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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.

Monday, July 12, 2021

SPC Jul 12, 2021 0600 UTC Day 1 Convective Outlook

SPC 1200Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1239 AM CDT Mon Jul 12 2021 Valid 121200Z - 131200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS CENTERED OVER WEST-CENTRAL PARTS OF THE FLORIDA PENINSULA... ...SUMMARY... Storms may produce damaging wind gusts over parts of Florida this afternoon. Isolated strong gusts or hail will also be possible over parts of New Mexico and Arizona, with a few strong storms across the Ohio Valley into southern New York. ...Synopsis... A weakening upper trough will linger over the MS Valley today as an upper ridge builds into the Mid Atlantic. A warm front will remain over southern NY and New England, beneath rising heights aloft. Modest shear near the warm front may again support isolated strong storms. South of the East Coast ridge, an upper/TUTT low will drift northwestward across FL, providing cooling aloft, and enhancing instability. A weak surface low will exist over southeast MO into southern IL, with a trailing front across AR and into north TX. Only sporadic strong storms with gusty winds are expected with this boundary as shear will be weak. To the west, an upper high will build over the Great Basin as a low-amplitude feature crests the ridge over the Pacific Northwest. Scattered storms will again be possible over parts of AZ and NM, beneath north to northeast winds aloft. ...FL... Strong instability will develop over FL today as midlevel temperatures cool resulting in midlevel lapse rates in excess of 7.0 C/km. When combined with 70s F dewpoints and heating, severe downbursts will be possible, along with hail in the stronger cells. Storms may develop across interior FL during the afternoon, and will likely move northwestward. Additional storms are possible along the west coast sea breeze around Tampa. Various CAMs are in good agreement with this scenario as well, suggesting merging storms with enhanced severe outflow risk. Cold temperatures aloft could support marginal hail with the stronger pulse storms. ...Central NM into AZ... Developing steep lapse rates and lingering moisture will result in over 1000 J/kg MLCAPE by afternoon, with storms initiating along the Rim and over the higher terrain into northern NM. Storms should move in south/southwestward direction through early evening, with locally strong gusts and marginal hail again possible. ...OH Valley into the Northeast... Upper ridging will occur today, as a warm front lingers across southern NY and New England. MUCAPE to around 1500 J/kg appears likely with heating, but shear will be less than on previous day. However, modest westerlies aloft may result in enough storm relative inflow for a localized severe risk after about 20Z as scattered cells develop over PA and move across NJ and southern NY. The most likely threat is expected to be isolated wind damage. ..Jewell/Wendt.. 07/12/2021 Read more LIVE: