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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, May 16, 2023

SPC May 16, 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 1259 AM CDT Tue May 16 2023 Valid 161200Z - 171200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN AND CENTRAL APPALACHIANS... ...SUMMARY... Strong to severe thunderstorms, associated with wind damage, isolated large hail and a few tornadoes are expected to develop across parts of the southern and central Appalachians this afternoon into early evening. ...Southern and Central Appalachians... An upper-level trough will dig southeastward today across the Ohio Valley, as a 45 to 55 knot mid-level jet develops and translates eastward through the central Appalachians. At the surface, a low will move eastward across Kentucky today, with moisture advection occurring ahead of the track of the low. Surface dewpoints are expected to increase into the lower to mid 60s F across much of the southern and central Appalachians, where moderate instability will likely develop by early afternoon. A line segment is expected to move eastward across southern Kentucky this morning. This line could be associated with a wind-damage threat. Low-level convergence is forecast to increase near the surface low. This, along with surface heating should result in scattered convective initiation around midday. Several clusters or short line segments are expected to develop and move eastward across the southern and central Appalachians this afternoon. The mid-level jet associated with the approaching upper-level trough, will steadily increase in strength over the region around midday. In response, moderate deep-layer shear will develop over much of the warm sector. Forecast soundings suggest that winds will be mostly unidirectional from the west-southwest above 850 mb. Also, 0-3 km lapse rates will steepen to near 7.5 C/km. This combination will be favorable for damaging wind gusts, along the leading edge of intense multicell line segments. Cells that remain discrete will have potential to become supercells. Supercells could produce isolated large hail, and perhaps a few tornadoes. The greatest tornado threat is forecast to develop during the mid to late afternoon from southeast Kentucky and northeast Tennessee eastward into western Virginia and far northwestern North Carolina. The wind-damage threat is expected to continue into the early evening as additional cells form in the higher terrain and move eastward into the foothills of the Appalachians. ...Central High Plains... An upper-level trough will move southeastward across the central High Plains today. As surface temperatures warm along a lee trough, convective initiation is expected in the higher terrain of eastern Wyoming. Thunderstorms will move south-southeastward along an axis of instability from western Nebraska into far northwestern Kansas. RAP forecast soundings at 21Z along the instability axis have MLCAPE around 1000 J/kg, 0-6 km shear near 36 knots, and 700-500 mb lapse rates above 8 C/km in a few locations. This should support a threat for isolated large hail with rotating storms that form during the late afternoon. ..Broyles/Weinman.. 05/16/2023 Read more CHECK UPDATE ZOOM GRAPHIC
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