Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Sun Apr 02 2017 Valid 021200Z - 031200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FOR EAST TEXAS...CENTRAL AND NORTHERN LOUISIANA...AND FAR SOUTHWEST MISSISSIPPI... ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF CENTRAL TEXAS AND MUCH OF EAST TEXAS EASTWARD INTO SOUTHERN ARKANSAS AND CENTRAL MISSISSIPPI... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL TEXAS INTO THE LOWER MISSISSIPPI VALLEY... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE SLIGHT RISK... ...SUMMARY... Numerous severe thunderstorms are forecast from parts of Texas eastward into the lower Mississippi Valley today and into tonight. A concentrated area of significant wind damage is likely near and north of the I-20 corridor in east Texas and Louisiana. The risk for tornadoes, a few of which may be strong/damaging, will probably maximize near and south of I-20 in Texas and Louisiana, along with the threat for hail. ...Synopsis... A closed mid-level low will evolve into an open wave and move from northern Mexico/Far West TX eastward to the ArkLaTex by early Monday morning. A broad area of surface low pressure over the Rio Grande Valley will consolidate and develop northeast across central TX during the day and be near the OK/AR border at the end of the period. A maritime warm front will advance northward across the northwest Gulf Coast region during the day as a cold front accelerates eastward across central TX during the afternoon and into LA during the overnight. ...Central TX eastward into the lower MS Valley... A multi-hazard, likely multi-scenario forecast with intrinsic complexity/uncertainty is seemingly evident for today into tonight. Late Saturday evening surface analysis and radar imagery show rich low-level moisture over the TX coast with a developing thunderstorm cluster in the middle Rio Grande Valley. Strong to severe thunderstorms will likely be ongoing over central TX. Severe gusts/wind damage appears to be the predominate threat with the early-day MCS. As the surface low deepens, a concurrent strong low-level mass response will occur and the development of a 50-kt LLJ by mid morning is expected. Strong low-level moist advection on the nose of the LLJ will be favorable for a continuation of early morning storms as the LLJ's terminus shifts eastward from east-central TX into the ArkLaTex by mid-late afternoon. A concentrated zone of higher probability wind potential may be realized with a potential bowing system as increasing buoyancy (1000-3000 J/kg MUCAPE) and strong shear lead to an intense bowing MCS moving from TX into the ArkLaTex. Coincident with the diurnal heating cycle, free warm sector thunderstorm initiation is likely from east TX into LA on the northern rim of the elevated mixed layer's stronger capping inversion (north of Interstate 10). Persistent south-to-north oriented confluence zones in the warm sector will serve as the genesis areas with gradual thunderstorm/supercell development as stronger updrafts penetrate the LFC---beginning as early as the late morning and through the afternoon. A moderate to very unstable boundary layer (MLCAPE ranging from 2000-3000 J/kg) is forecast from eastern parts of TX into LA. Forecast soundings show large hodographs (200-400 m2/s2 0-1 km SRH) with strong effective shear of at least 50-kt. It seems plausible several supercells may evolve from this activity and pose a threat for tornadoes and large to very large hail. A couple of strong/damaging tornadoes are possible. The latest model guidance suggests thunderstorm coverage will be less generally south of Interstate 10. Nonetheless, models show isolated to widely scattered storms developing perhaps in conjunction with stronger deep forcing for ascent. During the evening and overnight over the lower MS Valley, storms will likely spread into the region from the west. Increasing moisture/buoyancy as the maritime front advances northward will favor an organized severe storm risk continuing into the region. Thunderstorms within the strong flow fields will conditionally support the possibility for wind damage and tornadoes after dark. ..Smith/Gleason.. 04/02/2017Read more
from SPC Forecast Products http://ift.tt/s7Jkvo
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