Texas Fall 2013

[joshskeety]

at 36h.. So far spitting image of 12z run..

[downsouthman1]

at 36h.. So far spitting image of 12z run..

It's been too long since I've looked at this stuff. How are temps derived? I thought it had something to do with the 540 thickness line indicating approximately 100% humidity but I could be way off. Like that's where atmospheric temps @ 500MB are freezing?

[Tireman4]

Track the front here!!!!!!!!!!

http://www.wunderground.com/wundermap/? ... on%2c%20TX

[joshskeety]

at 36h.. So far spitting image of 12z run..

It's been too long since I've looked at this stuff. How are temps derived? I thought it had something to do with the 540 thickness line indicating approximately 100% humidity but I could be way off.

Well I always just use the 850mb 0 line for quick viewing of the previous hours.. So if I am looking at 36h on a 3 hour run, I look at the 850mb line on the 33h run and use that determination.. Then if that shows rain/snow, Ill check the skew-t model on that run to double check all layers of the atmosphere..

As far as Temps, the NWS only gives us a small amount of data the NAM runs, but other sites can calculate temp at the surface much better than you will get from the NWS site.. But sometimes you have to wait for that data to port over to someone else's map systems and it can be longer.. But using the formula above, its a good poor man's way of determining what the precip will be.. The Skew-T maps are your biggest friend..

[downsouthman1]

at 36h.. So far spitting image of 12z run..

It's been too long since I've looked at this stuff. How are temps derived? I thought it had something to do with the 540 thickness line indicating approximately 100% humidity but I could be way off.

Well I always just use the 850mb 0 line for quick viewing of the previous hours.. So if I am looking at 36h on a 3 hour run, I look at the 850mb line on the 33h run and use that determination.. Then if that shows rain/snow, Ill check the skew-t model on that run to double check all layers of the atmosphere..

As far as Temps, the NWS only gives us a small amount of data the NAM runs, but other sites can calculate temp at the surface much better than you will get from the NWS site.. But sometimes you have to wait for that data to port over to someone else's map systems and it can be longer.. But using the formula above, its a good poor man's way of determining what the precip will be.. The Skew-T maps are your biggest friend..

Never learned to read those lol.

[joshskeety]

Btw.. 48h out still spitting images.. If anything I would say they are about an hour difference or so slower (low placement) than the 12z run..

[wxman57]

:uarrow:

I think that you have to ask yourself why is the NAM forecasting such a snow event? Well, because the NAM is thinking this cold core upper low will stay intact and be a strong one. That will create an atmospheric profile, vertically, which would support snow for those underneath the low as it moves across the state. These upper lows are hard to forecast, joshskeety, and I don't think NWSFO Dallas/Fort Worth wants to go "all in" just yet until they see more model support. I actually would do what they're doing.

OK, I see that wxman57 is here now. He'll set us all straight!

I'm pretty confident the front will stall way to our north and the temperature will reach the mid 80s in Houston this weekend.

One difference I do see here (vs. 1993) is that back in 1993, the GFS forecast a similar pattern but forecast the cold front to stall near Dallas then retreat to the north to Kansas by the 25th. Actually, the front was in the Gulf on Nov. 25th of 1993. This time, at least, the GFS is doing much better and forecasting the front to blast on through to the Gulf. Looking at the forecast soundings for Austin, the GFS indicates temps way above freezing just above the surface Sunday/Monday (upper 40s). Can't rule out a little sleet as the precip ends, though.

[Tireman4]

:uarrow:

I think that you have to ask yourself why is the NAM forecasting such a snow event? Well, because the NAM is thinking this cold core upper low will stay intact and be a strong one. That will create an atmospheric profile, vertically, which would support snow for those underneath the low as it moves across the state. These upper lows are hard to forecast, joshskeety, and I don't think NWSFO Dallas/Fort Worth wants to go "all in" just yet until they see more model support. I actually would do what they're doing.

