{"id":5627,"date":"2026-09-04T16:01:19","date_gmt":"2026-09-04T16:01:19","guid":{"rendered":"https:\/\/ialert.com\/blog\/?p=5627"},"modified":"2026-09-04T16:01:19","modified_gmt":"2026-09-04T16:01:19","slug":"great-lakes-mid-atlantic-severe-sep-4","status":"publish","type":"post","link":"https:\/\/ialert.com\/blog\/news-events\/great-lakes-mid-atlantic-severe-sep-4\/","title":{"rendered":"Great Lakes Mid-Atlantic Severe Thunderstorms: Slight Risk of Damaging Wind and Hail September 4, 2026"},"content":{"rendered":"<p>  <iframe src=\"https:\/\/ialert.com\/blog_outlook.php?event=great-lakes-mid-atlantic-severe-sep-4\" title=\"Great Lakes Mid-Atlantic Severe \n  Thunderstorms: Slight Risk of Damaging Wind and Hail September 4, 2026\" loading=\"lazy\" style=\"width:100%;border:0;\" height=\"660\"><\/iframe><\/p>\n<p>Great Lakes Mid-Atlantic severe thunderstorms are the main weather story on September 4, 2026. The NOAA Storm Prediction Center&#8217;s Day 1<br \/>\n  Convective Outlook, issued at 12:55 UTC (8:55 am EDT \/ 7:55 am CDT), places a corridor from southern Michigan and Ohio through Pittsburgh,<br \/>\n  Charleston, and Washington D.C. to the Virginia and North Carolina coast under a Slight Risk (level 2 of 5). Damaging wind gusts are the primary<br \/>\n  threat, and the highest probability, 30%, is centered on Columbus, Akron, Canton, and Pittsburgh.<\/p>\n<p><strong>Key points:<\/strong><\/p>\n<ul>\n<li>Slight Risk (level 2 of 5) covers the southern Great Lakes into the Mid-Atlantic. The outlook is valid from 13Z (9:00 am EDT \/ 8:00 am CDT)<br \/>\n  September 4 through 12Z (8:00 am EDT \/ 7:00 am CDT) September 5.<\/li>\n<li>A 30% damaging wind probability, the highest for Great Lakes Mid-Atlantic severe thunderstorms today, covers 20,713 square miles and about 6<br \/>\n  million people across central and eastern Ohio into western Pennsylvania, including Columbus, Akron, Canton, and Pittsburgh.<\/li>\n<li>A 15% damaging wind probability covers 117,491 square miles and 26 million people, including Detroit, Cleveland, Toledo, Charleston,<br \/>\n  Washington D.C., Richmond, and Norfolk.<\/li>\n<li>Bowing line segments are the expected storm mode. No tornado probability is drawn anywhere in the outlook.<\/li>\n<li>Two Marginal Risk bands flank the Slight Risk: one from Flint and Cincinnati to Raleigh, and one from the Lake Erie shore through western<br \/>\n  Pennsylvania to Baltimore and Annapolis.<\/li>\n<\/ul>\n<div style=\"background: #000000; padding: 20px 24px; margin: 20px 0; border-radius: 4px;\">\n<p style=\"color: #ffffff; font-size: 16px; font-weight: bold; margin: 0 0 6px 0;\">Get Severe Weather Alerts for Your Location<\/p>\n<p style=\"color: rgba(255,255,255,0.9); margin: 0 0 14px 0;\">When any NWS watch, warning, or advisory is issued for your area, iAlert sends you an<br \/>\n  immediate notification by email, text message, or phone call, 24 hours a day, 7 days a week.<\/p>\n<p>  <a href=\"https:\/\/ialert.com\/services\/severe-weather-alerts.php\" style=\"background: #C41226; color: #ffffff; padding: 10px 22px; text-decoration: \n  none; border-radius: 3px; font-weight: bold; display: inline-block;\">Sign Up for Severe Weather Alerts &rarr;<\/a>\n  <\/div>\n<h2>Where Great Lakes Mid-Atlantic Severe Thunderstorms Are Most Likely<\/h2>\n<p>The Slight Risk for Great Lakes Mid-Atlantic severe thunderstorms runs from southwest Michigan and northern Indiana across Ohio and West<br \/>\n  Virginia to the Chesapeake Bay and the North Carolina Outer Banks. Cities inside it include Detroit, Ann Arbor, Lansing, Grand Rapids, Kalamazoo,<br \/>\n  South Bend, Fort Wayne, Toledo, Cleveland, Akron, Youngstown, Columbus, Lima, Findlay, Pittsburgh, Morgantown, Charleston, Roanoke, Richmond,<br \/>\n  Norfolk, Virginia Beach, Washington D.C., and Salisbury, Maryland. The Slight Risk outline matches the combined 15% and 30% wind polygons to<br \/>\n  within 0.2% of its area, so the wind threat alone earned the category.