Temps | Gusts | WU KORD Data

CLICK for this month's BIG night sky ...




Cardinal SAT


MOBILE DEVICE? Turn sideways. 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.

Sunday, September 12, 2021

SPC Sep 12, 2021 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sun Sep 12 2021 Valid 122000Z - 131200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE GREAT LAKES...NORTHEAST U.S. AND THE CENTRAL HIGH PLAINS... ...SUMMARY... Scattered strong to severe thunderstorms are possible this afternoon into tonight across Lower Michigan into the Northeast States, in addition to parts of the central High Plains. ...Discussion... Only minor adjustments have been made to previous forecast. For the Great Lakes area see swomcd 1729 for additional near-term information. ..Dial.. 09/12/2021 .PREV DISCUSSION... /ISSUED 1124 AM CDT Sun Sep 12 2021/ ...Lower MI this afternoon to NY this evening/overnight... A gradual accumulation of low-level moisture has occurred along a slow-moving baroclinic zone from IA to Lower MI, beneath a plume of midlevel lapse rates in excess of 8 C/km. Convective inhibition is rather strong at the moment in this corridor, but continued destabilization and the approach of a perturbation/MCV from southern MN will contribute to increasing probabilities of elevated storm initiation along the baroclinic zone by mid-late afternoon across Lower MI. Storms that form along this boundary will encounter moderate buoyancy and effective bulk shear of 50-60 kt, which will favor organized clusters/supercells with an attendant threat for damaging winds and isolated large hail. Convection that forms across Lower MI late this afternoon will move quickly eastward and reach western NY by late evening/early tonight, with a continued threat for damaging winds along the stalled front until the convection weakens overnight. ...Central High Plains this afternoon/evening... A surface cold front is sagging southward into northeast CO and northwest KS as of late morning. Strong surface heating/mixing along and south of the boundary in CO will support scattered high-based thunderstorm development east of the higher terrain by mid-late afternoon. A couple of small clusters may persist through the evening while moving eastward, with the potential to produce occasional outflow gusts of 55-70 mph. ...Lower TX coast and Tropical Storm Nicholas... Tropical Storm Nicholas has formed in the Bay of Campeche, and is expected to slowly strengthen while moving north-northwestward (please see latest NHC advisories for details). Since the cyclone is in its early formative stages and located relatively far south, sufficient increases in flow/shear to support any tornado threat should be delayed until Monday into Tuesday, depending on storm details of the track/structure/intensity. Read more LIVE: