Cold Storm System to Bring Showers to Pasadena Thursday Night Through Friday

National Weather Service forecasters are predicting a significant cooling trend for Pasadena this week, culminating in a cold upper-level low pressure system that will likely bring showers to the area between Thursday night and Friday night.

Temperatures are expected to drop from the mid-70s today to the low 60s by Friday.

Monday begins with patchy morning drizzle and fog across Pasadena, with a deep marine layer well entrenched throughout the region. Skies will remain cloudy through the morning hours before gradually becoming mostly sunny by afternoon, with high temperatures reaching near 75 degrees. South winds of 5 to 10 mph will continue the onshore flow pattern.

Over the next 24 to 48 hours, the cooling trend will intensify as a deep upper-level trough anchored off the California coast continues to influence the region. Tuesday will see similar morning conditions with patchy drizzle and fog before 11 a.m. and mostly cloudy skies throughout the day.

High temperatures will drop slightly to around 72 degrees with light south-southeast winds becoming south-southwest at 5 to 10 mph by midday. Night through morning low clouds and fog can be expected with continued drizzle possibilities each night and morning.

Temperatures will continue their downward trend throughout the work week. After today’s high near 75, Tuesday will cool to around 72, Wednesday dropping further to the mid-60s, with Thursday and Friday seeing the coolest temperatures of the period with highs only reaching the low to mid-60s. A gradual warming trend will begin over the weekend with temperatures returning to the 70-degree range by Saturday.

The most significant weather event of the week will occur between Thursday night and Friday night as a cold upper-level low pressure system moves through the region. Shower chances will increase Thursday night with the National Weather Service indicating the highest chance for precipitation on Friday.

While the forecast doesn’t specify expected rainfall amounts, the precipitation is described as light showers rather than heavy rainfall. Weather models suggest instability will be at its peak on Friday, creating conditions that could potentially generate thunderstorms, especially in mountain and desert areas.

The weekend outlook brightens considerably for Pasadena residents. By Saturday, skies will turn mostly sunny with temperatures rebounding to around 70 degrees. Sunday looks even better with sunny conditions and highs near 71 degrees. The marine layer is expected to thin, resulting in less cloud coverage and more sunshine throughout the weekend.

Looking beyond the weekend into next week, extended forecasts suggest the warming trend will continue with dry conditions prevailing. The upper-level ridge building over the West Coast should maintain milder temperatures and diminishing marine layer influence.

Here is the latest forecast for Pasadena from the National Weather Service as of 5:01 a.m. on Monday, April 14:

Monday: Patchy drizzle and fog before 11:00 a.m. Cloudy, then gradually becoming mostly sunny, with a high near 75. South wind 5 to 10 mph.

Monday Night: Patchy drizzle and fog after 11:00 p.m. Mostly cloudy, with a low around 50. South southwest wind 5 to 10 mph becoming light south in the evening.

Tuesday: Patchy drizzle and fog before 11:00 a.m. Mostly cloudy, with a high near 72. Light south southeast wind becoming south southwest 5 to 10 mph in the morning.

Tuesday Night: Patchy drizzle after 11:00 p.m. Mostly cloudy, with a low around 49. Southwest wind around 5 mph becoming calm in the evening.

Wednesday: Patchy drizzle before 11:00 a.m. Mostly cloudy, with a high near 65.

Wednesday Night: Mostly cloudy, with a low around 51.

Thursday: Mostly cloudy, with a high near 64.

Thursday Night: A chance of showers, mainly after 11:00 p.m. Mostly cloudy, with a low around 49.

Friday: A chance of showers, mainly after 11:00 a.m. Partly sunny, with a high near 62.

Friday Night: A chance of showers. Partly cloudy, with a low around 48.

Saturday: Mostly sunny, with a high near 70.

Saturday Night: Mostly clear, with a low around 50.

Sunday: Sunny, with a high near 71.