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Archives for the SPC Convective Outlook are updated daily (approximately) with a live map at the beginning of each article. Follow the link at the end of the article to check for current updates on the NOAA/NWS Storm Prediction Center website. Also, see Archives for Chicago's hourly weather data on CARDINAL NEWS Magazine.

Monday, April 18, 2022

SPC Apr 18, 2022 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0243 PM CDT Mon Apr 18 2022 Valid 182000Z - 191200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF SOUTH FLORIDA...AND OVER THE OUTER BANKS OF NORTH CAROLINA... ...SUMMARY... Isolated severe thunderstorms are possible near the Atlantic Coast of Florida and the Outer Banks of North Carolina. Little change was made from the previous outlook, except to reduce the Marginal Risk area over eastern NC behind the cold front. Minimal SBCAPE exists except near the Outer Banks, and any isolated severe risk is expected to end in the next few hours. Otherwise, heating over southern FL combined with cool midlevel temperatures may support isolated severe storms along the sea breeze, with marginal hail or localized damaging gusts. ..Jewell.. 04/18/2022 .PREV DISCUSSION... /ISSUED 1120 AM CDT Mon Apr 18 2022/ ...Synopsis... Mid-morning water vapor imagery and analyses reveal mean troughing from the Great Lakes into the Mid-Atlantic with a series of embedded vorticity maxima from the upper MS river valley into the Mid-Atlantic. A broad swath of cold advection across the Plains into the Southeast and modest warm advection along the East Coast will support an amplifying pattern over the next 24 hours. A weak surface low, currently over the GA/SC coast, will deepen as it lifts to the north/northeast ahead of the amplifying wave and strengthening upper-level jet. The surface cold front over the northern Gulf Coast/Southeast will continue to sweep to the southeast across the FL peninsula today. ...Coastal Carolinas... A broad region of stratiform precipitation is ongoing this morning across much of the Carolinas. This is diabatically reinforcing a wedge front to the east of the Appalachians where temperatures are in the 40s to low 50s and instability is negligible (per the 12 UTC GSO sounding). Along the coast, however, onshore flow is supporting a shallow marine warm front where temperatures and dewpoints are in the low to mid 60s. Lapse rates along the coast are slightly steeper compared to locations inland and may support meager, but sufficient, instability for convection this afternoon as temperatures gradually warm under extensive cloud cover. Coastal VWP observations show strong veering in the lowest 2 km with around 200 m2/s2 0-1 km SRH. SRH will likely increase through the early to mid afternoon as the low-level wind fields strengthen in response to the deepening low. This will continue to support an isolated tornado, and damaging wind, potential through the afternoon if sufficient instability can be realized. KMHX imagery over the past 2 hours has shown an offshore MCV with embedded cells exhibiting organized mesocyclones. While the offshore thermodynamic environment is more unstable compared to onshore, this activity may persist into the afternoon as the MCV glances the NC Outer Banks. ...Southeast Florida... A growing cumulus field is noted across the southern FL peninsula where temperatures are already warming into the 80s. Modified 12 UTC soundings and trends in weak thunderstorm activity suggest any lingering diurnal inhibition is waning. Surface-based instability will continue to improve through the early afternoon (upwards of 3000 J/kg by around 21 UTC), and combined with improving upper-level flow, will support a hail/wind risk as thunderstorms develop along and ahead of the approaching cold front. Read more CHECK UPDATE ZOOM GRAPHIC