SPC Apr 15, 2018 0600 UTC Day 1 Convective Outlook

By Newsroom America Feeds at 15 Apr 02:15

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0107 AM CDT Sun Apr 15 2018 Valid 151200Z - 161200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF WESTERN NORTH CAROLINA...NORTHWEST SOUTH CAROLINA...AND A SMALL PART OF SOUTHWEST VIRGINIA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM FLORIDA TO VIRGINIA... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF THE SOUTHEAST AND MID ATLANTIC... ...SUMMARY... Widespread thunderstorms, some severe, will spread across the Mid Atlantic and Southeastern states today into the evening. The greatest threat will be across parts of the Carolinas into southwest Virginia with a few tornadoes possible. ...Synopsis... An upper trough will pivot in a negative-tilt fashion from the MS Valley across the Southeast during day, continuing across the Mid Atlantic overnight. This will result in lift over a large area with rapid cooling aloft and height falls. At the surface, low pressure will deepen from OH across WV and across the lee of the Appalachians, with strong southeasterly low-level flow contributing to moisture advection as well as upslope flow into the higher terrain. Dewpoints into the low to perhaps mid 60s F will contribute to sufficient instability given extreme shear to support severe storms focused over the Enhanced Risk area, as well as farther south along the advancing cold front across GA and FL. ...Mid Atlantic... Surface winds will strengthen out of the southeast in response to the deepening low, with strong meridional flow aloft. Hodographs will favor supercells, and/or QLCS structures just ahead of or near the main front. Heating as well as upslope flow may contribute to destabilization and updraft strength. CAM solutions indicate a relative concentration of updraft helicity during the afternoon across the Enhanced Risk area where a few tornadoes will be possible. Given the strong backed low-level winds, an isolated severe threat may extend a bit farther west or north than currently depicted. Farther north, a stationary front will likely extend from northern VA across the Delmarva, with stable air to the north. As storms approach this boundary, they should cross quickly with only a marginal hail risk. A low chance of a severe storm or two may also exist across WV into OH, near the surface low and where shear will be strong but instability quite weak. ...Florida... A broken line of storms is expected to push eastward across the Gulf of Mexico, traversing the Florida Panhandle during the morning. Cells will likely affect much of the peninsula during the late afternoon and evening as they move ashore. Supercells will be possible given veering winds with height. Preceding the cold front, another broken line of storms is expected to form during peak heating, and affect mainly eastern FL and into southeast GA. Marginal hail, locally strong winds or a brief tornado will all be possible. ..Jewell/Cook.. 04/15/2018 Read more



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