Tag Archives: storm prediction center

Supercells Likely on Wednesday in Eastern Panhandle – Chase On!


As always before diving into the details with any severe weather setup I want to start by highlighted the latest severe weather outlook from the Storm Prediction Center. Compared to the outlook I shared early this morning there have not been many changes. An enhanced risk of severe weather is in place across the eastern Texas Panhandle and portions of Northwest Texas for the late afternoon and evening hours on Wednesday. Perryton, Pampa, Shamrock, Clarendon, Childress, Quanah, and Vernon are in the enhanced risk zone. Much of Western Oklahoma is also in the enhanced risk zone. Surrounding the enhanced risk zone is the area where severe thunderstorms will be possible but will be more isolated (possibly only one or two storms). This zone encompasses the eastern half of the Panhandle, parts of West Texas, and West-Central Texas into part of Northwest Texas. Borger, Plainview, Lubbock, Lamesa, Midland, Snyder, Abilene, and Wichita Falls are included in this risk zone.


The enhanced risk zone is where confidence is highest that several severe thunderstorms are likely to occur on Wednesday. Initial thunderstorms are expected to develop in the 4 PM to 6 PM timeframe and will likely be in the form of discrete supercells. Atmosphere ingredients are favorable for severe weather with destructive hail possibly exceeding the size of baseballs in the strongest storms. Localized damaging winds and a tornado are also possible. Further south in the ‘possible’ risk zone is where confidence is lower in thunderstorms developing. I still believe we’ll likely see at least one or two supercells develop with an associated risk of golf ball to baseball size hail and localized gusty winds. Wind shear and instability values would support a tornado threat on Wednesday BUT moisture is going to be a problem thus keeping cloud bases high and reducing the tornado threat. I’ll have more on the moisture issue in my ‘nerd’ discussion in a bit.

By the early evening hours storms will likely begin congealing into one or two clusters of storms. These clusters will move east and pose a threat of damaging winds over 60 MPH along with a marginal hail threat. Similar to the last few nights any cluster that develops could remain until the early morning hours on Thursday as it moves east towards the eastern edge of the “possible” risk zone of severe weather. The good news is if we can get a cluster of storms to develop in Northwest Texas hopefully we can get some more rain to our most drought-stricken communities. If you’re not a weather nerd or short on time that’s the gist of the forecast.

Weather Nerd/My Personal Chase Thoughts


This graphic is a model representation from the 18 Zulu (1 PM CDT) run of the high resolution North American Model (NAM) showing surface dewpoint temperatures at 7 PM on Wednesday. The first and most obvious thing to note is the dryline which is located across the eastern Texas Panhandle into West-Central Texas. To the west of the dryline very dry air will be in place along with gusty west winds promoting critical fire danger. To the east of the dryline is where moisture will be streaming northward from the Gulf of Mexico (technically South/Southeast Texas based on the current moisture trajectory). Dewpoints should be in the lower to mid 50s by early afternoon with values continuing to increase through the late afternoon. By about 5 to 6 PM we expect dewpoint values to range from 54°F to 58°F along and ahead of the dryline. 60 degree dewpoint values will be spreading north/northwest across the Red River further east towards Vernon and Wichita Falls into Southern Oklahoma from Texas.

You might be asking yourself why I just spent so much time describing a five degree difference in dewpoints across several hundred miles. Well in terms of forecasting surface-based severe weather, cloud heights, and the threat of tornadoes the dewpoint is a key-factor. The base of a cloud or the point in which water vapor will condense into a cloud is determined in part by the surface temperature and surface dewpoint temperature difference. For example: A surface temperature of 81°F with a surface dewpoint of 72°F would likely yield a lifted condensation level (LCL) and cloud base height of about 500-750 meters above the ground which is prime-time territory for tornadoes (assuming you have the ingredients in place to support tornadoes).

Being a little selfish and forecasting for my chase-target area near Interstate 40 and Shamrock, TX in the Panhandle I find that the 18Z NAM has a surface temperature in in the 86°F-88°F with a surface dewpoint at about 57°F. Generally speaking you want your temperature/dewpoint spread to remain less than 15 to 20 degrees for cloud bases to be low enough for tornado potential (again assuming you have all the other ingredients in place). The forecast temperature/dewpoint difference for tomorrow in the eastern Texas panhandle and Northwest Texas looks to be around 30° which will mean cloud bases are around 1500-2000 meters above the ground. In most circumstances that makes the tornado threat minimal because the cloud bases are simply too high off the ground to produce tornadoes. That said those storms may not produce tornadoes but they are in fact some of the most impressive structure-wise and can produce giant hail.

There’s a little catch about tomorrow though: The eastern Texas Panhandle is a bit higher in elevation then other parts of Texas and thus sometimes lower dewpoint values are able to be compensated somewhat by the higher terrain. In Wednesday’s case wind shear and instability will both be favorable for rotating supercells. If we end up with a storm that can remain discrete and supercellular during the 7:30 PM to 9:30 PM time-frame there is a small possibility the lowering surface temperatures may be enough to cause cloud bases to lower to the point where a isolated tornado may occur. That’s very speculative at this point and more related to my chase experience verses forecasting. The tornado threat tomorrow is marginal because of the low dewpoint values and high cloud bases, but we’ve seen rare setups produce a tornado or two even with higher cloud bases. It would require the mesoscale environment (aka the environment in close proximity to the storm) to be almost perfect to produce a tornado. the likelihood of that happening is low, but not zero. My goal for tomorrow is to capture a photogenic supercell producing very large hail (hopefully not on my windshield). I’ll be keeping an eye out for any signs of local features that could enhance the storm around sunset since cloud bases will begin lowering somewhat as surface temperatures begin falling after the prime-heating of the day. Based on weather model data from this morning and afternoon I’d have to say my target (where I’ll head first and go from there) is Shamrock, TX in the eastern Panhandle. If the dryline sets up further west and storms fire further west than obviously I’d have to go west on I-40 and adjust from there. My target storm should be crossing into Oklahoma by around 7 PM and move into a slightly better environment moisture-wise with dewpoint values in the 58-60 degree range. Combined with strong wind shear that might be enough to get at least some low level rotation. We’ll see what happens but in terms of seeing a supercell tomorrow I’d say the chances are good for me.

