday the high pressure aloft will weaken enough to kick off a cooling trend through mid-week. Highs Monday will be 5 to 10 degrees cooler than Sunday for inland locations.
Weak troughing over the US West Coast will continue to cool conditions back to near seasonal average by Wednesday. A few additional degrees of cooling on Thursday will make it the coolest day of the week for most locations. Widespread cloud coverage can be expected for the middle of the week. Westerly winds will increase over the mountains and into the deserts in the afternoons and evenings Tuesday through Thursday. Strongest winds are expected Wednesday and Thursday with peak gusts of 40 to 55 mph.
Precipitation chances on Wednesday are holding steady at around 15 to 25 percent chance of measurable rain, with the highest chances on the coastal slopes of the mountains. The track of the trough will keep the bulk of the moisture to our north. Rainfall totals for the coast and valleys will be 0.10" or less, with the coastal slopes of the mountains having a 20 to 25 percent chance of rainfall totals exceeding 0.10".
Once the aforementioned low is to our east, the majority of global model ensemble solutions show it digging south into the Great Basin Friday and Saturday. This would turn the pressure gradient offshore, bringing chances of Santa Ana winds, dry air, and another uptick in temperatures west of the mountains. While most guidance is in agreement on this general pattern, there remain differences in how far south the low will dig and how fast it will continue to move east. Both of those factors will have an impact on the strength and duration of Santa Ana winds that develop. Latest guidance from the CW3E WRF ensemble has a 60 to 80 percent chance of a weak Santa Ana wind event Friday and Saturday, with a 40 to 60 percent chance of a weak to moderate Santa Ana wind event.
One more day of widespread record breaking temperatures today with highs 15 to 20 degrees above average for inland locations. Cooler, windier, and cloudier conditions expected for the middle of week. Slight chance (15-20 percent) of light precipitation on Wednesday for areas along and west of the mountains. Drier and warmer conditions for the end of the week with potential for Santa Ana winds.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, UPDATED 06Z AVIATION/MARINE DISCUSSION BELOW,
Visible satellite at 10 AM was showing a fog bank along the southern Orange County beaches, extending south towards Mission Beach in San Diego County. Lifeguards have reported visibility of 1/8 to 2 miles where the clouds are reaching land. Visibility should improve by later this afternoon but areas of low clouds and fog are expected redevelop overnight into Monday morning. One last day of record breaking temperatures for inland locations can be expected today. By Monday the high pressure aloft will weaken enough to kick off a cooling trend through mid-week. Highs Monday will be 5 to 10 degrees cooler than Sunday for inland locations.
Weak troughing over the US West Coast will continue to cool conditions back to near seasonal average by Wednesday. A few additional degrees of cooling on Thursday will make it the coolest day of the week for most locations. Widespread cloud coverage can be expected for the middle of the week. Westerly winds will increase over the mountains and into the deserts in the afternoons and evenings Tuesday through Thursday. Strongest winds are expected Wednesday and Thursday with peak gusts of 40 to 55 mph.
Precipitation chances on Wednesday are holding steady at around 15 to 25 percent chance of measurable rain, with the highest chances on the coastal slopes of the mountains. The track of the trough will keep the bulk of the moisture to our north. Rainfall totals for the coast and valleys will be 0.10" or less, with the coastal slopes of the mountains having a 20 to 25 percent chance of rainfall totals exceeding 0.10".
Once the aforementioned low is to our east, the majority of global model ensemble solutions show it digging south into the Great Basin Friday and Saturday. This would turn the pressure gradient offshore, bringing chances of Santa Ana winds, dry air, and another uptick in temperatures west of the mountains. While most guidance is in agreement on this general pattern, there remain differences in how far south the low will dig and how fast it will continue to move east. Both of those factors will have an impact on the strength and duration of Santa Ana winds that develop. Latest guidance from the CW3E WRF ensemble has a 60 to 80 percent chance of a weak Santa Ana wind event Friday and Saturday, with a 40 to 60 percent chance of a weak to moderate Santa Ana wind event.
300450z, Low clouds are beginning to filter in along the coast with bases at 500ft MSL. Low clouds are still expected to slowly fill in now through Monday morning, pushing inland 5-10 miles from the coast. Bases near 300-700ft MSL with lower visibilities in fog on higher coastal terrain. Low clouds will begin to clear after 17Z-19Z.
Otherwise, VFR conditions prevail. Clouds AOA 20,000ft MSL will increase in coverage through the period.
No hazardous marine conditions expected through Wednesday. Northwest winds increase Thursday to near 20 kts across all marine areas.
Ca, None. PZ, None.
