May is normally our wettest month of the year and if I were to ask you if you thought this past month was wetter or drier than normal, I suspect most would think it was indeed a very wet month. A look at the map on the right from the Ok Mesonet over the last 30 days would seem to confirm that initial thought. However, the heavy, flooding rains that occurred during the month were actually rather spotty and for Tulsa proper, we ended the month more than 2.5" below normal with respect to precipitation.
Regarding temperatures, the month of May was also cooler than normal by more than a half a degree which may also come as somewhat of a surprise until you recall how cool we were to start the month.
We are now jumping straight into Summer with this early June heat wave that is building over the state. Temperatures will be running as much as 10 degrees warmer than normal at night as well as during the day with little relief in sight anytime soon. Although these are not record temperatures for Tulsa, it is nonetheless unusual to get this hot and humid so early in the year. Speaking of the humidity, yesterday I mentioned the dew point temperature which at that time was in the lower 70s. I also mentioned the possibility of it mixing out with drier air aloft. That has indeed happened during the day today with dew point temperatures dropping into the mid 60s this afternoon after holding in the 70s through most of the morning hours.
Given the lush, green vegetation and the wet soils, we should expect the evapo-transpiration to maintain dew point temperatures generally in the upper 60s or lower 70s for the late night and early morning hours and probably mix out into the low-mid 60s during the heat of the day and as the winds pick up. Bottom line: as long as the dew point is in the 60s during the hottest part of the day, we do get a bit of a break in that the heat index will only be a few degrees above the actual air temperature. It is when that dew point remains at or above 70 during the heat of the day that the heat and humidity become quite oppressive.
Having said all that, we are still expecting heat index values to be getting close to the century mark heading into the weekend as the actual air temperature will be reaching the mid 90s each day. Fortunately, we will have a brisk southerly wind to provide some good ventilation each day as well.
As far as our rain chances are concerned, they will be in the slim to none category for the next several days. As always, given the heat and moisture that is available, an isolated shower or storm is not completely out of the question on any given day and most likely in the more favored terrain locations in E OK. As Alan mentioned in his excellent morning discussion, there are also indications of an easterly wave moving along under the upper level ridge that may provide a little better chance of some cooling, late afternoon showers or storms by early next week.
Until then, stay cool, stay tuned, and check back for updates.