Temps | Gusts | WU KORD KPWK

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.


Thursday, July 1, 2021

SPC Jul 1, 2021 1630 UTC Day 1 Convective Outlook

SPC 1630Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1121 AM CDT Thu Jul 01 2021 Valid 011630Z - 021200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON THROUGH EARLY EVENING ACROSS PARTS OF THE MID-ATLANTIC... ...SUMMARY... Scattered damaging winds are likely across parts of the Mid-Atlantic Coastal Plain this afternoon into early evening. ...Mid-Atlantic this afternoon into early evening... A midlevel trough will continue to dig south-southeastward from ON/QC to the lower Great Lakes and central Appalachians by early Friday. An associated/weak surface cyclone will move from the Mid-Atlantic to the southern New England coast, as a cold front drifts southeastward to near the Mid-Atlantic coast. Ahead of the cold front and band of thicker clouds/rain, a pre-frontal trough and differential heating will help focus thunderstorm development into this afternoon, in phase with subtle/embedded speed maxima ejecting eastward around the southern periphery of the digging midlevel trough. Surface heating is underway with temperatures warming into the upper 80s to lower 90s from VA into DE/southern NJ, where boundary-layer dewpoints remain in the upper 60s to lower 70s. Despite rather modest midlevel lapse rates, MLCAPE will increase to 1500-2500 J/kg this afternoon, in an environment with steep low-level lapse rates and 30-40 kt midlevel flow (effective bulk shear 25 kt south to 40 kt north). Storms that form near the Blue Ridge by about midday will spread eastward through the afternoon as a mix of clusters and short line segments capable of producing damaging winds. The northern extent of the primary severe threat will be limited by the thicker clouds and late morning convection hampering destabilization, and the southern extent will be limited by weakening forcing for ascent and diminishing vertical shear. ...Southern High Plains this afternoon... A slow-moving cold front from southeast CO into northwest OK will focus thunderstorm development this afternoon, as the front encounters a gradually warming surface layer with dewpoints in the 60s to near 70. Clouds will tend to slow surface heating and midlevel lapse rates are poor (6-6.5 C/km) compared to typical Plains warm sectors, both of which will mute the potential for strong updrafts and downdrafts. Thus, while vertical shear may become sufficient for some weakly rotating storms along the boundary, the threat for severe storms still appears quite marginal. ..Thompson/Moore.. 07/01/2021 Read more LIVE:
SUNRISE AND SUNSET TIMES IN UTC (if you're not logged in to Google)
CHICAGO UTC-6 during CST (Central Standard Time, e.g., winter)
CHICAGO UTC-5 during CDT (Daylight Savings Time, e.g., summer)