SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1252 AM CDT Wed Oct 06 2021 Valid 061200Z - 071200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHEAST... ...SUMMARY... Isolated strong to severe storms capable of producing mainly damaging winds and marginally severe hail may occur today across parts of the Southeast. ...Synopsis... A closed mid/upper-level low centered over AR and the Mid-South this morning will meander slowly northward over MO later this afternoon and tonight. Around 25-35 kt of mid-level flow should be present across the eastern half of the upper low. At the surface, a rather moist low-level airmass characterized by mid 60s to low 70s surface dewpoints will remain across much of the Southeast to the east of a nearly stationary surface front. Generally southerly flow at low/mid levels will persist over the warm sector. ...Southeast... Scattered to numerous storms are expected to develop in the modest low-level warm advection regime through the period. Where some cloud breaks and filtered diurnal heating of the moist low-level airmass can occur, weak instability should develop. Even MLCAPE of 500-1000 J/kg will likely be sufficient to support surface-based storms. Some guidance suggests stronger instability, with MLCAPE up to 1500 J/kg, may develop by mid afternoon across parts of western AL/TN/KY and middle TN in closer proximity to the cool mid-level temperatures associated with the upper low. With a mostly southerly component to the low/mid-level winds, there will be only a modest directional component to the deep-layer shear as winds veer from south-southeasterly at the surface to south-southwesterly aloft. Still, gradual strengthening of the wind field with height should exist to foster around 25-35 kt of effective bulk shear. This will probably be enough in tandem with the weak to locally moderate instability to support occasional updraft organization. Damaging winds may occur with any clusters moving generally northward this afternoon and early evening. Marginally severe hail may also occur with the strongest storms where greater instability can develop. A brief tornado or two appears possible where modestly stronger low-level southeasterly winds on the eastern periphery of the mid/upper low can overlap sufficient instability to support surface-based storms. Have expanded the Marginal Risk to include more of the Southeast from parts of southern KY to northern/central AL and western GA, which should be in a fairly similar thermodynamic and kinematic environment. Finally, opted to include a small separate Marginal Risk area across parts of the FL Panhandle. Storms are forecast to develop later this morning over the nearshore Gulf waters and subsequently spread inland. Enough deep-layer shear and increasing instability should be present ahead of this convection to pose an isolated threat for mainly damaging winds through at least the early afternoon. ..Gleason/Bentley.. 10/06/2021 Read more LIVE: spc.noaa.gov
http://dlvr.it/S91NDp
