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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, May 11, 2023

SPC May 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 1233 AM CDT Thu May 11 2023 Valid 111200Z - 121200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND SOUTHERN PLAINS... ...SUMMARY... Strong/severe thunderstorms are forecast Thursday across the central and southern Plains, where large hail and a few tornadoes can be expected along with locally damaging winds. Isolated hail/damaging winds are also possible across the lower Mississippi Valley into the Southeastern states. ...Central/Southern Plains... Latest water-vapor imagery depicts a well-defined upper low beginning to eject northeast across northwestern NM as 500mb speed max translates through the base of the trough. This speed max is forecast to progress into the eastern TX Panhandle by 18z, then gradually weaken as it shifts into northwestern OK by early evening. Subsequent weakening is expected during the overnight hours as the associated short-wave trough lifts into the mid-MO Valley by the end of the period. In response to this feature, LLJ should be focused across the High Plains from northwest TX into western KS early in the period. Scattered strong/severe thunderstorms are currently ongoing ahead of the trough from the NM/TX border, north into western KS. As large-scale ascent spreads into the High Plains this activity should be maintained to some degree, likely continuing into the early part of the day1 period. With more significant height falls forecast to spread into the central High Plains, southern extent of this activity should weaken/dissipate by mid day with only weak showers and associated cloud debris expected to spread across portions of the southern Plains. Of potentially more significance, cooling mid-level temperatures and steep lapse rates will spread across eastern CO/western KS early in the period. Strong boundary-layer heating is expected to contribute to steep low-level lapse rates across eastern NM into southwest KS by 18z. As a result, renewed thunderstorm development is expected fairly early in the period within the exit region of the aforementioned mid-level jet. Supercells should evolve and lift north-northeast across the central High Plains within a strongly sheared and modestly unstable environment. Hail, wind, and tornadoes are possible with these storms. Farther southeast, negligible height changes will be noted across OK/northwest TX. As a result, strong surface heating will prove instrumental in convective development along the dryline by late afternoon. If early-day convective debris is not that appreciable, surface temperatures are expected to warm into the lower 90s across northwest TX into extreme southwest OK by 22z. Convective temperatures will be breached along the dryline with these readings and isolated thunderstorms will likely develop soon thereafter. While high-level flow is not forecast to be that strong, surface-6km bulk shear will be strong and 0-3km SRH will be notable (300 m2/s2), especially by early evening along the I-35 corridor where the LLJ is expected to strengthen. NAM forecast sounding for OKC at 01z exhibits 4100 J/kg MLCAPE with significant veering with height in the lowest 5km. Any storms that develop near the dryline should advance northeast into an environment favorable for maintaining supercells. Very large hail, severe wind gusts and a tornado threat will be noted with this more isolated activity. ...Gulf States... Low-latitude trough, currently located over the lower MS Valley, is forecast to gradually weaken as it advances into the central Gulf States. Despite expansive cloudiness ahead of this feature, strongest boundary-layer heating is forecast along the FL Gulf Coast into eastern MS. Scattered robust convection should evolve ahead of the trough and isolated gusts/hail could be noted with the strongest storms. ..Darrow/Bentley.. 05/11/2023 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)