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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.

Tuesday, January 3, 2023

SPC Jan 3, 2023 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1148 PM CST Mon Jan 02 2023 Valid 031200Z - 041200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM SOUTHEAST LOUISIANA TO CENTRAL/SOUTHERN ALABAMA... ...SUMMARY... Severe thunderstorms are expected across the central Gulf states into the Tennessee Valley Tuesday. Tornadoes, damaging winds, and large hail are all possible. The greatest risk is expected from southeast Louisiana into southern/central Alabama where a couple of strong tornadoes are possible. ...Central Gulf States/Tennessee Valley... Strong mid-level short-wave trough is currently ejecting northeast across the central Plains. 500mb speed max affiliated with this feature is forecast to translate across MO into IL by 18z. As a result strong 500mb height falls (150m in 12hr) will overspread the mid MS Valley region as a warm front advances north across central IL/IN. Latest model guidance suggests the primary synoptic cold front will arc from southeast IA-eastern MO-lower Sabine River Valley by 18z, then into the lower OH Valley, extending into the lower MS Valley by 04/06z. Low-level warm advection will likely contribute to early-day convection ahead of the aforementioned short wave with the primary corridor of strong convection likely extending from western KY into northern TN. This band of storms should sag southeast as the strongest mid-level forcing spreads north of this region. While strong updrafts/scattered severe may be noted with this early activity, boundary-layer destabilization across the central Gulf states is expected to aid buoyancy for potentially more robust convection later in the afternoon. Surface temperatures will likely warm into the lower 70s across much of the lower MS Valley into central AL. With dew points in the mid 60s to near 70F, surface-based CAPE should approach 2000 J/kg in the presence of strong shear. Any updrafts that evolve within this environment could obtain supercell characteristics. Long-lived updrafts capable of generating tornadoes, and even a strong tornado, seem possible. Damaging winds are also a risk along with hail. While convection that evolves through early evening will not be strongly forced, a secondary, notable short-wave trough will eject across TX by 06z, and this feature should encourage renewed convection during the overnight hours as height falls increase ahead of the cold front. Frontal convection should organize and propagate across LA/MS into AL after midnight. ...IL... Surface warm front is forecast to advance north across MO/IL/IN this morning. Instability will also increase as dew points recover across this region. There is some concern that isolated strong/severe thunderstorms could initiate ahead of the cold front over IL around 17-18z but strengthen downstream where temperatures warm into the lower 60s . This activity will be strongly sheared and a few supercells may ultimately evolve. If so, hail and wind are possible, along with some tornado risk. Have extended severe probabilities north into IL to account for this risk. ..Darrow/Wendt.. 01/03/2023 Read more CHECK UPDATE ZOOM GRAPHIC