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Weather conditions directly above are near Lakefront. Top tabs refer to O'Hare (official).

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, August 30, 2022

SPC Aug 30, 2022 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0254 PM CDT Tue Aug 30 2022 Valid 302000Z - 311200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHEAST AND MID-ATLANTIC... ...SUMMARY... Isolated wind damage may occur this afternoon and evening from parts of Virginia northward into New York and northern New England. ...20Z Update... Severe wind probabilities have been trimmed behind ongoing clusters of convection across the Northeast and Mid-Atlantic. Occasional damaging winds will continue to be the main severe threat with these thunderstorms as they move eastward through the rest of the afternoon and early evening. ..Gleason.. 08/30/2022 .PREV DISCUSSION... /ISSUED 1118 AM CDT Tue Aug 30 2022/ ...VA to NY and northern New England this afternoon/evening... A midlevel trough over IN/OH will move eastward to the Mid-Atlantic and New England by tonight, along with an associated surface cold front. A thick cloud band precedes the midlevel trough and accompanies the frontal zone, and midlevel lapse rates are poor in the warm sector. Differential heating and ascent along the east edge of the thicker clouds will support thunderstorm development in bands early this afternoon from northern VA northward across central/eastern PA and NY. Surface temperatures warming into the 80s with boundary-layer dewpoints in the upper 60s to lower 70s will support MLCAPE of 500-1500 J/kg, though poor midlevel lapse rates and relatively moist profiles in the zone of storm initiation will tend to mute downdraft potential. Thus, isolated strong outflow gusts and some wind damage may occur with the stronger clusters/line segments this afternoon in an environment with roughly 30 kt midlevel flow, but the potential for severe outflow winds appears to be low enough to maintain 5% wind/Marginal risk. ...Lower MS Valley area this afternoon... Cloud breaks will allow surface temperatures to warm to near or just above 90 F, while boundary-layer dewpoints will be maintained in the low-mid 70s. Forcing for ascent and vertical shear will be weak, but widely scattered thunderstorms will be possible this afternoon as convective inhibition is removed via daytime heating/mixing. Regional 12z soundings revealed the potential for afternoon MLCAPE near 3000 J/kg, but relatively moist profiles will limit the potential for intense downdrafts. Isolated/localized wind damage could occur with precipitation-loaded downdrafts, but the potential for severe outflow winds appears too low to warrant adding an outlook area. Read more CHECK UPDATE ZOOM GRAPHIC