Administrators NorthGeorgiaWX Posted December 7, 2023 Administrators Share Posted December 7, 2023 SPC 0830Z Day 3 Outlook Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0156 AM CST Thu Dec 07 2023 Valid 091200Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EAST TX ACROSS THE LOWER MS VALLEY... ...SUMMARY... Scattered severe thunderstorms will be possible from east Texas across the Lower Mississippi Valley, mainly on Saturday afternoon into the early evening. ...Synopsis... The broader synoptic trends noted in D2 persist into D3 with a leading shortwave impulse and attendant cyclogenetic surface low rapidly progressing across the central Great Lakes towards James Bay. The trailing cold front from the Midwest to east TX will continue to push southeast, aided by a seasonably tight surface pressure gradient between it and a stout anticyclone over the northern Great Basin. Much weaker secondary cyclogenesis is generally progged from the Ark-La-Tex on Saturday morning to at least the TN Valley by Saturday night, as an upstream basal shortwave impulse shifts from the Four Corners across the southern Great Plains. Model spread in placement of the surface cyclone/front increases late in the period. ...East TX to the Mid/Deep South... Slower timing of appreciable mid-level height falls over the warm sector on Saturday suggests that more than isolated thunderstorm development should hold off until midday through the afternoon. This would likely allow for a plume of moderate buoyancy characterized by MLCAPE of 1000-1500 J/kg to become established from the Upper TX Gulf Coast towards the Ark-La-Tex amid surface dew points into the mid to upper 60s. Deep-layer southwesterly shear vectors should be nearly parallel to the orientation of the cold front, supporting a predominant clustered to linear convective mode. As such, convection will likely become widespread by late afternoon into the evening with favorable effective bulk shear for organized updrafts. Low-level shear will be modest with southwest extent where the larger buoyancy is expected, suggesting a predominant severe wind/hail threat. Enlarged low-level hodographs should generally be confined from the Ark-La-Miss to the northeast and east, where surface-based instability should be diminishing with spatial extent. Given the overall model trends for only weak secondary cyclogenesis through 12Z Sunday, the eastern extent of the 15 percent probability area has been held as-is. Confidence is low in just how far east the extent of low-probability wind/tornado threats exist overnight. ..Grams.. 12/07/2023 Read more View the full article Quote Link to comment Share on other sites More sharing options...
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