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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, October 7, 2021

SPC Oct 7, 2021 1730 UTC Day 2 Convective Outlook

SPC 1730Z Day 2 Outlook Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1201 PM CDT Thu Oct 07 2021 Valid 081200Z - 091200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN PLAINS...AND ACROSS PARTS OF SOUTHERN GA INTO NORTHERN FL... ...SUMMARY... Thunderstorms associated with isolated hail are expected to develop across parts of the northern Plains from late Friday afternoon into the early overnight period. Additional strong storms capable of strong wind gusts and hail are possible across parts of southern Georgia into northern Florida through Friday evening. ...Northern Plains... Forecast guidance is inconsistent in how much convection will develop through early evening across parts of the northern Plains. Capping around 850-700 mb will likely preclude more than very isolated thunderstorm development through the day. However, a weak shortwave impulse is forecast to eject into ND/SD by early evening and increasing ascent may allow for isolated elevated storms. Surface dewpoints in the upper 50s to low 60s and modest midlevel lapse rates will support a corridor of 500-1000 J/kg MLCAPE amid 20-30 kt effective shear magnitudes. Any stronger storms that develop could produce marginally severe hail. ...Southern GA/Northern FL... An upper trough will shift east across the Southeast on Friday. Deep-layer flow will remain fairly weak, but cooling aloft will result in modestly steepening midlevel lapse rates. While cloud cover and some areas of showers/thunderstorms persisting through the period will limit stronger heating, surface dewpoints in the upper 60s to low 70s will foster moderate instability across the region. Effective shear magnitudes around 25 kt may allow for some briefly organized, stronger cells/clusters capable of marginal hail and locally strong wind gusts through early evening. ...Northeast NV/Northern UT/Southeast ID... The western upper trough will eject eastward over the Great Basin and northern Rockies on Friday. A surface cold front will sweep east/southeast across the region during the afternoon/evening and scattered showers/isolated thunderstorms are expected. Boundary-layer moisture and instability will be less compared to Day 1/Thursday, but modest vertical shear and steep midlevel lapse rates will still be in place. A couple of strong storms could produce small hail, but overall severe potential appears low at this time. ..Leitman.. 10/07/2021 Read more LIVE:
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