Ation and Marine sections,
Update: Any remaining shower or two along the foothills should dissipate or move out within the next couple of hours as high pressure continues to build in behind the exiting trough, which is now well to the southeast of the region. Onshore winds will continue to strengthen, and there has been very little change in terms of the timing and strength of these winds, which should begin to increase by later in tonight into tomorrow morning, and peak by late morning into early afternoon. The strongest winds look to occur east of the Tecate Divide, and impacting locations such as Boulevard and Live Oaks Springs with wind gusts occasionally peaking over 50 mph, and even stronger across the lower deserts with gusts possibly getting over 60 mph for the Ocotillo Wells area. As the pressure gradient weakens, winds should decouple and then begin to shift from onshore to offshore throughout the evening tomorrow and going into Friday. The overall pattern looks to remain the same, with a broad ridge becoming established over the eastern Pacific Ocean, and with a low to the southeast, will continue to enhance the offshore flow winds going into the weekend, with a gradual warming trend taking shape on into next week. This will also help to mitigate marine layer intrusion for the coastal and inland areas through early next week.
Previous discussion submitted at 137 PM:
Key Points:
*Gusty westerly winds are expected across all area deserts, through the San Gorgonio Pass, and on the desert slopes of the San Diego and Riverside county mountains tonight into Thursday afternoon.
*Moderate to locally strong Santa Ana winds are expected Thursday for portions of Orange county, Inland Empire, and coastal slopes of the San Bernardino county mountains. Moderate winds become more widespread into San Diego county Friday night into the weekend.
*Cold mornings are expected Friday through Sunday for the deserts, mountains, and wind sheltered valleys. Coldest conditions expected Friday morning.
A few localized moderate rain showers have developed this afternoon, mainly focused along and south of Interstate 8, mountains, and deserts. Localized light to moderate showers will continue through the afternoon. Any lingering showers should dissipate by this evening.
Our attention quickly turns to a fast-moving inside slider tracking through the interior West tonight into Thursday. This system will bring gusty westerly winds to the mountains and desert slopes. Wind gusts for the desert mountain slopes will peak at around 50-65 mph, locally higher gusts possible in westerly wind favored locations. In the deserts peak gusts of 40-55 mph are expected. Winds will quickly turn northerly for San Bernardino county, bringing elevated northerly winds to the coastal slopes of the San Bernardino mountains as early as Thursday morning. Those northerly winds will become more widespread and strengthen Thursday afternoon and evening, impacting portions of the Inland Empire, foothills of the Santa Ana mountains, and portions of inland Orange County. There could be impacts to travel due to strong cross-winds below the Cajon Pass and high profile vehicles should drive with caution Thursday night into Friday morning. Additionally, due to the recent rains the saturated soil may make trees more vulnerable to uprooting (especially on the coastal slopes of the San Bernardino mountains). Peak wind gusts for portions of inland Orange County and the Inland Empire will be 35-45 mph, gusts may be locally to 50 mph below the Cajon Pass. Gusts on the coastal slopes of the San Bernardino and Santa Ana mountains of 45-65 mph, locally higher in wind prone locations near the Cajon Pass.
Winds will become more northeasterly Friday night through the weekend as the main driver of the Santa Anas becomes the pressure gradient between Southern California and the Intermountain West. This will spread moderate strength northeast to east Santa Ana winds to the San Diego mountain foothills, locally into the valleys. As the winds become more northeast to east in direction, winds previously mentioned in places north of San Diego county will weaken, but remain elevated. Overall gusts 35-55 mph are possible, with strongest winds on the coastal slopes of the mountains into the foothills and below passes. Those more widespread, moderate strength winds look like they will continue into Sunday. Periods of Santa Ana winds are expected to continue into next week. While there remains uncertainty in wind strength, there are indications winds will be similar to slightly weaker than Saturday and Sunday's wind forecast. Thankfully, due to all the rain we've received in December, fire weather conditions will likely only remain elevated due to gusty winds and minimum relative humidity falling to the teens. Fuel moisture will remain above critical levels.