<\/p>\n<p>The core of the threat from Great Lakes Mid-Atlantic severe thunderstorms is a 30% damaging wind probability over central and eastern Ohio into<br \/>\n  western Pennsylvania and the northern West Virginia panhandle. The SPC puts that area at 20,713 square miles and 5,988,149 people and names<br \/>\n  Columbus, Pittsburgh, Akron, Canton, and Cuyahoga Falls inside it. Point-in-polygon checks against the frozen outlook also place Mansfield,<br \/>\n  Marion, Wooster, Newark, Zanesville, Cambridge, Steubenville, Wheeling, and Parkersburg in the 30% area. Youngstown sits about 3 miles outside the<br \/>\n  30% line and Cleveland about 17 miles outside, so both carry the 15% probability.<\/p>\n<p>The broader 15% damaging wind probability covers 117,491 square miles and 25,967,296 people. The SPC names Detroit, Washington D.C., Cleveland,<br \/>\n  Virginia Beach, and Toledo, and the polygon also takes in Fort Wayne, Grand Rapids, Lansing, Kalamazoo, Ann Arbor, South Bend, Lima, Findlay,<br \/>\n  Charleston, Huntington, Beckley, Roanoke, Lynchburg, Richmond, Fredericksburg, Norfolk, and Salisbury. Every Slight Risk city carries at least a<br \/>\n  15% wind probability from Great Lakes Mid-Atlantic severe thunderstorms.<\/p>\n<p>Large hail is a secondary hazard with Great Lakes Mid-Atlantic severe thunderstorms. A 5% large hail probability covers 137,103 square miles<br \/>\n  and 31,906,068 people, nearly the whole Slight Risk, with the SPC naming Detroit, Columbus, Washington D.C., Cleveland, and Virginia Beach. A few<br \/>\n  Slight Risk cities on the polygon&#8217;s edge carry no hail probability: Grand Rapids (less than a mile outside the hail line), Pontiac, Michigan,<br \/>\n  Salisbury and Ocean City, Maryland, and Kitty Hawk, North Carolina. For those cities, damaging wind is the only outlined hazard.<\/p>\n<p>Two separate Marginal Risk bands, the first of five SPC severe categories, wrap the Slight Risk for Great Lakes Mid-Atlantic severe<br \/>\n  thunderstorms, and each traces a 5% damaging wind line. The western and southern band arcs from Muskegon, Saginaw, and Flint in Michigan through<br \/>\n  Dayton and Cincinnati, southern Ohio, eastern Kentucky, and southwest Virginia to Winston-Salem, Greensboro, Durham, Raleigh, Rocky Mount, and<br \/>\n  Greenville, North Carolina, ending on the Outer Banks near Cape Hatteras. No hail probability is drawn in that band.<\/p>\n<p>The northeastern band runs from Ashtabula and Painesville on the Lake Erie shore through Sharon, Butler, Kittanning, Indiana, Johnstown,<br \/>\n  Altoona, Bedford, and Chambersburg, Pennsylvania, to Hagerstown, Frederick, Westminster, Baltimore, Columbia, Annapolis, and Easton, Maryland.<br \/>\n  Hagerstown, Frederick, Johnstown, and Sharon also sit inside the 5% hail probability, which spills over the Slight Risk line there. The SPC puts<br \/>\n  the total 5% wind area at 67,685 square miles and 13,449,219 people, naming Baltimore, Raleigh, Cincinnati, Greensboro, and Durham.<\/p>\n<p>Cities in a General Thunderstorms area with no severe probability include Erie, State College, Harrisburg, York, Lancaster, Philadelphia,<br \/>\n  Wilmington, Delaware, Lexington, Louisville, Indianapolis, Chicago, Milwaukee, and Charlotte. Buffalo, Rochester, Syracuse, Binghamton, Scranton,<br \/>\n  Allentown, and New York City are outside any thunderstorm area for this outlook period.