Much Colder, Chance of Wintry Precipitation.

Thursday, November 21st 2013, 3:40 pm
By: News On 6

Still looking mighty interesting for later tonight through the day Friday and into Friday night. Not only that but again late Sunday and into Sunday night or Monday morning could be rather interesting as well.

For tonight into the day Friday, the real question mark continues to center around how much precipitation we receive and the precipitation type. The cold air will certainly be in place at the surface and just above the surface, but aloft to around the 5,000 foot level the air will be much warmer with temperatures in the 40s to near 50. Any precipitation that falls through that layer will quickly become all liquid, but as it falls through the colder air near the surface is where it gets interesting. Also, some of the guidance suggests ¼ inch or more may accumulate whereas some of the other guidance suggests much lesser amounts. For now, am leaning toward the lesser amounts, but that could still create some problems.

Temperatures are expected to be near the freezing mark at the surface by first thing Friday morning with even colder air just above that and then the warmer layer above that. As a result, freezing rain and/or sleet should be the primary precipitation type but any variation in the surface and near surface air temperatures could change that to rain with just some ice pellets mixed in or to an all freezing rain event. For now, we are leaning toward the precipitation amounts to be rather light. But, it does not take much ice to create problems, particularly if it is of the freezing rain variety. Elevated surfaces such as trees which in many cases still have quite a few leaves, power lines, and that sort of thing have the greatest risk of becoming coated with ice and with northerly winds of 20+mph, that could create some issues.


Travel should have minimal impacts largely due to the very warm ground temperatures. Notice the soil temperature map on the right, courtesy of the OK Mesonet. That is at the 2 inch level under sod and typically the soils cool off rather slowly despite the dramatic change in air temperatures. Of course, elevated surfaces such as some bridges and overpasses will quickly cool to the air temperature and there could be some ice accumulation at those locations.

As the cold front passes through this afternoon, strong northerly winds of 20 mph or more will continue through the rest of the night and much of the day Friday. Together with air temperatures holding around the freezing mark, that will put wind chill values in the teens and lows 20s all day Friday. As mentioned, there will also be some occasional light freezing rain, sleet, drizzle, or a very cold rain depending on location for much of the day. That should be tapering off Friday night with only a slight chance into the day Saturday and Saturday night and primarily for the more southern counties at that.

However, cloudy skies and a north wind will keep daytime temperatures in the 30s all day Saturday and Sunday as well for that matter. Also, another disturbance aloft will be passing overhead later Sunday into early next week and this system will have somewhat colder air aloft associated with it. It will be spreading a cold rain our way again during the day Sunday and the temperature profile aloft makes the precipitation type for Sunday night into Monday morning questionable once again. A wintry mix certainly will be possible. This will keep Monday into Tuesday also in the 30s with a chance of lingering light precipitation finally ending by Wednesday. That should lead to improving, but cool conditions going into Thanksgiving Day itself.

As always, stay tuned and check back for updates.

Dick Faurot