OK, I see that wxman57 is here now. He'll set us all straight!

I'm pretty confident the front will stall way to our north and the temperature will reach the mid 80s in Houston this weekend.

Ha ha ha. No.

[Longhornmaniac8]

Btw.. 48h out still spitting images.. If anything I would say they are about an hour difference or so slower (low placement) than the 12z run..

You're right. It looks like it's just a touch slower, and looks like it digs south by about the same amount that it's slower, which is to say, virtually nothing.

Cheers,
Cameron

[joshskeety]

Now we are getting the meat and potatoes.. NAM is definitely warmer and less moist so far to 60h out, but this is when the low began to backfill on the 12z run.. 0 line at 60h is sitting just northwest of the DFW metroplex say around Jacksboro, Texas where it is at 57h as well.. Still in line, but definitely not as cold and not as moist on this run so far.. GFS just may pull this one out or as I first figured they will converge...

[Rgv20]

From an expected high of 91 this afternoon to a forecast high of 44 on Sunday, Gotta love Texas weather huh? lol



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[joshskeety]

Btw, if the Front continues its path it should hit Wichita Falls in the next half hour or so. Clearing is happening now here in Downtown Ft. Worth and the instability is going off the chart. I would expect Thunderstorms to begin to develop somewhere between Wichita Falls and Jacksboro within the next 1 to 2 hours.. FYI..

[downsouthman1]

NAM 18Z run Hours 66+ are wetter than the 12Z run along the I35 corridor. It has also slowed down the precip onset & duration times.

[Portastorm]

As of 2:45 pm, front is through Lubbock. Temperature drop of close to 10 degrees in 20 minutes. North winds gusting to near 40 now with blowing dust.

[joshskeety]

Wow, just like last run.. Major ice storm in San Antonio/Austin.. If you take a line from Ft. Worth to Fredericksburg west from a line of Abilene to Big Lake it shows ALL SNOW and heavy snow at that..

No way that can ignore this any longer.. This potentially could be a very dangerous situation in central Texas.. When I see below freezing precip from .75 to 1.5 inches as the NAM is indicating in the form of freezing rain or sleet on the east side and 6-10 inch snows on the west side you can't ignore it any longer.. This is the 3rd run in a row..

[Cuda17]

:uarrow:

I think that you have to ask yourself why is the NAM forecasting such a snow event? Well, because the NAM is thinking this cold core upper low will stay intact and be a strong one. That will create an atmospheric profile, vertically, which would support snow for those underneath the low as it moves across the state. These upper lows are hard to forecast, joshskeety, and I don't think NWSFO Dallas/Fort Worth wants to go "all in" just yet until they see more model support. I actually would do what they're doing.

OK, I see that wxman57 is here now. He'll set us all straight!

I'm pretty confident the front will stall way to our north and the temperature will reach the mid 80s in Houston this weekend.

Ha ha ha. No.

Pffffffffffffft!!!!!!!! I almost spewed beer onto my keyboard!!!! Sorry but that was funny!

[Kelarie]

Can you give me input on what the weather situation looks like for Texarkana? Thanks!

Time frame, please?

Saturday through Monday. Sorry for missing that.

[joshskeety]

Holy cow and add another 6-10 inches on the backside of this if you life in northwest Texas if this model is right.. No way I believe 2 feet of pure snow in North Texas in mid november.. No friggen way..

[Rgv20]

18zNAM brought to you by Snow Apocalypse November 2013....

[Portastorm]

Holy cow and add another 6-10 inches on the backside of this if you life in northwest Texas if this model is right.. No way I believe 2 feet of pure snow in North Texas in mid november.. No friggen way..

Just a friendly reminder that the NAM has been, and continues to be, the outlier of the model solutions. If you go over to NOAA's Weather Prediction Center page and look over the discussions, you'll see that. The expect forecasters believe it ejects the upper low way too fast. Among other things.