Texas winter wx thread (2009-2010)

[Ntxw]

I'm concerned by the forecasts of 3"+ of rain before the front moves through. That would bring some localized flooding problems for sure.

With that much water saturated into the ground I would think that it would take quite some time for the ground to reach freezing even after the air temperature dips below freezing, so I don't anticipate any accumulations of ice or snow except perhaps on overpasses.

More standing water would probably mean a bigger headache overnight. I've noticed that once temps get into the 28ish range doesn't matter how much water there is, it's probably going to freeze over.

[Weatherdude20]

At 34, Is a univerasal temp for snow to stick to grass.

At 32, Moisture freezes.

At 30, All Precip falling from the sky must freeze before some sort of Physical contact.

At 28, If there is present moisture ice forms on roadways.

[msstateguy83]

this pretty much sums it up a graphic from kfor tv out of oklahoma city..

[WacoWx]

^^^thats some pretty bold stuff right there!

[wxman57]

exactly... thats been my point thats why i have been so dang animated about this and to the point, hopefully people on here that listen to us are catching on *IF* the front comes thru early enough this could all spell MAJOR, MAJOR AND I MEAN MAJOR problems with ice & snow... if the air is cold enough in the upper levels it could be a major snowstorm unlike we have seen...

If the front comes through earlier, it'll mean that the precip would end earlier, as the front is moving through just ahead of the upper-level disturbance. So your logic that the heavy precip would shift into the colder airmass is flawed. The heavier precip would just fall earlier - in the above-freezing airmass.

[Ntxw]

Wxman could you explain why Amarillo to OKC would get heavy snow/precip in the cold sector then if that's the logic? I know it's a dumb question but just curiosity, it doesn't seem either is that cold before the storm infact quite a warm up beforehand.

[orangeblood]

exactly... thats been my point thats why i have been so dang animated about this and to the point, hopefully people on here that listen to us are catching on *IF* the front comes thru early enough this could all spell MAJOR, MAJOR AND I MEAN MAJOR problems with ice & snow... if the air is cold enough in the upper levels it could be a major snowstorm unlike we have seen...

If the front comes through earlier, it'll mean that the precip would end earlier, as the front is moving through just ahead of the upper-level disturbance. So your logic that the heavy precip would shift into the colder airmass is flawed. The heavier precip would just fall earlier - in the above-freezing airmass.

I think what wxman57 is saying, correct if I'm wrong, the areal coverage of winter precip wouldn't expand or increase amounts if the front moves in sooner. The winter precip zone would shift further to the south. It appears that the biggest unknown with this forecast is where winter precip will fall not how much winter precip will fall. This forecast seems entirely dependent on where the front is when the storm system comes out of far west Texas.

[Ntxw]

That's a lot of rain just to think I just washed my car . What are your thoughts wxman for the upcoming feb time frame. What is your general idea of where\when winter precip would set up if any?

[weatherguy425]

Guys, he's saying that most of the precip totals are coming from the rain along and ahead of the front, and a sooner front arrival would just mean an earlier onset to the squall line and would havelittle affect on frozen accum.

[wxman57]

Guys, he's saying that most of the precip totals are coming from the rain along and ahead of the front, and a sooner front arrival would just mean an earlier onset to the squall line and would have little affect on frozen accum.

Right, but it DOES depend upon your location. For example, we have to consider the orientation of the cold front. What we expect to happen is for frontogenesis (a front to form) on an east-west orientation across southern Oklahoma early on Thursday. As the upper-level trof moves in later on Thursday, heavy precip breaks out in advance of it. A wave/low will form along the east-west oriented frontal boundary and the cold air will rush southward from the Texas Panhandle into west Texas. From the wave/low, the front will extend to the southwest. East of the low, the front will be oriented east-west.

So OKC-AMA will be in the cold air from the start, as frontogenesis will occur to the south of these two cities. The D-FW area would be south of the developing frontal boundary - in the warm air - when the heavier precip moves across. The only way there could be a significant winter event farther south is if the frontogenesis takes place farther south, because once that NE-SW oriented front trailing out the back side of the low/wave moves through D-FW, for example, that means the upper-level trof is moving through and there isn't much moisture to work with in the cold air.

What governs the location of the frontogenesis? It's the path of the upper-level vorticity center. So we're not watching for the front to move south faster than forecast, as it's not really there yeet. We're looking for a change in the path of the mid to upper-level energy that would shift the frontogenesis zone southward.

[Ntxw]

Learn something new everyday thanks.

