A weak cold front overhead is beginning to make the transition to a stationary front which should drift back to the NW beginning Thursday morning. This will lead to slightly more coverage in storm development heading into the weekend. Going into the weekend, the pattern will be in a state of flux as the boundary retreats to the NW, moisture flow will be on the increase as surface high pressure slides eastward.
Saturday looks to only see widely scattered afternoon showers and t-storms, mainly across more coastal areas where the seabreeze can provide a convective focus. The lack of more typical afternoon convective coverage should allow temperatures to persist above normal – especially across inland areas where highs could top out in the mid-90s. Closer to the coast, lower 90s seem more reasonable.
Another thing we’ll have to watch is the afternoon heat index values. Saturday’s heat index readings currently look to peak in the 100 to 105 degree range. With continued increases in moisture, though, Sunday may see borderline heat advisory criteria in some areas. The caveat on Sunday is that rain chances will be on the rise, so scattered showers and storms could help cool down the afternoon temperatures a bit – especially in areas that get a good outflow from any convection.
By the start of the work week, upper level pattern will be generally flat and the local area will generally be on the western periphery of low level high-pressure. This set up should allow for a return to more typical summertime conditions with highs around 90 and scattered afternoon convection.