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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.


Wednesday, January 18, 2023

SPC Jan 18, 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 1142 PM CST Tue Jan 17 2023 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE MISSISSIPPI VALLEY INTO THE SOUTHERN OHIO VALLEY... ...SUMMARY... Severe thunderstorms are possible from far east Texas and the Lower Mississippi Valley into the Tennessee and Lower Ohio Valleys today. ...Synopsis... A mid-level trough will amplify today as it moves from eastern Colorado to the Missouri Valley. A 100+ knot mid-level jet will move from the southern Plains to the Lower Ohio Valley during this period. A surface low will move from the TX/OK Panhandle this morning to Missouri to western Illinois by 12Z Thursday. As this surface low moves northeast, a cold front will move quickly east across the southern Plains and Mississippi Valley. ...Mid Mississippi Valley... Low-level moisture advection has begun this morning across eastern Texas and Louisiana with mid 60s dewpoints now approaching I-20. This low-level moisture advection will increase after sunrise as the low-level jet strengthens to 50+ knots. This warm-air advection will likely initiate some storms across eastern Texas, northern Louisiana, and southern Arkansas. Strong shear (50-60 kts) and MLCAPE around 750-1000 J/kg should support supercells in an environment with 0-500m SRH in excess of 150 m2/s2. However, these storms will be occurring before any appreciable surface heating, and therefore, low-level lapse rates will be weak. Therefore, while a tornado or two cannot be ruled out with this activity, the limited low-level buoyancy should mostly limit the tornado threat. By mid-day, some heating will likely occur across the warm sector. However, warm mid-level temperatures and a lack of strong forcing to aid updraft acceleration will likely keep warm sector storms limited. Farther west, storms are expected along the cold front as it moves east through the afternoon. The progressive nature of the cold front and southerly lower tropospheric flow will support mostly anafrontal convection. Some severe storms are possible along the front with a primary threat of damaging wind and perhaps a tornado or two. As this line of storms moves farther east and buoyancy decreases after sunset, expect convection to become increasingly anafrontal which will significantly decrease the severe weather threat overnight. ...Eastern Oklahoma into the Ozarks... Mid to upper 50s dewpoints will advect into southeastern Oklahoma early this morning which will lead to weak destabilization. A few thunderstorms are possible in a strongly sheared atmosphere. These storms may pose a threat for marginally severe hail and a few damaging wind gusts. Upscale thunderstorms growth farther southeast should limit destabilization across the Ozarks, but weak instability is expected into the afternoon which should continue the damaging wind/hail threat. The strongly sheared atmosphere could support a tornado, but weak instability will likely mitigate the tornado threat this far north. ...Missouri Bootheel into the Lower Ohio Valley... Widespread thunderstorm activity is expected across this region for most of the day which should keep instability limited. However, strong low-level flow will likely bring low 60s dewpoints into the region ahead of the fast moving cold front which may lead to some weak instability. This could support some threat for damaging winds along the cold front as it moves east. ..Bentley/Broyles.. 01/18/2023 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)