Three consecutive days of severe weather are in store for the Lone Star State this week. Unfortunately this outbreak will unfold after just four days of reprieve in Texas since the start of a widespread severe weather event last week that spawned a whopping 97 tornadoes between last Wednesday and Friday in 12 states, taking at least 6 lives. Fortunately, such extensive destruction is not expected with this week’s outbreak. But the storms will nonetheless be dangerous in their own right, capable of producing baseball-sized hail, damaging winds, and a few isolated tornadoes.
The severe weather threat was in its infancy Monday afternoon as a slow-moving cold front draped across the Texas panhandle, southeastern New Mexico, and central Oklahoma. South of the cold front, warm and moist air flowing from the Gulf of Mexico has supplied abundant fuel for thunderstorms. Meanwhile, an upper-level feature approaching from northern Mexico has been working with the cold front in generating lift across portions of southeastern New Mexico, central Texas, and southern Oklahoma. Given the ample instability supplied largely in part by the Gulf of Mexico, thunderstorms have already began to develop in these areas. By late evening they will become more numerous, with some of them proving to be quite powerful.
By late evening the storms will become scattered in eastern New Mexico and western and central Texas. Enough deep-layer shear–change in wind speed or direction with increasing height–will be present across the region to allow many storms Monday afternoon and evening to develop rotating updrafts and evolve into supercells. Just enough shear will be present near the surface to allow development of a tornado in isolated thunderstorms. Otherwise, damaging winds and hail will be the primary threats. Steeply decreasing temperature with height will offer favorable conditions for the development of dangerously large hail stones within the updrafts of these supercells, the most potent threat of Monday’s storms. The updrafts of some storms could be strong enough to support baseball-sized hail. Hail stones of that size will shatter windows, dent vehicles, puncture roofs, and cause serious bodily injury. Cities at risk for these threats include Roswell, NM and Lubbock, TX.
Scattered thunderstorms will eventually merge into stout linear segments overnight. The hail and minor tornado threat will wane upon formation of these structures, but the wind threat will become greatly enhanced, especially near the center of these segments. Such structures are most likely to impact the southern Texas Panhandle and portions of southwestern Oklahoma.
The cold front will continue to crawl southeastward Tuesday, making little progress south of the Texas panhandle by mid-afternoon. The warm, moist, unstable conditions behind Monday’s severe threat will also be present Tuesday, yielding nearly identical severe weather risks over central Texas and western Texas. The main difference between Monday and Tuesday’s setup will be the building intensity of cool air mass behind the cold front.
By mid-afternoon, a temperature contrast of up to 30°F will develop across the frontal boundary. The stronger cold pool will finally allow the cold front to pick up the pace by late evening. Scattered thunderstorms, some of which will become supercellular, will organize in the warm sector ahead of the front. As it accelerates southeastward, this will help to organize the sporadic supercells into a broken line of thunderstorms pushing across central Texas and central Oklahoma overnight. There is a strong chance that segments within the broken line bow outward due to locally strong winds pushing storms forward. These bowing structures will possess elevated risks for dangerous wind gusts. The line of severe thunderstorms storms will impact cities like Dallas, Fort Worth, Wichita Falls, and Odessa in central and western Texas plus Lawton in southern Oklahoma.
The severe thunderstorm threat will shift southeastward Wednesday as the cold front pushes further into the South-Central US and eats away at the unstable Gulf of Mexico air mass. Tuesday night’s line of thunderstorms will largely survive into the morning, albeit in a weakened state. With increasing heating from the sun, fuel for thunderstorms will build throughout the day. The heating will help rebuild the line of thunderstorms while also triggering development of scattered thunderstorms ahead of the main line throughout southern Texas and the Arklatex during the afternoon. Damaging winds and large hail will again be the main threats Wednesday, but an isolated tornado or two cannot be ruled out.
The thunderstorms won’t die without a fight. The upper-level system driving the upward motion needed for thunderstorms will gradually get cut off from its cool air mass Wednesday night. It will be in a weakened state Thursday but will nonetheless have just enough vigor to support the redevelopment of thunderstorms in Louisiana, Arkansas, and Mississippi, which like Texas have been battered by fatal severe thunderstorms over the past few weeks. Unlike earlier severe threats however, the threat for tornadoes is expected to be low.
A long-lasting severe weather event is unfolding across the southwestern and south-central US, especially across Texas. All modes of severe weather are possible, although damaging wind gusts and dangerously large hail are the most probable. Those in the risk area are urged to heed warnings from the National Weather Service and to take precautions ahead of the storms to prevent loss of life and property. If a garage is not an option, invest in a carport or smother your vehicle in thick blankets to prevent hail damage. Secure or bring-inside loose outdoor plants, furniture and other belongings before the storms strike. Be sure to have batteries, warm blankets, a radio, a flashlight, a first-aid kit, wrench to shut-off utilities, medications, and at least three days of water and non-perishable food in the event of a power outage or strong tornado. Be sure to check back with WeatherOptics over the next few days as new information becomes available.