Administrators NorthGeorgiaWX Posted March 4 Administrators Share Posted March 4 SPC 1200Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1155 PM CST Sun Mar 03 2024 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE SOUTHERN PLAINS INTO THE LOWER/MID MS VALLEY AND MIDWEST... ...SUMMARY... Isolated strong to severe thunderstorms will be possible this afternoon into tonight from parts of central Texas into the lower Mississippi Valley, as well as from the Ozarks into the Midwest. Large hail is expected to be the main threat, but strong/gusty winds and a tornado or two may also occur. ...Synopsis... A large-scale mid/upper-level trough will cover much of the central/western CONUS through the day. Within the broader trough, multiple belts of stronger flow will impinge upon portions of the southern Plains, lower/mid MS Valley, and Midwest. A strong northern-stream shortwave trough will move quickly northeastward away from the upper Great Lakes during the morning, with multiple lower-amplitude vorticity maxima following in its wake. Meanwhile, a southern-stream mid/upper-level shortwave trough will move from northern Mexico into Texas by afternoon, and towards the lower MS Valley by late evening. A surface cyclone is forecast to move along a frontal boundary from the south-central Plains northeastward toward the mid MS Valley by evening. ...Parts of IL/MO into eastern IA and southern WI... A surface boundary is forecast to move northward as a warm front into parts of eastern IA, northern IL, and perhaps southern WI during the day, before stalling and then moving southeastward as a cold front during the evening. Across the warm sector, modest low-level moisture (dewpoints generally in the mid/upper 50s F) beneath relatively cold temperatures aloft will support MLCAPE increasing into the 1000-1500 J/kg range this afternoon. Some weakening of mid/upper-level flow is expected through the day in the wake of the departing shortwave, but will remain sufficient to support effective shear of 35-45 kt, which is conditionally favorable for organized convection. While a strong elevated storm or two will be possible across WI during the morning, the primary concern is for storm development in the vicinity of the surface front by late afternoon or early evening. Guidance varies regarding the timing of initiation and placement of the surface features, but in general, scattered thunderstorm development is expected from northeast MO/eastern IA into northern IL and southern WI. An initial supercell or two will be possible, though there may be a tendency toward more of a complex or linear mode with time as the front begins to push southeastward. Hail appears to be the most likely hazard at this time, though there will also be some potential for isolated strong/damaging gusts. Some tornado potential could also evolve if a surface-based supercell or two can be sustained. Uncertainties regarding placement/timing of the surface front and longevity of any supercell potential preclude higher probabilities across the region at this time. ...Parts of TX/eastern OK into the Ozarks and lower MS Valley... Relatively rich low-level moisture (with dewpoints increasing through the 60s F) will stream northward through the day across parts of TX, eastern OK, AR, and LA. Thunderstorm development will be possible by late morning into the afternoon along the northern periphery of the deeper returning moisture across parts of LA and perhaps into adjacent portions of southwest MS and southeast TX. Steep midlevel lapse rates atop the deepening moisture will support preconvective MLCAPE of 1500-2000 J/kg, with sufficient deep-layer shear for organized convection. A few strong multicells and perhaps a supercell or two will be possible, with an attendant threat of hail and locally damaging gusts. Farther west into TX, the diurnal severe threat is more conditional, with large-scale ascent expected to remain rather weak and relatively limited convergence along the dryline. However, a very isolated supercell or two cannot be ruled out during the late afternoon and evening, which would pose a large-hail threat. Overnight, most guidance suggests renewed storm development near the ArkLaTex region, likely in response to the southern-stream shortwave trough approaching the region. Storms within this late-night regime would likely be slightly elevated, but moderate buoyancy and favorable deep-layer shear may support an isolated hail and/or damaging-gust threat into early Tuesday morning. ..Dean/Weinman.. 03/04/2024 Read more View the full article Quote Link to comment Share on other sites More sharing options...
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