Texas winter wx thread (2009-2010)

[CYCLONE MIKE]

Here is the lastest long range discussion out of Baton Rouge pertaining to the gulf low. They are saying central gulf, would be something if it forms in western gulf again.

HEADING INTO THE WEEKEND...LARGE DISAGREEMENTS BETWEEN THE GFS AND
EURO MODELS DEVELOP. HOWEVER...THESE DISAGREEMENTS ARE MOSTLY
CONFINED TO THE LOW LEVELS...AND THE DEVELOPMENT OF ANOTHER GULF
LOW HEADING INTO FRIDAY NIGHT AND SATURDAY. IN THE UPPER
LEVELS...BOTH MODELS ARE IN VERY GOOD AGREEMENT THAT A STRONG AND
DEEP UPPER LEVEL TROUGH WILL DIVE THROUGH THE PLAINS STATES AND
INTO THE GULF SOUTH. THE MAIN TROUGH AXIS SHOULD PASS THROUGH THE
AREA FRIDAY NIGHT...ALONG WITH A VERY STRONG FRONTAL BOUNDARY.
BOTH MODELS ARE ALSO IN GOOD AGREEMENT...THAT STRONG COLD AIR
ADVECTION IN THE WAKE OF A COLD FRONT FRONT PROGGED TO SWEEP
THROUGH FRIDAY NIGHT WILL TAKE PLACE. TEMPERATURES WILL DROP BELOW
FREEZING ACROSS THE NORTHERN THIRD OF THE FORECAST AREA FOR FRIDAY
AND SATURDAY NIGHTS. DAYTIME HIGHS WILL BE A GOOD 10 DEGREES BELOW
NORMAL AS THIS DEEP COLD POOL SLIDES THROUGH THE REGION. THE MAIN
DIFFERENCE ARISES WITH THE AMOUNT OF CYCLOGENESIS EXPECTED WITH
THIS APPROACHING TROUGH. THE GFS IS VERY AGRESSIVE AND QUICKLY
SPINS UP ANOTHER DEEP LOW PRESSURE SYSTEM IN THE CENTRAL GULF OF
MEXICO. THIS STRONG LOW WRAPS DEEP TROPICAL MOISTURE UP INTO THE
GULF SOUTH...JUST AS THE COLDER AIR BEGINS TO BLEED INTO THE
REGION. BASED ON THIS FORECAST...SOME TYPE OF WINTER PRECIPITATION
WOULD BE POSSIBLE. HOWEVER...THE ECMWF HAS A MUCH WEAKER LOW FORM
IN THE CENTRAL GULF. MOISTURE IS LIMITED ALONG THE FRONT...AND
EXITS THE REGION WELL BEFORE THE COLDEST AIR MOVES IN. THIS
SCENARIO WOULD KEEP ANY WINTER WEATHER OUT OF THE FORECAST. GIVEN
THE HIGH UNCERTAINTY OF THE SITUATION...HAVE DECIDED TO KEEP THE
ONGOING FORECAST IN PLACE AND WAIT FOR ADDITIONAL GUIDANCE OVER
THE NEXT DAY OR SO.

[srainhoutx]

I know that everyone is focused on the Friday and Saturday event, but the 18z GFS is showing a massive 1056 high coming down the western side of Canada next week. It looks like we might be getting our Christmas presents early if you like COLD!

This feature will be one to watch. There will be a lot of Sub Tropical Jet activity involved again IMHO.

[mysterymachinebl]

I know that everyone is focused on the Friday and Saturday event, but the 18z GFS is showing a massive 1056 high coming down the western side of Canada next week. It looks like we might be getting our Christmas presents early if you like COLD!

This feature will be one to watch. There will be a lot of Sub Tropical Jet activity involved again IMHO.

What time frame are we looking at for this?

[Big O]

18z GFS Shows ABI/SJT with .30-.40 QPF with snow ratio's 12:1 That would be 3-5 inches of snow..

What about Austin? What type of precipitation (i.e., snow, rain, sleet, ice)? When would it begin and end? Amounts?

Sorry if this is one of those IMBY questions, but I am traveling (car) from McAllen to Austin for a graduation and need to decide if I should leave late Thursday afternoon or Friday morning/afternoon.

Thanks in advance.

