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Friday, November 5, 2021

SPC Nov 5, 2021 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0235 PM CDT Fri Nov 05 2021 Valid 052000Z - 061200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE THIS AFTERNOON AND EVENING ACROSS PARTS OF THE CENTRAL AND SOUTHERN FLORIDA PENINSULA... ...SUMMARY... Strong thunderstorms may still impact parts of the central and southern Florida Peninsula late this afternoon and evening, and pose at least some risk for severe weather. ...20Z Outlook Update... Models continue to vary concerning surface frontal wave development across the eastern Gulf of Mexico into the western Atlantic, east of northern Florida coastal areas by late tonight. However, the NAM appears too deep with the initial low over the eastern Gulf as it approaches coastal areas south of Tampa into early evening. Most guidance maintains a weaker wave, with another wave forming along Atlantic coastal areas near/north of Cape Canaveral this evening before migrating offshore. As a result, low-level hodographs appear likely to remain fairly modest to weak across much of central and southern Florida, as a seasonably moist boundary layer destabilizes ahead of the approaching mid-level trough. The leading edge of mid-level subsidence and drying, beneath a 50+ kt southwesterly 500 mb jet streak, does appear to be contributing to development of breaks in the convective cloud cover and precipitation which has slowed destabilization to this point. With some insolation still possible, along with weak low-level warm advection into early evening, instability might become sufficient to support the initiation of isolated to widely scattered vigorous thunderstorms, in the presence of strong deep-layer shear. If this occurs, stronger storms could pose the risk for locally damaging wind gusts. A generally brief/weak tornado might still not be out of the question, but the potential for anything more sustained and/or stronger currently appears low. ..Kerr.. 11/05/2021 .PREV DISCUSSION... /ISSUED 1108 AM CDT Fri Nov 05 2021/ ...Portions of central and southern Florida... A zone of enhanced mid- and upper-level ascent continues to move slowly across central and southern Florida this morning per WV imagery, in advance of a dry slot that will nose into western Florida with time. This should permit a period of relative decrease overall with respect to precipitation coverage across the peninsula during the day, while a surface warm front drifts northward with time. Still, persistent scattered/showery convection and cloud cover should substantially limit heating/destabilization in most areas. At this time, it appears that the greatest potential for any diurnal, modest boost in heating will be across western portions of the peninsula as the dry slot spreads eastward/inland. Any resulting/modest increase in CAPE would support potential for slightly more vigorous convection to spread onshore/inland starting later this afternoon. Along with any such enhancement of convection, updraft intensity would be aided by gradually increasing deep-layer shear, occurring as a result the expected, modest strengthening of flow at all levels through the mid troposphere as a surface low approaches -- and eventually reaches -- western Florida during the evening hours. Overall, expected environmental evolution suggests a relative increase in potential for a brief tornado or two, or a few instances of locally strong/damaging wind gusts, beginning late this afternoon focused on the west-central Florida area. However, at this time uncertainty prevails as to whether risk will rise to a level that warrants an outlook upgrade. As such, we will re-evaluate the scenario for the 20Z outlook update -- particularly related to thermodynamic evolution through the afternoon -- that will likely be a key variable with respect to any need to nudge severe risk category/probability upward for the evening hours. Read more LIVE: spc.noaa.gov