• SPC Apr 3, 2020 1630 UTC Day 1 Convective Outlook
    on April 3, 2020 at 4:30 pm

    SPC 1630Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1126 AM CDT Fri Apr 03 2020 Valid 031630Z - 041200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SOUTH TX... ...SUMMARY... Scattered large hail, severe wind gusts, and a brief tornado will be possible through this evening across south Texas. ...South TX... Initial thunderstorm development is underway just west of Del Rio near the Coahuila border as persistent but light easterly low-level winds aid in weak upslope forcing for ascent, and along the surface cold front over the Edwards Plateau. This vigorous cold front will plow south into the Brush Country through the afternoon and eventually into Deep South TX tonight. Rich surface dew points from about 69-73 F in conjunction with pockets of modest boundary-layer heating will support a broad plume of 2000-3000 J/kg MLCAPE amid steep mid-level lapse rates of 7.5-8 C/km. While light winds below 700 mb will limit effective SRH, substantial veering of the wind profile with height along with pronounced speed shear through the mid/upper-levels will foster an elongated hodograph favorable for splitting supercells. This setup should support potential for a couple strongly rotating supercells in the mid-levels that may yield very large hail, resulting in a significant area delineation. The small SRH, weak MLCIN, and progressive/anafrontal nature of the front suggest that a messy mode with a mix of clusters and embedded HP supercells may ultimately evolve southeast this afternoon and evening. The best chance for large hail, severe wind gusts, and a brief tornado will exist with any supercell that can be sustained just ahead of the front, mainly into Deep South TX this evening. ..Grams/Karstens.. 04/03/2020 Read more

  • SPC - No watches are valid as of Fri Apr 3 16:31:01 UTC 2020
    on April 3, 2020 at 4:30 pm

    No watches are valid as of Fri Apr 3 16:31:01 UTC 2020.

  • SPC - No MDs are in effect as of Fri Apr 3 16:31:01 UTC 2020
    on April 3, 2020 at 4:30 pm

    No Mesoscale Discussions are in effect as of Fri Apr 3 16:31:01 UTC 2020.

  • SPC Apr 3, 2020 1300 UTC Day 1 Convective Outlook
    on April 3, 2020 at 12:47 pm

    SPC 1300Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0743 AM CDT Fri Apr 03 2020 Valid 031300Z - 041200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTH TEXAS... ...SUMMARY... Severe hail and gusts are most probable through tonight across parts of south Texas. ...Synopsis... The mid/upper-level pattern will remain highly amplified and blocky over most of North America, north of a subtropical jet extending over northwestern MX, central TX and the northern Gulf Coast. The center of one cyclone, that has been retrograding off New England, should pivot southward/southeastward before reaching the coast. Meanwhile, a very broad, distorted cyclonic gyre, with multiple embedded vorticity/circulation centers and orbiting shortwaves, will persist over western Canada and the northern Rockies region. At the surface, 11Z analysis showed a strong cold front, from a low over ON near Lake of the Woods, across eastern IA, central MO, eastern OK, north-central TX to the lower Pecos Valley, northwestward to central NM. By 00Z this front should be located over central IL, central AR, east TX, and northern Coahuila. By the end of the period, the front should reach western Lower MI, western KY, northern LA, and deep south TX. ...South through east TX... Episodic, scattered to numerous thunderstorm development is expected from late morning or midday through tonight, in a swath across the corridor from the foothills of the Serranias del Burro in northern Coahuila, across the middle/lower Rio Grande Valley, southern Hill Country, and parts of south-central/southeast TX. Damaging gusts and severe hail are the main concerns, though a tornado cannot be ruled out. More-isolated, less-organized thunderstorms may produce isolated/marginal severe over parts of east TX. Northern parts of the outlook areas have been suppressed southward due largely to current/anticipated frontal motion. While weak capping may support initiation in the free warm sector, the most likely foci for convection will be the cold front and heating of higher terrain in MX. The decidedly anafrontal baroclinic regime -- characterized by strong and deepening post- frontal cold advection, will result in only brief windows for severe with near-frontal convection. Potential for more-sustained, persistently organized activity will be greater within 2-3 hours of frontal motion to its south, especially with activity forming near and west of the Rio Grande. Warm-sector kinematic and thermodynamic parameters will be more favorable with southwestward extent. Rich low-level moisture will occupy the warm sector outlook-wide, with surface dew points commonly in the upper 60s to low 70s F, and 1.3-1.8-inch PW. Greater midtropospheric lapse rates (residual EML) and low-level lapse rates (diabatic heating, behind ongoing mesoscale cloud area) are likely over south-central TX and the Rio Grande Valley, resulting in peak MLCAPE of 2000-3000 J/kg. In the absence of a DRT sounding, objective analyses reasonably indicate MLCINH already is weak across roughly a SAT-DRT-LRD triangle westward into Coahuila. This suggests potential early initiation of the first prefrontal convective episode -- perhaps before noon. A limiting element will be weak low-level winds -- generally less than 10 kt through most of the surface-700-mb layer -- keeping hodographs small and SRH minimized. Regardless, strong deep shear is forecast under the mid/upper-level subtropical jet, with 50-60-kt effective-shear magnitudes. Given those factors and the weak CINH, a messy array of variably organized multicell clusters and heavy- precip supercells is possible. Significant hail cannot be ruled out with any relatively discrete supercells, especially near the Rio Grande and over adjoining south-central TX. However, uncertainties regarding timing, location and persistence of favorable mode precludes a focused 10%/hatched area at this time. Deep, strongly water-loaded downdrafts will support at least localized severe-wind potential, with upscale organization possible. ..Edwards/Gleason.. 04/03/2020 Read more