Hot again today then cooling trend Thursday into the weekend. Locally elevated fire weather concerns today and Thursday with areas of afternoon to evening gusty wind and lower humidity. Threat of afternoon thunderstorms today near Sierra Nevada crest eastward.
Discussion
597 DM upper high centered over the Great Basin will continue hot weather across interior NorCal today with widespread moderate to major heat risk. High temperatures expected to be near or a few degrees lower than Tuesday. Delta breeze looks to be slightly stronger today, but cooling effect is limited as marine layer remains shallow under strong subsidence. Upvalley pressure gradient increases today with stronger afternoon to evening southerly wind over the interior. This could result in a short period of elevated fire weather conditions today and Thursday. Slight chance of afternoon showers or thunderstorms over higher elevations of our Sierra Nevada zone, however main activity expected to be crest eastward similar to the last several days.
Cooling trend Thursday into Friday as heights/thicknesses lower in response to deep short wave trough moving through the PacNW and cutoff low progged through the CWA Friday afternoon into night. Synoptic cooling with deepening marine layer and increased onshore flow expected. Enhanced midlevel SWly flow should keep any Sierra Nevada deep moist convection crest eastward. Locally gusty wind continues to be possible during the afternoons as humidity trends up into Friday.
Broad upper troughing remains along the West Coast into the weekend. NBM advertising below normal temperatures Saturday with mid 80s to lower 90s for the Central Valley and upper 60s to lower 80s for mountains and foothills.
Extended Discussion (Sunday through Wednesday)
Long wave troughing remains along the West Coast through the weekend keeping high temperatures below normal. Models diverge with solutions early next week as cluster analysis varying from unseasonably deep short wave trough moving into the PacNW Tuesday to strong Desert SW high expanding back northwestward over NorCal through midweek. NBM favoring a gradual warming trend with high temperatures returning to near or slightly above normal Tuesday into Wednesday.