May 15, 2019
Summary: Temperatures in Kern County are running around five degrees cooler than 24 hours ago. North of the Kern County line, readings are between 10 to 12 degrees cooler than yesterday at this time and are in the lower 70s. mostly just trace amounts of rain have fallen so far at various locations on the valley floor until you get as far north as Merced and Los Banos where a few hundredths have been recorded. Models show the main rain event will probably begin about 11:00pm to midnight from Fresno County northward and it will progress to the south valley during the early morning hours. This batch of precipitation will be associated with a strong cold front, especially considering the time of year.
By the late morning to afternoon hours Thursday, a pool of cold, unstable air will have moved in aloft, setting the stage for numerous showers and a chance for thunderstorms. The chance for thunderstorms will greatly increase if we see the sun peeking through the cloud deck during the afternoon, destabilizing the environment even more. Showers will continue Thursday night, tapering off by sunrise Friday. Most of the showers Friday will be confined to the mountain areas, especially the Sierra Nevada where the snow level will drop down to 5,000 to 6,000 feet.
A weak ridge will move quickly through Friday through Saturday morning. By Saturday afternoon, clouds will increase ahead of the next weather system developing off the northern California coast. This system appears to also have good jet stream dynamics and will have that as far south as Kern County for an excellent chance of showers with another possible round of thunderstorms. The chance of showers will continue Sunday night.
Models are diverging again for the pattern for much of next week. However, if there is a common theme, it is that a broad expanse of low pressure will be elongated from northeast to southwest over the western United States. This would favor unsettled weather mainly from Fresno County north and over the Sierra Nevada. Whether or not more rain arrives after Tuesday is very speculative at this time, but at the very least, temperatures will remain well below average.
Forecast: Light showers possible this evening. Rain likely from the late evening into Thursday morning, turning to showers with a chance of scattered thunderstorms from late Thursday morning through Thursday evening. If thunderstorms develop, they will be accompanied by localized heavy rain and small hail. Showers will continue Thursday night with a few lingering showers possible near the foothills Friday morning. Partly cloudy Friday afternoon through Saturday morning. Increasing cloudiness Saturday afternoon. Periods of showers later Saturday night through Sunday night. a chance of showers Monday through Tuesday with a slight chance of showers Tuesday night and Wednesday, mainly from Tulare County north.
Temperatures: Lows tonight will cool into the mid to upper 50s. Highs Thursday will only warm into the mid to upper 60s. Overnight lows Thursday will range in the upper 40s to the lower 50s with highs Friday again only topping out in the mid to upper 60s.