Interesting, Very Interesting for Saturday.

Hope you enjoyed the cool start to our day as the next time we have temperatures that cool will probably not occur till sometime in September.  Notice the max/min values across the state today, courtesy of the OK Mesonet, and you can see that after that cool start, temperatures rebounded quite well this afternoon, particularly in the SW corner of the state where Hollis made triple digits.  For Tulsa, so far today the max/min has been 84/50 and you can click here for the normal and extreme values.

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Tonight will be much warmer as the brisk southerly winds of today will continue through the overnight hours and the dew point temperature will be rising through the night as well.  Bottom line is that the morning lows to start the day on Friday will be in the mid-upper 60s to near 70.  Afternoon temperatures will range from the upper 80s to the lower 90s so this will be one of the hottest days so far this year.  As we go through the day, we will have partly cloudy skies but a weak surface boundary will try to make it to near the I-44 corridor by late afternoon.  Together with the heat and humidity levels that will be present, that would ordinarily pose a threat of storms.  Problem is that a layer of very warm, dry air a few thousand feet above the surface will effectively provide a lid that will make it very difficult for any storms to develop.  If, and that is a big if, a storm does form in this environment late in the day, it would pose a severe threat, primarily wind/hail.  For now, will only carry a slight 10% chance of an isolated storm or two for late Friday afternoon into the early night time hours.

For Saturday, that surface boundary will have retreated back to the west by early morning and a stronger cool front will be moving this way which is expected to arrive along the I-44 corridor around sunset.  Saturday will also be very warm and humid as you can see on our forecast page.  Saturday will also be very interesting from a storm perspective as the combination of heat and humidity will result in extreme values of CAPE(Convective Available Potential Energy).  Notice the map of projected CAPE values valid Saturday evening; I have labeled the extreme values which are in excess of 6000 and I have also drawn an approximate frontal position on the map for that evening.

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I mention the CAPE values because that is a measure of the instability present for storm formation.  Although there will be another strong capping inversion present for much of the day, the approaching cool front will likely provide enough lift to overcome that limitation and storms are expected to be developing that evening.  Given those extreme values of CAPE, the storms that do develop will be explosive and will have the potential for very large hail which also implies damaging down burst winds.  Tornadoes will also be possible although the dynamics are somewhat limited in that regard. 

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Torrential rainfall will also accompany the storms that do form but at least the potential for storms to repeatedly move over the same location appears to be minimal so excessive amounts of rain are not expected.  Notice the QPF values suggest the potential for an inch or so, primarily over the more E/SE counties but those amounts could fall in a very short time resulting in some local drainage issues.

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After that, the front will push on southward with the possibility of a few lingering showers into the early morning hours of Sunday.  But, brisk northerly winds will bring drier, somewhat cooler air back into the state leading to some pleasant weather for the rest of the Memorial Day weekend, including Memorial Day itself.

After that, our next chance for showers/storms looks to be along about the middle of next week.  Also, the longer range guidance for the 8-14 day period is still suggesting another active period along with a trend to below normal temperatures as we go on into June.  

So, stay tuned for updates.

Dick Faurot