SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0156 PM CST Wed Dec 16 2020 Valid 162000Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF COASTAL NORTH CAROLINA... ...SUMMARY... Isolated strong to severe thunderstorms will remain possible across parts of coastal North Carolina and west-central Florida this afternoon. ...20Z Update... An isolated damaging wind and brief tornado threat should continue for the next couple of hours along/near the NC Coast and Outer Banks. Strong low-level shear is present to the northeast of a deepening surface low across this region, which should continue to prove favorable for updraft rotation. Although instability should remain fairly weak, strong low-level warm/moist advection should support surface-based storms where dewpoints can increase into the low to mid 60s. Severe probabilities have been adjusted to account for the northeastward movement of a band of convection located near and north of the surface low. For more information on the short-term severe risk across eastern NC, see Mesoscale Discussion 1853. Widespread precipitation has limited the degree of instability across much of the central FL Peninsula this afternoon. The potential for an isolated strong to damaging wind gust should remain confined along/near parts of the west-central FL Gulf Coast through the remainder of the afternoon as storms move onshore. Upper 60s to low 70s surface dewpoints are present across this area and slightly greater destabilization has occurred in the presence of moderate deep-layer shear. ..Gleason.. 12/16/2020 .PREV DISCUSSION... /ISSUED 1054 AM CST Wed Dec 16 2020/ ...NC... An intense shortwave trough is tracking across the lower MS and TN valleys today, with large-scale forcing overspreading much of the southeast US. Surface cyclogenesis is currently occurring off the SC/NC coast. Latest radar loop shows a line of showers and thunderstorms developing in vicinity of the surface low/warm front. These storms are expected to track northward today and affect the coastal counties of eastern NC. Most model solutions keep surface-based CAPE over the Sound and Outer Banks. Nevertheless, strong vertical shear may support supercell structures in this activity, with a risk of locally damaging wind gusts or a brief tornado. This threat should end by 23z as storms move out to sea. ...FL... Scattered thunderstorms are occurring this morning over the northeast Gulf of Mexico, along and ahead of an approaching cold front. There is considerable doubt that storms can maintain this strength as they move ashore into west-central FL this afternoon, due to the limited moisture/instability over that region. While a storm or two may produce gusty winds, the overall severe threat appears marginal.
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