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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, July 28, 2022

SPC Jul 28, 2022 1300 UTC Day 1 Convective Outlook

SPC 1300Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0745 AM CDT Thu Jul 28 2022 Valid 281300Z - 291200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON FROM EASTERN NY TO NH AND MA... ...SUMMARY... Occasional damaging gusts and marginally severe hail are expected across parts of the Northeast this afternoon. Isolated wind damage will also be possible from parts of the Mid-Atlantic to the Ozarks, and marginally severe wind/hail may occur near the Front Range in Colorado. ...Northeast this afternoon... A deep midlevel low over ON will move slowly eastward toward western QC, as embedded speed maxima translate eastward from the Great Lakes to New England on its southern periphery. An associated/diffuse surface cold front will likewise move eastward across the upper OH Valley and lower Great Lakes by early tonight. Thunderstorm development is expected by early afternoon along/ahead of the cold front, and along a pre-frontal trough from eastern NY into eastern PA, with the greater storm coverage expected from NY northward in the zone of larger height falls. Afternoon surface temperatures warming into the 80s in cloud breaks and boundary-layer dewpoints in the upper 60s to lower 70s will support MLCAPE of 1000-1500 J/kg. Midlevel lapse rates will be poor (< 6.5 C/km), but long and relatively straight hodographs with 35-45 kt effective bulk shear will favor a mix of supercells and short line segments capable of producing occasional damaging outflow gusts this afternoon. ...Portions of the Mid-Atlantic to the Ozarks this afternoon... Vertical shear will be weaker with southward extent away from NY, though modestly enhanced midlevel flow may extend as far south and northern VA. Cloud debris with morning convection will tend to slow surface heating today from eastern KY into WV and western VA, with the stronger buoyancy expected on the southern and eastern fringes of the morning clouds. During the afternoon, widely scattered thunderstorms could form in the zone of differential heating, and the strongest storms could produce isolated wind damage with downbursts. Wind profiles will be relatively weak in the low-mid levels along the southern periphery of the early clouds/convection from northern AR/southern MO to western TN. However, strong surface heating and steep low-level lapse rates south of the clouds could support a few multicell storms/clusters capable of producing isolated strong/damaging outflow gusts near and just after peak heating. ...Eastern CO and vicinity this afternoon/evening... Outflow with overnight convection has moved southwestward to the Front Range in CO. Some clouds will linger across the eastern Plains of CO, and vertical shear will be weaker with less steep midlevel lapse rates compared to Wednesday afternoon. Still, boundary-layer dewpoints near 60 F, pockets of surface heating, and low-level upslope flow should support the development of scattered thunderstorm clusters this afternoon near the Front Range. The strongest storms will pose a threat for marginally severe hail and isolated strong-severe outflow gusts. ..Thompson/Gleason.. 07/28/2022 Read more CHECK UPDATE ZOOM GRAPHIC
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