They let me out of my cage for a few days, back in the saddle now. Notice the first map, courtesy of the OK Mesonet, which shows the 24 hour temperature change as of late this afternoon. Obviously, much colder air has moved into the state and it will hang around for a while. In fact, notice the max/min temperature map for today where temperatures did not get above freezing for the western counties and the high temperatures for the eastern counties were not much above freezing. Actually, those numbers are misleading as for the most part the maximum temperatures for today occurred during the late night and early morning hours.
Now that the cold air is in place, there are several forecast issues in the days ahead. Since this is relatively shallow but very cold air, it is typically not handled very well by our numerical forecast models which have a tendency to warm things up too quickly at the surface. At the same time, much warmer air aloft will be spreading over the state so that we will have a vertical temperature profile in which the coldest air will be near the ground with a layer of warmer air just above the ground and then colder air again further up. Bottom line is the location of the freezing line at the surface and aloft will be highly uncertain over the next few days making it very difficult to pinpoint precipitation type and amounts. Notice the third graphic which provides an explanation of how the vertical temperature profile impacts precipitation type.
Notice also the 7 day QPF map which is the third map. It does suggest as much as ½” of precipitation which would be pretty well confined from late Thu into Sat morning. With the kind of temperatures expected, obviously there could be some travel issues.
Here is how we see it at this time. Tonight and Wednesday will just be cold. Cloudy skies and a brisk northerly wind will keep temperatures from totally bottoming out tonight, but morning lows in the teens to low 20s along with winds of 10-15 mph will bring wind chill values into the low teens and perhaps even the single digits at times. We should see a few breaks in the clouds by Wednesday afternoon along with much lighter winds, but temperatures are expected to stay below freezing all day. For any New Year's Eve festivities, just plain cold with temperatures in the 20s overnight and to start New Year's Day along with mostly cloudy skies.
Cloudy skies for New Year's Day but a light southerly wind will try to warm things up and we should make it just above freezing. However, the air will also be relatively dry and some light precipitation should begin by late in the day, particularly for the more southern counties in response to a disturbance aloft. That will lead to at least the potential for a mixed bag of freezing rain or sleet for that evening and into the night, again more likely further south. The warmer air aloft will produce rain, but as it falls through the cold, drier air near the surface, evaporative cooling will likely bring surface temperatures to near or just below freezing; thus the potential for sleet or freezing rain. Amounts are expected to be very light at this time and the winds are expected to be very light; so, the only real impacts would be on bridges and overpasses for Thursday night.
Friday morning should start off with a break but a stronger system aloft will be moving across the state that afternoon through that night. By then, temperatures should have moderated above freezing so this would be a very cold rain event and that is when most of the precipitation shown on the QPF map should occur. As that system moves on eastward Friday night, the backside will then have colder temperatures at the surface and aloft so that snow is likely into early Saturday morning. An inch or so will be possible by the time that ends.
After that, our skies should be clearing from W-E during the day Saturday, but as you can see on the extended forecast, temperatures will remain quite cold and we expect to stay below the 40 degree mark through the weekend. Some moderation will be possible early next week.
So, this is a relatively low confidence forecast scenario we are dealing with potential impacts ranging from only some minimal travel issues to something much more significant. Subsequent model solutions will hope to pin down some of those uncertainties over the next 24 hours or so.
In the meantime, stay tuned and check back for updates.