We're optimistic a major pattern change will occur for the second half of the weekend with below normal temps following for most if not all of next week. But today should be the hottest day of the current summer season with readings near or even above 100 from Tulsa to the west. Temperature heat index values ( THI) will be from 105 to 112 and our friends from the National Weather Service will continue an excessive heat warning for most of eastern OK through Friday evening.
The big ridge of high pressure in the mid-levels has now migrated to the Rockies and has increased intensity during the last 24 hours. This ridge will weak after today and continue to retro-grade ( move westward) this weekend as a major upper level trough ( colder air aloft) develops across Hudson Bay Canada and drops southward across the Midwestern portion of the United States. This highly unusual pattern for late June and early July will have big benefits for our area regarding the temperatures, but it will take a few days to see this pattern paying dividends for our part of the state.
The first change in the weather will be later tonight as a weak surface boundary ( cold front) will slide southward from southeastern Kansas into northern and central OK by early Friday morning. A line of thunderstorm activity is likely to occur across southern and central Kansas but it's unclear about the coverage across northeastern OK. Some of the operational models attempt to limit the coverage of thunderstorm activity later tonight and early Friday morning and we'll continue to keep only a 20 to 30% pop in the forecast. The time period or window for storms will open around 8pm tonight and close around 2am Friday morning. Any storms during this window would be strong to severe with damaging winds the main threat followed by large hail.
The front will slide across northern OK and stall near or south of I-40 Friday midday. The presence of slightly drier air across southern Kansas and northern OK will cut down the THI values, but the dry air can also heat very efficiently. This means Friday's highs, even behind the cold front, will probably be in the mid-90s and could be even warmer than our currently advertised high of 96.
A second and more significant cold front will sweep over the area Saturday evening into Sunday morning bringing a very slight chance of storms. Northeast winds Sunday will usher in more dry air for the northern part of the state, while southern OK could see a few showers or storms Sunday midday to early evening. Highs Sunday across northern OK will top out around 90 to 93 with gusty north winds.
Monday morning the dry air will allow morning lows in the lower to mid-60s followed by afternoon highs in the mid-80s! The main upper air pattern will keep the "not as hot" air across the central and portions of the southern plains for most of the next week. A trough (possibly closed type low) will be nearing our area Wednesday and could provide storm chances for the middle to end of next week including the July 4th holiday.
The official high in Tulsa yesterday was 96 from 5:11pm.
The normal daily average high is 91 and the low is 71.
Daily records for today include a high of 106 from 2011 and a low of 53 from 1968.
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You'll hear my state-wide and regional weather forecast discussions on numerous Radio Oklahoma News Network affiliates across the state through the noon hour today.
I'll also be discussing our forecast with Dan Potter and The KRMG Morning News in Tulsa today, and possibly Friday morning.
Thanks for reading the Thursday Morning Weather Discussion and Blog.
Have a great day!