So far this year, Tulsa is about 9.5" below normal on our rainfall and this calendar year is the second driest on record. Fortunately, a slow moving storm system has already dropped some beneficial rainfall for the more western parts of the state and that system will be spreading showers/storms our way over the coming week or so. Notice the map on the right, courtesy of the OK Mesonet, which shows some very generous rainfall over the last 24 hours in places that have been hardest hit by the ongoing drought.
The system producing those rains will be slowly working its way eastward and as it does so there will be embedded waves in the upper level winds that will provide chances of showers/storms most any time of the day or night. That does not mean the holiday weekend will be a complete washout. Keep in mind, the chances of rain are a product of two other percentages. The percentage chance that it will rain at all times the percentage of the area that receives measurable precipitation. Each day through this forecast cycle has a 100% chance of rain; it is going to rain. But, it is not going to rain everywhere all the time which is why the chances of any one particularly location getting wet is usually much lower. In this case, it still looks like the best chance of getting wet, or the greatest areal coverage of rain, will be on Tuesday. At least scattered showers/storms can be expected leading up to and after Tuesday as this slow moving system gradually drifts on eastward.
Rainfall totals may be generous as well. Notice the second map on the right which is the 7 day QPF and suggests widespread amounts of at least 1-2" across the state. Keep in mind, this is an areal average and locally much higher amounts will be possible, perhaps resulting in local drainage problems.
The clouds and scattered showers/storms will also keep temperatures somewhat in check with morning lows in the 60s and daytime highs generally in the low-mid 80s at most and perhaps only in the upper 70s by Tuesday when the showers will be most widespread. We will also keep generally light S/SE winds and mostly cloudy to overcast skies each day.
So, stay tuned and check back for updates.