Disclaimer: The above discussion is related to my personal chasing thoughts for Wednesday and not the overall forecast.

7:30am Winter Weather Update

Starting to see an uptick in icing reports from between Waco and Austin… and also from areas north/northwest of Houston..mainly across Brazos, Walker and Burleson counties including the cities of Bryan/College Station, Huntsville and Caldwell.  Seeing reports of black ice in and around Salado with multiple accidents reported along that stretch of I-35.  With morning rush hour just getting underway, please follow your local media for the latest on road conditions in your area.  We simply do not have the time to keep up with the latest closures and slick spots, but will continue to pass along the major ones as we hear about them.


Icy Roads

Here’s a look at the latest radar grabs for the Austin area and also the Houston area.  Most of the precip falling across these areas is in the form of sleet…indicated in red…with some snow indicated in blue and then rain indicated in green.  The areas most likely to see frozen precipitation through the morning hours will be along and north of the I-10 corridor.  Areas south of I-10 have remained just above freezing, so just rain so far.

Austin Area Houston Area

The Storm Prediction Center has also issued a discussion for the increasing threat of sleet as the primary precipitation type over far southeast Texas and into southern Louisiana.  This would include the Beaumont/Port Arthur areas later this morning.  We’ll continue to monitor and keep you updated with the latest.  If you have any reports of sleet or snow accumulation in your area, feel free to share it with us on our Facebook page or on Twitter @TxStormChasers.



12:45 AM Severe Weather Update

We’ve been monitoring an area of Northeast Texas over the past hour as thunderstorm intensity has gradually increased. Two different storms have shown signs of becoming supercells with broad rotation. As we continue into the early morning hours there is an increasing probability that one or two storms will be able to strengthen into supercells. Wind shear is fairly supportive of severe weather this morning. Although the atmosphere is only marginally unstable, the strong wind shear could help compensate and allow for a few severe thunderstorms. While I don’t expect a widespread event, there is the potential for a few tornadoes this morning if thunderstorms can become organized ahead of the cold front. Over the next few hours the threat should be confined to an area highlighted by the Storm Prediction Center about an hour ago.


Later today our neighbors to the east will be facing a possible tornado outbreak with long-lived tornadoes and the possibility of widespread straight-line winds over 70 MPH. It’s not looking good out in Louisiana, eastern Arkansas, parts of Tennessee and Mississippi. If you’re heading out there for vacation or have family/friends in those areas be sure to let them know that today is a serious severe weather day.

12-21-2013 1-21-43 AM

Significant Severe Weather Event Expected to Impact the Northern Midwest

high risk

This is NOT Texas weather related, but because we know many of our fans have friends and family outside of Texas, we wanted to make you aware of a potentially SIGNIFICANT severe weather event expected to impact parts of Iowa, Illinois, Indiana, lower Michigan and northwest Ohio later today and this evening.  As highlighted on the graphic above, the Storm Prediction Center has placed this portion of the US under a HIGH RISK of Severe Weather for this afternoon and evening.  This is the highest designation possible in the severe weather threat categories, and this is the first HIGH RISK designation issued  this year.   

The biggest threat is going to be wind…possibly in the form of a derecho, or “bow echo” as you’ve probably heard on TV or radio.  Widespread wind damage is expected with winds in excess of 75 mph..possibly even close to or exceeding 100mph in some areas.  Very large hail to the size of baseballs is also possible…and if this hail is also wind-driven, it will most certainly be damaging and possibly lethal if caught out in it.   There is also a  elevated threat is for several large and strong tornadoes within any discreet storm cells that form in the afternoon, especially in the central Illinois areas.   The Chicago area is expected to feel the greatest impacts between 6pm and 11pm.   

If you have friends or family in any of the elevated risk areas above, please reach out to them and make sure they are aware of the potential for threatening weather this afternoon and evening.  Hopefully everyone has a way to receive weather warnings and a safe place to shelter if a warning is posted for their area.    

05/23/2013 Tornado Threat in Northwest Texas



Just a quick forecast as I’ve stayed overnight in Norman, OK and need to hit the road for the Texas Panhandle shortly. The above graphic is the Storm Prediction Center graphic for tornado potential today in Northwest Texas.  A boundary will set up in an area favorable for supercell development somewhere likely in the yellow 10% tornado area.  We are confident in severe storms in northwest Texas, particularly in that area, but the exact location will highly depend on exactly where that boundary will end up, and the confidence is lower in where that will happen. Any storm on or near the boundary late afternoon through early evening will have an enhanced chance to produce tornadoes.  My current thinking it will be in roughly the Hwy 287 corridor, perhaps north or south of it by 50 miles.

In addition, any storms in the Panhandle today will be potentially capable of producing very large hail, perhaps baseball size or larger. The SPC map below indicates the area with the greatest hail threat.  Again, storms on or near that boundary, will certainly be enhanced, and will be the greatest threat for very large and damaging hail.


Additionally, there is also some concern for flash flooding as these storms will be moving rather slowly early on and by late evening should be evolving into large thunderstorm clusters.  I guess on the good side, lots of folks could see lots of rain.

It’s that time of year folks, and it’s climatologically the peak of tornado season in Northwest Texas. Stay tuned to your weather information sources and have those weather radios on if you live in Northwest Texas today.


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