TX winter wx thread: Spring-like pattern

[Ed Mahmoud]

For anyone wanting a little hope. The 6z GFS once again delivers. Check it out...

Highs in the 40s and 50s (30s panhandle) with rain statewide next Friday (Dec. 7th - 204 hours) = http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_204l.gif

Another chilly and rainy day next Saturday (Dec. 8th - 228 hours) = http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_228l.gif

Then, beyond this rainy and cold setup, the GFS once again shows a glimmer of hope for wintery precipitation in the extended...

Snow and ice reach far south into TX on Wednesday, December 12th through Thursday, December 13th =
http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_312l.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_324l.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_336l.gif

Somehow I doubt it verifies, but with a NW wind and the 850 mb freezing line that close to Houston, I'd suspect the surface freezing line would be even closer to HOU, and icy fun and frolics would ensue.

[double D]

Now if we could get three or four of those runs together, then I might be a little more excited. The GFS that far out is usually in la la land and I'm sure the 12z will squash our glimmer of hope.

[Portastorm]

Actually, the 12z looks somewhat similar to the 6z run. The GFS progs a fairly stout cold front through the state during the Dec. 8-9 timeframe ... something that would take our temps to 5 degrees or so below normal for a few days ... then very late in the 12z run ... we see the makings of a major trough in the Southwest moving east and dragging down a lot of Arctic air.

EWG, take heart!

Here is a link to the 12z run:

http://www.nco.ncep.noaa.gov/pmb/nwprod ... /fpc.shtml

[Extremeweatherguy]

I am liking this new trend. So far we have had two fairly decent looking runs (cold weather-wise) in a row. If we can continue this through tomorrow and into the weekend, then we might finally have something interesting to watch again!

[Extremeweatherguy]

The 18z GFS continues (this is the 3rd run in a row now) to show a significant arctic blast for Texas in about 9 to 11 days (with a lesser cold wave arriving before then). Hopefully this consistency keeps up, because I am really liking this latest model trend!

Arctic blast arrives the afternoon of December 9th = http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_240l.gif

December 10th starts out downright cold and raw with temperatures in the 30s for most of central and SE Texas and below freezing for north Texas. Rain, snow and ice is falling in many areas of the state = http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_252l.gif

By the afternoon of the 10th, the model shows a good chunk of TX below freezing with 850mb temperatures also below 0C in many areas. This kind of setup would be favorable for a transition from rain along the immediate coast and south TX, to freezing rain and sleet for SE Texas to snow for north and central TX = http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_264l.gif

The storm finally begins to wind down by December 11th, but not before dropping more freezing rain and sleet in parts of SE Texas = http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_276l.gif

Here are the freeze durations that the GFS is showing for different Texas cities during this projected event...

Houston (IAH) = Below freezing from the afternoon of December 10th until the afternoon/evening of December 11th.
Dallas/Fort Worth = Below freezing from the morning of December 10th until morning of December 12th. The only exception is a small window of 33-34 degree temperatures on the afternoon of the 11th.
Austin = Near or below freezing from the morning of December 10th until the afternoon of December 11th.

BTW - - After this initial storm, the model then goes on to keep us very cold through December 15th. In fact, another arctic blast is even depicted arriving in Texas (though not as severe) around December 14th that would only help to reinforce the cold. A setup like this could easily lead to a string of back to back sub-50 degree days for many.

[Ed Mahmoud]

That blue line is the 2 meter, not the 850mb, freezing line.


Although, if all else works out, the GFS is usually a tad warm at the surface on shallow Arctic airmasses. So that blue line of happiness might make it to HOU.

[Extremeweatherguy]

:uarrow:


That blue line is the 2 meter, not the 850mb, freezing line.


Although, if all else works out, the GFS is usually a tad warm at the surface on shallow Arctic airmasses. So that blue line of happiness might make it to HOU.

Oh, I know. It is the 2m temperature line, not the 850mb line.

