Smoky Conditions ContinueJuly 31, 2018 – Smoke will help to keep daytime temperatures cooler the next couple of days. Then a gradual decrease in high temperatures mid week returning to near average. Latest satellite and radar imagery showing light showers and a few isolated thunderstorms over the northern Sierra (mainly north of HWY 50) this morning. A few additional showers or lightning strikes are possible this morning given elevated instability. Haze and areas of smoke will continue through the day. Forecast remains on track.
Discussion (Today through Wednesday)
The upper level ridge will be pushing to the south and east during the short term period as a trough tracks into the PacNW. The main concern will continue to be wildfire smoke. This will make the temperature forecast difficult with wildfire smoke holding temps down but it`s hard to say how much. In general we should see similar highs today as to what we saw on Monday. Smoke will be noticeable throughout the area being thickest in the north valley and Sierra. Some smoke relief is expected across the Delta influenced areas during the evening and overnight as the Delta breeze kicks in.
Monsoon moisture may bring an isolated chance for a shower or t-storm by the evening in the far southeast part of the CWA but the better chances will remain south and east where the higher precipitable water values are. Zonal flow develops by late to midweek as the upper level ridge continues to push to the east, bringing a slight cooling trend with highs returning to near normal although the wildfire smoke will likely continue to make for a difficult temperature forecast. Monsoon moisture will move east with the upper level ridge and this will keep thunderstorm chances out of the forecast.
Extended discussion (Saturday through Tuesday)
A gradual cooling trend is expected through the weekend into next week as upper level ridging is flattened at times by a series of disturbances. Temperatures are expected to drop below normal levels, with highs in the 90s. Wildfire smoke could also continue to bring some cooling if it remains widespread. Dry weather is expected to continue through the extended period at this point. Models are suggesting now that a trough that arrives next week will have limited moisture, limiting any precipitation to the northwest coast of California.