textproduct: San Diego

SYNOPSIS

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.

SHORT TERM (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.

LONG TERM (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.

AVIATION

161030Z...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 18-02Z. Strong southerly winds 20-30 kts with gusts to 35 kts will accompany this band. The band will pass through 23-03Z, and SHRA and a slight chance of TSRA will follow along with westerly winds 15-25 kts. Cigs will lift some and vis will improve after 03Z except in SHRA and isold TSRA.

Mountains...Increasing and lowering clouds will eventually obscure most mountain terrain as a band of RA/SN moves through 18-02Z. Vis will be reduced 0-2SM much of this time. South winds increasing this morning 30-45 kts with local gusts 55 kts, strongest 18-02Z. SHRA/SHSN to follow, with some improvement in terrain obscuration overnight.

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.

MARINE

A storm system will generate strong southerly to westerly winds and high and choppy seas today, weakening slightly tonight and Tuesday before intensifying again for Wednesday into Thursday. A Gale Warning is in effect and contains the details. There is also a slight chance of thunderstorms this afternoon through tonight.

BEACHES

Increasing westerly swell will produce high surf later today through Thursday morning, highest in San Diego County on Wednesday. Dangerous swimming conditions are likely along with localized beach erosion and flooding. A High Surf Advisory is in effect and contains the details.

HYDROLOGY

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.

SKYWARN

Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions.

SGX WATCHES/WARNINGS/ADVISORIES

CA...Wind Advisory from 7 AM this morning to 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 from 10 AM this morning to 4 AM PST Thursday for Orange County Coastal Areas-San Diego County Coastal Areas.

Winter Storm Warning from 10 AM this morning to noon PST Wednesday for Riverside County Mountains-San Bernardino County Mountains.

Wind Advisory from 10 AM this morning to 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 from 6 AM this morning to 10 PM PST this evening for Apple and Lucerne Valleys.

PZ...Gale Warning from 7 AM this morning to 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.