Round three, here it comes.
The third in our series of winter weather events is still on schedule to arrive late tonight and through the day Wednesday before moving out Wednesday night. Fortunately, this promises to be the last one as a much more stable weather pattern will prevail through the coming weekend and well into the following week.
Early tonight will be relatively mild with a good chance of showers, rain, drizzle, fog, etc., with southerly winds and temperatures in the 40s. Then, a strong cold front will arrive followed by strong northerly winds and temperatures falling below freezing by early morning and staying in the 20s all day Wednesday.
Northerly winds of 15-25 mph with higher gusts will bring wind chill values down into the teens and perhaps even the single digits at times so it will be brutally cold all day.
As the shallow, cold air at the surface surges southward the rain and showers will transition over to freezing rain, sleet, and then snow. That transition will develop as the air column aloft cools and that will take place more slowly than the cooling that occurs at the surface. That is why the precipitation type and time of transition is so difficult to pin point at any particular location and those factors will play a huge role in total accumulations of wintry precipitation.
Notice the first graphic, which I have referenced in the past, which illustrates the vertical profile of temperature for different precipitation types. We can thank our excellent OK Mesonet for providing surface temperatures every 5 minutes across the state, but we only receive data above the surface twice a day, so that is where the real question marks come in.
The next graphic is one example of model guidance showing the transition from rain to freezing rain to sleet to snow (green to blue on the color scale) and is valid at 8:30 Wednesday morning; that transition occurs as the colder air at the surface and aloft continues to surge southward during the day.
Notice the estimated QPF map, valid through Thursday morning, which suggests up to ½” or more of liquid for much of E OK. If that were to all fall as snow, and, assuming a 10:1 snow:rain ratio, we would be looking at 5-6” or perhaps more. But, since there will be that transition from rain to a mixed bag before finally becoming all snow, the actual snowfall should be much less. Best estimate at this time suggests anywhere from 1-4” of snow as shown on the snowfall graphic.
Keep in mind though, that the snow will fall on top of sleet and/or freezing rain, so travel will be tricky to say the least. Also, there will likely be some banding that will drop, locally, heavier amounts of frozen/freezing precipitation and when/where those develop is something that is only apparent in real time and cannot be forecast in advance.
The wintry precipitation will be ending from W-E Wednesday night followed by clearing skies by Thursday morning. That means Thursday will finally have abundant sunshine but with NE winds and snow/sleet on the ground it will still be cold.
After that, mostly sunny skies will prevail and, as you can see on our forecast page, temperatures will begin to finally rebound. In fact, we should be at or perhaps even a bit warmer than normal during the day by this weekend and warmer than normal temperatures are expected through all of next week.
So, hang in there, there is a light at the end of the tunnel. Also, stay tuned and check back for updates as this is a very dynamic system coming our way and there will be some changes and perhaps even a few surprises by the time it is all over with.