October 11, 2018 – Weak weather systems will bring light showers to the Sierra today. Near to a little warmer than normal temperatures Friday through the middle of next week. Locally breezy northerly wind today through the weekend with lowering humidity.
Showers associated with an upper trough over the southwest U.S. have moved south and east of the CWA this morning. Another shortwave dropping down the back side of this upper trough will bring another threat of Sierra showers this afternoon. Any precipitation associated with the shortwave will be quite light but some snow may fall at the highest elevations. Other than the northern Sierra, the CWA will remain dry today with just some scattered clouds. The cooling associated with the trough will keep daytime highs today a little below normal. The upper trough drops south of the area on Friday with high pressure nosing in to the Pacific Northwest and NorCal. This should bring daytime temperatures Friday up to a little above normal for this time of year. Temperatures warm to several degrees above normal on Saturday as the upper ridge over the eastern Pacific starts to push inland. Meanwhile, surface high pressure pushing into the Pacific Northwest will bring an increased northerly surface gradient. Combined with upper level northerly flow, this will bring breezy north winds over the weekend. At this time, the northerly winds are not expected to be exceptionally strong but will bring lowering humidity and therefore increased fire danger.
Extended Discussion (Monday through Thursday)
Dry conditions expected across interior NorCal as a ridge of high pressure remains in control. Daytime highs will remain 3 to 7 degrees above seasonal normals. Look for temperatures in the low to mid 80s across the Valley, with 60s and 70s over the foothills/mountains. Locally gusty north to east wind possible at times with lowering humidity.