July 18, 2021
The main body of a fairly significant batch of monsoon moisture is currently moving through southern California. Some of the heaviest moisture is now moving through the southern San Joaquin Valley. Doppler radar is indicating scattered showers and isolated thunderstorms over the mountains and deserts of southern California and as far north as Kern County. The flow aloft is now out of the south/southeast, rotating clockwise around upper level high pressure which has shifted northwest over Utah, making the flow aloft more desirable for moving moisture into California. The main question for today is how much sunlight will reach the ground. If the cloud cover remains dense enough, and it may, temperatures will sag down into the 90s today. Most models show the backside of this moisture clearing the valley before noon Sunday. However, satellite imagery also indicates skies have cleared somewhat over the lower deserts. This may add more daytime heating for the possible development of additional storms. So far, no measurable rain has been recorded on the valley floor. Many locations, however, in southern California did pick up measurable rain. Rincon recorded .42.
The possibility of precipitation will decrease over the valley floor this afternoon with only a slight chance of measurable rain, mainly over the mountains, Monday through Wednesday. during the summer it’s not uncommon for large scale high and low pressure systems to pick up steering currents, and that will be the case of this high, as it wobbles anywhere from Texas to Utah over the next week or so. It does appear another batch of monsoon moisture will work a bit northward into Arizona and southern California Thursday through Friday, but for now we’ll go with a dry forecast.
Medium range models show the continuation of hot weather with periods of mid and high level clouds at times.
Forecast: Variable cloudiness through around midday today. Mostly clear to occasionally partly cloudy Sunday afternoon through Monday with a slight chance of isolated sprinkles. An isolated thunderstorm or two cannot be ruled out. Mostly clear Tuesday through Thursday with occasional high clouds and continued hot. Mostly clear to occasionally partly cloudy Thursday through Friday. Mostly clear Friday night through Sunday with occasional mid and high level clouds.
Temperatures: Highs today will range in the mid to upper 90s in areas which are mostly cloudy to the upper 90s to 104 where skies are partly cloudy to mostly clear. Lows tonight will range mostly in the low to mid 70s, however readings in the upper 70s to the lower 80s are possible in Kern County. Highs Sunday through Monday will range between 101 and 106. Overnight lows will range in the 70s, possibly in the low 80s in parts of Kern County.
Next update: July 19/am