Big Picture: See the picture below for forecast on Friday. This is the 500 mb level in the upper atmosphere. Notice the 594 circle in the Southern Gulf Coast States? That is the ridge. Then notice the 582 circle to the east of Hudson Bay in Canada? That too is the ridge. The thinking was that there would be one big ridge thus building heat ... however, notice the dip in the lines over our region. Yes, that is the trough. It leads to a much cooler forecast than originally thought. This change is due to a blocking pattern to our northeast.
Wed and Thu will likely be the wettest, but I am not convinced how far east the rain will get. Just a couple of weekends ago we had a slow moving system that brought heavy rain to the western half of the state. Many areas got 1-2" or even more rain. We got some light sprinkles as it died coming east. I would not be surprised to see a similar set up this time. But where will that line of rain and no rain set up? I feel that we will be close to it, but will get some showers. Some of which could be heavy.
I do not expect a heatwave next week either. Temps will warm into the mid 80s by Tue-Wed. A cold front should then come through on Wed/Wed night bringing more rain and cooler weather. Could we get another 90 degree day before fall sets in? Not sure. But I not doubt it. I really thought this last week of Aug was the big chance for heat. But of course I am not complaining ... just explaining what happened. (Which by the way, the models have handled this pattern change very poorly so far) .