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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.


Friday, September 2, 2022

SPC Sep 2, 2022 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Fri Sep 02 2022 Valid 022000Z - 031200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF ARIZONA AND THE LOWER COLORADO RIVER VALLEY... ...SUMMARY... Isolated severe thunderstorms are possible late this afternoon and evening over parts of central/southern Arizona and the Lower Colorado River Valley, and from the central Great Plains to the Upper Great Lakes. ...20Z Update... No changes have been made to the outlook. Convection is beginning to develop along the Mogollon Rim in Arizona, with storms expected to grow in coverage and move westward into this evening, with a threat of strong to locally severe wind gusts eventually spreading into the lower deserts and Colorado River Valley. Isolated severe storms capable of hail and damaging wind gusts are still expected to develop late this afternoon into this evening from the central Plains into the upper Midwest, though coverage of strong/severe storms remains uncertain across the region at this time. See the previous discussion below for more information. ..Dean.. 09/02/2022 .PREV DISCUSSION... /ISSUED 1130 AM CDT Fri Sep 02 2022/ ...Arizona/Lower Colorado Valley... Visible satellite shows relatively cloud-free skies, which will be conducive for ample insolation/heating coincident with a relatively moist air mass, with prevalent 60s F surface dewpoints in the lower elevations of southern Arizona and middle 50s F dewpoints along the Mogollon Rim as of late morning. An increase in storm coverage as compared to yesterday seems probable. Easterly mid-level/steering winds are and will remain notably strong as the upper high builds to the north over the Great Basin/central Rockies. Upwards of 25-30 kt mid-level winds are plausible across the southern half of Arizona, which would be conducive for storm organization/upscale growth and propagation onto the lower elevations/desert floor and Lower Colorado River Valley. Initial discrete development over the higher terrain/near the Rim will pose a risk for localized severe wind gusts and marginally severe hail. However, a more organized/substantial wind threat may emerge with upscale-growing/MCS development by evening. ...Central Plains to Upper Great Lakes... The primary shortwave trough over northeast Manitoba will shift east across southern Hudson Bay/far northern Ontario, with the trailing part of this trough moving across the Upper Great Lakes. A weak mid-level trough will meander east across the Ozarks. In between these features, deep-layer shear will be enhanced across the central Great Plains owing to 25-35 kt mid-level north-northwesterly winds. Weaker deep-layer shear is anticipated with northeast extent along a cold front pushing southeastward across the Upper Midwest. A greater potential for scattered thunderstorms along the front should exist in the southeast Minnesota/northern Wisconsin/Upper Michigan vicinity given more pronounced low-level convergence and trailing influence of the Ontario trough. Multicell clusters mainly producing isolated damaging winds and perhaps marginally severe hail will be the primary threats. A more isolated thunderstorm coverage is anticipated into southeast Nebraska and northern Kansas, but given the greater vertical shear and nearly perpendicular orientation of mid-level flow with respect to the front, a few transient supercells embedded within a cluster or two may develop. Isolated severe wind and hail will be possible, with increasing MLCIN after dusk being detrimental for sustaining severe potential later into the evening. Read more CHECK UPDATE ZOOM GRAPHIC
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