[jasons2k]

OK, I guess it is my turn to gripe about my local NWS forecaster.

I'm still waiting to see which forecast office first says it is "unseasonably cold" even though it is now December and the meteorological winter season.

[CYCLONE MIKE]

Concerning models showing winter storms 3-4 days out, is there one better than others? In this instance the GFS develops another strong gulf low behind trough which would seem to lead to a better chance of winter weather. Whereas the NAM Euro are much drier but just as cold. Is there one more reliable than the other?

[Ntxw]

They all have their flaws and perks. I've noticed often times that forecasters from the weather service uses a blend of each based on their strengths.

[Portastorm]

18z GFS Shows ABI/SJT with .30-.40 QPF with snow ratio's 12:1 That would be 3-5 inches of snow..

What about Austin? What type of precipitation (i.e., snow, rain, sleet, ice)? When would it begin and end? Amounts?

Sorry if this is one of those IMBY questions, but I am traveling (car) from McAllen to Austin for a graduation and need to decide if I should leave late Thursday afternoon or Friday morning/afternoon.

Thanks in advance.

If you want to believe the National Weather Service office in New Braunfels, they say rain only. Most of the computer models, however, suggest amounts ranging from a trace to 2 inches of the Austin metro area by Friday night. However, there is still A LOT of uncertainty about who gets what in Texas over this event.

[double D]

I know that everyone is focused on the Friday and Saturday event, but the 18z GFS is showing a massive 1056 high coming down the western side of Canada next week. It looks like we might be getting our Christmas presents early if you like COLD!

This feature will be one to watch. There will be a lot of Sub Tropical Jet activity involved again IMHO.

What time frame are we looking at for this?

Probably sometime next week, but I do have to admit that the GFS never brings the real cold into Texas. This could change though as these strong high pressures are dense enough to overtake a strong southwest flow.

[srainhoutx]

Regarding the colder air. Remember that we are seeing a stepping down to colder airmasses. We will not see a 'dump' of Arctic Air like we have seen in the past in TX. There is little to no snow cover to the N. That will likely change as the days unfold IMHO.

[cheezyWXguy]

Regarding the colder air. Remember that we are seeing a stepping down to colder airmasses. We will not see a 'dump' of Arctic Air like we have seen in the past in TX. There is little to no snow cover to the N. That will likely change as the days unfold IMHO.

We may see it moderate, I agree with that. But the GFS seems like its weakening the high too fast. It builds it to a peak of 1059mb in the 18z, and about a day or so later, the thing is about 1040, and stalls, and by the time it reaches to CONUS, its in the low 1030's. If it were to really weaken that fast, then sure, the cold air would stay north. But I have a hard time believing anything is going to stall a 1060mb high that far north once it starts moving.

[Ntxw]

On the thought of stepping down to cold, on a bigger picture would this result into a winter that produces more snow than ice for much of Texas? I know each storm is different on it's own, but from gradually cooling sounds less likely for shallow pools of cold to undercut warm air.

[Extremeweatherguy]

Regarding the colder air. Remember that we are seeing a stepping down to colder airmasses. We will not see a 'dump' of Arctic Air like we have seen in the past in TX. There is little to no snow cover to the N. That will likely change as the days unfold IMHO.

We may see it moderate, I agree with that. But the GFS seems like its weakening the high too fast. It builds it to a peak of 1059mb in the 18z, and about a day or so later, the thing is about 1040, and stalls, and by the time it reaches to CONUS, its in the low 1030's. If it were to really weaken that fast, then sure, the cold air would stay north. But I have a hard time believing anything is going to stall a 1060mb high that far north once it starts moving.

Yeah, this appears to be something we see quite often with the models. They are notorious for mishandling dense arctic airmasses, especially 5-8 days out. They tend to always over weaken the highs and keep the cold locked too far north. I don't expect the models to start getting a really good handle on the complex situation coming up for next week until we are only a couple of days out.

[joshskeety]

Concerning the question about Austin.. You guys are definitely in the snow zone with the models.. However, I am in the minority right now and think the models will trend further north and not as cold with this over the next 24-48 hours.. The models right now Austin sees maybe an inch or two of wet snow.. If the system does what I think its going to do you guys will see much more..

