Severe weather this weekend March 14-15

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...Day 6/Fri - Mid to Lower MS Valley vicinity... A powerful upper cyclone and attendant trough is expected to develop east across the Plains toward the MS Valley on Friday. An intense southwesterly jet (100+ kt at 500 mb) is expected to be oriented from the southern Plains to the Mid-MS Valley by Friday evening. Meanwhile, a rapidly intensifying surface cyclone will shift northeast from the central Plains to the Upper Midwest vicinity through the period. Strong southerly low-level flow ahead of this low and an attendant eastward-advancing cold front will support rapid northward transport of Gulf moisture. While details regarding quality of northward moisture transport remain, this overall pattern will be very favorable for a regional severe weather episode from late Friday afternoon into early Day 6/Sat morning. Overall, cross-model consistency has improved compared to the past couple of days, and guidance generally appears to be converging on similar solutions. When compared with the operational ECMWF, the operational GFS remains a bit further north with the placement of the low-level and upper-level cyclones, as well as northward extent of better moisture return. However, the GEFS and EPS ensemble means are quite similar. While this indicates there is still a moderate degree of spread in the north and east extent of severe potential, the envelop is narrowing, and a broad area favorable for an all-hazards severe episode is expected on Friday/Friday night, centered on the Mid to Lower MS Valley vicinity. This trends is also aligned with SPC and NSSL experimental machine learning guidance. Given uncertainties still exist regarding timing and location of key features, as well as with northward extent of deeper moisture return, this area is likely to change/shift some over the coming days as details become better resolved (and higher probabilities will likely become necessary as well). ...Day 7/Sat - Southeast vicinity... While the upper cyclone from Day 6/Fri will lift northeast over the Upper Great Lakes into Canada on Saturday, the base of the larger-scale upper trough over the southern Plains will eject east over the Southeast states. Convection will likely already be occurring ahead of the cold front, and will have access to deeper Gulf moisture downstream across MS/AL. The north and east extent of severe potential is uncertain as the evolution of the system on Friday will impact downstream potential. Nevertheless, the overall pattern will be favorable for a continuation of severe potential into Saturday given strong vertical shear overlapping a seasonally moist and at least modestly unstable airmass.

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Look at the pressure for the Midwest

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Even James Spann getting on board early. Not typical of him 6 days out.
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What we know....

*A dynamic weather system with strong wind fields will impact the Deep South. The forecast synoptic scale look certainly suggests a risk of severe storms.

*The overall pattern will be favorable for severe potential given strong vertical shear overlapping a seasonally moist and at least modestly unstable airmass.

*Gradient winds (not related to thunderstorms) will likely be strong with this system.

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New update from Tuesday...

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...DISCUSSION... ...Days 4-6/Fri-Sun - Mid/Lower MS Valley to the Southeast and Mid-Atlantic... An intense spring storm system will deliver a multi-day severe weather episode to portions of the central and eastern U.S. beginning Friday and continuing through the weekend. All severe thunderstorm hazards are expected, including widespread damaging winds, tornadoes (some strong), and large hail. On Friday, an anomalously intense upper cyclone is forecast to deepen as it tracks northeast across the southern/central Plains to the Upper Midwest. An intense jet streak (greater than 100 kt at 500 mb) will overspread the Ozarks and Mid-MS Valley during the afternoon into the overnight hours. Likewise, a low-level jet will intensify Friday night to 65+ kt. As intense surface cyclogenesis occurs, southerly low-level flow will transport modest moisture as far north as eastern IA, southeast MN and southern WI. Deeper boundary-layer moisture will remain focused southward from the Mid-South toward the Lower MS Valley/central Gulf coast. Nevertheless, strongly forced convection within intense deep-layer flow will pose a widespread risk for severe (potentially significant severe) thunderstorm winds and tornadoes from late afternoon into the overnight hours across a large area centered on the Mid/Lower MS Valley vicinity. On Saturday, the upper cyclone over the Upper Midwest will lift northeast into Ontario, but a larger-scale upper trough will remain over the Plains. The Plains trough will intensify and spread east toward the MS/OH Valleys. This will maintain the eastward progression of a strongly forced line of convection from the Ohio Valley south/southwest into the Deep South/central Gulf coast vicinity through Saturday night. Portions of the Deep South into GA may see multiple rounds of severe convection with a mix of both supercell and QLCS storm modes potentially moving across the region, posing a concern for damaging tornadoes and swaths of severe winds. On Sunday, the system will continue to shift east, with a moist airmass and strong deep-layer flow continuing to support a line of convection producing damaging winds into the Carolinas and Mid-Atlantic vicinity. Outlook areas will continue to be refined over the coming days as key features become better resolved.

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