<\/p>\n<figure class=\"wp-block-image size-full\" style=\"max-width:880px;margin:28px auto;padding:10px;border:1px solid \n  #dde3ec;border-radius:6px;background:#ffffff;\"><br \/>\n    <img decoding=\"async\" \n  src=\"https:\/\/ialert.com\/blog\/wp-content\/uploads\/2026\/09\/ialert-great-lakes-mid-atlantic-severe-thunderstorms-spc-wind-risk-september-4-2026.jpg\" \n  alt=\"Great Lakes Mid-Atlantic severe thunderstorms SPC damaging wind probability map for September 4, 2026, showing a 30% wind risk over central \n  and eastern Ohio into Pittsburgh, a 15% wind risk from Detroit and Cleveland through Charleston to Washington D.C., Richmond, and Norfolk, and 5% \n  wind risk bands from Michigan through Cincinnati to Raleigh and from western Pennsylvania to Baltimore\" width=\"1355\" height=\"711\" \n  style=\"max-width:100%;height:auto;border-radius:4px;\" loading=\"lazy\" \/><figcaption style=\"font-size:0.86em;color:#1a3a5c;text-align:center;margin:12px 6px 2px;line-height:1.45;\">SPC damaging wind probabilities for<br \/>\n  September 4, 2026. The 30% area (red) covers central and eastern Ohio into Pittsburgh. The 15% area (yellow) traces the Slight Risk outline for<br \/>\n  Great Lakes Mid-Atlantic severe thunderstorms from Detroit and Cleveland through Charleston to Washington D.C., Richmond, and Norfolk. The 5%<br \/>\n  bands (brown) mark the two Marginal Risk areas. Source: NOAA Storm Prediction Center; iAlert.com.<\/figcaption><\/figure>\n<h2>Meteorologist&#8217;s Take on Great Lakes Mid-Atlantic Severe Thunderstorms<\/h2>\n<p>The setup for Great Lakes Mid-Atlantic severe thunderstorms begins with a deep cyclone over the Pacific Northwest and upper-level ridging<br \/>\n  across most of the country east of the Rockies. A belt of enhanced mid-level flow arcs between those two features from southern California through<br \/>\n  the central Rockies and northern Plains into the Upper Midwest and eventually the Northeast. South and east of that belt, a reservoir of<br \/>\n  low-level moisture sits beneath the ridge. A weak front runs from southern New England through southern New York, central Lower Michigan, and<br \/>\n  central Wisconsin to a weak low over southern Minnesota.<\/p>\n<p>A large cluster of showers and thunderstorms, initiated by warm-air advection across Minnesota and Wisconsin, was already in progress early<br \/>\n  this morning from southern Wisconsin into southern Lower Michigan. The SPC expects that cluster to continue southeastward today into an airmass<br \/>\n  destabilized by daytime heating. Steeper mid-level lapse rates stay displaced west of the region, but dewpoints in the upper 60s to low 70s and<br \/>\n  afternoon temperatures from the mid 80s to mid 90s will still support moderate to strong instability for Great Lakes Mid-Atlantic severe<br \/>\n  thunderstorms.<\/p>\n<p>Reintensification of the ongoing cluster or new development is expected as it tracks southeast. Most of the region sits on the southern fringe<br \/>\n  of the stronger deep-layer shear, so bowing line segments are the predominant storm mode in the forecast. The best overlap of instability and<br \/>\n  shear is expected across central and eastern Ohio, which is why the 30% wind corridor is drawn there. The SPC summary describes a couple of<br \/>\n  organized clusters across the southern Great Lakes and the mid and upper Ohio Valley today through tonight.