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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, September 6, 2023

SPC Sep 6, 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 1251 AM CDT Wed Sep 06 2023 Valid 061200Z - 071200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE ARK-LA-MISS VICINITY INTO NORTHERN MS...NORTHERN AL...AND MIDDLE TN... ...SUMMARY... Severe thunderstorms capable of damaging gusts and isolated hail are possible from the Ark-La-Miss vicinity into northern Mississippi, northern Alabama, and middle Tennessee. ...Synopsis... Shortwave trough currently moving into the Upper MS Valley is expected to continue gradually eastward throughout the day, ending the period over the Lower MI. As associated surface low will take a similar track eastward, while an attendant cold front pushes eastward/southeastward across the OH Valley and Mid MS Valley. A moist air mass will precede this front, with scattered to numerous thunderstorms anticipated as the front moves eastward/southeastward. Upper ridging will persist southwest of this shortwave trough, centered over far west TX. To the northwest of this ridging, the low-amplitude shortwave trough currently moving across central CA is expected to progress northeastward through the western Great Basin and into southern portions of the northern Rockies. Increasing mid-level moisture and modest large-scale ascent attendant to this shortwave will result in isolated to widely scattered thunderstorms from the interior Pacific Northwest and northern Great Basin into the northern Rockies. ...TN/Mid MS Valleys... Isolated showers and thunderstorms will likely be ongoing early in the period, supported by modest warm-air advection ahead of the approaching shortwave trough and associated cold front. This early activity should weaken, with strong heating and ample low-level moisture resulting in airmass destabilization by the early afternoon. Convergence along the front will be modest, but, given the lack of convective inhibition, still sufficient for thunderstorm development. Moderate mid-level flow will accompany the approaching shortwave, with some of this enhanced flow already over the region when thunderstorms initiate. Strong buoyancy will support robust updrafts, with the moderate shear contribute to some limited updraft organization and a low probability for severe hail. Storms will likely then trend quickly towards largely outflow-dominant structures after initial development, with water loading contributing to strong downbursts. Shear will likely be strong enough for some updraft/cold pool balance, with the development of one or more forward-propagating convective lines probable. These convective lines could take the threat for damaging gusts from the Mid-South into more of middle TN and northern MS/AL during the evening. ...Lower MI and Mid/Upper OH Valley... Several rounds of showers and thunderstorms are anticipated across the region today, starting later this morning amid broad warm-air advection ahead of the front. Additional development, or perhaps re-intensification of any ongoing storms, is expected as a pre-frontal trough moves across the region during the afternoon. Another round is possible later in the early evening as the cold front moves through, particularly if earlier storm coverage remains isolated. Despite poor lapse rates, moderate buoyancy is still expected across the region, supported by temperatures in the low 80s and dewpoints in the low 70s. However, shear will be weak, and will likely limit the overall severity of any thunderstorms. As such, only isolated damaging gusts are currently anticipated. ..Mosier/Wendt.. 09/06/2023 Read more CHECK UPDATE ZOOM GRAPHIC
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