Area Forecast Discussion

SYNOPSIS

19/910 AM.

A cooling trend will begin today and continue through mid week as a storm approaches. Light to moderate rain is expected late Monday into Tuesday, focused over San Luis Obispo County with minimal impacts. Widespread gusty west to northwest winds will follow Wednesday through Friday.

SHORT TERM (TDY-TUE)

19/920 AM.

***UPDATE***

A quiet couple of days today and Monday weather-wise. Gradients continue to trend onshore meaning cooling will reach farther inland with increasing chances for some morning marine layer near the coast. Highs expected to drop 2-4 degrees each day through Wednesday with rain expected late Monday night into Tuesday. Amounts below still look reasonable with minimal impacts aside from a slight chance of a thunderstorm in SLO County.

***From Previous Discussion***

This upper low will bring another round of measurable precipitation to the area. Rain will develop across the Central Coast Monday evening with rain spreading south and east through the day on Tuesday. Based on current guidance, it looks like the rain band will lose it's "oomph" after it passes through Santa Barbara county. So, highest rain totals (0.50-1.50 inches) are expected across San Luis Obispo and Santa Barbara counties with lesser amounts (0.10-0.50 inches) across Ventura and Los Angeles counties. Some foothill areas will likely see locally higher amounts due to orographic effects. Also, there still is a 10-20% chance that amounts could be around double of current expectations (based on some ensemble members). Rainfall rates are generally expected to be in the 0.10 to 0.33 inch/hour range, resulting in minimal hydrologic impacts. Even if the rainfall totals do trend upwards towards the higher end scenario, overall flooding risk will remain minor to moderate. Additionally, there will be a 10-20% chance of thunderstorms on Tuesday across San Luis Obispo and Santa Barbara counties.

As for snow levels, they look to remain above the 6500 to 7000 foot range. So, no significant snowfall impacts are anticipated. South to southwest winds will bring gusts of 20 to 40 mph to parts of the area on Tuesday, especially over the mountains and much of San Luis Obispo and Santa Barbara Counties.

LONG TERM (WED-SAT)

19/336 AM.

The low pressure system is likely to exit the region Wednesay into Thursday, though there will remain a slight chance of showers, particularly along north facing mountains slopes. West to northwestern winds are likely after the passage of the front, with gusty conditions expected across the beaches, mountains, and deserts. Winds will then become northwesterly later Thursday and Friday as a weak inside slider noses into the region, with winds focused over the more typically windy mountain/desert areas.

Cool temperatures will continue on Wednesday (widespread 60s), increasing to near normal by the end of the week. Additional light rain is again possible sometime between next weekend and early next week (4/25-4/28), as some models have the inside slider system traveling westward and centering over the coastal waters.

AVIATION

19/1158Z.

At 07Z at KLAX, the marine layer was 1500 feet deep. The top of the inversion was 2500 feet with a temperature of 17 C.

Overall for the TAF package, high confidence in VFR conditions for KPRB, KSBP, KSBA, KOXR, KCMA, KBUR, KVNY, KPMD and KWJF.

For KSMX, there is a 40% chance of VFR conditions through the period. For KSMO, KLAX and KLGB, there is a 15% chance of IFR/LIFR conditions until 17Z.

KLAX...Moderate to high confidence in TAF. There is a 15% chance of bkn004-BKN010 cigs until 17Z. No significant easterly wind component is expected.

KBUR...High confidence in TAF.

MARINE

19/338 AM.

High confidence in winds and seas remaining below Small Craft Advisory (SCA) levels through tonight. A system will move through the coastal waters Monday afternoon through Wednesday morning bringing a chance of showers to much of the area. Cannot rule out a thunderstorm or two across the northern waters Tuesday morning.

SCA level southerly winds are possible along the cold front. By Wednesday afternoon into the evening hours, SCA level NW winds will develop south of Point Conception. These winds will likely expand to include the majority of waters by Thursday afternoon. SCA winds may persist into the weekend at least for some waters.

LOX WATCHES / WARNINGS / ADVISORIES

CA...NONE. PZ...NONE.