A winter storm will move into the area today into early Tuesday bringing widespread moderate to heavy rain, mountain snow, and gusty onshore winds. There is a 15 to 20 percent chance of thunderstorms tonight. Showers will continue on Tuesday with strengthening west winds along the mountain crests and desert slopes, which peak Tuesday evening into Wednesday morning with gusts in excess of 60 mph. A second round of rain and lower elevation mountain snow is expected late Tuesday into Wednesday. Cool with decreasing chances for showers for Thursday and Friday. Drier and a little warmer for next weekend.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, New Aviation Discussion For the 18z TAF Package,
(today through Wednesday), The first in a pair of Pacific storms will move into the area today with a second bringing another round of more widespread precipitation for Tuesday night into Wednesday morning. High temperatures will cool 5 to 10 degrees today with additional lesser cooling for Tuesday and Wednesday. Wednesday high temperatures will be 5 to 10 degrees below average near the coast with the higher elevations of the mountains as much as 15 to 20 degrees below average.
Winds will strengthen this morning, then diminish late this evening and tonight. There will a second round of winds for Tuesday afternoon through Wednesday afternoon. For the desert slopes of the mountains into the deserts, the second round of winds for late Tuesday into Wednesday is expected to be stronger with gusts to 60 to 70 mph. For details on precipitation through Wednesday, please refer to the HYDROLOGY section below.
(Thursday through Sunday), There will be decreasing chances for mostly lighter showers for Thursday into Friday. Chances for precipitation for next weekend are 10 to 15 percent. High temperatures will warm slightly for Thursday and Friday, then gradually warm for Saturday through Monday with Monday high temperatures a few to around 5 degrees above average. High temperatures for next Monday will range from the mid to upper 60s near the coast to the lower to mid 70s for the valleys with the lower deserts around 80.
A winter storm will bring widespread moderate to heavy precipitation and mountain snow from late this morning through this afternoon, followed by scattered showers into early Tuesday morning along with a slight chance of thunderstorms tonight. Another round of more widespread precipitation with lower snow levels is expected for Tuesday night into Wednesday morning. Additional light showers are possible Thursday into early Friday. Precipitation chances are currently below 15 percent for Friday and Saturday, but there is the potential for light showers at times.
Peak hourly rainfall rates during the frontal passage today will range from 0.50-0.75 inch per hour, mostly between 10 AM and 4 PM. Rainfall and liquid-equivalent above the snow level for today through Tuesday morning will range from around 1 to 1.5 inch for coastal areas to 2.5 to 3.5 inches in the mountains with locally greater amounts. For the deserts, 0.50 to 1 inch is expected for the Apple and Lucerne Valleys with 0.15 to 0.50 inch for the lower deserts.
The snow level will rise to 6500 to 7500 feet late this morning and early this afternoon, then fall to 5000 to 5500 feet for late this evening and 4500 to 5500 feet for Tuesday morning. Snowfall of 4 to 8 inches is expected from 5500 to 6000 feet, 8 to 14 inches from 6000 to 7000 feet, and locally 2 to 3 feet above 7500 feet.
Additional rainfall and liquid-equivalent above the snow level for Tuesday night through Wednesday morning is expected to range from 0.33 to 0.50 inch for coastal areas to 0.75 to 1.25 inch in the mountains, locally to 2 inches for the San Bernardino County mountains. For the deserts, 0.25 to 0.50 is expected for the Apple and Lucerne Valleys with 0.10 to 0.33 inch in the lower deserts. The snow level will lower to 3500 to 4500 feet for Wednesday afternoon with additional snowfall of 3 to 6 inches from 5000 to 6000 feet, 6 to 12 inches from 6000 to 7000 feet, and 12 to 18 inches above 7000 feet.
If higher-end rainfall amounts materialize across the northern Coachella Valley, increased flows on the Whitewater River could cause flooding at some of the low-water crossings. Latest river forecast ensembles have around a 15 percent chance of the San Diego River reaching Monitor Stage for late today and on Wednesday.
161830z, Coast and Valleys, Gradually lowering clouds this morning will lead to RA and cigs generally 2500-3500 feet MSL, but down to 800-1200 feet MSL with vis reduced 1-5SM in +RA in a band moving west to east 19-02z. Strong southerly winds 20-30 kts with gusts to 35 kts will accompany this band. SHRA and a slight chance of TSRA after the band moves through along with westerly winds 15-25 kts. Cigs will lift some and vis will improve after 03z except in SHRA and isold TSRA. SHRA prevails through 18z Tue with winds picking back up around this time.
Mountains, Increasing and lowering clouds will eventually obscure most mountain terrain as the band of RA/SN moves through today, lessening after 02z Tue. Vis will be reduced 0-2SM much of this time. South winds 30-45 kts with local gusts 60 kts, strongest 18- 02z. SHRA/SHSN to follow, with some improvement in terrain obscuration overnight. Winds gust again on Tuesday in the mountains after 16z.
Deserts, Increasing and lowering clouds along with -RA/RA passing through the region west to east 19-03Z. South winds increasing this morning 30-45 kts with local gusts 55 kts, strongest 20-04z.
A storm system is generating strong winds with high and choppy seas beginning today, but will weaken a bit on Tuesday before increasing again on Wednesday. Seas expected to be around 8-12 feet with wind gusts 25-35 knots, with briefly higher to 40 knots. A Gale Warning is in effect through tonight with another Gale Warning in effect for Wednesday. There is also a slight chance of thunderstorms over the waters today/tonight.
Strong westerly swell (9-11 feet with an average period of about 10- 12 seconds) will produce large breaking waves up to 8-12 feet on most beaches across Orange and San Diego Counties today through Friday night. Widespread, strong rip currents are also likely with these waves and dangerous swimming conditions expected. A High Surf Advisory is in effect and contains more information.
Ca, Wind Advisory until 8 PM PST this evening 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.
Wind Advisory from 8 PM Tuesday to 8 AM PST Wednesday 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.
High Surf Advisory until 10 PM PST Friday for Orange County Coastal Areas-San Diego County Coastal Areas.
Winter Storm Warning until noon PST Wednesday for Riverside County Mountains-San Bernardino County Mountains.
Wind Advisory until 1 AM PST Tuesday for San Diego County Deserts-San Diego County Mountains-San Gorgonio Pass near Banning.
Wind Advisory from 10 AM Tuesday to 4 PM PST Wednesday for Apple and Lucerne Valleys-San Diego County Deserts-San Diego County Mountains-San Gorgonio Pass near Banning.
Wind Advisory until 10 PM PST this evening for Apple and Lucerne Valleys.
PZ, Gale Warning until 7 AM PST Tuesday 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.
Gale Warning from 8 PM Tuesday to 1 PM PST Wednesday 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.
