Temps | Gusts | WU KORD KPWK

CLICK for this month's BIG night sky ...




Cardinal SAT


MOBILE DEVICE? Turn sideways. Weather conditions directly above are near Lakefront. Top tabs refer to O'Hare (official).

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 17, 2023

SPC Jul 17, 2023 1630 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1630Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1153 AM CDT Mon Jul 17 2023 Valid 171630Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL/SOUTHERN PLAINS EAST TO THE OHIO VALLEY...AND FROM EASTERN WYOMING INTO SOUTHWEST SOUTH DAKOTA AND NORTHERN NEBRASKA... ...SUMMARY... Severe storms producing large hail and damaging wind gusts are mainly expected from the Black Hills southeastward into Nebraska tonight, and across portions of the Ozarks and Lower Ohio Valley today. ...Central/southern Plains east Ozarks and Ohio Valley... Moderately strong northwest/west mid-level flow will persist from the central/southern Plains east to the OH Valley through tonight. Heating of a moist air mass ahead of a nearly stationary front, combined with a plume of steep mid-level lapse rates will result in a rather large region of strong to locally extreme instability in the presence of substantial deep-layer shear supportive of organized storms. Ongoing severe storm cluster over southeast KS will likely continue moving south-southeast into an environment characterized by 40-50 kts of shear and MLCAPE of 3000-4000 J/jg. Damaging winds and potentially very large hail will be possible with this complex as it moves across northeast OK. Additional thunderstorm development is likely across the Ozarks vicinity along remnant outflow boundaries this afternoon, ultimately resulting in additional clusters or line segments moving southeast/south through this evening. Damaging winds will be the primary severe threat, and with large (isolated very large) hail with the more discrete/intense updrafts. Across the OH Valley, clusters of thunderstorms are expected to develop as clearing/heating occurs in the wake of morning storms. Effective shear of 30-40 kts will support both supercell and multicell clusters persisting through the late afternoon and early evening with severe wind/hail potential. ...Eastern Wyoming/Black Hills/Nebraska... A sharpening lee trough ahead of the northern Rockies upper trough will result in moist low-level upslope flow into the Black Hills/eastern Wyoming and southeast Montana vicinity. The proximity of the upper ridge may somewhat temper the extent of deeper convection, however at least isolated thunderstorms are expected to develop by late afternoon/early evening in a moderately unstable and strongly sheared environment, with storms increasing in coverage toward/after sunset. Steep lapse rates and long straight hodographs will support large to locally very large (greater than 2 inch diameter) hail. As the low-level jet strengthens during the evening, upscale development into a bowing MCS is possible as convection tracks southeastward across western/southern South Dakota and Nebraska. Damaging gusts, potentially significant, may accompany this MCS during the evening and overnight hours, and a Significant Wind area has been added with this outlook. ...Northern Great Basin and Central/Eastern Montana... Moderate to strong west-southwest mid/upper-level flow will overspread the region ahead of the northern Rockies upper trough. Steep mid-level lapse rates and moistening will support MLCAPE around 500-1250 J/kg. Well-mixed boundary layers will result in mostly high-based, low-precipitation convection capable of sporadic strong dry microburst winds from far northeast Nevada/northern Utah into central Montana. With eastward extent into parts of eastern Montana, deeper boundary-layer moisture will result in the potential for isolated strong gusts as well as hail. ...Southern AZ... Diurnal heating of a moist environment (PW 1.5 inches) will contribute to afternoon MLCAPE of 1000-1500 J/kg. Thunderstorm development is expected this afternoon, and dry mid-levels with 15-20 kts of easterly flow will result in a risk for gusty/damaging winds as storms move west through evening. ..Bunting/Weinman.. 07/17/2023 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)