Severe Storm Risk - Mount Vernon, IN

• Severe Storm Risk

  Fri 11:30 AM - Sat 07:00 AM

  There is a Moderate Severe Storm Risk for your location. Continue reading for today's outlook from the National Weather Service's Storm Prediction Center. -------------------- National Severe Storm Outlook THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING MIDDLE MISSISSIPPI AND LOWER OHIO VALLEYS SUMMARY A regional outbreak of severe thunderstorms is likely this afternoon into tonight across parts of the mid Mississippi, Ohio and Tennessee Valleys. This will include intense supercells with strong, potentially long-track tornadoes and very large hail. The threat for damaging winds in excess of 75 mph will increase into this evening as storms grow into larger clusters. Mid MS Valley to the Mid-Atlantic through tonight An occluded 984 mb cyclone will move slowly eastward toward the upper Great Lakes and fill through tonight, as a trailing cold front progresses across MO/IL/IN/MI. Ongoing thunderstorm clusters will likely persist through the afternoon along the primary moisture/buoyancy gradient into the northern Mid-Atlantic, and with a developing cold pool from TN/KY into VA/NC within the warm sector. MLCAPE increasing to 2000 J/kg or greater, steepening low-level lapse rates, and sufficient deep-layer vertical shear (effective bulk shear of 40-50 kt) will maintain a mix of embedded supercells and bowing segments capable of producing very large hail (2 inch diameter or larger), thunderstorm gusts of 60-75 mph, and a couple of tornadoes. Farther west and in the wake of the ongoing TN/KY storms, rapid recovery is underway across southern MO where moisture advection and strong surface heating will result in rapid destabilization. Visible imagery shows evidence of ascent over northwest AR/southwest MO that will soon interact with the destabilizing warm sector. Supercell development is expected by midday into early afternoon from south central into east central MO, and storms will subsequently expand in coverage while spreading quickly east-northeastward across southern/central IL this afternoon and into IN late this afternoon/evening. The initial storms in MO will likely remain semi-discrete with the potential to producing very large hail (in excess of 3 inches in diameter) and a couple of strong tornadoes given very long hodograph with sufficient low-level shear. Gradual upscale growth into clusters/line segments is expected through storm interactions, with an increase in the potential for swaths of 65-85 mph gusts into this evening. More isolated supercell development may also occur later this afternoon along the modifying outflow boundary into KY, where all hazards are expected. Northern IL into Lower MI this afternoon/evening An embedded speed max and associated zone of ascent now over northern MO will eject quickly east-northeastward toward Lower MI by early tonight. The degree of moistening/destabilization will be modulated by how quickly storms form and how widespread coverage is this afternoon farther to the south from IL into IN. AR into southeast OK and northeast/central TX this afternoon Despite some cloud cover, surface heating in cloud breaks is allowing surface temperatures to warm into the 80s with low-mid 70s boundary-layer dewpoints, beneath midlevel lapse rates in excess of 8 C/km. Scattered thunderstorm development is expected this afternoon along the primary wind shift from AR/southeast OK into northeast and potentially central TX. MLCAPE of 3000-4000 J/kg and long hodographs with strong deep-layer shear will favor supercells capable of producing very large hail (3-4 inches in diameter) with the initial discrete storms, and damaging gusts of 60-75 mph. The tornado threat is less certain given relatively weak low-level shear (as a result of the primary mass response/low-level jet into the TN/OH Valleys), and will likely rely on favorable storm interactions.