{"id":5619,"date":"2026-09-02T11:49:55","date_gmt":"2026-09-02T11:49:55","guid":{"rendered":"https:\/\/ialert.com\/blog\/?p=5619"},"modified":"2026-09-02T11:49:55","modified_gmt":"2026-09-02T11:49:55","slug":"great-lakes-mid-atlantic-severe-sep-2","status":"publish","type":"post","link":"https:\/\/ialert.com\/blog\/news-events\/great-lakes-mid-atlantic-severe-sep-2\/","title":{"rendered":"Great Lakes Mid-Atlantic Severe Thunderstorms: Slight Risk of Damaging Wind, Hail, and Tornadoes September 2, 2026"},"content":{"rendered":"<p>  <iframe src=\"https:\/\/ialert.com\/blog_outlook.php?event=great-lakes-mid-atlantic-severe-sep-2\" title=\"Great Lakes Mid-Atlantic Severe \n  Thunderstorms: Slight Risk of Damaging Wind, Hail, and Tornadoes September 2, 2026\" loading=\"lazy\" style=\"width:100%;border:0;\" \n  height=\"660\"><\/iframe><\/p>\n<p>Great Lakes Mid-Atlantic severe thunderstorms are the main weather story for September 2, 2026. In its 05:57 UTC (1:57 am EDT \/ 12:57 am CDT)<br \/>\n  Day 1 outlook, the NOAA Storm Prediction Center drew a Slight Risk (level 2 of 5) from Detroit and Cleveland through Buffalo, Pittsburgh,<br \/>\n  Philadelphia, Baltimore, and Washington D.C., with damaging wind gusts as the primary hazard and large hail and a few tornadoes also possible<br \/>\n  today and tonight. A separate Slight Risk covers Great Falls, Montana, where the SPC expects scattered severe gusts with peak intensity of 65 to<br \/>\n  80 mph.<\/p>\n<p><strong>Key points:<\/strong><\/p>\n<ul>\n<li>Slight Risk (level 2 of 5) covers the Great Lakes Mid-Atlantic severe corridor from Detroit to Washington D.C., plus a second Slight Risk<br \/>\n  over Great Falls, Montana. Issued 05:57 UTC (1:57 am EDT \/ 12:57 am CDT), valid through 12Z (8:00 am EDT \/ 7:00 am CDT) September 3.<\/li>\n<li>Damaging wind is the lead hazard: a 30% wind probability covers 57,691 square miles and 14.7 million people from Cleveland and Buffalo across<br \/>\n  Pennsylvania to Baltimore.<\/li>\n<li>A 2% tornado probability covers Washington D.C., Detroit, Baltimore, Cleveland, Buffalo, and Rochester; the tornado risk may increase this<br \/>\n  evening over southern New York and central Pennsylvania.<\/li>\n<li>A 15% large hail probability covers Detroit, Cleveland, Pittsburgh, Buffalo, Rochester, and Syracuse.<\/li>\n<li>Montana storms could produce 65 to 80 mph gusts; a hatched Intensity Level 1 wind outline covers Great Falls, Helena, Butte, Kalispell, and<br \/>\n  Havre.<\/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 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: none; border-radius: 3px; font-weight: bold; display: inline-block;\">Sign Up for Severe Weather Alerts &rarr;<\/a>\n<\/div>\n<h2>Great Lakes Mid-Atlantic Severe Thunderstorms: Where the Highest Risks Sit<\/h2>\n<p>The SPC places the highest Great Lakes Mid-Atlantic severe wind threat, a 30% damaging wind probability, in a corridor from northeast Ohio and<br \/>\n  the Lake Erie shore across central and eastern Pennsylvania to northern Maryland and Delaware. Cities inside the 30% area include Baltimore,<br \/>\n  Cleveland, Buffalo, Allentown, Harrisburg, Wilmington, Youngstown, Hagerstown, Frederick, York, Lancaster, Reading, Erie, State College,<br \/>\n  Williamsport, and Chambersburg. The SPC summary puts the 30% area at 57,691 square miles and 14.7 million people.<\/p>\n<p>Rochester, New York, sits less than a mile outside the 30% line, and the SPC summary lists it among the 30% cities, so treat Rochester as a<br \/>\n  30% wind city. A broader 15% damaging wind probability covers Philadelphia, Washington D.C., Detroit, Pittsburgh, Toledo, Syracuse, Scranton,<br \/>\n  Trenton, Annapolis, Akron, Lansing, Flint, and Binghamton. The eastern Slight Risk outline follows that 15% wind line almost exactly, which tells<br \/>\n  you the wind threat alone earned the category. Every city in a severe risk area today carries some damaging wind probability.<\/p>\n<p>The Great Lakes Mid-Atlantic severe hail picture is more focused. A 15% large hail probability covers Detroit, Cleveland, Pittsburgh, Buffalo,<br \/>\n  Rochester, Syracuse, Harrisburg, Akron, Youngstown, Flint, Saginaw, Ann Arbor, Hagerstown, Frederick, Binghamton, York, and Erie. Philadelphia,<br \/>\n  Washington D.C., Baltimore, Toledo, Allentown, Scranton, Wilmington, Annapolis, Lancaster, and Reading sit at a lower 5% large hail<br \/>\n  probability.