Winter Weather Update

Even after the NWS today issued a Winter Storm Watch for all of North Texas starting Friday night, I was still being stubborn. After looking at the 00Z ETA this evening, it's even tougher to continue sticking with my forecast. We're only talking a range of 5 degrees here which is within typical error range this far out. However, the cold ari up in the central plains at this hour is pretty strong and cold with single digits in Nebraska and NW Kansas. It's sub-zero in the western fringes of Nebraska as I write. That's colder than I expected and is certainly on par with the ETA 6-hour forecast. Some of that will filter down into Texas. The other caveat is that the upper system out west isn't quite as strong resulting in a little weaker zonal flow. This will allow more of the cold air to ooze south rather than get swept eastward. With expected evaporative cooling from the precipitation along with everything else I mentioned, I see no reason to doubt the forecast temperatures. This spells trouble for Northern Texas for freezing rain and sleet as the cold air will be shallow.

As far as precip, the NAM is really showing a good 850mb pattern for warmer, humid overrunning from generally the south with pretty strong 700mb winds from the SW. I've seen this exact pattern on numerous occassions produce more precipitation than the models forecast. We almost always can be guaranteed a few ripples and impulses in the upper flow trekking across the area which are rarely picked up or handled well by the models. So, I'm pretty confident that we'll see more precip than is currently advertised by the NAM. Look for a trend from this model towards more precip for the weekend. With temps hovering near freezing and a shallow polar airmass in place, this will result in freezing rain and sleet.

I don't see a heavy ice storm at all with this event, but enough to really cause major headaches on the bridges and overpasses. Roads will NOT ice over because the ground has been baking pretty much all winter....it was 85F at DFW today. The ground is extremely warm for this time of year. It will not get cold enough or long enough to ice the roads (except in shadow areas like under bridges). But, bridges and overpasses will turn into a skating rink. If history repeats itself, the TxDOT folks will wait until the bridges ice BEFORE applying sand/salt. Beuracracy at its finest. So, hang around and sleep in until things improve in the afternoons when the temps get above freezing again. I'll be in Denver all weekend for the stormchaser convention. So, I'll miss all the fun. :-)