The 850mb line for the event looks like this...
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_240l.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_252l.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_264l.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_276l.gif

It shows that the air column capable of snowfall would remain to our northwest. However, with surface temperatures (according to the 18z GFS 2m text temperature output) at or below freezing, we would still likely see a freezing rain or sleet event here in Houston which could lead to quite a mess. This is, however, assuming that this run even played out. As we all know, the 200 hour+ timeframe is prone to large changes, and there is no telling what will happen this time. The only thing that makes this slightly more interesting than other occasions, is the fact that the GFS has shown a "significant" cold airmass sometime around December 9th-11th for three consecutive runs now. That is a bit unusual for the longer range. If this trend continues into tomorrow and the weekend, then we will definitely need to pay closer attention to the possibility that there might be some truth to this scenario.

[Extremeweatherguy]

The 00z GFS has pushed back the cold air arrival by a day or two, but it does continue to show a major blast of cold arriving around December 10th (give or take a day or two).

Here are the 00z GFS run specifics...

Strong front slices into TX on December 11th = http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_276l.gif

The evening of December 11th looks cold. Most areas are falling to near freezing or below with temperatures in the TEENS working into the panhandle region. Some light wintry precipitation could be falling in a few spots = http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_288l.gif

Morning of December 12th looks freezing (literally). The 32 degree line reaches all the way to the coast and north Texas could be looking at temperatures in the SINGLE DIGITS and TEENS. 850mb temperatures are also near or below freezing in most places...but, precipitation is very limited and the probably only sufficient enough (in this run) for some light flurries/sleet pellets/freezing rain showers closer to the gulf coast = http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_300l.gif

This run then goes on to show most of Texas staying below 40-degrees through December 14th followed by another strong front late on the 14th or early on the 15th. So far, this is definitely the coldest run yet, but the big difference is that it shows less precipitation than earlier runs. That doesn't really matter at this point though. We are still far enough out that the specifics do not mean much. The main thing to consider right now is that this makes 4 runs in a row to depict a major arctic blast for TX around the December 10th timeframe. That is a pretty good streak for a model that usually likes to flip flop every other run beyond the 200 hour mark.

[Ed Mahmoud]

Well, that is close, IIRC, to the usual time of the first freeze around HOU. My house gets seven or ten frosts a year, often with IAH barely dropping below 40ºF


I'm not overly optimistic about winter precip, but I never give up hope.

[double D]

Well the 12z and 18z of the GFS look much warmer for us in Texas than it did 24 hours ago. Hopefully the 00z will flip back to a colder solution for next weekend. I think from now on I will wait till it's 3 days out to get excited about an arctic blast for Texas.

[Extremeweatherguy]

Well the 12z and 18z of the GFS look much warmer for us in Texas than it did 24 hours ago. Hopefully the 00z will flip back to a colder solution for next weekend. I think from now on I will wait till it's 3 days out to get excited about an arctic blast for Texas.

yes, they do look "warmer", but that really isn't saying much. The 12z and 18z runs still look quite cold for Texas and though they do not show the ice/snow and highs below freezing like the GFS did yesterday, they do still show a long stretch of below normal temperatures.

Here is a day-by-day 18z GFS run down starting December 9th...

December 9th
12pm - http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/images/gfs_ten_216l.gif
^^Strong front slices through the state on Sunday afternoon. Numerous storms accompany the frontal passage.^^

December 10th
12am - http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/images/gfs_ten_228l.gif
12pm - http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/images/gfs_ten_240l.gif
^^The day starts cold with some light snow possible in north Texas. By sunrise, many start off in the 30s with below freezing temps. likely for most of the northern 1/3rd of the state. Afternoon highs then also look cold with temperatures struggling to get out of the low to mid 50s in Houston and Austin and remaining in the 40s for Dallas.^^

December 11th
12am - http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/images/gfs_ten_252l.gif
12pm - http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/images/gfs_ten_264l.gif
^^A reinforcing cold airmass works into Texas during the 11th with a north wind becoming breezy and afternoon temperatures ranging from the 50s for Houston to the 40s for Dallas to the 30s for the Panhandle.^^

December 12th
12am - http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/images/gfs_ten_276l.gif
12pm - http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/images/gfs_ten_288l.gif
^^The day starts very cold with temperatures likely at or below freezing from I-10 northward. The afternoon is not much better. Highs struggle to get out of the 40s from Houston to Austin and northward and southern Texas is stuck in the 50s. The panhandle is stuck in the 30s for highs.^^

The 18z run then goes on to keep this cold pattern around through December 16th (and possibly beyond)...and by hour 384, it is showing yet another potent frontal system entering our area.