In addition to the gusty Santa Ana winds, high temperatures for the coast and valleys will reach the 70s to locally low 80s by early next week. Low temperatures in the deserts and wind sheltered locations in the valleys and mountains are expected to fall to the 30s and low 40s, even as low as the upper 20s in the High Desert. Based on the current forecast, the coldest morning is expected to be Friday. Overnight lows should gradually increase for the weekend into early next week with less cold air advecting into our local deserts. From Friday onward, marine layer low clouds and fog are expected to be absent from coastal areas due to the dominate offshore flow.
Isolated showers this evening continue to come to an end. Gusty westerly winds will develop across desert slopes of the mountains into the deserts tonight into early Thursday afternoon. Winds will quickly become northerly, starting as early as Thursday morning for some locations, from north to south across the area. This will bring a period of moderate to locally strong north to northeasterly Santa Ana winds to the San Bernardino mountain foothills, Inland Empire, Santa Ana mountain foothills, and inland Orange County Thursday into Friday. Santa Ana winds will become more northeast to easterly Friday into Saturday, which will spread more moderate strength winds into the San Diego county mountain foothills, locally into the valleys. Periods of Santa Ana winds will continue into next week. Warm days west of the mountains can be expected Friday into early next week with cold nights in the deserts and any wind sheltered locations in the valleys and mountains.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, Updated Aviation and Marine sections,
Update: Any remaining shower or two along the foothills should dissipate or move out within the next couple of hours as high pressure continues to build in behind the exiting trough, which is now well to the southeast of the region. Onshore winds will continue to strengthen, and there has been very little change in terms of the timing and strength of these winds, which should begin to increase by later in tonight into tomorrow morning, and peak by late morning into early afternoon. The strongest winds look to occur east of the Tecate Divide, and impacting locations such as Boulevard and Live Oaks Springs with wind gusts occasionally peaking over 50 mph, and even stronger across the lower deserts with gusts possibly getting over 60 mph for the Ocotillo Wells area. As the pressure gradient weakens, winds should decouple and then begin to shift from onshore to offshore throughout the evening tomorrow and going into Friday. The overall pattern looks to remain the same, with a broad ridge becoming established over the eastern Pacific Ocean, and with a low to the southeast, will continue to enhance the offshore flow winds going into the weekend, with a gradual warming trend taking shape on into next week. This will also help to mitigate marine layer intrusion for the coastal and inland areas through early next week.
Previous discussion submitted at 137 PM:
Key Points:
*Gusty westerly winds are expected across all area deserts, through the San Gorgonio Pass, and on the desert slopes of the San Diego and Riverside county mountains tonight into Thursday afternoon.
*Moderate to locally strong Santa Ana winds are expected Thursday for portions of Orange county, Inland Empire, and coastal slopes of the San Bernardino county mountains. Moderate winds become more widespread into San Diego county Friday night into the weekend.
*Cold mornings are expected Friday through Sunday for the deserts, mountains, and wind sheltered valleys. Coldest conditions expected Friday morning.
A few localized moderate rain showers have developed this afternoon, mainly focused along and south of Interstate 8, mountains, and deserts. Localized light to moderate showers will continue through the afternoon. Any lingering showers should dissipate by this evening.
Our attention quickly turns to a fast-moving inside slider tracking through the interior West tonight into Thursday. This system will bring gusty westerly winds to the mountains and desert slopes. Wind gusts for the desert mountain slopes will peak at around 50-65 mph, locally higher gusts possible in westerly wind favored locations. In the deserts peak gusts of 40-55 mph are expected. Winds will quickly turn northerly for San Bernardino county, bringing elevated northerly winds to the coastal slopes of the San Bernardino mountains as early as Thursday morning. Those northerly winds will become more widespread and strengthen Thursday afternoon and evening, impacting portions of the Inland Empire, foothills of the Santa Ana mountains, and portions of inland Orange County. There could be impacts to travel due to strong cross-winds below the Cajon Pass and high profile vehicles should drive with caution Thursday night into Friday morning. Additionally, due to the recent rains the saturated soil may make trees more vulnerable to uprooting (especially on the coastal slopes of the San Bernardino mountains). Peak wind gusts for portions of inland Orange County and the Inland Empire will be 35-45 mph, gusts may be locally to 50 mph below the Cajon Pass. Gusts on the coastal slopes of the San Bernardino and Santa Ana mountains of 45-65 mph, locally higher in wind prone locations near the Cajon Pass.
