From a Cold to Stormy Start to Spring

Temperatures on Monday took a big downward turn behind a strong early spring storm system. It mostly spared Green Country from severe weather, but we’ll feel the effects of it for the next few days as colder air continues to filter into the region. As we flip the season over to spring officially on Tuesday, we’ll still be stuck in this more winter-like set-up. But that will be changing significantly before Spring Break week is over.

                The vernal equinox (fancy term for the start of astronomical spring) is 11:15am Tuesday Central Time. That is when the rays of the sun are directly perpendicular to the Equator. We are seeing our days length because of this northward shift in the solar rays. What you wouldn’t perceive in this cool spell is that each day moving forward has more warming potential due to the more direct sunlight. Later this week, we’ll break into a rapidly warming pattern. Over the next two nights however, wind chill values may drop into the 20s for some places!

                In the process of warming beyond a frosty Wednesday morning, winds will increase again. Despite the quiet weather pattern, we’ll still be on guard for enhanced fire danger. While our vegetation is greening up, we still have enough dormant and dry vegetation to be fuel for wildfires. Perhaps in a week or two, our wildfire season will be officially over. But at least for the remainder of this one, we urge people not to set fires outside of prescribed burns under appropriate conditions. Below, you’ll see our fire threat outlined through Friday.

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                We’ll transition to a potentially stormy pattern starting this weekend as the next trough in the jet stream ejects eastward from the West Coast. This allows Gulf moisture to return to Oklahoma at the surface and waves of energy to race northeastward in the jet stream – a set-up that allows for wind shear and potential severe weather by this time of year (shown below).

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                As we close out Spring Break week, we may see our first round of storms. Unlike in previous storm systems, greater surface warming and moisture may not be as much of an inhibiting factor. It’s too early to expect severe weather by Sunday, but it certainly is a possibility. The pattern essentially gets stuck like this for much of next week, allowing for several rounds of rain and storms to impact Green Country. If Sunday or next Monday doesn’t prove to be a threat, other days in the following week might. If we carry on the tradition of recent years, the last week in March could be our first encounter with tornadoes in the season. The Outlook below shows above-normal rainfall potential through the end of March and Easter weekend.

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                When it comes to long-range forecasting, it’s hard to be anything but general and here is a visual example why. The further out in time we go, our computer models display greater levels of chaos because of the added factors through time that can change any particular outcome. The first image is the first of several “Spaghetti plots” that show the orientation of the upper-level air thickness just two days out. Most of the lines are packed together, indicating high confidence in that weather pattern.

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                Go beyond a week and you usually find a spaghetti plot showing many variations of a computer model (known as an ensemble) with wildly different solutions. Picking one or averaging them out, even with their known biases leaves a whole lot of room for error. This would lead to a forecast that changes significantly as that time frame gets closer. As computing power grows, we’ll likely end up with better and better data to use for forecasts that far out. But even the best short-term model guidance falls short of providing perfectly precise forecasts.  All of this is to say that a forecast for the next day or two should be regarded with much higher confidence than one beyond a week when it comes to the specifics. Hopefully that helps your understanding as we start to predict severe weather in the coming season!

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                  Be sure to go to my Facebook page to see my favorite Spaghetti Plot image!  Enjoy Spring Break week and the warming trend to come. For more weather updates, be sure to follow me on Twitter: @GroganontheGO as well.