Texas winter weather thread - Cold snap next week

[Extremeweatherguy]

everyone in Houston should watch the weather forecast video on ABC13.com (scroll down and look on the right hand side of the screen to get to the video):

http://abclocal.go.com/ktrk/index?secti ... id=4118234

The meteorologist mentions that we have to watch closely in Houston for a possible change over from rain to winter precipitation if the situation is right. I know the chances are low, but just the fact he is saying this is pretty exciting.

[wall_cloud]

the front is already through GCK and DDC. It will be in the TX panhandle in another 2 hours or so. well ahead of what any models were spitting out (I have been off for about 36 hours so they may have changed a bit). at AMA, we kept the frontal timing Tue night despite the slower models and it looks pretty good. The models typically are too slow with this type of airmass. The density alone should push this airmass (modified of course) all the way to the coast. It will be a cool (to cold) 2nd half of the week for almost all of TX

[Portastorm]

the front is already through GCK and DDC. It will be in the TX panhandle in another 2 hours or so. well ahead of what any models were spitting out (I have been off for about 36 hours so they may have changed a bit). at AMA, we kept the frontal timing Tue night despite the slower models and it looks pretty good. The models typically are too slow with this type of airmass. The density alone should push this airmass (modified of course) all the way to the coast. It will be a cool (to cold) 2nd half of the week for almost all of TX

Now that is some interesting info, wall_cloud. Somewhere I seem to recall reading that cold fronts slow during the day and move quicker at night ... is that right? Oh well, the plot thickens ...

[Extremeweatherguy]

Latest temperatures:



It is pretty interesting to see almost an entire state below 0F right now.

[Yankeegirl]

Yeah, thats one cold state... makes me cold just lookin at it!

[JenBayles]

The models typically are too slow with this type of airmass.

Can anyone answer this question for me: I so often hear these types of comments with either winter cold air masses or tropical systems, so why are the models not adjusted accordingly? Obviously, I am not even a good amateur met, but I have enough computer experience to understand tweaking a program here and there. Why is it that everyone seems to know about various faults in the models, but those faults never seem to be corrected?

[Yankeegirl]

Because its men running the show.... JUST KIDDING!!!!!

[vbhoutex]

The models typically are too slow with this type of airmass.

Can anyone answer this question for me: I so often hear these types of comments with either winter cold air masses or tropical systems, so why are the models not adjusted accordingly? Obviously, I am not even a good amateur met, but I have enough computer experience to understand tweaking a program here and there. Why is it that everyone seems to know about various faults in the models, but those faults never seem to be corrected?

There actually has been quite a bit of tweaking over the last few years and the models are doing better than they used to. However, part of the problem is that the weather is so dynamic and probably not understood(as far as interactions/cause and effect is concerned)nearly as good as we wish it was so that when tweaks are made to the models they have to be hugely comprehensive in order not to "mess up" the model output overall. Sometimes a tweak for one thing could skew other things in the model the wrong way and give false output iow. I know a met who was writing his own tropical model(former NHC employee)and as good as it was he was still working on it and continuing to tweak it each year, sometimes with good consequences and sometimes with not so good consequences.

[aggiecutter]

The front has evidently passed through Dallas as they are already -4. This front has a little more punch than I thought.

Current US TEMPS:

http://twister.sbs.ohio-state.edu/surface/ustemp.gif

[wall_cloud]

another issue is the resolution...both vertically and horizontally. Many of these airmasses tend to be shallow and the lack of good vertical resolution in the low-levels can lead to the airmasses being modified way too fast by the models and not capturing their strength.

As for the previous question, fronts do seem to accelerate at night. I think that is more because duing the day, the stronger mixing makes it more difficult for the front to "plow through".

[Kennethb]

I don't think the front has passed Dallas yet. Even Amarillo still has south winds at 9:00 pm. Probably clear skies has allowed for some heat to escape.

[cheezyWXguy]

uhh...its 73 here

[gboudx]

The front has evidently passed through Dallas as they are already -4. This front has a little more punch than I thought.

Current US TEMPS:

http://twister.sbs.ohio-state.edu/surface/ustemp.gif

I just stepped outside and it doesn't feel like -4. More like about 2.

[Portastorm]

Thanks wall_cloud ... "mixing" ... I should know that by now.

As for the Dallas temp, guys ... aggiecutter is kidding! The map he references messed up the Dallas temp.

[aggiecutter]

You guys are wrong. The Ohio State surface map says it is -4 in Dallas, just click on the link.

http://twister.sbs.ohio-state.edu/surface/ustemp.gif

[wall_cloud]

I don't think the front has passed Dallas yet. Even Amarillo still has south winds at 9:00 pm. Probably clear skies has allowed for some heat to escape.

the front is just now moving into the OK panhandle. Springfield, CO has a 20kt north wind and is 34 degrees. Garden City, KS has a NE wind at 25kts and is 33. Guymon, OK has a south wind a 6 mph and is 45 degrees. temps ahead of the front in the panhandles aren't as warm due to the drier boundary layer. There is a good thermal gradient farther east. 36 in Dodge City, 55 in Medicine Lodge.

[Yankeegirl]

lol... dallas sure did get cold real quick... i think the dude inputting the temps in the computer needs some more coffee...

[gatorcane]

another issue is the resolution...both vertically and horizontally. Many of these airmasses tend to be shallow and the lack of good vertical resolution in the low-levels can lead to the airmasses being modified way too fast by the models and not capturing their strength.

As for the previous question, fronts do seem to accelerate at night. I think that is more because duing the day, the stronger mixing makes it more difficult for the front to "plow through".

In Florida the fact that the fronts move quicker at night is definitely true. It seems that nearly every strong front that pushes through the peninsula goes through at night...seems like during the day they have a tougher time.

[Kludge]

The front has evidently passed through Dallas as they are already -4. This front has a little more punch than I thought.

Current US TEMPS:

http://twister.sbs.ohio-state.edu/surface/ustemp.gif

And though funny as heck, this is a case-in-point; somewhere in the system, DFW's temp got registered as -4. You and I both know that this is a goof, but some model will blindly pick it up as real, and incorporate this data into its next run. We caught this one, but this must happen millions of times of day. As bad as the models are, I think it's amazing how close they actually get.

Still, though, I'm always amazed when I see professional and on-camera mets forecasting strictly based on model outputs. I like seeing the old pros go with their gut.

[wall_cloud]

I don't know how much QC goes on with those maps, but I do know that NCEP will throw out the -4 if it made it through to them. It won't contaminate the map. They purge upper air winds (like 150 mb) if they are somewhat out of whack so I'm sure they'll catch this.