Now that the month of May is history, there are several notable weather events of this past month and so far this year. Notice for example, the 30 day rainfall totals across the state, courtesy of the good folks at the OK Mesonet. It may have seemed like a very wet month, but as you can see there has been considerable variation from one place to the next. Officially, this May for Tulsa will go into the record books as a dry month. Our normal rainfall for May is 5.91” and the official amount so far stands at 3.01” so we are 2” below normal.
It has also been a cool month compared to normal; in fact, the first calendar month that has been below normal since August of last year. As an example of how relatively cool the month has been, we have not had a 90 degree day yet this month. By the way, there were no 90 degree days in May of last year either which was also cooler than normal but May of last year was much wetter than what we have experienced this year.
The pattern that has produced the widespread clouds and occasional periods of rain, showers, and storms over the last week or two will persist for at least another couple of days. A weak surface boundary is slowly working its way into the state today and will continue to slowly move southward over the next few days before getting a more substantial push over the weekend. With the weak surface boundary in the area and a generally favorable wind pattern aloft, look for cloudy to mostly cloudy skies to be the general rule for the rest of this week with only some occasional breaks in the cloud deck. That also means occasional periods of rain, showers, and the possibility of some locally heavy storms.
Notice the 7 day QPF map for example which suggests a pretty good N/S gradient with the heaviest rainfall over the more southern counties as compared to lesser amounts along the OK/KS state line. That is due to the surface boundary working its way slowly southward in the coming days and providing the main focus for showers/storms. However, keep in mind this is an areal average and locally much higher amounts remain possible most anywhere one of those scattered storms develops.
The cloudy skies and periods of rain/showers/storms during each of the next couple of days will keep our daytime highs in the 70s. At the same time, a general E to NE surface wind will also keep dew point temperatures in the 60s which means our overnight lows will be generally in the 60s. Normal going into the month of June is 83/64 for the max/min so the month will start off somewhat cooler than normal.
By the weekend, as mentioned earlier, the surface boundary should finally get more of a shove further southward bringing drier air at the surface and aloft over the state. That translates into more sunshine but the northerly surface winds should keep temperatures from getting out of hand. In fact, as you can see on our forecast page, daytime temperatures are not expected to make it above normal till early next week.
Looking further down the road, the 8-14 day outlook suggests that the active pattern of recent weeks will not return as below normal chances of showers/storms are expected during that week. Temperatures are expected to trend closer to normal over that time frame.
So, stay tuned and check back for updates.