[vbhoutex]

Well the 12z and 18z of the GFS look much warmer for us in Texas than it did 24 hours ago. Hopefully the 00z will flip back to a colder solution for next weekend. I think from now on I will wait till it's 3 days out to get excited about an arctic blast for Texas.

yes, they do look "warmer", but that really isn't saying much. The 12z and 18z runs still look quite cold for Texas and though they do not show the ice/snow and highs below freezing like the GFS did yesterday, they do still show a long stretch of below normal temperatures.

Here is a day-by-day 18z GFS run down starting December 9th...

December 9th
12pm - http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/images/gfs_ten_216l.gif
^^Strong front slices through the state on Sunday afternoon. Numerous storms accompany the frontal passage.^^

December 10th
12am - http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/images/gfs_ten_228l.gif
12pm - http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/images/gfs_ten_240l.gif
^^The day starts cold with some light snow possible in north Texas. By sunrise, many start off in the 30s with below freezing temps. likely for most of the northern 1/3rd of the state. Afternoon highs then also look cold with temperatures struggling to get out of the low to mid 50s in Houston and Austin and remaining in the 40s for Dallas.^^

December 11th
12am - http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/images/gfs_ten_252l.gif
12pm - http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/images/gfs_ten_264l.gif
^^A reinforcing cold airmass works into Texas during the 11th with a north wind becoming breezy and afternoon temperatures ranging from the 50s for Houston to the 40s for Dallas to the 30s for the Panhandle.^^

December 12th
12am - http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/images/gfs_ten_276l.gif
12pm - http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/images/gfs_ten_288l.gif
^^The day starts very cold with temperatures likely at or below freezing from I-10 northward. The afternoon is not much better. Highs struggle to get out of the 40s from Houston to Austin and northward and southern Texas is stuck in the 50s. The panhandle is stuck in the 30s for highs.^^

The 18z run then goes on to keep this cold pattern around through December 16th (and possibly beyond)...and by hour 384, it is showing yet another potent frontal system entering our area.

OK, explain to me how you get your temps. I am not seeing them in the models. Are my conversion programs wrong?

[Extremeweatherguy]

OK, explain to me how you get your temps. I am not seeing them in the models. Are my conversion programs wrong?

Well some of it is just smart estimation based on the trends. The 18z only shows the 12pm and the 12am temperatures in the long range, so to predict the 6/7am low temperature and the mid afternoon high temperature, you have to look at the entire situation (cloud cover, winds, etc) and then predict what the temperature would likely be a few hours from the given point. Eventually, once we start getting into closer range though (under 180 hours), we will have access to 4 daily temperatures (6am, 12pm, 6pm and 12am) instead of just two. This will make the situation much easier to read. For now though, we have to use a broader approach and try to fill in the missing time slots on our own.

An example of this would be as follows...

-The 18z shows temperatures in the 30s at IAH and freezing in north Texas at 12am on the morning of December 12th. Considering we will have a good 6-7 hours of additional cooling left, you can easily estimate that the freeze line would likely reach somewhere around the I-10 corridor by sunrise.

BTW - - Keep in mind that the 12pm and 12am temperature in the long range is only given on the 6z and 18z runs. The 0z and 12z runs (such as the one currently running tonight) feature the 6am and 6pm temperatures instead. This means that they are of much better use in the low temperature predictions and of much worse use in the high temperature predictions. Either way though, at this point (over 180 hours out), the exact specifics are not really that important anyway. It is more of the "general" idea that we care about right now.

[vbhoutex]

OK, explain to me how you get your temps. I am not seeing them in the models. Are my conversion programs wrong?

Well some of it is just smart estimation based on the trends. The 18z only shows the 12pm and the 12am temperatures in the long range, so to predict the 6/7am low temperature and the mid afternoon high temperature, you have to look at the entire situation (cloud cover, winds, etc) and then predict what the temperature would likely be a few hours from the given point. Eventually, once we start getting into closer range though (under 180 hours), we will have access to 4 daily temperatures (6am, 12pm, 6pm and 12am) instead of just two. This will make the situation much easier to read. For now though, we have to use a broader approach and try to fill in the missing time slots on our own.