<\/p>\n<p>Six cities inside a severe risk area carry no large hail probability at all: Richmond, Charlottesville, Elkins, Rockford, Missoula, and Great<br \/>\n  Falls. For those cities, damaging wind is the only hazard the SPC has outlined.<\/p>\n<p>The Great Lakes Mid-Atlantic severe tornado probability is narrower still. A 2% tornado probability covers 88,351 square miles and 26.5<br \/>\n  million people, including Washington D.C., Detroit, Baltimore, Cleveland, Buffalo, Rochester, Harrisburg, Wilmington, Annapolis, Youngstown,<br \/>\n  Flint, Saginaw, Hagerstown, Frederick, Winchester, Leesburg, Arlington, York, Lancaster, Reading, and Erie. Philadelphia, Pittsburgh, Toledo,<br \/>\n  Syracuse, Allentown, Scranton, and Trenton are inside the Slight Risk but outside the tornado outline, so for those cities the outlined hazards<br \/>\n  are wind and hail.<\/p>\n<p>A Marginal Risk, the first of five SPC severe categories, surrounds the Slight Risk in three separate pieces. The New York City metro,<br \/>\n  including Newark and Paterson, sits in Marginal territory with a 5% damaging wind and a 5% large hail probability. A second Marginal area covers<br \/>\n  Milwaukee, Madison, Kenosha, Rockford, Grand Rapids, Morgantown, Elkins, Richmond, and Charlottesville, and a third covers Williston, North<br \/>\n  Dakota, and Missoula, Montana. 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 how each level is<br \/>\n  defined.<\/p>\n<h2>Montana Severe Thunderstorms: Great Falls in the Crosshairs<\/h2>\n<p>The Great Falls area holds its own Slight Risk, driven by a compact but strong shortwave trough the SPC expects to move rapidly northeastward<br \/>\n  from the Great Basin into the northern Rockies today and tonight. Mid-level flow of 35 to 50 kt will overspread a modestly moist but warm and<br \/>\n  unstable air mass across central and eastern Montana, and storms should develop over the higher terrain of western Montana through the<br \/>\n  afternoon.<\/p>\n<p>Steep lapse rates and a deep, well-mixed boundary layer will enhance the severe wind gust potential, and 30 to 40 kt of deep-layer shear<br \/>\n  supports a fast-moving line building northeastward through the late afternoon and early evening. Scattered severe gusts are likely, with peak<br \/>\n  intensity of 65 to 80 mph possible.<\/p>\n<p>The Montana Slight Risk matches the 15% damaging wind area exactly, and it sits inside a much larger hatched Intensity Level 1 wind outline,<br \/>\n  the SPC conditional intensity layer, which covers 66,701 square miles here and is drawn as a dashed line on the map. That hatched conditional<br \/>\n  intensity area marks where storms that do form could reach the higher end of the wind hazard, which the SPC discussion pegs at 65 to 80 mph for<br \/>\n  this event. The SPC summary lists Great Falls, Butte, Helena, Kalispell, and Havre inside it.<\/p>\n<p>Great Falls carries a 15% damaging wind probability and no large hail probability. Unlike the Great Lakes Mid-Atlantic severe corridor, the<br \/>\n  Montana Slight Risk carries no tornado probability at all. Williston, North Dakota, sits in the Marginal Risk with a 5% damaging wind and a 5%<br \/>\n  large hail probability, and Missoula carries a 5% damaging wind probability only.<\/p>\n<p>Additional storms are possible across eastern Montana into the evening within a zone of warm advection along a nocturnally strengthening<br \/>\n  low-level jet. The SPC identifies isolated large hail as the primary hazard with those overnight storms, which is why a 5% large hail area is<br \/>\n  drawn over eastern Montana and western North Dakota, including Williston.<\/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-2-2026.jpg\" \n  alt=\"Great Lakes Mid-Atlantic severe thunderstorms SPC damaging wind probability map for September 2, 2026, showing a 30% wind risk from \n  Cleveland and Buffalo across Pennsylvania to Baltimore, a 15% wind risk reaching Detroit, Pittsburgh, Philadelphia, and Washington D.C., and a \n  15% wind risk with an Intensity Level 1 outline over Great Falls, Montana\" width=\"1371\" height=\"747\" \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 2, 2026. The 30% area (red) runs from Cleveland and Buffalo across Pennsylvania to Baltimore. The 15% area (yellow) traces the Great<br \/>\n  Lakes Mid-Atlantic severe Slight Risk outline and reaches Detroit, Pittsburgh, Philadelphia, and Washington D.C. In Montana, the 15% area over<br \/>\n  Great Falls sits inside the dashed Intensity Level 1 outline. 