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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.

Sunday, June 18, 2023

SPC Jun 18, 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 0103 AM CDT Sun Jun 18 2023 Valid 181200Z - 191200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM SOUTHEASTERN ARKANSAS/NORTHERN LOUISIANA SOUTHEASTWARD TO PARTS OF ALABAMA AND THE FLORIDA PANHANDLE... ...SUMMARY... Severe thunderstorms are expected on Sunday from The Arklatex area to the central Gulf Coast states. Damaging gusts and large hail will be the main hazard with these storms. A severe gust or two may also occur across eastern Montana. ...Arklatex region across the central Gulf Coast states and vicinity... A complex scenario is unfolding for today, as clusters of strong/severe storms are ongoing across Oklahoma and southern/western Arkansas which will spread east-southeastward with time. As this convection continues moving eastward/southeastward with time, and other storms develop near remnant/associated outflow, forecasting the timing and location for episodes of strong/severe storms across the risk area is quite difficult at this time. With that said, the large-scale setup remains favorable for locally severe storms, with a very moist boundary layer to become moderately to strongly unstable away from ongoing storms and associated cloud cover. This, combined with moderately strong flow through the lower and middle troposphere, suggests organized/rather fast-moving storms, including potential for both supercells and linear/bowing structures. Given this potential, a 30% potential for wind/hail (i.e. ENH risk) is being maintained across the lower Mississippi Valley vicinity and central Gulf Coast region. Again however, details within this region remain difficult to discern, aside from likelihood for a primary/early band of storms followed by secondary/later development later in the period. Various CAMs depict drastically different convective evolutions -- reflective of the complexity of the forecast, and thus a more detailed assessment will await later outlooks. ...Eastern Montana... As a cold front shifts eastward across Montana during the afternoon, ahead of a deep upper low drifting slowly southeastward across Washington state, very weak afternoon destabilization is expected. The destabilization will result from very deep boundary-layer mixing through the diurnal peak heating hours. Given this deep/dry sub-cloud layer, isolated/weak frontal convection that develops may produce gusty, evaporatively aided outflow winds, before convection weakens after dark. ..Goss/Flournoy.. 06/18/2023 Read more CHECK UPDATE ZOOM GRAPHIC