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.


Friday, August 11, 2023

SPC Aug 11, 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 1249 AM CDT Fri Aug 11 2023 Valid 111200Z - 121200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MID AND UPPER MISSISSIPPI AND LOWER MISSOURI VALLEYS... ...SUMMARY... Severe thunderstorms capable of large hail, damaging gusts, and perhaps a tornado or two are possible across portions of the Mid and Upper Mississippi Valley and Lower Missouri Valley areas today. ...Synopsis... A shortwave trough across the northern Plains will intensify as it moves into the Upper Midwest today. Across the southern Plains, ridging aloft will modestly increase. At the surface, a low will move through the Upper Midwest along with its parent trough. An MCV is expected to move through Iowa into northern Illinois/southern Wisconsin early in the period. An outflow boundary from this activity will lie roughly east-west near the Missouri-Iowa border into parts of central/northern Illinois. Farther northwest, a cold front will move south and east through the day. A remnant boundary will also remain in the Southeast. ...Eastern Iowa...southern Wisconsin...northern/central Illinois... The most complex portion of the forecast will be the evolution of the MCV. The character of the convection associated with this feature remains rather loosely organized Thursday night. By this morning, additional boundary-layer stabilization is likely to weaken this activity further as it reaches the Mississippi River. Some reintensification can occur as the boundary layer tries to warm this morning/early afternoon, but cloud cover moving downstream of the MCV does not lend much confidence in this scenario. A secondary possibility is that storms could from along the outflow during the afternoon. This activity would be more likely to impact parts of central Illinois. However, convergence along this boundary appears weak and deep-layer ascent is also minimal. Should one of these scenarios play out, damaging winds and perhaps a brief tornado would be possible. A categorical Slight will be maintained this outlook despite the described uncertainties. ...Mid-Missouri/Mid-Mississippi Valleys... Strong buoyancy is expected to develop south of the outflow boundary. Northwesterly flow aloft will contribute to 40-50 kts of effective shear across this boundary. This environment will support supercells capable of large hail and strong to severe wind gusts. The main uncertainty with this activity will be the overall coverage of storms during the afternoon due to weak forcing for ascent. Capping appears evident on forecast soundings during the afternoon. By late afternoon/early evening, the front will approach the region along with an increase in the low-level jet. Storm initiation will become more likely into the evening due to these factors. While storms could be slightly elevated by that point, large hail and perhaps more isolated wind damage would remain threats. ...Minnesota/Wisconsin... Lingering moisture and strong heating behind the cold front will promote convective development along with the passage of the shortwave trough. Moderate northwest flow at mid levels will increase effective shear to 40-45 kts by the afternoon. With cold temperatures aloft and long hodographs, widely scattered to scattered storms will be capable of large hail and wind damage. ...Southeast... Though shear will not be overly strong, a very moist airmass and modestly steep mid-level lapse rates will promote MLCAPE on the order of 3000-4000 J/kg. Wind damage from downbursts will be the primary risk. A corridor or two of more organized wind damage potential could develop as cold pools congeal, but predictability on where this will occur is low. ..Wendt/Lyons.. 08/11/2023 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)