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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 31, 2023

SPC Jul 31, 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 Mon Jul 31 2023 Valid 311200Z - 011200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE SOUTHEAST INTO SOUTHERN VIRGINIA...THE MID-MISSISSIPPI VALLEY INTO EAST TEXAS AND LOUISIANA...THE CENTRAL HIGH PLAINS AND THE NORTHERN PLAINS...AND SOUTHERN ARIZONA... ...SUMMARY... Isolated strong to severe thunderstorms capable of producing large hail and gusty winds appear possible today across parts of the northern/central Plains. Additional thunderstorms producing mainly strong to damaging winds may occur across parts of the lower/mid Mississippi Valley, coastal Southeast, and southern Arizona. ...Synopsis... The mid-level flow across the CONUS will amplify today as a ridge builds across the central CONUS and a trough deepens across the East. This will result in a tightening height gradient and strengthening mid-level northwesterly flow across the Mid-Missouri Valley and vicinity. A mid-level jet streak will round the northern periphery of the ridge and will overspread the northern Plains this evening. A convectively enhanced mid-level shortwave trough will slowly drift around the mid-level anticyclone and should be the impetus for thunderstorm activity in the central/northern High Plains this afternoon/evening. ...Southeast into the Carolinas and southern Virginia... A cold front moved south across the Southeast today. Some residual moisture remains in the wake of this front early this morning from the Carolinas into southern Virginia. As temperatures aloft cool through the day with the amplifying larger scale trough across the eastern CONUS, sufficient destabilization is expected for scattered thunderstorm development. The lack of strong heating should mitigate the overall severe weather threat, but pockets of 2000 to 2500 J/kg MLCAPE with effective shear around 25 knots may be sufficient for some multicell clusters capable of some damaging wind gusts. ...Mid-Missouri Valley into Louisiana and eastern Texas... A severe MCS moving through northern Arkansas this morning is expected to weaken as it continues south. However, the remnant MCV/outflow boundary may provide a focus for thunderstorms this afternoon, particularly on the western periphery where better mid-level lapse rates will be located. Additional thunderstorms may form farther north along this frontal zone, perhaps in the vicinity of the remnant MCV/convectively enhanced mid-level shortwave trough currently moving through central Nebraska early this morning. Stronger mid-level flow across this region could provide shear for a more organized threat, but the combination of cloud-cover concerns and dewpoints only in the upper 60s in the wake of the Sunday night MCS will be mitigating factors to a greater severe-weather threat. Nonetheless, some localized threat may occur within this frontal zone if strong destabilization can occur beneath the stronger mid-level flow, however, it is not clear at this time if or where that may occur. The greatest threat for severe storms could be late in the period (06-12Z) as a 30 to 35 knot low-level jet develops across eastern Kansas and western Missouri with strong low-level isentropic ascent. Moisture recovery is also forecast during this period with 3000 to 4000 J/kg MUCAPE and effective shear of 45 to 50 knots. This would potentially support training supercells capable of large hail along the frontal zone in central Missouri. ...Central High Plains into the Northern Plains... A convectively enhanced mid-level shortwave trough is expected to emerge across the central High Plains this afternoon, and lead to widespread thunderstorm development along the Front Range amid strong instability and weak upslope flow. However, despite the favorable environment for thunderstorms, weak shear (20 to 25 knots per RAP forecast soundings) should mitigate more than a marginal threat for large hail or severe wind gusts. Farther north, across eastern Montana and North Dakota, a more conditional severe weather threat is expected. The building upper ridge will lead to mid-level warming and subsidence through the day, but strong heating should erode inhibition by midday. A supercell wind profile will be present, so if any thunderstorms can develop, supercells will be the likely storm mode with a threat for large hail (potentially 2+ inch) and severe wind gusts. However, building heights and a lack of obvious forcing (other than perhaps a weak shortwave trough embedded in the northwesterly flow) casts considerable uncertainty on storm coverage in this region. ...Southern Arizona... Numerous thunderstorms are expected to develop across southern Arizona today as 1.5 to 1.75 inch PWAT values are lifted northward on the western periphery of the mid-level anticyclone. Inverted-v soundings in the area will support damaging wind gusts with any of these storms, but a lack of stronger mid-level flow appears to be the greatest limiting factor to organization and the potential for a greater severe-weather threat. ..Bentley.. 07/31/2023 Read more CHECK UPDATE ZOOM GRAPHIC
SUNRISE AND SUNSET TIMES IN UTC (if you're not logged in to Google)
CHICAGO UTC-6 during CST (Central Standard Time, e.g., winter)
CHICAGO UTC-5 during CDT (Daylight Savings Time, e.g., summer)