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 Great Lakes Mid-Atlantic severe setup starts with several low-amplitude impulses embedded in a belt of moderate northwest mid-level flow<br \/>\n  of 40 to 60 kt, moving from the lower Great Lakes into the Northeast and Mid-Atlantic today and tonight. A surface low over James Bay trails a<br \/>\n  slow-moving cold front southwest across southern Ontario, the lakes, and into Michigan and Ohio, while a backdoor front sits stalled across the<br \/>\n  eastern Hudson Valley and southern New England. The warm sector holds a very moist air mass, with boundary layer dewpoints in the upper 60s to<br \/>\n  low 70s.<\/p>\n<p>Steep mid-level lapse rates of 7 to 7.5 degrees C per kilometer on top of that moisture should build 2,000 to 3,000-plus J\/kg of MLCAPE by<br \/>\n  afternoon from lower Michigan into western New York and Pennsylvania. The primary upper trough moves from Wisconsin and lower Michigan into<br \/>\n  western New York and Pennsylvania later in the afternoon, and the SPC expects storms to develop ahead of the trough and cold front as well as on<br \/>\n  any residual outflow from the morning storms. A mix of supercells and line segments is expected, with all hazards possible.<\/p>\n<p>The tornado question is the open one. The SPC says a greater tornado risk may evolve this evening across southern New York and central<\/p>\n<p>The tornado question is the open one. The SPC says a greater tornado risk may evolve this evening across southern New York and central<br \/>\n  Pennsylvania, contingent on air mass recovery behind the earlier storms and a more supercellular mode. NAM and RAP forecast soundings show some<br \/>\n  elongation of the low-level hodographs, and any modifying cold pool or outflow boundary could further enhance the low-level shear. The SPC<br \/>\n  considered higher tornado probabilities but held at 2% because uncertainty on those factors remains large.<\/p>\n<p>Timing for the Great Lakes Mid-Atlantic severe thunderstorms comes in rounds. The outlook is valid from 12Z (8:00 am EDT \/ 7:00 am CDT)<br \/>\n  September 2 through 12Z (8:00 am EDT \/ 7:00 am CDT) September 3. Round one: storms tied to a lead shortwave trough exiting southern Ontario are<br \/>\n  likely along the front across the lower Great Lakes and New York this morning, with isolated large hail and damaging winds as they move southeast<br \/>\n  into southern Pennsylvania and possibly Virginia and Maryland.<\/p>\n<p>Round two is the main event. It develops later this afternoon ahead of the primary trough and cold front, and the tornado risk may increase<br \/>\n  into the evening over southern New York and central Pennsylvania. The SPC gives no clock times beyond that, but its wording is clear: the morning<br \/>\n  hazards are described as isolated, and the afternoon round as all hazards possible.<\/p>\n<p>Outside the severe risk areas, the SPC mentions high-based storms with sporadic strong outflow gusts across Wyoming this afternoon and a few<br \/>\n  elevated storms capable of marginally severe hail overnight from the mid-Missouri Valley into Iowa and southern Minnesota. Neither earned a<br \/>\n  severe category, and the SPC calls confidence in an organized threat there low.<\/p>\n<h2>How to Stay Safe in Great Lakes Mid-Atlantic Severe Thunderstorms<\/h2>\n<p>Because damaging wind is the lead hazard in Great Lakes Mid-Atlantic severe thunderstorms, move indoors before storms arrive and stay away<br \/>\n  from windows and exterior walls while a storm is overhead. Secure or bring in outdoor furniture, umbrellas, and other lightweight items that wind<br \/>\n  can turn into projectiles. Wind damage can escalate quickly once a line of storms organizes, so do not wait for the first gust.<\/p>\n<p>If you live in the 15% hail probability zone covering Detroit, Cleveland, Pittsburgh, Buffalo, Rochester, and Syracuse, move vehicles into a<br \/>\n  garage or under a solid structure before storms develop. Hail damage to roofs, windows, and vehicles is expensive, and early action costs<br \/>\n  nothing.<\/p>\n<p>For residents in the tornado probability zone, identify your shelter location now: an interior room on the lowest floor, away from windows.