SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0247 PM CDT Sun Oct 18 2020 Valid 182000Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are unlikely through tonight. ...Northwest Arkansas into far southern Missouri... As the frontal surge deepens this evening, lift through the LFC will occur, with scattered storms likely. Forecast soundings indicate elevated instability, perhaps as much of 1000 J/kg MUCAPE rooted between 850 and 700 mb. Deep-layer effective shear will be most favorable over northern areas of the thunderstorm forecast area in Missouri, but instability will also be less. Overall, it appears that while small hail will be possible, severe hail unlikely. As such, will maintain less than 5% severe probabilities. ..Jewell.. 10/18/2020 .PREV DISCUSSION... /ISSUED 1120 AM CDT Sun Oct 18 2020/ ...Eastern Oklahoma/Ozarks to Lower Ohio Valley... Recent surface analysis placed a cold front extending from central Lower MI southwestward to a low over the TX Big Country. A broad warm-air advection regime will be in place in the vicinity of this front as it push gradually southward/southeastward amid persistent southerly low-level flow. Instability will be limited but still sufficient for occasional lightning strikes in the stronger embedded convective elements. Highest thunderstorm coverage is anticipated from southern MO/southern IL into northern AR this evening and overnight as lift provided by the warm-air advection is augmented by large-scale forcing attendant to a low-amplitude shortwave trough moving into the mid MS Valley. Vertical shear is strong enough for a few more robust updrafts, but the modest instability should temper updraft strength and persistence, limiting the overall severe threat and precluding the need to introduce any hail probabilities. ...Florida Peninsula... Easterly wave currently approaching the southeast FL coast will contribute to widespread thunderstorms across central and southern FL this afternoon. A relatively warm and moist air mass remains in place over the FL Peninsula, promoting moderate instability and the potential for a few stronger storms. Even so, lapse rates will remain weak and vertical shear modest, resulting in a relatively low-probability severe potential.
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