Our temperature trend has been remarkable for the first week of the new year. Temperatures remained below freezing for the first two days of 2019 and rose all the way to a high of 70° on Monday! It’s not all that uncommon to see big temperature swings in the middle of winter. Oklahoma often finds itself on the cusp of Arctic air lending itself to big changes in short time frames. In the case of the week ahead, the change will be a bit more gradual, but quite noticeable – especially as our next storm system draws near.


                That storm system is just moving ashore in California and will be better sampled by our surface and upper-air measurement tools in the next day or so. That means in about 24 hours, our confidence in how this system evolves for us in Oklahoma will be higher. In the meantime, here’s how it looks. Clouds will increase late Wednesday night into Thursday, but we should be dry through then. Thursday night into early Friday, drizzle and showers will begin to break out across the area. This should then turn into a steady light to moderate rain during the day Friday. Above is the overall set-up, showing the upper-level low triggering this broad area of rain. Below is the timeline for precipitation.


                As of now, our temperatures should manage to stay above freezing for the duration of this event. Barely, though. As the air becomes saturated Friday, our temperatures are likely to level out in the 30s. As that upper low moves over Friday night into early Saturday, the air aloft should cool enough that some snow could form and fall. This may drop temperatures near enough to freezing that very minor accumulations could occur on grassy surfaces, mainly northeast of Tulsa. There just will not be much cold air advection (movement into our area) until after the forcing for precipitation is past. Should the temperatures come in just a few degrees colder, this could be a full-blown winter storm. We are just in better shape because Arctic air has retreated well to the north. If you are driving into Kansas, Missouri or even the Ozarks of Arkansas this weekend, you might be traveling onto snow-covered roads just beyond the Oklahoma border. Stay tuned for more on this system as it gets closer!


                Our late-week storm will have enough cold air to bring our temperatures below normal for a few days, at least for highs. Then by early next week, mild air surges back into the region with another ridge building overhead. As is often the case in an El Niño year, the southern branch of the jet stream is our main weather-maker. While this keeps Arctic air locked up to the north, it means we often see a conveyer belt of storm systems. This could leave us with a wetter than normal second half of January as well while maintaining the unseasonable warmth overall as shown below. For those wanting snow, just remember we have more than half of the winter still to go!



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