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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.


Thursday, March 16, 2023

SPC Mar 16, 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 1259 AM CDT Thu Mar 16 2023 Valid 161200Z - 171200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR NORTH-CENTRAL/NORTHEAST TX...SOUTH-CENTRAL/SOUTHEAST OK...EXTREME SOUTHWEST AR... ...SUMMARY... Scattered severe thunderstorms capable of producing large hail, damaging winds, and a few tornadoes appear likely Thursday afternoon and evening across parts of the southern Plains. Some of the hail could be very large over south-central Oklahoma and north-central Texas. ...Synopsis... A low-amplitude mid/upper-level shortwave trough will move quickly from the southern Rockies across the southern Plains today, and into the mid-MS Valley tonight. Meanwhile, a northern-stream trough will amplify through the period as a mid/upper-level cyclone moves southward across Manitoba. The primary surface cyclone will deepen across the upper Great Lakes region, in response to the northern-stream system. A strong cold front will surge southeastward across much of the Great Plains and Midwest, reaching deep south TX and the lower MS Valley by Friday morning. ...Southern Plains... The environment will become quite favorable for organized severe storms across the parts of the southern Plains into the ArkLaTex this afternoon into tonight. Low-level moisture will stream northward through the day, south of the surging cold front and along/east of a weak surface trough that may effectively become a weak dryline due to differential heating/mixing. Diurnal heating will promote moderate to locally strong destabilization (MLCAPE of 1500-2500 J/kg) across the warm sector, in the presence of relatively steep midlevel lapse rates. Effective shear will increase into the 40-60 kt range as strong midlevel flow overspreads the region. Despite the favorable environment, some aspects of the synoptic pattern may mitigate the threat of long-lived supercells, at least to some extent. The primary southern-stream shortwave will emerge rather early in the day, moving across OK in the 18-21Z time frame and quickly moving away from the warm sector by 00Z. The low-level jet will remain relatively veered through the day and become focused into parts of the mid MS Valley and Midwest, in response to the deepening cyclone over the Great Lakes. The fast-moving cold front may tend to quickly undercut any discrete cells that develop across the warm sector. These factors cast some uncertainty on the coverage and duration of supercell development this afternoon and evening, though scattered severe thunderstorms potentially capable of producing all severe hazards are still expected this afternoon and evening. Surface-based storms may develop along the front as soon as 18Z across central OK into western north TX, as the main shortwave trough ejects eastward. Meanwhile, isolated to widely scattered discrete storm development will be possible later this afternoon from south-central OK into north-central TX along the pre-frontal trough/weak dryline. The initial frontal storms and any discrete development across the warm sector may quickly evolve into supercells across south-central OK and north-central TX, with a threat of very large hail and isolated severe gusts. Also, despite somewhat veered low-level flow, effective SRH of 200-400 m2/s2 (larger with eastward extent) will support a tornado threat (including a conditional risk for a strong tornado) with any sustained supercells that can avoid being undercut by the front. Higher tornado probabilities may eventually be needed if multiple long-lived pre-frontal supercells appear increasingly likely. The potential for pre-frontal storm development is more uncertain with southwestward extent across south-central TX, with this area being further removed from the ejecting shortwave trough. However, any discrete supercell development along the pre-frontal trough or the front itself would quickly pose a threat of large hail and isolated severe gusts. Storm coverage will increase with time along the front tonight. While there will be a tendency for storms to be undercut by the front in this area, the strongest updrafts may still be accompanied by hail and isolated strong gusts. ...ArkLaTex region into the lower MS Valley... A supercell or two may develop out of initially elevated convection across the ArkLaTex region later today. While this scenario remains very uncertain, low-level shear/SRH will be sufficient for a tornado or two, should any convection become surface-based in this area during the afternoon or early evening. Later tonight, extensive frontal convection will spread into the region, with low-level and deep-layer shear remaining sufficient for a threat of damaging gusts and a couple of tornadoes, especially where any embedded supercells or bowing segments can be maintained without being undercut by the front. A weakening trend is expected late tonight as storms move into a less unstable environment, but some threat for locally damaging wind and possibly a brief tornado may extend as far as the lower MS Valley by 12Z Friday morning. ..Dean/Wendt.. 03/16/2023 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)