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Weather conditions on bar directly above are near Lakefront. Tabs under Moon Phases refer to O'Hare (official).

Archives for SPC Convective outlook are updated daily with a live map a the beginning of the article. Touch or click map to get possible update, and follow link at end of article for referral to NOAA/NWS Storm Prediction Center. Archives for Chicago's hourly weather data were updated 24-48 hours after end of each day prior to Dec. 2020.

Monday, March 21, 2022

SPC Mar 21, 2022 0600 UTC Day 1 Convective Outlook

SPC 1200Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1237 AM CDT Mon Mar 21 2022 Valid 211200Z - 221200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS CENTRAL AND EASTERN TEXAS INTO EXTREME WESTERN LOUISIANA... ...SUMMARY... Severe thunderstorms capable of producing very large hail, damaging wind gusts, and several tornadoes are likely across portions of central and eastern Texas, starting this afternoon and lasting through much of the night. A couple of strong tornadoes are possible. ...Synopsis... A neutral-tilted trough will gradually traverse the southern Plains today as a surface cyclone gradually intensifies across northwestern Texas and propagates east-northeast. An embedded 500 mb impulse will pivot around the upper trough during the afternoon/early evening hours across Texas, encouraging the eastward shunting of a dryline across the Texas Hill Country while a warm front gradually drifts northward towards the Red River through the afternoon. Given prolonged deep-layer ascent from the approaching upper trough, coupled with a continuous feed of moist, buoyant air from the south, multiple rounds of strong to severe storms are expected across central/eastern Texas and surrounding areas this afternoon to 12Z Tuesday. All facets of severe will be possible. ...Central and eastern Texas into far southern Oklahoma today... The mid-level impulse embedded within the upper trough will overspread central and eastern TX by noon, accompanied by an 80+ kt 500 mb speed max, which will in turn encourage the development of a 60 kt 850 mb jet across central and eastern TX this afternoon. Deep-moisture/warm-air advection associated with the low-level jet will support widespread showers and elevated thunderstorms, starting in the morning. These preceding showers and storms complicate the forecast somewhat as they may impede the northward speed of surface airmass recovery. Nonetheless, latest guidance consensus shows 64 F dewpoints and surface-based buoyancy in far northeast TX by 00Z. Some marginally severe hail may accompany the initial WAA-driven elevated storms in northern TX/far southern OK. Later in the afternoon, semi-discrete supercells and small bowing-segments are expected to develop ahead of the dryline, given the presence of 1000-2000 J/kg MLCAPE and 50+ kts of effective bulk shear. 8 C/km mid-level lapse rates closer to the dryline, along with unidirectional deep-layer shear, suggests that large hail will be the initial main threat across central into northern Texas, with some significant severe hail possible. As storms advance eastward into the moister environment and approach the low-level jet axis, storms may acquire stronger low-level rotation and produce tornadoes. A strong tornado may accompany any sustained, discrete supercell. Meanwhile, the linear segments may produce damaging gusts in addition to some severe hail. ...Eastern Texas into the Arklatex later tonight... As the main upper trough continues to advance towards the lower Mississippi Valley, earlier day storms may coalesce into more linear segments capable of several damaging gusts and at least a couple of tornadoes given the strong low-level shear. Several CAM guidance members depict the initiation of a second line of storms across eastern TX, which will advance towards Louisiana in the 09-12Z period. Given adequate buoyancy and long, curved hodographs, stronger segments/cells within the broader line may acquire strong rotation, capable of producing damaging gusts and tornadoes. A strong tornado is also possible with the more intense QLCS circulations given the magnitude of strong low-level shear. ...Portions of northwest Texas into southwest Oklahoma this afternoon... Modest low-level moisture will wrap around the eastern/northern portion of the surface low across northwest TX this afternoon, overspread by -20C 500 mb temperatures and steep mid-level lapse rates. Semi-discrete supercells will develop near the triple point along the northwest TX/southwest OK border by early afternoon. The cold temperatures aloft suggest that severe hail will be the main threat, with an instance of 2+ inch hail possible, though a couple damaging gusts and perhaps a tornado also cannot be ruled out. ..Squitieri/Broyles.. 03/21/2022 Read more CHECK UPDATE ZOOM GRAPHIC