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Weather conditions on bar directly above are near Lakefront. Tabs under Moon Phases refer to O'Hare (official).

Archives for SPC Convective outlook are updated daily with a live map a the beginning of the article. Touch or click map to get possible update, and follow link at end of article for referral to NOAA/NWS Storm Prediction Center. Archives for Chicago's hourly weather data were updated 24-48 hours after end of each day prior to Dec. 2020.

Saturday, April 16, 2022

SPC Apr 16, 2022 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0249 PM CDT Sat Apr 16 2022 Valid 162000Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR SOUTHERN ARKANSAS INTO NORTHEAST LOUISIANA...SOUTHERN MISSISSIPPI AND SOUTHWEST ALABAMA.... ...SUMMARY... The corridor of greatest severe-thunderstorm concern today appears to be from southern Arkansas to southeastern Alabama. More-isolated and/or marginal severe weather is possible elsewhere from parts of south Texas to the coastal Carolinas, as well as across northern Utah into southeast Idaho. Trimmed the northern periphery of the marginal delineation where instability is now limited north of the front and any additional development later tonight should remain sub-severe. No changes were necessary for the general slight risk area. Trimmed the tornado probabilities southwest to areas ahead of the southwestward moving outflow boundary. However, elevated hail remains possible northeast of this boundary. Therefore, kept the 15 percent hail probabilities across this region. Elsewhere, the forecast remains on track. ..Bentley.. 04/16/2022 .PREV DISCUSSION... /ISSUED 1126 AM CDT Sat Apr 16 2022/ ...Synopsis... Late-morning regional radar mosaics show ongoing thunderstorms along an outflow boundary from western AR into the Ark-La-Miss region. This activity will continue to sag south/southeastward through the day in tandem with the outflow boundary, posing a severe wind/hail threat. While the highest severe weather potential will be associated with storms along this outflow, thunderstorms developing a cold front draped from the mid-Appalachians into southern OK/northern TX will pose a more isolated severe risk. Further west, an upper-level wave moving across central CA is expected to push into the inter-mountain West by this afternoon. Thunderstorms developing ahead of this wave/along a cold front may be capable of severe winds. ...Southern AR into southern MS/AL... Over the past hour, most remote sensing observations suggest that the ongoing thunderstorms along the outflow boundary have been gradually weakening with predominantly sub-severe wind/hail reported. Despite mostly cloud skies ahead of this line, temperatures have begun to warm into the mid to upper 70s, which is supporting gradual destabilization with MLCAPE values increasing to near 1500 J/kg. Moderate buoyancy (MLCAPE values to near 2000 J/kg) is expected to be in place across northern LA and southern MS/southeast AL by late afternoon, leading to a re-intensification by this afternoon. Surface to 850 mb convergence along the boundary combined with boundary-parallel deep-layer shear vectors should support thunderstorm clusters to mainly linear modes, potentially with a few bowing structures. A weak MCV is noted in the Ark-La-Miss region as of 1600 UTC, which may intensify and organize into such a bowing structure by the early afternoon hours. Damaging winds are the primary concern, but elongated hodographs above 3 km will support an attendant severe hail risk. Veering in the lowest 1 km may support a brief tornado threat for any surface-based storm rooted on the outflow boundary. Later tonight across central AR, scattered elevated thunderstorms are likely as warm advection increases atop the residual cold pool. While mid-level lapse rates will be somewhat limited, sufficient instability and deep-layer shear may support a few strong to severe storms capable of severe hail. ...Southern to eastern TX... Isolated to scattered thunderstorm development is expected along the cold front by mid to late afternoon as daytime heating erodes mixed-layer inhibition noted in morning soundings. Despite weak low-level flow, strong winds aloft combined with 7-8 C/km lapse rates will support a few organized storms with an attendant hail/wind risk. ...Southeast to the Carolinas... Weak convection is ongoing across GA into SC ahead of the surface cold front. This activity will continue to meander towards the coast through the afternoon hours. Intensification and additional convection is probable through the afternoon hours as modest daytime heating occurs and supports some boundary-layer destabilization. Somewhat poor mid-level lapse rates and modest forcing for ascent will limit the overall severe potential, but a few robust updrafts are possible given adequate deep-layer shear. ...Utah... Steep mid-level lapse rates are noted in the 12 UTC SLC RAOB, which will likely be maintained for much of the day as temperatures aloft fall and mid-level moisture increases ahead of the approaching upper-level wave. This will support isolated to scatted thunderstorms across the inter-mountain West by late afternoon. A dry, well-mixed boundary layer across northwest UT into southeast ID will support a microburst potential with strong to severe winds. Read more CHECK UPDATE ZOOM GRAPHIC