The map on the right, courtesy of the OK Mesonet, is called the fractional water index and is a method of determining the amount of soil moisture available at that level; in this case 2 inches under sod. Clearly, there are only a few pockets of adequate soil moisture as most of the state remains far too dry. Another factor is the low relative humidity levels which have been dropping to less than 30% during the heat of the day and that will be the case for Thursday and Friday as well. This also places additional stress on the abundant vegetation. The combination of dry soils, low humidity levels, and stressed vegetation also leads to an enhanced fire danger potential so be extra careful with the outdoor activities.
A good rain would go a long way in providing at least some short term relief and there is some hope in that regard, but not in the short range. The next few days will see a continuation of the ongoing heat wave with temperatures running about 10 degrees above normal. That translates into daytime highs of 100+ and overnight lows in the upper 70s. Outlying areas will be somewhat cooler with respect to the nighttime temperatures.
Our winds have been strong enough to keep air quality issues at bay, but that also increases the evaporation rates and contributes to the fire danger potential. Those southerly winds will subside to 5-10 mph after sunset each evening and back up around 10-15 mph or more on Thursday. Lighter winds are expected for Friday and Saturday.
By Sunday, a pattern change should be underway which has been advertised by the longer range guidance for several days now. There are still some timing and intensity differences that remain to be resolved, but the bottom line is that the dominant ridge aloft will be shifting much further west. That will allow for more moisture to move into the state which together with a weak cool front which should be arriving by Sunday night or Monday will also provide a break in the heat wave. Don't get your hopes up too high, but showers and storms will be in the forecast beginning on Sunday and for the beginning of next week. Conditions aloft also suggest that the break in the triple digit heat will continue through the week as well.
So, that gives us something to look forward to. In the meantime, stay tuned, stay cool, and check back for updates.