Muggy summer weather has overstayed its welcome, at least according to the calendar anyway. As we transitioned “officially” to fall last Friday, it felt more like the start of summer. A substantial cold front is slowly pushing into Green Country, bringing that long-awaited drop in temperatures and much-needed rainfall. It’s a change that will set the stage for a series of mild days, but it won’t be the new normal… quite yet.
This storm system has already brought cool, wet conditions to the western third of Oklahoma with some areas receiving nearly 3” of rain, sending temperatures down into the 60s and 50s. It’s a tale of two states though. The state of summer heat and humidity for us in Green Country and the state of fall out west. The upper-level flow is the reason this storm system isn’t barreling at us quickly as the jet stream is more parallel to the orientation to the front’s position. As such, this front will arrive Tuesday morning in northeast Oklahoma and later in the day south of I-40. Thus, we’ll see a range of high temperatures from the 70s to the north to near 90° in southeast Oklahoma.
The rainfall forecast is a bit more nebulous. We’ll see a few waves of energy allowing showers and a few storms to flare up along and behind the front, but the locations of the heavier rain isn’t clearly defined as of yet. If anything, areas west of Tulsa will see a bigger soaking than areas further east, simply due to the weaker forcing the further east you go. You can see estimated rainfall amounts below through midweek.
This storm system will have a lot more bark than bite with widespread cloud cover over the region for several days. The moisture running over the cold front moving north will create the broad cloud shield, but drier air moving south behind the front at the surface will limit what reaches the ground as rain. Post-frontal showers on Wednesday likely dry up by Thursday with the exception of a few sprinkles.
This leads to a beautiful kick-off to the Tulsa State Fair. The mild air lingers will the rain goes away. Daytime highs in the 70s and morning lows in the 50s will remind us that October is nearly here. Eventually we’ll see a shift in the jet stream pattern, forcing the clouds to our east and shifting warmer air back to the north again. This happens as the jet stream lifts well to the north, bringing back the upper-level ridging in a week’s time. That means southerly winds and ample sunshine return as the warming trend ensues. This bodes well for fair-goers as a dry, pleasant pattern takes hold. However, it may get quite toasty to walk the midway during the day by the middle of next week with temperatures pushing well into the 80s and possibly low 90s!
As you can see in the images above, much of the country will be basking in summer-like warmth for the first 8 days of October. If we don’t get much rain in the next few days, we may really be hurting for water in the ground as head later into next month. There are signs of a more powerful cold front in the second week of October that will be much stronger than the current one at hand. This is consistent with climatology. October is usually a month of big changes toward the cooler here in Oklahoma.