Storms and Continued Warmth Through Halloween

October is turning out to be the new September. Temperatures this month will likely make this the 5th warmest October on record for Tulsa.  Our average high temperatures continue to dip a degree every two or three days.  Our ACTUAL high temperatures have leveled out in mild to warm range over the past few weeks.  That means, each day’s warmth becomes more and more unseasonable.  There’s no sign of that changing anytime soon.

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                The culprit is a zonal jet stream.  That means the flow of the upper-level winds are generally from west to east without any substantial troughs or dips over the central U.S.  We’ve had a few days where cooler air has made a run at our state, but the progressive pattern has allowed warmer air beneath ridges of high pressure to build back into our area quickly. This pattern is likely to continue for another week or two.

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                There is a kink in this flow, which is indicative of a storm system, arriving Wednesday. It’s a fast-moving, low-amplitude shortwave so the impact on temperature is very minimal. However, it will generate enough lift and interact with enough moisture to give us a chance of rain and storms, starting Wednesday morning. Storms may fire later tonight with the leftovers reaching parts of northeast Oklahoma around sunrise.  The main upper-level energy will be past Oklahoma by afternoon, but the lingering surface front may be enough to trigger more storms with afternoon heating. Instability may be strong enough for a few instances of large hail and locally strong winds. The risk map below shows that it’s a low-end threat and storms (and even rainfall) will be spotty.  It’s just not a super potent storm.

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                In its wake, unseasonably warm air will linger and build.  By Friday, our winds turn southerly and sunshine that day could propel us to another record or near-record high of 86°.  Another dry, fairly weak cold front will sink south into our area over the weekend, but once again, that zonal flow in the jet stream keeps any cold, Canadian air from really reaching us.

                Once we get to Halloween, it sure won’t feel like it weather-wise. High temperatures will likely be in the 80s, about 15° above normal. Instead of adding the layers on the trick-or-treaters, they’ll be hoping to have a well-ventilated costume this year!  It’ll be nice and dry, but there will not be that characteristic chill in the air (unless you spook easily of course).

                Our temperatures usually take a pretty dramatic nose-dive in November, but this year, this warm spell is likely to continue perhaps a full week into the new month. Below, you’ll see the outlook for this time frame. The difference from where we are now and where we’ll be in November is a more active storm pattern.  While these storms may not bring much cold air initially, they may tap into more moisture and bring us much-needed rainfall.  Tulsa is nearly 10” behind on rain for the year!  We aren’t noticing any big pattern change in the jet stream until we get to perhaps the first weekend in November when stronger pieces of energy aloft may try to latch onto some of the building cold air in the high latitudes and shove it south.  At some point in time, we’ll be playing catch up with our seasonal cool-down. In the end, it’ll just be a bigger shock to our system once we get there.

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              One final note about the warmth: it is having a sizable impact on our fall foliage this season.  Sunshine and warmth both play a role in how quickly our leaves lose their green pigment. We are delayed by one to two weeks in Green Country… meaning it will be green just a bit longer this fall. Some places in far eastern Oklahoma already have some nice color, but the rest of us, especially in the city of Tulsa, may have to wait until the second week in November or even slightly later for peak color. We’ve had mixed signals on how vibrant the colors will be.  A wetter spring and early summer bode well for color. The recent warmth and drought does not.  Hopefully we’ll still enjoy these bright colors in the coming weeks, without a strong wind to knock them down too quickly!

                Enjoy the warmth!  These consistent “bonus” days are sure a treat for many of us and not all that common by now.  For more weather updates, be sure to follow me on Twitter: @GroganontheGO and on my Facebook page!