<\/p>\n<p>In the Mid-Atlantic, the damaging gust threat arrives this afternoon and evening in a very warm and moist airmass. Vertical wind shear is weak<\/p>\n<p>In the Mid-Atlantic, the damaging gust threat arrives this afternoon and evening in a very warm and moist airmass. Vertical wind shear is weak<br \/>\n  there, but precipitable water values of 1.8 to 2 inches, strong instability, and steep low-level lapse rates support strong outflow capable of<br \/>\n  wind damage. Bowing line segments are again the expected mode. The SPC gives no clock times beyond &#8220;this afternoon and evening&#8221; for the<br \/>\n  Mid-Atlantic, and it describes the storms east of the Blue Ridge as more widely scattered than the Ohio Valley clusters.<\/p>\n<p>A separate, lower-confidence storm area exists across the Central Plains, where weak lee troughing could focus low-level convergence from<br \/>\n  western Kansas across western and central Nebraska into southwest South Dakota. Warm mid-levels, leftover convective inhibition, and large-scale<br \/>\n  height rises cast doubt on whether storms initiate at all, so the SPC drew no severe probabilities there.<\/p>\n<h2>How to Stay Safe During Great Lakes Mid-Atlantic Severe Thunderstorms<\/h2>\n<p>Damaging wind is the lead hazard in Great Lakes Mid-Atlantic severe thunderstorms today. Damaging wind means a gust of 58 mph or greater, the<br \/>\n  National Weather Service severe threshold. Large hail, at least one inch in diameter, is possible across most of the Slight Risk as well. Move<br \/>\n  indoors and away from windows when storms approach, and secure or bring inside outdoor furniture and anything else strong wind can lift. Keep a <a\n  href=\"https:\/\/ialert.com\/analysis.php#alerts\">close watch on active weather alerts<\/a> so you know the moment a Severe Thunderstorm Warning is<br \/>\n  issued for your county.<\/p>\n<p>If you are driving when a storm moves through, pull off the road and park away from trees and utility poles. Fallen trees and downed power<br \/>\n  lines are the most common sources of injury in wind damage events like the ones expected with Great Lakes Mid-Atlantic severe thunderstorms.<\/p>\n<p>The storm clusters are expected to track through the region from this morning into tonight, so stay weather-aware through the evening,<br \/>\n  especially in the Mid-Atlantic where the arrival is later. SPC uses a five-tier system to communicate severe weather potential; see the <a \n  href=\"https:\/\/ialert.com\/blog\/weather-articles\/severe-weather-outlook\/\">iAlert guide to SPC outlook risk categories<\/a> for a full explanation.<br \/>\n  You can also check your <a href=\"https:\/\/ialert.com\/forecast.php\">local weather forecast<\/a> for the latest storm timing in your area.<\/p>\n<h2>Great Lakes Mid-Atlantic Severe Thunderstorms FAQ<\/h2>\n<h3>Where is the highest risk for damaging wind today?<\/h3>\n<p>The 30% damaging wind probability over central and eastern Ohio into western Pennsylvania is the highest for Great Lakes Mid-Atlantic severe<br \/>\n  thunderstorms today. It covers Columbus, Akron, Canton, Cuyahoga Falls, Pittsburgh, Mansfield, Zanesville, Steubenville, Wheeling, and<br \/>\n  Parkersburg, and it means a 30% chance of a damaging wind report within 25 miles of any point in that area. The SPC ties it to the best overlap of<br \/>\n  instability and deep-layer shear across central and eastern Ohio.<\/p>\n<h3>How large could hail get in Great Lakes Mid-Atlantic severe thunderstorms?<\/h3>\n<p>The SPC draws a 5% large hail probability across nearly the whole Slight Risk and into the northeastern Marginal band, but the discussion does<br \/>\n  not name a hail size for this event. The National Weather Service definition of large hail is at least one inch in diameter. The discussion<br \/>\n  focuses on damaging wind, and the hail probability is the lowest tier the SPC draws.