TULSA, Oklahoma - The mid-level ridge of high pressure will expand from the central plains into most of eastern Oklahoma Thursday night into Friday setting the stage for some hot weather to arrive across eastern Oklahoma.  The only issue may continue to be a few scattered showers or storms today and an isolated storm chance Thursday and Friday along the Oklahoma-Arkansas and the Red River Valley regions.  The GFS remains aggressive with a few storms Friday into the weekend across eastern Oklahoma that would keep our highs down a few degrees but, right or wrong, we have discounted this solution due to the magnitude of the expected mid-level ridge. The heat index values may also continue to slowly climb to near advisory levels through Friday before drier air mixes down the dew points a few degrees and consequently lowers the RH but brings the temps up.   NWS Heat advisory criteria (regarding heat index values) is 105 to 109 for eastern Oklahoma.  Heat advisories are also issued when actual temperatures are forecast from 103 or higher.   Heat warnings are issued by the NWS when index values are forecast from 110 or higher or actual temperatures from 105 or higher.   Past criteria also had a morning low criterion (max low reading) but is no longer used.

Our main issues will continue to be the possible influence of some easterly wave action for the next few days despite the southward expansion of the ridge.  The 12k NAM is developing another vort across north TX Thursday and then lifts this feature to the northwest, on the western side of the 594 ridge.  The GFS brings this disturbance more northward and that’s why the model is cranking out some QPF for eastern Oklahoma Friday into the weekend.  Again, we’re banking on this feature remaining right along the western periphery of the ridge and having little impact precip wise on our area. 

Data continue to differ regarding what happens next week with another western U.S. trough influencing the nation with a surface front possibly nearing the central plains Monday into Wednesday and near our area sometime next week.  The EURO continues to keep this boundary along the southern Kansas region until about Wednesday night into Thursday while the GFS brings the boundary into the state early next week.  We’ll not make any big changes at this point to the forecast and will see how the data stacks up for the next few days before offering some temp reductions and adding a few storm chances for the middle of next week.   At this point, our forecast brings this boundary near our area next Thursday.   Before this happens, the southwest surface profile may allow slightly lower dew points next week which would cause the temps to move upward. 

Thanks for reading the Wednesday morning weather discussion and blog.