SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0159 PM CST Wed Dec 11 2024 Valid 112000Z - 121200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS INTO THIS EVENING OVER THE COASTAL MID-ATLANTIC... ...SUMMARY... Severe wind gusts and a tornado or two are possible from the eastern Carolinas to southern New England. ...20Z Update... Severe probabilities have been trimmed along the western portion of the outlook, and reduced along the southern New England coast. For both areas, widespread stratiform rain has limited destabilization and the overall severe threat. Farther south, severe probabilities were removed from the FL peninsula, as convection has decreased in strength and coverage owing to the front lagging south of the large-scale forcing for ascent. The main severe threat through the remainder of the afternoon will be associated with any line segments that can organize along the coastal Mid-Atlantic, posing a risk for severe wind gusts and perhaps a brief tornado. For additional details, reference the latest mesoscale discussion (MCD #2261). ..Weinman.. 12/11/2024 .PREV DISCUSSION... /ISSUED 1026 AM CST Wed Dec 11 2024/ ...Delmarva region into the Carolinas... A large and fast-moving upper trough is tracking across the TN Valley and Gulf Coast region today, with the associated surface cold front sweeping toward the East Coast. Low and mid level wind fields are very strong ahead of the front, with VAD observations and model guidance suggesting 50-70 knot southwesterly flow in the 1-2km layer throughout the area. This will lead to a conditional risk of damaging winds and tornadoes in organized thunderstorms that can develop. However, thermodynamics are quite weak, limiting overall confidence in the extent of severe activity later today. Morning CAM solutions continue to suggest the development of a fine-line of convection this afternoon along the front from the Delmarva region southward into the Carolinas. This appears to be the area of highest confidence in locally gusty/damaging thunderstorm winds and a tornado or two. ...Southern New England... Rapid surface cyclogenesis and intense low-level wind fields will result in some risk of damaging winds in the fast-moving showers that affect Southern New England this afternoon. Forecast soundings show very weak instability, suggesting that frontal activity may struggle to develop robust updrafts/lightning. Will maintain the ongoing SLGT due to the conditional risk, but confidence in the coverage of severe weather is not very high. ...FL... The southern end of the frontal band of convection will sweep across the FL Peninsula this afternoon, with scattered thunderstorms expected to continue. This area will be farthest removed from the synoptic system, but will have better low level moisture/instability. A few strong storms are expected, capable of gusty winds and perhaps a tornado.