<\/p>\n<h3>Are tornadoes expected with Great Lakes Mid-Atlantic severe thunderstorms today?<\/h3>\n<p>No. The SPC drew no tornado probability anywhere in this outlook, and the tornado risk table reads &#8220;No Risk Areas Forecast.&#8221; The discussion<br \/>\n  describes bowing line segments as the storm mode, with the Great Lakes region on the southern fringe of the stronger shear and vertical shear weak<br \/>\n  across the Mid-Atlantic.<\/p>\n<h3>When will storms arrive in the Mid-Atlantic?<\/h3>\n<p>The SPC says the damaging gust threat extends into the Mid-Atlantic, including Washington D.C., Richmond, and Norfolk, this afternoon and<br \/>\n  evening. It does not give a specific arrival hour. The outlook is valid from 9:00 am EDT September 4 through 8:00 am EDT September 5, and the Ohio<br \/>\n  Valley clusters are expected today through tonight, so Great Lakes Mid-Atlantic severe thunderstorms can continue after dark.<\/p>\n<p><strong>Sources:<\/strong><\/p>\n<ul>\n<li><a href=\"https:\/\/www.spc.noaa.gov\/products\/outlook\/archive\/2026\/day1otlk_20260904_1300.html\" target=\"_blank\" rel=\"noopener\">NOAA Storm Prediction Center, Day 1 Convective<br \/>\n  Outlook, issued 12:55 UTC (8:55 am EDT \/ 7:55 am CDT), September 4, 2026<\/a><\/li>\n<\/ul>\n<div style=\"background: #000000; padding: 20px 24px; margin: 20px 0; border-radius: 4px;\">\n<p style=\"color: #ffffff; font-size: 16px; font-weight: bold; margin: 0 0 6px 0;\">Get Severe Weather Alerts for Your Location<\/p>\n<p style=\"color: rgba(255,255,255,0.9); margin: 0 0 14px 0;\">When any NWS watch, warning, or advisory is issued for your area, iAlert sends you an<br \/>\n  immediate notification by email, text message, or phone call, 24 hours a day, 7 days a week.<\/p>\n<p>  <a href=\"https:\/\/ialert.com\/services\/severe-weather-alerts.php\" style=\"background: #C41226; color: #ffffff; padding: 10px 22px; text-decoration: \n  none; border-radius: 3px; font-weight: bold; display: inline-block;\">Sign Up for Severe Weather Alerts &rarr;<\/a>\n  <\/div>\n","protected":false},"excerpt":{"rendered":"<p>Great Lakes Mid-Atlantic severe thunderstorms threaten damaging wind gusts September 4, 2026. Columbus and Pittsburgh face the highest 30%.<span class=\"more\"> <a href=\"https:\/\/ialert.com\/blog\/news-events\/great-lakes-mid-atlantic-severe-sep-4\/\">Read More&#8230;<\/a><\/span><\/p>\n","protected":false},"author":6,"featured_media":5631,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":"","rank_math_focus_keyword":"Great Lakes Mid-Atlantic severe","rank_math_title":"Great Lakes Mid-Atlantic Severe Thunderstorms: 30% Wind Risk","rank_math_description":"Great Lakes Mid-Atlantic severe thunderstorms threaten damaging wind gusts September 4, 2026. Columbus and Pittsburgh face the highest 30%."},"categories":[719],"tags":[772],"class_list":["post-5627","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news-events","tag-spc-outlook"],"acf":[],"_links":{"self":[{"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/posts\/5627","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/comments?post=5627"}],"version-history":[{"count":3,"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/posts\/5627\/revisions"}],"predecessor-version":[{"id":5630,"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/posts\/5627\/revisions\/5630"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/media\/5631"}],"wp:attachment":[{"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/media?parent=5627"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/categories?post=5627"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/tags?post=5627"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}