After a few days of quiet weather our next cold front will be pushing south into the state beginning late tonight and into Wednesday. Whenever you get a cold front in May down here you’re probably going to be dealing with a chance of thunderstorms. After the events of this past Saturday we know folks are sensitive to the threat of severe weather. In fact, we’ll probably have new folks visiting our blog for the first time. We’ll share with you what we know and let you know of what we’re not so sure about. We won’t hype or try and scare folks just to get website views. Tomorrow does not look like a day where we’re going to see numerous tornadoes. We said the same thing for Saturday because we assumed we’d be dealing with a squall line. We did end up dealing with a squall line, but that was after we had supercells for a few hours. An outflow boundary helped to locally enhance low-level wind shear in eastern North Texas. That same outflow boundary also provided the lift necessary to spark off the scattered storms. Had those factors not been present, which wasn’t something that could have been forecast more than a few hours in advance, we would have just had some hail and damaging winds on Saturday. Obviously the outcome was quite different. There is the potential for a couple of tornadoes on Wednesday in East Texas, but it will be a day where we’ll need the ingredients to actually come together. In the probable chance they don’t the risk for tornadoes will remain isolated and low. If the ingredients do come together we could have a few tornadic thunderstorms. We’ll talk about that in detail below.
The first chance for a few marginally severe storms will be late tonight in the Texas Panhandle. An approaching cool front combined with modest amounts of moisture return will present the opportunity for a couple of hailers. Wind shear is favorable for organized storms, but we just haven’t had time for the high moisture levels to reach that far north after Saturday’s cold front. These same regions saw snow on Saturday and Sunday. There could be just enough moisture to support a few storms capable of producing localized wind gusts up to 60 MPH and quarter size hail. It seems kind of funny to talk about localized damaging wind gusts when most of the Texas Panhandle experienced 55-70 MPH wind gusts on Sunday.
I can’t rule out one or two storms late this afternoon in the Texas Panhandle, but those storms shouldn’t amount to much. Perhaps some small hail and a microburst threat. The primary window for scattered storms will be from 10-11PM through about 4AM tonight. This is as the low-level jet ramps up out of the south. That LLJ will help spark off storms near the cold front tonight. These storms should primarily move east, perhaps east/southeast. The strongest of these storms may contain hail up to the size of quarters and localized wind gusts over 60 MPH. The tornado threat is minimal. Most of the storms should move east of the Texas Panhandle into Oklahoma by 4 to 5 AM Wednesday.
Wednesday is when we could see the threat of severe weather become more active in portions of East and Southeast Texas. The Storm Prediction Center has outlined an “enhanced” risk of severe weather, a level 3 out of 5, across portions of East and Southeast Texas tomorrow. This risk includes Center, Nacogdoches, Lufkin, Corrigan, Woodville, Jasper, San Augustine, and Hemphill – and points east into Louisiana. A “slight” risk of severe weather, level 2 out of 5, runs east of a line from Longview to Fairfield to Giddings to La Grange to El Campo to Freeport – east into Louisiana. Finally, the “marginal” risk, level 1 out of 5, runs east of a line from Paris to Dallas to Gatesville to Burnet to San Antonio to Freer to Hebbronville to just east of Rio Grande City. The higher the risk level number the higher chance you have of experiencing severe weather. In addition, the “enhanced” level 3 risk is where the possibility of a couple of tornadoes is highest tomorrow. These risk zones will be adjusted tomorrow when we start to see the ‘smaller-scale picture’ like boundaries and local enhancements that could support severe storms. So if you’re in or near these zones, keep an eye on the weather tomorrow – both before and during the event.
There is a slight chance of thunderstorms along the coast in Southeast Texas late tonight and Wednesday morning. It is possible a capping inversion may keep thunderstorms from development. If the cap holds we could see a few showers and perhaps some fog. If storms do form they’d have the potential of being severe with gusty winds, hail, and a risk of a tornado. At this point the chance of pre-dawn storms doesn’t look too terribly high. We’ll keep an eye on it and Jenny will have an update tonight with the latest forecast.
What is more certain is the threat of storms by late Wednesday morning into the afternoon hours further north. These storm chances will be due to another cold front moving south into the state. South of the front surface dewpoints will be in the upper 60s to lower 70s. Wind shear values in the middle and upper levels of the atmosphere will be strong enough to support organized thunderstorms. Low-level wind fields will feature turning with height, but they’ll be low. However, just like this past Saturday, we’re going to have to watch for any outflow boundaries or localized features that may enhance low-level wind shear. Saturday is a case where every ingredient needed to support significant tornadoes came together over a few counties in eastern North Texas. Ninety-five percent of the time that kind of situation would have likely had ingredients missing, so we would have only seen weak/brief tornadoes or just hail/wind. Just because we’re dealing with the potential for a few tornadoes tomorrow does not mean we’re expecting another Saturday-like event. Obviously if there is one tornado tomorrow and it comes down your street it will be your December 26 or your April 29. When it comes to thunderstorms expect the unexpected as the late Al Moller always said.
We’re confident that a line of storms will develop along a cold front by Wednesday afternoon. Some of the storms in that squall line may be severe with a risk of hail and damaging wind gusts. Brief tornadoes would also be possible, but not the primary threat, with the squall line. The concern for tornadoes would be highest with any storms that developed south of that cold front and could remain discrete. These isolated storms could happen, or they may not happen at all. Its conditional on the atmosphere destabilizing ahead of the cold front and on there being a lifting mechanism to allow individual storms to develop. If either of those don’t happen or some other factor falls out of play, we’d probably just have a squall line to deal with tomorrow. The location of those mechanisms would dictate where the risk zone would be tomorrow. The “enhanced” level 3 risk could need to be adjusted a bit north or a bit south tomorrow depending on where the focus-zone sets up. Should we see discrete cells they could produce all modes of severe weather, including a couple of tornadoes. I’ve explained in-depth what uncertainties we have for tomorrow while also giving you the facts. The squall line will probably fire up southeast of the D/FW Metroplex by the early afternoon hours tomorrow. That line will move southeast into East Texas, the Brazos Valley, Southeast Texas, and parts of Central Texas tomorrow afternoon and tomorrow evening. By the late evening hours it should be in a weaker state, but still capable of producing strong wind gusts as it moves into the Coastal Bend and South Texas. After this front moves through we’ll be looking at several days of calmer weather.