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SPC Apr 28, 2024 0100 UTC Day 1 Convective Outlook

1 year 4 months ago

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0802 PM CDT Sat Apr 27 2024 Valid 280100Z - 281200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTH TEXAS...OKLAHOMA...FAR SOUTHEAST KANSAS AND FAR SOUTHWEST MISSOURI... ...SUMMARY... Severe thunderstorms are expected this evening into tonight across much of the southern Plains and lower Missouri Valley. The greatest severe threat will be from north Texas northeastward through Oklahoma into far southeast Kansas and southwest Missouri. All hazards will be possible including tornadoes, with some strong, damaging wind gusts above 70 mph, and very large hail exceeding 2 inches in diameter. Scattered severe storms will also be possible later this evening in parts of west-central and southwest Texas. Isolated severe storms are also expected to occur this evening in parts of the mid to upper Mississippi Valley northeastward into the Great Lakes. ...Southern Plains/Lower Missouri Valley... An upper-level trough, evident on water vapor imagery, is approaching the southern High Plains. An associated 60 to 80 knot mid-level jet streak is currently ejecting northeastward into the southern Plains. This feature has been slower than forecast, and convective coverage across much of the southern Plains has been slow to increase. The lack of convection across much of Oklahoma has likely been a result of a capping inversion, that is evident on the 00Z Norman sounding just below 700 mb. As the mid-level jet streak moves over the southern Plains this evening, this cap is expected to weaken and the low-level jet will continue to strengthen. This should result in a ramp up in convective coverage over the next 2 to 3 hours, with a line of strong to severe storms developing along the western edge of the low-level jet from north Texas through central and northeast Oklahoma into southwest Missouri. The overall environment from north Texas into Oklahoma and southwest Missouri is characterized by moderate instability (MLCAPE around 2500 J/kg), 0-6 km shear near 60 knots, and 700 to 500 mb lapse rates from 8 to 8.5 C/km. This should continue to support the development of supercells with large hail this evening. The more intense supercells could produce hailstones greater than 2 inches in diameter. In addition, the 00Z sounding from Norman has 0-3 km storm-relative helicity around 400 m2/s2. This will also be favorable for tornadoes. The tornado threat is expected to be greatest with either supercells embedded in the line, or with discrete cells ahead of the line. Strong tornadoes will be possible. As the QLCS organizes this evening, tornadoes may also develop with rotating elements within the line itself. This linear MCS is expected to produce widespread wind damage and large hail from north Texas into central and eastern Oklahoma, and west-central/southwest Missouri. The severe threat will likely continue well into the overnight period. ...Mid to Upper Mississippi Valley/Great Lakes... The latest surface analysis shows a front from eastern Iowa northeastward into the western Great Lakes. A moist airmass is located to the southeast of the front, where surface dewpoints are mostly from near 60 into the mid 60s F. The RAP is analyzing MLCAPE in the 1000 to 2000 J/kg range, and moderate deep-layer shear across much of this airmass near the front. The latest WSR-88D VWP from Chicago has 0-6 km shear near 40 knots, and strong speed shear in the low-levels. RAP forecast soundings this evening in the vicinity also have steep lapse rates. This environment should support supercell development with large hail. Wind damage will also be possible with supercells and short bowing line segments. ..Broyles.. 04/28/2024 Read more