An example of this would be as follows...

-[b]The 18z shows temperatures in the 30s at IAH and freezing in north Texas at 12am on the morning of December 12th. Considering we will have a good 6-7 hours of additional cooling left, you can easily estimate that the freeze line would likely reach somewhere around the I-10 corridor by sunrise. [/b]

BTW - - Keep in mind that the 12pm and 12am temperature in the long range is only given on the 6z and 18z runs. The 0z and 12z runs (such as the one currently running tonight) feature the 6am and 6pm temperatures instead. This means that they are of much better use in the low temperature predictions and of much worse use in the high temperature predictions. Either way though, at this point (over 180 hours out), the exact specifics are not really that important anyway. It is more of the "general" idea that we care about right now.

I might believe the 40's at this time, but not the 30's. Now the 30's are possible by 6am our time based on this I will agree.

[lrak]

Banana trees don't like 30s and 40s for very long, and if a wee bit of Arctic slithers on in might have a chance. I've been waiting a long time for this excuse to plant something different. Maybe if it doesn't freeze I'll just spray something around those darn bug houses and still blame it on the weather.

[Extremeweatherguy]

The 00z GFS continues to look "warm" (compared to runs from yesterday), but by "warm" that still means chilly. The 00z run is showing a low below freezing at IAH on the morning of Thursday, December 13th, with IAH sitting at a cold 31.4˚ at 6am.

[Extremeweatherguy]

The 18z GFS shows a major arctic airmass piling up near the Canada/US border around the 9th/10th, but it then goes on to show it only making slow progress south and stalling to our north. I am not so sure that this will actually happen, but as of now, that is what the latest model run is showing...

http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_216l.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_240l.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_264l.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_288l.gif
http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_312l.gif

...If this airmass charges southward instead of hanging up to our north though, then a scenario as depicted by yesterday or the day before's GFS runs could easily still play out. The model watching continues...

Hopefully by the end of next week we will have a much better idea as to what will actually happen.

[Ed Mahmoud]

Banana trees don't like 30s and 40s for very long, and if a wee bit of Arctic slithers on in might have a chance. I've been waiting a long time for this excuse to plant something different. Maybe if it doesn't freeze I'll just spray something around those darn bug houses and still blame it on the weather.

You do know a freeze that kills the part of the banana plant above ground, unless it is a hard and prolonged freeze, won't kill the roots, and a 'new' banana plant will pop up the following Spring.



I like the tropical look of banana plants, myself.

[vbhoutex]

Even if the Arctic air does head this way it will be sharply modified before it gets to our area. Until there is a LOT more snowpack to our North any Arctic air that makes it this way will be short lived and/or so heavily modified that it won't be near as cold as it is initially depicted or as the pressures might suggest. When there is a lot more snow pack(if there is) in January and February is when the Artic air can really affect us here in SE TX.

[Extremeweatherguy]

Even if the Arctic air does head this way it will be sharply modified before it gets to our area. Until there is a LOT more snowpack to our North any Arctic air that makes it this way will be short lived and/or so heavily modified that it won't be near as cold as it is initially depicted or as the pressures might suggest. When there is a lot more snow pack(if there is) in January and February is when the Artic air can really affect us here in SE TX.

That is usually true, but not always. Significant arctic airmasses can still reach this area even with relatively little snowpack to our north.

For example, take a look at the December 2004 arctic outbreak (responsible for the historic snowstorm)...

Two days before the event, there was very little (if any) snow cover in Oklahoma, Kansas or Nebraska: http://www.ssd.noaa.gov/PS/SNOW/ARCH04/ ... 57_usa.gif

And even with this little amount of snow, the airmass was still able to speed south, bringing with it low enough thicknesses to provide up to 13" of snow in parts of the central TX coastal region and even 1-2" in Brownsville! This just goes to show that if an airmass is cold enough and fast enough, it can easily overcome the issue of a low snow-pack to our north.


BTW - - here is a look at our current [December 1st, 2007] snow-cover for comparison = http://www.ssd.noaa.gov/PS/SNOW/ARCHIVE ... 35_usa.gif