Tornado Threats From Northeast Back to Southern Plains Today
Plus a look at the week ahead: tornado threats continue.
Severe thunderstorms are expected today across the Lower Great Lakes, Mid-Atlantic, and Southeast. More isolated severe thunderstorms are possible this afternoon and evening across much of central and east Texas, southwest Oklahoma, and the mid/upper Mississippi Valley.
Locations:
Primary Risk Areas: Much of the Atlantic Seaboard and north/central Texas.
Threats:
Damaging Winds: Expected across the Lower Great Lakes, Mid-Atlantic, and Southeast.
Large Hail: Particularly over north-central and parts of central Texas.
Isolated Tornadoes: Possible mainly across the Mid-Atlantic and Southeast.
Timing:
Storm Initiation occurs midday to afternoon and continues into the evening. In Texas, it occurs late afternoon into the overnight hours.
Peak Threat: This afternoon and evening.
Discussion:
Atlantic Seaboard to Southeast:
Setup: A complex synoptic-scale trough with several shortwaves and vorticity maxima will proceed eastward across the Upper Great Lakes and the Ohio/Tennessee Valleys. A northern-stream perturbation will pivot over Lake Huron and the Upper Ohio Valley/Lower Great Lakes today. In contrast, a strong upstream perturbation moves southeastward to southern MN and IA by 00Z.
Surface Analysis: A well-occluded low over northern Lake Michigan with an occluded/cold front arching across lower MI, OH, the Ozarks, and north-central to west-central TX will precede extensive convective outflow across the Appalachians, Southeast, and Mid-South.
Storm Development: Ongoing complexes of strong-severe thunderstorms over AL and GA may produce continued damaging wind, isolated large hail, and a tornado while moving into a favorably moist and destabilizing airmass over GA. Additional thunderstorms are expected to develop along the front from the Mid-Atlantic into upstate NY by midday and through the afternoon.
Severe Potential: Surface dewpoints in the low/mid-70s across GA and the Carolinas Piedmont/Coastal Plain to the 60s over the rest of the outlook corridor, combined with veering winds with height and related hodograph curvature, will support effective SRH of 150-300 J/kg, with potential for supercells and some tornado threat, as well as organized multicells in lines or clusters.
Southern Plains:
Setup: Isolated to scattered thunderstorms are possible from north-west TX southeastward across parts of LA and southern MS. Damaging gusts and large hail are the most significant concerns, with a conditional potential for isolated supercells offering large to very large/destructive hail, especially over north-central and parts of central TX.
Surface Analysis: A dryline will remain in place across north-central TX to northern Coahuila, becoming more sharply defined as moisture returns northward.
Storm Development: Strong diurnal heating and decreasing EML-related capping with eastward extent will result in more significant convective potential along/ahead of the front this afternoon from northwest TX to the central Gulf Coast states.
Severe Potential: Surface dewpoints in the 70s F and steep midlevel lapse rates will support MLCAPE of 4000-5000 J/kg over central/north TX, decreasing to 2500-3500 J/kg over southern MS. Veering winds with height and a lengthy hodograph structure will be well-suited for hail production in any sustained supercells. Coverage concerns linger due to forecast height rises across the region behind the synoptic trough.
Technical Chase Discussion
A pulled sounding from Northern Texas shows an environment strongly unstable with sufficient 0-6km bulk shear values for storms to produce large and damaging hail if one can get going. Capping is minimal, but large-scale subsidence aloft due to rising heights will make forcing for ascent negligible. A storm that can form in this environment would likely be somewhat isolated and quite powerful. Supercell risk-wise, the 0-3km SRH and BRN both point to only transient structures, but a supercell is likely due to the likelihood of a robust right turn that would locally increase both values to supercell levels. Tornado risk isn’t zero, but it is very low given extremely weak low-level wind shear.
As of this writing, the HREF from last night only had a 10-30% chance of storms in the North Texas region, which seems about right. Today is a true boom or bust. If a storm goes, wow. If a storm doesn’t, what a beautiful sunset indeed.
Have you subscribed to our YouTube channel?
The Week Ahead
This week probably won’t feature as many destructive tornadoes as last week, which is good news for everyone. However, the risk of tornadoes will continue, with an active subtropical jet giving us plenty of chances of severe storms throughout the week. The biggest threat days are Tuesday and Thursday, with risks every day this week otherwise. Boundaries from the previous day’s activity may limit or enhance days locally at any point this week.
Today
We covered a large part of today in our recent forecast blog. If a storm can go across Texas today, very large hail is likely.
Tuesday
On Tuesday, we anticipate widespread storms, with the most concentrated area over the Southern Plains. This day could potentially see a tornado or two, damaging winds, and very large hail. The number of storms on this day could warrant an enhanced (3/5) risk.
Wednesday
A storm or two should form off of the higher terrain from Eastern Colorado and NE New Mexico and move onto the adjacent portions of the High Plains with a chance of large hail and a tornado. The most likely scenario on this day is a well-structured supercell that is a beautiful photography subject for the storm-photography-minded person. More violatile storms are possible in Central Texas, in higher instability.
Thursday
It will be active on Thursday, with storms forming along a dryline and a stalled boundary with threats from NE Kansas back to the Texas Panhandle. Ample shear mixed with a stronger low-level jet will set the stage for the most significant and most impactful tornado risk of the week. The details are still TBA, but this is the day to watch for the upcoming week.
Friday
The wind shear weakens Friday, but this day should essentially repeat Wednesday with perhaps weaker shear but better moisture. I still think a supercell or two is possible on this day. However, the overall threat will be large hail over the open High Plains.
Weekend
More storms are likely over the following weekend, with a continued large hail and very low tornado risk on the Southern Plains. Flow is weakening rapidly at this point, so the nature of storm coverage and mode are an open question. There is a possibility of boundaries and such affecting each day. So we’ll say the risk continues, but the details are TBA.