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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.


Monday, July 3, 2023

SPC Jul 3, 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 1239 AM CDT Mon Jul 03 2023 Valid 031200Z - 041200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF THE MIDDLE ATLANTIC AND NORTHERN GREAT PLAINS... ...SUMMARY... Scattered strong to severe thunderstorms are expected across the Mid Atlantic Region and portions of the northern Great Plains Monday into Monday night. ...Middle Atlantic... Early-morning water-vapor imagery depicts a well-defined upper trough advancing east across the OH Valley. Strongest 500mb flow has advanced through the base of the trough and is forecast to translate across WV into the Delmarva by 18z, then off the Atlantic Coast during the evening. This scenario will result in strengthening wind/shear profiles such that any convection that develops later today has the potential to organize across much of the Middle Atlantic. Seasonally moist profiles currently reside across this region with ample low-level moisture (surface dew points in the lower 70s). As a result, modest buoyancy should develop by mid day ahead of the aforementioned speed max. Early this morning, several small clusters of convection continue across the central Appalachians. This activity is expected to propagate east-northeast but slowly weaken by the start of the day1 period. Aside from weak showers/convective debris, boundary-layer heating is expected to aid instability as temperatures warm to near 90F across the Delmarva. Forecast soundings suggest convective temperatures will be breached by 19z and isolated-scattered storms are expected to evolve ahead of the trough. Soundings suggest some threat for a few supercells, otherwise organized clusters appear possible. Gusty winds and hail are the primary threats with these storms. ...Northern Great Plains... Upper troughing will establish itself over the northern Rockies/northern Plains later today with weak height falls forecast as far south as WY into the upper Red River Valley. Lee surface low should settle into the Black Hills region by 18z, then propagate into northern NE during the overnight hours as surface pressures rise across the northern High Plains. Primary corridor of low-level convergence during the afternoon will focus along the boundary from the ND/SD border into northern WY where upslope flow will contribute. Surface temperatures should rise rapidly through the 80s into the lower 90s over much of SD, south of the boundary. CINH will weaken considerably by 21z and isolated thunderstorms will likely evolve. Forecast soundings suggest substantial sub-cloud dry layer as surface temp-dew point spreads may be on the order of 40F. Ample PWs will result in modest SBCAPE with steep lapse rates. It also appears flow will be strong enough for supercells and large hail can be expected. Additionally, very gusty winds could evolve with this activity if sufficient clustering occurs and an MCS evolves. Some consideration was given to increasing severe probabilities across this region. Two main areas of initiation may occur, one along/near the front over SD and the other within the upslope region of northern WY. Multiple clusters could evolve then spread east during the evening/overnight hours. ..Darrow/Weinman.. 07/03/2023 Read more CHECK UPDATE ZOOM GRAPHIC
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)