Here in the heart of winter, we find ourselves facing a classic Arctic Outbreak of air. It’s not set to occur for another couple of days, but confidence is gradually growing on how this winter storm evolves. It involves both the chance of thunderstorms and snow within 12 hours of each followed by wind chill values down to 0°.

                The weather up until the weekend will be quite mild in comparison. Temperatures are projected to stay above freezing now until the Saturday morning. A weak storm system may bring a few showers tonight across northeast Oklahoma. Otherwise, our weather will remain rather quiet until Friday afternoon. That is when the main forcing arrives, triggering widespread showers and some storms on the warm side of the system as shown above. Our initial concern will be on the strong storm and flooding threat. Instability is lacking (as is usually the case this time of year), but the strength of the overall upper-level energy may be enough to trigger some hail-makers and strong gusts of wind, mainly across southeast Oklahoma. We can’t rule out some thunder and heavy rainfall around Tulsa after dark on Friday, but the main threat of severe weather will remain closer to the Red River it appears now. However, enough rain may fall in a few hours to generate some flash flooding. Our saturated soils just can’t take on much water without run-off right now.

 

Now we turn to the wintry side of this storm. How it evolves is a lot less certain this far out, but here’s what we know. Arctic air will arrive early Saturday morning behind a sharp cold front. This will allow for any rain to change readily over to sleet and snow. Strong north winds up to or even over 30 mph will drop our wind chill into the teens and single digits later in the day as actual temperatures fall into the 20s by mid-morning for the Tulsa area. This means that any snow will cause visibilities to quickly be reduced and accumulating snowfall to drift.

 

Here is what we believe is likely. A band of snow is likely to form on the wrap-around part of this system somewhere across Green Country early Saturday and move eastward, out of the area later in the afternoon. Some of the snow could fall at a moderate or even heavy rate. Where that occurs, a couple inches of snow will likely accumulate. Elsewhere, light to occasionally moderate snow may occur for a short stretch bringing a dusting to an inch. Parts of the area may miss out on any accumulating snow due to a dry slot in the system. This dry slot could be more prevalent across the area if the system takes a more northward path. It’s likely the snow will fall between 6am and 3pm with some wiggle room. One computer model doesn’t wrap up the snow until after dark.

 

Here's what is still unknown: where the heaviest band of snow sets up. We may not even have a clear idea of that until Friday evening just due to the small-scale factors that allow that to occur. It’s very possible that the heaviest snow stays north into Kansas and Missouri and we just end up with a few snow showers. The other unknown factor is how travel will be impacted. It should be cold enough for all snow during the day Saturday for Tulsa northward, but ground temperatures may initially keep surfaces wet. Any heavy rate of snow will likely cause roads to quickly become slick and hazardous. Blowing snow may also cause brief near-white-out conditions.

Once this is out of our hair Saturday, we’ll have to contend with wind chill values dropping to around 0° that night. Fortunately, the latest data does not look as cold as it did before. It is still a good bet that this is the coldest air of the season, at least until the middle of next week when another Arctic cold front arrives. The next two weeks offer several serious cold spells with near-average temperatures in between. Hopefully it will be cold enough to take care of some outdoor pests, but not cold enough to cause many pipes to burst. Now is the time to take inventory of that cold weather gear – you will not want to be caught lacking in your winter wardrobe through the end of January! Snow-lovers may finally get what they’ve been wanting all season as well!

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