Winds will become more northeasterly Friday night through the weekend as the main driver of the Santa Anas becomes the pressure gradient between Southern California and the Intermountain West. This will spread moderate strength northeast to east Santa Ana winds to the San Diego mountain foothills, locally into the valleys. As the winds become more northeast to east in direction, winds previously mentioned in places north of San Diego county will weaken, but remain elevated. Overall gusts 35-55 mph are possible, with strongest winds on the coastal slopes of the mountains into the foothills and below passes. Those more widespread, moderate strength winds look like they will continue into Sunday. Periods of Santa Ana winds are expected to continue into next week. While there remains uncertainty in wind strength, there are indications winds will be similar to slightly weaker than Saturday and Sunday's wind forecast. Thankfully, due to all the rain we've received in December, fire weather conditions will likely only remain elevated due to gusty winds and minimum relative humidity falling to the teens. Fuel moisture will remain above critical levels.
In addition to the gusty Santa Ana winds, high temperatures for the coast and valleys will reach the 70s to locally low 80s by early next week. Low temperatures in the deserts and wind sheltered locations in the valleys and mountains are expected to fall to the 30s and low 40s, even as low as the upper 20s in the High Desert. Based on the current forecast, the coldest morning is expected to be Friday. Overnight lows should gradually increase for the weekend into early next week with less cold air advecting into our local deserts. From Friday onward, marine layer low clouds and fog are expected to be absent from coastal areas due to the dominate offshore flow.
080410z, Coasts/Valleys, SCT-BKN low clouds with bases around 2000 ft MSL mainly in San Diego County. Occasional CIG impacts at KSAN and KCRQ are possible through about 09Z. Low clouds obscuring higher terrain through 17Z. Otherwise, VFR conditions should continue through Thursday with only a few clouds near 7500-15,000ft at times.
West winds strengthening across the mountains and deserts after tonight. Wind gusts across the deserts 25-40 kts and 40-55 kts across the desert slopes and passes will create MOD/STG UDDFS east of the mountains through much of Thursday.
Gusty northwest winds strengthen tonight, with gusts 25-30 knots in the outer waters and gusts 20-25 kts within 10 miles of the coast on Thursday, peaking in the afternoon.
Additionally, combined seas of 8 to 11 feet with an 8-9 second period (steep waves) will occur in the outer waters starting tonight, peaking on Thursday afternoon, and waning Thursday night. Seas briefly reach 7 to 9 feet within 10 miles of the coast during the daytime and evening Thursday. A Small Craft Advisory contains more details. Outside of this period, no hazardous marine conditions expected through this weekend.
Ca, Wind Advisory from 10 AM Thursday to 1 PM PST Saturday for San Bernardino and Riverside County Valleys-The Inland Empire.
High Wind Warning from 10 AM Thursday to 1 PM PST Saturday for San Bernardino County Mountains.
Wind Advisory until 1 PM PST Thursday for Apple and Lucerne Valleys-Coachella Valley-Riverside County Mountains-San Diego County Deserts-San Diego County Mountains-San Gorgonio Pass near Banning.
Wind Advisory from 9 PM Thursday to 1 PM PST Saturday for Santa Ana Mountains and Foothills.
Wind Advisory from 9 PM Thursday to 1 PM PST Friday for Orange County Inland Areas.
PZ, Small Craft Advisory from 7 AM to 10 PM PST Thursday for Coastal Waters from San Mateo Point to the Mexican Border and out to 10 nm.
Small Craft Advisory until 10 PM PST Thursday for Waters from San Mateo Point to the Mexican Border Extending 10 to 60 nm out including San Clemente Island.