[funster]

wxman57 - Cool frontogenesis info - thanks

[Ntxw]

Well, wfaa met Delkus just explained position of the low and says ice accumulations possible from DFW to the north and west.

[PineyWoods]

Right, but it DOES depend upon your location. For example, we have to consider the orientation of the cold front. What we expect to happen is for frontogenesis (a front to form) on an east-west orientation across southern Oklahoma early on Thursday. As the upper-level trof moves in later on Thursday, heavy precip breaks out in advance of it. A wave/low will form along the east-west oriented frontal boundary and the cold air will rush southward from the Texas Panhandle into west Texas. From the wave/low, the front will extend to the southwest. East of the low, the front will be oriented east-west.

So OKC-AMA will be in the cold air from the start, as frontogenesis will occur to the south of these two cities. The D-FW area would be south of the developing frontal boundary - in the warm air - when the heavier precip moves across. The only way there could be a significant winter event farther south is if the frontogenesis takes place farther south, because once that NE-SW oriented front trailing out the back side of the low/wave moves through D-FW, for example, that means the upper-level trof is moving through and there isn't much moisture to work with in the cold air.

What governs the location of the frontogenesis? It's the path of the upper-level vorticity center. So we're not watching for the front to move south faster than forecast, as it's not really there yeet. We're looking for a change in the path of the mid to upper-level energy that would shift the frontogenesis zone southward.

I think even I can understand that sequence of events to occur for the wintry weather to form in. Doesn' t look promising for snow in Tyler with this event.

I think I now realize why I don't like your meteorological analysis ................. It's usually right!

[srainhoutx]

Let's take a look at WV Imagery and see what is going on...

http://adds.aviationweather.noaa.gov/sa ... g&itype=wv

We have a short wave located up in Central Canada rotating around the PV. Also note an Upper Low inland in the Northern Rockies and our storm nearing SO CA. The Polar boundary is up in Canada with the shortwave. That feature should drop the Canadian air mass (front) S during the day tomorrow across the Upper Mid west and northern Plains. There is an area of Canadian high pressure poised to spill S along the lee side of the Rockies several hours (3-6) behind the boundary. Now enter our storm from the W.As wxman57 stated, frontogenesis will occur across NW TX/OK. Where will the surface reflection of that storm meet the Canadian boundary is really key in how this system plays out in N Central TX (Midland/Odessa and San Angelo) Also of note, where will the Upper Low (5H) be located? These are questions that reamin to be answered right now. Regardless, the much talked about system has/will be well modeled and will have additional RAOBS data in the 00Z runs as well as future runs. There has been 2 RECON aircraft flying Pacific missions (G-IV Upper Air and C-130 out off Anchorage). Now we wait and see how things unfold. Thanks for chiming in wxman57 as well as txagwxman. You both as well as our other fine Mets and members have made this a great learning experience this winter season. That's what makes this board so great.

[Ntxw]

This is why I enjoy reading these forums so much. Snow or no snow the knowledge gained from you guys is priceless. There are some mets on TV that explains things every so now and then but there's always missing blanks.

[jasons2k]

Now, I can handle this

Friday Night: Partly cloudy, with a low around 35.

Saturday: Sunny, with a high near 52.

Saturday Night: Mostly clear, with a low around 33.

http://forecast.weather.gov/MapClick.ph ... it=0&lg=en

[srainhoutx]

One more thought regarding longer range forecasts. There are strong signals that winter is far from over beyond this system. That will be addressed after we get beyond the current storm threat and keep the activity going in this Topic beyond the unfolding event.

[jasons2k]

I'm concerned by the forecasts of 3"+ of rain before the front moves through. That would bring some localized flooding problems for sure.

With that much water saturated into the ground I would think that it would take quite some time for the ground to reach freezing even after the air temperature dips below freezing, so I don't anticipate any accumulations of ice or snow except perhaps on overpasses.

More standing water would probably mean a bigger headache overnight. I've noticed that once temps get into the 28ish range doesn't matter how much water there is, it's probably going to freeze over.

The moisture dries-up from the roads pretty fast - especially on overpasses because they drain fast (they are sloped to begin with) and they tend to be exposed to wind. I've seen it rain many times in the DFW just before a hard freeze and it's rare for there to be any major ice problems the next morning.

[Portastorm]

I know one thing ... webcams along Interstate 40 in Texas and Oklahoma are going to provide some good viewing on Thursday. Let's be sure and share some good links as that is always fun to watch.