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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.


Sunday, September 11, 2022

SPC Sep 11, 2022 1730 UTC Day 2 Convective Outlook

SPC 1730Z Day 2 Outlook Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Sun Sep 11 2022 Valid 121200Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE MID-ATLANTIC INTO NORTH CAROLINA...AND PORTIONS OF ARIZONA... ...SUMMARY... Isolated strong to severe thunderstorms may occur across parts of the Mid-Atlantic into North Carolina on Monday, with occasional damaging winds the main threat. A few severe thunderstorms also appear possible across portions of Arizona. ...Mid-Atlantic into North Carolina... A closed mid/upper-level cyclone will be present over the Midwest and Great Lakes on Monday. This feature is forecast to advance slowly eastward across these regions through the period. At the surface, a weak low initially over southern WI/northern IL should further occlude as it develops eastward across the Great Lakes and OH Valley through Monday evening. A cold front should move east-southeastward across much of the eastern CONUS and Southeast. A moist low-level airmass is expected to be in place ahead of the front across much of the Mid-Atlantic and Southeast. Due to occluded nature of the cyclone, mid-level lapse rates should generally remain poor across the warm sector. Even so, daytime heating is forecast to aid in the development of weak to locally moderate instability, with MLCAPE increasing into the 1000-2000 J/kg range by Monday afternoon. Thunderstorms should gradually develop through the day both along the surface cold front and ahead of it along weak low-level confluence bands. The best potential for robust convection appears to extend across portions of PA/NJ southward into MD/DE/VA and NC. This region should have some enhancement to mid-level southwesterly winds, even with the strongest flow aloft forecast to generally lag behind the cold front across the OH Valley. It appears that around 25-35 kt of deep-layer shear will be present to support updraft organization. Multicell clusters capable of producing isolated strong to damaging winds should be the main severe threat as they spread eastward through Monday evening. Where the deep-layer shear is forecast to be strongest (VA/MD/DC vicinity), marginal supercells may occur and pose a threat for both isolated hail and perhaps a brief tornado. ...Arizona... The remnants of a tropical cyclone should spread northward from southern CA into the Great Basin on Monday. A belt of modestly enhanced mid-level southerly flow is expected to be in place between this feature and upper ridging centered over the Four Corners. A rather moist low-level airmass should be present over the lower elevations of AZ. Diurnal heating of this airmass and persistent southerly mid-level flow should aid in the development of scattered to numerous thunderstorms Monday afternoon and evening across parts of southeastern into central and northern AZ. Although deep-layer shear appears marginal for thunderstorm organization, some clustering may occur. Isolated severe wind gusts appear possible with any thunderstorms that can develop as low-level lapse rates steepen. Occasional hail may also occur with the strongest cores. ..Gleason.. 09/11/2022 Read more CHECK UPDATE ZOOM GRAPHIC
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CHICAGO UTC-6 during CST (Central Standard Time, e.g., winter)
CHICAGO UTC-5 during CDT (Daylight Savings Time, e.g., summer)