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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.


Saturday, April 8, 2023

SPC Apr 8, 2023 1300 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0748 AM CDT Sat Apr 08 2023 Valid 081300Z - 091200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few strong thunderstorms are possible in the I-10 corridor across northern Florida through early evening; however, organized severe weather appears unlikely. ...Synopsis... Overall, the mid/upper pattern across the CONUS will be fairly low in amplitude through the period, with the possible exception of the amplifying southern part of a synoptic ridge crossing the northern Plains and Upper Midwest, ahead of a trough now over the northern Rockies and Great Basin. Low-level theta-e ahead of that trough will be too weak to support a severe threat. However, large-scale lift preceding the trough, and weak moisture, will support isolated thunder potential across parts of the central/southern Rockies, with aid from low-level frontal forcing over parts of NE. Farther southeast, a southern-stream shortwave trough was apparent in moisture-channel imagery over parts of AR/LA, and is forecast to move eastward across the southern Atlantic Coast late tonight. A quasistationary surface front was analyzed at 11Z off the SC/NC coastlines, between NOAA buoys 41013 and 41002, southwestward across northern parts of the JAX area, then westward approximately along I-10 to a low near PNS. A cold front was drawn from there southwestward over extreme southeastern LA to the northwestern Gulf. The low is expected to migrate erratically eastward along the frontal zone and weaken through this evening. As the shortwave trough aloft approaches, a second, ultimately stronger low will form by late this evening over Atlantic waters off the Carolinas, leading to cold frontal passage over the FL Panhandle and parts of northern FL by 12Z tomorrow, with the front then extending southwestward across the central Gulf. ...FL Panhandle to northern FL... Widely scattered to scattered thunderstorms in clusters should affect the area through this afternoon and perhaps into early evening. Strong gusts are possible, and with some help from boundary interactions, a brief supercell cannot be ruled out. Relative thunderstorm concentrations most probable over two areas: 1. Immediately ahead of the surface low and near the front across parts of the Panhandle, where both large-scale lift aloft and frontal lift each will be maximized, and 2. Near the intersection of the diurnal, north/south-oriented peninsular sea-breeze boundary with the front, roughly in the JAX-Lake City corridor. Weak mid/upper-level lapse rates will substantially limit buoyancy, despite the rich boundary-layer moisture manifest in upper 60s to low 70s F surface dewpoints. The modified JAX RAOB (TAE being unavailable) and forecast soundings suggest peak MLCAPE in the 500-1000 J/kg range, with the greatest buoyancy somewhat less and in a narrower corridor eastward from Apalachee Bay. Weak low-level winds (generally 5 kt or less in the lowest km) will limit both low-level and deep shear, even with strong mid/upper-level venting flow. Effective-shear magnitudes of about 25-35 kt will be common, but may spike higher locally around any favorably oriented baroclinic (front, outflow, sea breeze) boundary processes. In response to the aforementioned Atlantic frontal-wave cyclogenesis, flow across northern Fl will veer from around 03-06Z onward, reducing both vertical shear and lift. Contemporaneous with a nocturnally stabilizing boundary layer, convective potential should weaken considerably through late tonight. ..Edwards/Smith.. 04/08/2023 Read more CHECK UPDATE ZOOM GRAPHIC
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CHICAGO UTC-6 during CST (Central Standard Time, e.g., winter)
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