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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.


Friday, March 18, 2022

SPC Mar 18, 2022 0600 UTC Day 1 Convective Outlook

SPC 1200Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Fri Mar 18 2022 Valid 181200Z - 191200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTHEAST MISSISSIPPI...ALABAMA...FAR WESTERN FLORIDA PANHANDLE AND FAR WESTERN GEORGIA... ...SUMMARY... Severe thunderstorms are expected today across the central Gulf Coast states, where tornadoes, wind damage and isolated large hail will be likely with the strongest of storms. Storms with large hail and wind damage may also occur further north across the Ohio and Tennessee Valley, some of which could have very large hail. ...Southeast... A progressive upper-level trough will move quickly east-northeastward from the southern Plains into the Arklatex and Ozarks today, as a 60 to 80 knot mid-level jet translates northeastward from the lower Mississippi Valley into the Tennessee Valley. At the surface, a warm front will move northeastward across the central Gulf Coast States. This warm front will be an important player for the severe threat. To the southwest of the warm front, surface dewpoints will be in the 60s F, contributing to a broad warm sector with moderate instability. Thunderstorms associated with a substantial severe threat, will be ongoing at the start of the period from central Mississippi south-southwestward into southeastern Louisiana. These storms will move northeastward across the central Gulf coast states during the morning into early afternoon. A low-level jet should be positioned over southern Mississippi at daybreak with the jet moving northeastward into central Alabama by midday. This feature combined with the mid-level jet will create strong deep-layer shear favorable for supercells. Forecast soundings from southeast Mississippi northeastward into south-central Alabama in the 15Z to 18Z time frame have 0-3 km storm relative helicity in the 300 to 400 m2/s2 range suggesting conditions will be ideal for tornadoes. If supercells can track northeastward at nearly the same speed as the warm front, then a long-track strong tornado will be possible. Other tornadic storms will be possible with cells that interact with the warm front. Isolated wind damage and large hail will also be likely with the more dominant supercells. There is some concern with the weak storm relative winds at mid-levels evident on forecast soundings across parts of central Alabama. This would be prone to have downdrafts raining down into the updrafts. But still some storms, with access to the strongest of instability on the southern edge of a large area of rain, should be able to maintain strong updrafts and maintain a persistent severe threat. ...Ohio and Tennessee Valleys... An upper-level low will track eastward across the lower Missouri Valley today as the left exit region of a 60 to 80 knot mid-level jet moves across the Ohio Valley. At the surface, a 1000 mb low will track east-northeastward across the mid Mississippi Valley. A narrow corridor of maximized low-level moisture will be in place from western Tennessee into southern Missouri, where surface dewpoints will be in the 50s F by late morning. Scattered thunderstorms are expected to form from this corridor eastward into the lower Ohio Valley this afternoon, where 700-500 mb lapse rates will be steep and large-scale ascent will be strong. This should be favorable for relatively low-topped supercells with isolated large hail. A few of the storms could produce hailstones of greater than 2 inches in diameter. An isolated wind-damage threat could also develop with the stronger supercells. The area with the greatest threat for very large hail will be from far southeast Missouri northeastward across western Kentucky and into far southern Indiana. In this area, lift associated with the mid-level jet, instability and mid-level lapse rates will be most favorable. ..Broyles/Squitieri.. 03/18/2022 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)