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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, July 1, 2022

SPC Jul 1, 2022 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0240 PM CDT Fri Jul 01 2022 Valid 012000Z - 021200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTHEAST WY...SOUTHWEST SD...AND NORTHWEST NE...AND ACROSS PARTS OF NORTHERN VA AND MD... ...SUMMARY... Scattered severe wind and hail will be possible from about 4 to 10 PM MDT in northeast Wyoming across the Black Hills to the Nebraska Sandhills. Additional strong to locally damaging wind gusts are possible across northern Virginia into the northern Chesapeake Bay vicinity through 7 PM EDT. ...20z Update... A Slight risk has been included across parts of northern VA into the northern Chesapeake Bay vicinity where WW 417 is in effect. Loosely organized, pulse-like convection across this area has occasionally produced tree damage from sub-60 mph gusts, and small hail. This activity will continue to develop eastward the next 2-3 hours and may continue to sporadically produce strong/locally damaging gusts. Otherwise, the previous outlook remains on track and no other adjustments to severe probabilities have been made with this update. See discussion below for more details. ..Leitman.. 07/01/2022 .PREV DISCUSSION... /ISSUED 1102 AM CDT Fri Jul 01 2022/ ...High Plains... Scattered thunderstorms are expected to develop off the Big Horns to the Sangre de Cristos and spread east across the adjacent High Plains later this afternoon within a plume of upper 40s to mid 50s surface dew points. The greatest potential for organized severe storms will exist across the northern portion of this region from eastern WY into western SD and northwest NE. Here, moderate to strong deep-layer speed shear with height will yield effective bulk values of 40-50 kt and an elongated straight-line hodograph. A few high-based outflow-dominated supercells with mid-level rotation should develop and congeal into a cluster this evening. Initial mix of severe hail and wind transitioning to predominately wind will be the primary threats. A lack of appreciable low-level forcing for ascent this evening in conjunction with a nocturnally stabilizing boundary layer should result in these threats diminishing towards late evening. Farther south to the Raton Mesa, slow-moving thunderstorms may pose a threat for very isolated severe wind gusts and marginally severe wind hail during the late afternoon and evening. ...Lower Great Lakes to the Lower MO Valley... A low-amplitude shortwave impulse near the NE/IA border will shift east along the southern periphery of seasonably moderate to strong mid-level westerlies across the Great Lakes to northern IL/IN/OH. Isolated to scattered thunderstorms will be possible along and just ahead of a cold front sagging southeast across southeast Lower MI through eastern KS later this afternoon. Abundant cloud coverage and weak mid-level lapse rates should temper updraft intensity in the more strongly sheared regime near the Lower Great Lakes. Nevertheless, a few multicell clusters and transient supercell structures may develop with a threat for isolated damaging winds and severe hail through about dusk. ...Mid-Atlantic States... Localized damaging winds and marginally severe hail will be possible through this afternoon as low-level warm theta-e advection-driven convection over the central Appalachians spreads east towards the Mid-Atlantic coast. Poor mid-level lapse rates evident in available 12Z observed soundings and modest deep-layer flow will be limiting factors to a more robust/organized severe threat. See MCD 1314 for further short-term discussion. Additional thunderstorms may spread towards the region tonight from the Lower Great Lakes/Upper OH Valley, but should largely be in a decaying state. ...Northern ME... Pronounced differential diabatic heating and weak low-level convergence may aid in isolated thunderstorms near the Saint Lawrence Valley into southeast QC later this afternoon. Morning guidance suggests a nadir in low-level moisture will be present across parts of western New England, but adequate moisture may still hold across northern ME. This may yield a corridor of weak buoyancy amid poor mid-level lapse rates. The most favorable factor will be effective bulk shear of 40-50 kts, which would conditionally support a supercell or two, but confidence is low. Read more CHECK UPDATE ZOOM GRAPHIC