5/22 5/23 5/24 5/25 5/26
0.371 0.467 0.616 0.255 0.420
The rows of numbers above represent the dates of May 22-26 on top and the corresponding evaporation rates from Lake Skiatook are the numbers on the bottom. This data is available for many of the lakes across the state through the local Corps of Engineers office and can be accessed here. I mention this to illustrate how quickly things can dry out when we have the sunny skies, very warm temperatures, low humidity values, and gusty winds such as we have experienced lately. When the evaporation rates can exceed ½ inch per day as has already been occurring, and you add to that the moisture that the growing vegetation is pulling out of the ground, it does not take long for the moisture in the soil to become depleted as well. The map on the right, courtesy of the OK Mesonet, illustrates how dry the soils are becoming.
Obviously, we need a good, widespread, soaking rain before our Spring rainy season comes to an end which usually occurs after the first couple of weeks in June. So far, we are on pace to set a record for the driest May ever, not only here in Tulsa but statewide. Fortunately, we are looking at a decent shot at some good rains before the month is over as was illustrated in the morning discussion. That has not changed as the middle of the coming week still has a good chance for widespread showers and storms, some of which may become severe as well. If so, it appears that winds/hail would be the primary threats.
In the meantime, we have another hot day ahead of us on Memorial Day itself. An approaching cool front will be moving across the state late in the day and overnight, but with a SSW wind ahead of the boundary and partly cloudy skies, temperatures will be about 10 degrees above normal once again. Any threat of showers or storms for Memorial Day should hold off till during the evening or overnight hours followed by better chances on Tuesday and better yet for the Wed-Thu time frame. In fact, the most recent data suggests that Wednesday night into Thursday morning may well see the best chance for rain.
The position of the stalling frontal boundary could wreck havoc with the forecast temperatures due to NE winds and milder conditions behind the boundary and SE winds and much above normal temperatures ahead of the boundary. Right now, it appears the boundary will stall out somewhere between I-40 and hwy 412 on Tuesday into Wednesday and will finally get a push on southward for Thursday. The temperature forecast is an attempt to strike the middle ground in that regard.
By Thursday and for Friday, much milder air should prevail as the boundary should have moved much further south by then. That means Friday into Saturday are looking pretty good, but a return to hot, humid conditions is likely by Sunday as our winds come back around to the south.
So, stay tuned and check back for updates.