SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1134 AM CDT Fri Jul 09 2021 Valid 091630Z - 101200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER SOUTHERN IOWA...NORTHERN MISSOURI AND WEST-CENTRAL ILLINOIS... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF THE MID-ATLANTIC... ...SUMMARY... Thunderstorms, some with potentially significant severe weather, are expected this afternoon into tonight across parts of the lower Missouri Valley westward into the parts of the north-central High Plains. ...IA/IL/MO... Residual clouds/showers and thunderstorms persist across the area from overnight convection, however strong heating this afternoon of a very moist air mass is expected to result in strong instability south of a developing warm front. Elevated thunderstorms may develop this afternoon over northern IA and pose a risk for large hail, however the primary concern is with supercell storm development near the warm front late this afternoon or perhaps early evening. Steep mid-level lapse rates and 40-45 kts of effective shear will result in a risk for all hazards, including the potential for very large hail and isolated tornadoes. These storms should evolve into a southeast-moving complex during the evening with an increasing risk of widespread damaging winds, with potentially significant severe gusts. ...WY/NE... Thunderstorm development is expected this afternoon near the higher terrain of WY/northeast CO, with very steep mid-level lapse rates and moderate MLCAPE supporting a supercell storm mode with a risk for very large hail and damaging winds, and perhaps a couple of tornadoes. Aided by a developing low-level jet, storms are expected to move east/southeast across much of NE and northern KS tonight with a continued severe wind/hail risk. ...Mid-Atlantic/Northeast U.S.... Tropical Storm Elsa was located over eastern Long Island and continuing to move northeast. The risk for a tornado or two over southeast New England should end by mid afternoon as the more favorable environment for brief tornadoes shifts northeast and offshore. A cold front will move east across the northeast and mid-Atlantic states this afternoon and tonight as a shortwave trough over the Great Lakes also shifts east. Scattered thunderstorms are expected to develop ahead of the front in a moderately unstable air mass this afternoon/evening. Effective shear averaging around 25-30 kts will promote organized storms in the form of multicells, and eventually a few clusters with a risk for mainly damaging winds. Have introduced a focused SLGT Risk for this afternoon over portions of the mid-Atlantic region where a higher concentration of storm coverage may exist. ..Bunting/Jirak.. 07/09/2021 Read more LIVE: spc.noaa.gov
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