A strong cold front is set to deliver a line of severe thunderstorms to parts of central and eastern Texas on Friday, with the risk of large hail, destructive winds and tornadoes. The strongest storms may move through major metropolitan areas toward the afternoon and evening commute, spelling concern for motorists struck on area roadways.
The National Weather Service Storm Prediction Center has highlighted a level 3 out of 5 “enhanced” risk of severe weather, which blankets much of central and East Texas, southeast Oklahoma, southwest Arkansas and adjacent northwest Louisiana.
“Several tornadoes are possible over far southeast Oklahoma and eastern Texas,” the agency wrote in its online outlook. “A strong tornado or two may occur from late afternoon into early evening.”
Nearly 12 million people are in the bull’s eye where the odds of dangerous thunderstorms and tornadoes are the highest. Among them are residents in the greater Dallas-Fort Worth metro area east toward the Louisiana and Arkansas borders.
The Weather Service issued a tornado watch until 8 p.m. Central time in the zone from roughly Waco, Tex., to Tulsa, including Dallas, cautioning that a few tornadoes were likely “with a couple intense tornadoes possible.” At 1:35 p.m., heavy storms were already starting to flare up just west of Dallas.
The hazardous weather stems from a dramatic clash of the seasons. In the West, frigid air is bleeding south from Canada, overlapping with Pacific moisture to plaster parts of the Rockies with snowfall. Winter weather advisories blanketed the Rockies, where snow showers were garnishing the high terrain after an earlier storm plastered some spots with feet of snow. Yet another system is delivering snow by the foot in the Cascades, and will target the Sierra Nevada in the days ahead.
Farther east, temperatures are spiking 20 degrees or more above average in spots as high pressure swells northward. Mobridge, S.D., set a monthly record high at 80 degrees Wednesday; its average high is closer to 50.
In between, the seasons are waging war — and the increasingly volatile atmosphere will rear its angry head Friday afternoon and evening.
Timing and impacts
A Level 3 out of 5 enhanced risk for severe weather encompasses the greater Dallas-Fort Worth area, and stretches from southeast of Austin into southeast Oklahoma, including Waco and McAlester. Much of Interstates 20 and 30 are also included, as are places farther east including Lufkin, Tex., Shreveport, La. and Hot Springs, Ark. A lesser Level 2 out of 5 slight risk spans from Oklahoma City and Tulsa all the way to the Gulf Coast, including Houston-Galveston.
Hazards: Widespread strong to damaging winds within the mainline, along with isolated tornadoes. If supercells form, a strong tornado or two are possible.
Timing: Thunderstorms will rapidly fire during the mid-to-late afternoon around Dallas, pushing into areas just to its east as the afternoon and evening commute is starting. They will cross into Arkansas and Louisiana, affecting Shreveport and Texarkana, between 9 p.m. and midnight local time.
On water vapor satellite imagery Friday morning, the instigating trigger — a lobe of high altitude cold air, low pressure and spin nestled within a dip in the jet stream — could be seen in New Mexico around sunrise. That so-called “kicker” was ejecting east, and will slip over Texas Hill Country Friday.
It will enhance ascent, or upward motion, ahead of it, fostering the formation of thunderstorms. Southerly winds were also helping draw warmth and moisture northward across the southern Plains, while a shot of cool, dry air from the northwest was wrapping in behind the instigating disturbance. The resulting battle between the air masses, which will play out along a strong cold front, is what will brew storms.
That boundary will be moving through Central Texas and should approach the Interstate 35 corridor around lunchtime. Thunderstorms will rapidly develop near and east of a line from Waco to Dallas-Fort Worth to near Ardmore, Okla., around 2 or 3 p.m. There is some uncertainty how much “discrete” development there is — in other words, how many lone thunderstorm cells will form ahead of the cold front. Along the front itself, a squall line of thunderstorms is anticipated.
Due to considerable wind shear, or a change in wind speed and/or direction with height, any thunderstorms that form ahead of the mainline will have the propensity to become supercells or rotating thunderstorms and produce large hail, damaging winds and tornadoes. A strong tornado cannot be ruled out if discrete development occurs — and can persist long enough before cell mergers muddle storm structure.
Within the line itself, scattered to widespread strong to damaging winds of 50 to 70 mph are likely, along with embedded circulations capable of producing quick-hitting tornadoes.