Concerning the question about which model is better.. There is no "better" model.. Each has its biases and perks.. For instance, the NAM is known for its more moist warm bias, while the GFS is known to be overly cold 84h and out with things.. A good meteorologist uses all the models he can and knows the biases of each, but he/she also uses more than models and uses prior year set ups, known biases that aren't seen by models..

The models are more than just a physical picture representation.. What you see is a map, but the models are in 3d.. Each portion of the atmosphere provides a different challanges with storm systems..

BTW.. Good to see some SJT area people on here.. I know SJT is a bowl.. Seems like Abilene gets good snow, yet SJT gets the shaft all the time.. However, you guys are 80 miles south of us so I guess I could see it a tad.. However, this upcoming storm looks so far to give SJT .4 QPF, while we get .25-.3, so you may make out better...

[srainhoutx]

E-mail from Jeff this evening...

Moderate to heavy rains overspreading the region late this afternoon...main concern is focused on the end of the week.

There has been a few changes in the guidance today with respect to the Friday event. 12Z GFS and NAM are slightly drier, but still produce a good bit of QPF over the region. Also, temperatures have been warmed slightly on the air column which now brings the Matagorda Bay region out of the snow area and focuses the majority of the frozen precip. along and N of US 59. GFS sounding profiles are above freezing through about 3000 ft Friday morning and then with strong cold air advection during the day fall to freezing or below through nearly the entire column by 600pm. Moisture is pulled into the column in the 700-500mb level with fairly dry layers noted below at KIAH. Dewpoint and air temperatures are fairly close together so not a lot of room for wet bulb cooling with this air mass. Dynamics with the short wave looks impressive and the strong lift may help to overcome a lack of good moisture. There is much uncertainty with the following aspects.

1) Track and timing of the short wave and dynamics. A slower track will allow for more cooling, while moisture may become less and shunted eastward.

2) Cooling of the above freezing levels during the day Friday. Strong CAA is noted with 850mb 0C line pressing toward downtown Houston by early afternoon with -2C 850mb temperatures overspreading our N counties.

3) Degree of moisture and level of the moisture. Soundings support good mid level moisture but a fairly large dry sub layer. This suggest precip. aloft may have a hard time reaching the ground and it may take a good bit of virga to moisten the low levels.

With all this said...will start to lean toward the stronger solution as both the GFS and NAM show this. Will not dabble in any QPF or accumulation amounts at this time as it is very uncertain. Will note a rain/snow line across SE TX midday Friday spreading toward the coast during the afternoon hours including metro Houston. Will also increase precip. chances in the 40-50% range with a frozen mix changing to snow from NW to SE during the day.

This period remains highly uncertain with extremely low forecast confidence. Significant changes will be possible over the next 24-36 hours. Will need to start to consider advisories/watches by early Thursday if model trends hold for another 24 hours as enough accumulation looks possible to cause some serious travel issues by Friday afternoon across portions of SE TX.

[wxman57]

Yeah, 18Z GFS shows heavier precip and colder air present - up to 4-6" accumulations just west and northwest of Houston. 1-4" in Houston.

[srainhoutx]

Yeah, 18Z GFS shows heavier precip and colder air present - up to 4-6" accumulations just west and northwest of Houston. 1-4" in Houston.

Oh joy. That should make travel on the N and W Belt flyovers as well as other overpasses a mess. Just in time for a Friday Rush hour.

[Weatherdude20]

41 Degrees in Haltom City with Fog/Mist/cold rain...
41 Degrees in North Richland Hills with Moderate Rain
40 Degrees in Denton with Light Rain
43 Degrees in Dallas with Rain
42 Degrees in Fort Worth with Fog/Drizzle

Intresting report out of Goldthwaite Texas a West of Waco area... 39 Degrees and Rain/Sleet? I don't think it's possible but the radars show heavy rain in the vicinity- And everyone Note this : Heavy Rain tonight WILL Mix with Sleet at times...
But i don't belive it will stick...

[HockeyTx82]

Ok, so what up here in Denton has changed to warrant mentioning flurries this Friday?

http://forecast.weather.gov/MapClick.ph ... 2=-97.1309

[Ntxw]

I don't quite understand it either, many of the mets around here states it will be to the west and south of dfw. Probably the track isn't certain at this time