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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.


Saturday, August 5, 2023

SPC Aug 5, 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 Sat Aug 05 2023 Valid 051200Z - 061200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN A CORRIDOR FROM EASTERN COLORADO ACROSS PARTS OF KANSAS...OKLAHOMA...AND TOWARD SOUTHWEST MISSOURI AND NORTHWEST ARKANSAS... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE PLAINS...AND FROM INDIANA INTO NORTHERN KENTUCKY... ...SUMMARY... Severe thunderstorms producing damaging winds are expected from late afternoon through evening over much of the central Plains. Scattered severe storms will also be possible extending north across Nebraska and South Dakota, with isolated severe storms possible from Indiana southward toward Arkansas and western Tennessee. ...Synopsis... A belt of moderate westerly winds aloft will exist over the central Plains today, with an upper trough over the Dakotas. This trough will shift southeastward through Sunday morning, with 500 mb northwesterlies up to 50 kt persisting into KS and OK. A surface low will be located over southeast SD at 00Z, with a cold front extending southwestward across NE and into northeast CO. Farther south, a secondary low is forecast over the TX Panhandle where steep low-level lapse rates will develop with hot conditions. Low-level moisture will contribute to a large area of moderate instability across the region, but potential early day precipitation may stabilize parts of the area early in the day. Low-level winds will also increase late in the day east of the low into MN and IA, and will result in increased shear. A conditional severe risk may therefore exist, depending on instability. Another area of enhanced low-level shear will be with an MCV which will continue east across IL and IN, providing a focus for scattered strong to severe storms during the late afternoon and early evening. ...Central Plains... Early day precipitation is forecast over parts of KS, northern OK, possibly extending into southern MO and northern AR, as storms move eastward out of CO overnight. This will likely have stabilizing effects for much of the day. Strong heating will occur just south of there, from central OK across the TX Panhandle and into southern CO and all over NM and west TX. This may also maintain moist but weak easterly low-level flow which will aid storms over CO late in the afternoon. Storms are expected to form over parts of the Front Range around 20Z, and into southeast CO through early evening. An additional area of likely development will be within the heated air over the Panhandles and into western OK. Much of this area has a strong outflow signal from the models, and damaging gusts appear likely over the Enhanced Risk area. Corridors of gusts over 75 mph are expected. Increasing mid to high level winds will also elongate hodographs, and favor significant hail with storms that remain cellular from the Panhandles into western OK and southwest KS. Otherwise, substantial outflow production from storm interactions will likely lead to strong to severe winds over the region, persisting overnight across KS, OK and perhaps into southwest MO/northern AR. ...Eastern SD/NE into southwest MN/western IA... Daytime rain/storms may occur across northern SD into ND, beneath the cool upper trough and where low-level convergence will remain robust near and north of the low. Stronger afternoon activity is likely to develop near the low, and may spread east as far as MN/IA by evening. A plume of MUCAPE over 2000 J/kg may reach into southeast SD, coincident with sufficient shear for a supercell or two. Any brief/weak tornado threat will be limited due to weak winds aloft, with most of the shear down low. Larger hail is more likely into NE, where both CAPE and deep-layer shear will be stronger. Damaging winds may also occur into the mid MO Valley. ...IL into IN... An MCV now moving across MO will continue east across IL today, reaching IN by late afternoon. Wind fields will be locally enhanced by this system, resulting in a small area of supercell potential, perhaps with isolated tornadoes. The tornado risk will be conditional on the instability plume and possible precipitation contamination. Even so, mid 70s F dewpoints will tend to counteract cooling effects, with low-level turning of winds with height near the MCV favoring rotation within the stronger storms. Severe storms are most likely after about 20Z over eastern IL, extending into central and southern IN through early evening. Models typically have a difficult time providing proper low-level shear resolution this far in advance with prominent MCVs. ..Jewell/Moore.. 08/05/2023 Read more CHECK UPDATE ZOOM GRAPHIC
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CHICAGO UTC-6 during CST (Central Standard Time, e.g., winter)
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