#2374 Postby wall_cloud » Tue Jan 18, 2011 2:09 am
a cursory glance at the models tells me that the cold air is forecast to arrive in north TX during the day Thursday. the NAM suggests a more realistic baroclinic zone across northwest TX with the modified arctic air already plunging south on the backside of the surface low across west TX. It also shows a nice thermal ridge at 850mb which would indicate strong warm advection and likely isentropic lift across north TX. I think we could expect an active warm conveyor belt with light/moderate rain occurring across the region (which I believe is underdone by the NAM).
The front then sweeps south and east across north TX, very near DFW by midday and continues to barrel south with strong cold advection setting in throughout the remainder of the day/night. The upper level trof is forecast to swing through the area pretty quickly which would mean the precip would shut off fairly quickly as subsidence overtakes the region. The models also suggest an open wave as the system moves across the Plains but given the strength of the baroclinic zone along the arctic boundary I would not be surprised if the low closed off and developed a modest region of precipitation wrapping around the low.
I had planned on showing some sounding examples from Bufkit but I'm on a new PC and I'm having password/FTP issues so you'll have to do without! Bottom line, I tend to forecast arctic fronts a bit faster than anticipated by the last front (last week) arrived slower than I had anticipated. So I'm not necessarily going to jump on board with that tendency yet. Put it this way, if the front arrives early (before 18z), I would expect some type of winter mix or light changeover but don't expect a whole lot. This system is moving pretty quick so it won't last long. If the front is slower, you may only get rain. Right now I'd lean toward a quicker change over across northeast TX. DFW, you may miss out again. We sure will down here.
In summary, some differences do exist between the GFS/NAM but they are not significant regarding the larger scale features. I did not analyze the GEM/ECMWF/Ensembles etc due to the brevity of my post (and the fact that a pissed off 2 year old interrupted me!). I think you'll see more liquid precip in north/northeast TX but could see a changeover to sleet/snow before it all ends Thursday evening. I wouldn't anticipate significant winter wx but that's why you have an NWS office there. I'm sure they've analyzed the crap out of this scenario while I've been enjoying some 40 year old Virgin and chips and salsa on my day off!
0 likes
My comments are my own and do not reflect those of NOAA or the National Weather Service.