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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, August 13, 2023

SPC Aug 13, 2023 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook Day 1 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 0317 AM CDT Sun Aug 13 2023 Valid 131200Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF SOUTHEASTERN KANSAS...FAR NORTHEASTERN OKLAHOMA...AND INTO THE OZARKS VICINITY... CORRECTED FOR DAY IN TEXT ...SUMMARY... Severe thunderstorms are possible Sunday from portions of the southern and central Plains into the Middle Mississippi, Lower Ohio and Tennessee Valleys. ...Synopsis... Ridging aloft will prevail over the western U.S. today, as well as over the south-central and southeastern states. Meanwhile, a rather vigorous mid-level short-wave trough will advance southeastward across the northern and central Plains through the day, and into the Upper Midwest overnight. At the surface, an evolving cold front is forecast to progress southeastward across the northern and central Plains. By sunset, the front should extend south-southeastward from a weak low over the eastern South Dakota vicinity to the Texas/Oklahoma Panhandles. Meanwhile, a weak warm front should extend southeastward across Missouri and into the Tennessee Valley area. Additionally, various convective boundaries are forecast to reside over the Kansas/Oklahoma/Missouri area. These surface features -- both synoptic and convectively induced -- will contribute to the likelihood for multiple rounds of convective activity through the period, from the central Plains vicinity to the Mid Mississippi/Lower Ohio/Tennessee Valley areas. ...Mid Missouri Valley to the Texas/Oklahoma Panhandles, and eastward to the Tennessee/Kentucky vicinity... A rather complex convective scenario is evident for today across the primary risk area that extends from the Plains to western fringes of the Appalachians. Convection will likely be ongoing at the start of the period across portions of the Plains and possibly into the Ozarks area. The storms should continue through the day, moving eastward with time, reinforcing the various convective boundaries across this area. As daytime heating occurs on the periphery of these boundaries, and along/ahead of the advancing cold front, additional storm development is expected. Given the belt of generally 35 to 45 kt mid-level westerlies atop the region, shear will be sufficient to support potential for strong/locally severe storms, with hail and locally damaging wind gusts the primary risks. Delineating any potential area of more concentrated severe risk remains difficult at this time, but one area where greater severe-weather coverage may manifest is across the Ozarks vicinity. Along with a warm front expected to lie across Missouri, a roughly west-to-east outflow boundary may evolve -- and possibly become the effective focus for multiple rounds of storms. With a corridor of enhanced (40 to 50 kt) west-southwesterly flow expected to lie atop this region, episodic strong/damaging gusts are expected, which warrants inclusion of 30% wind probability/ENH risk across this region. In addition, with backed low-level flow expected to the cool side of the aforementioned boundaries, corridors of enhanced low-level veering/shear suggests potential for a few tornadoes. Risk will likely continue through the evening and into the overnight hours, as additional storms associated with the southeastward cold frontal advance evolve/spread southward and eastward into early Monday morning. ...New England... Modest low-level moisture is expected to remain in place ahead of an eastward-advancing cold front. As diurnal heating peaks through the afternoon, mid-layer CAPE around 1500 J/kg is expected to evolve, supporting widely scattered afternoon storm development. With mid-level westerlies around 40 kt expected across the area, shear sufficient for organized storms suggests marginal hail and locally strong/damaging wind gusts will be possible with a few of the strongest storms, before convection weakens into the early evening hours. ..Goss/Lyons.. 08/13/2023 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)