<br \/>\n  Monitor <a href=\"https:\/\/ialert.com\/analysis.php#alerts\">active weather alerts<\/a> and have a way to receive warnings that does not depend on<br \/>\n  outdoor sirens. The SPC scenario for the Great Lakes Mid-Atlantic severe corridor puts the higher tornado risk in the evening over southern New<br \/>\n  York and central Pennsylvania, so stay weather-aware after dark, when tornadoes are harder to see and warnings are easier to miss.<\/p>\n<p>In Montana, the wind threat peaks in the late afternoon and early evening as storms line up and move northeast from the western Montana<br \/>\n  terrain across the Slight Risk area toward Great Falls. Track the evolving situation through <a \n  href=\"https:\/\/ialert.com\/analysis.php?tab=radar\">live radar and alerts<\/a> and check your <a href=\"https:\/\/ialert.com\/forecast.php\">local weather<br \/>\n  forecast<\/a> for storm timing specific to your area.<\/p>\n<h2>Great Lakes Mid-Atlantic Severe Thunderstorms FAQ<\/h2>\n<h3>Where is the highest risk for severe thunderstorms on September 2?<\/h3>\n<p>The highest categorical risk is a Slight Risk covering the lower Great Lakes through the Mid-Atlantic, including Detroit, Cleveland, Buffalo,<br \/>\n  Pittsburgh, Philadelphia, Baltimore, and Washington D.C. A separate Slight Risk covers Great Falls, Montana, but the Great Lakes Mid-Atlantic<br \/>\n  severe Slight Risk is by far the larger of the two. Within the eastern area, the 30% damaging wind corridor from Cleveland and Buffalo across<br \/>\n  Pennsylvania to Baltimore carries the highest probability of any hazard in the outlook.<\/p>\n<h3>How strong could wind gusts get in the Great Lakes and Mid-Atlantic region?<\/h3>\n<p>The SPC does not give a peak gust figure for the eastern region and drew no intensity level outline there. Damaging wind means a gust of 58<br \/>\n  mph or greater, the National Weather Service severe threshold. The 30% damaging wind corridor through Baltimore, Cleveland, Buffalo, Harrisburg,<br \/>\n  Allentown, and York is where Great Lakes Mid-Atlantic severe wind gusts are most likely.<\/p>\n<h3>Are tornadoes expected with Great Lakes Mid-Atlantic severe thunderstorms?<\/h3>\n<p>A 2% tornado probability covers Washington D.C., Detroit, Baltimore, Cleveland, Buffalo, Rochester, Harrisburg, Wilmington, and nearby cities.<br \/>\n  The SPC notes the tornado risk may increase this evening across southern New York and central Pennsylvania if the air mass recovers and storms<br \/>\n  stay supercellular, though it calls the uncertainty large.<\/p>\n<h3>When will the storms arrive?<\/h3>\n<p>The first round of Great Lakes Mid-Atlantic severe thunderstorms is expected this morning along the front across the lower Great Lakes and New<br \/>\n  York, moving southeast toward southern Pennsylvania. The main round develops later this afternoon as the primary trough reaches western New York<br \/>\n  and Pennsylvania, and the tornado risk may increase into the evening over southern New York and central Pennsylvania. The outlook is valid from<br \/>\n  8:00 am EDT September 2 through 8:00 am EDT September 3.<\/p>\n<p><strong>Sources:<\/strong><\/p>\n<ul>\n<li><a href=\"https:\/\/www.spc.noaa.gov\/products\/outlook\/archive\/2026\/day1otlk_20260902_1200.html\" target=\"_blank\" rel=\"noopener\">NOAA Storm Prediction Center Day 1 Convective<br \/>\n  Outlook, issued 05:57 UTC (1:57 am EDT \/ 12:57 am CDT) September 2, 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<br \/>\n  an 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 bring a Slight Risk September 2, 2026. Damaging wind, large hail, and tornadoes possible.<span class=\"more\"> <a href=\"https:\/\/ialert.com\/blog\/news-events\/great-lakes-mid-atlantic-severe-sep-2\/\">Read More&#8230;<\/a><\/span><\/p>\n","protected":false},"author":6,"featured_media":5621,"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 bring a Slight Risk September 2, 2026. Damaging wind, large hail, and tornadoes possible."},"categories":[719],"tags":[772],"class_list":["post-5619","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\/5619","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=5619"}],"version-history":[{"count":5,"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/posts\/5619\/revisions"}],"predecessor-version":[{"id":5626,"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/posts\/5619\/revisions\/5626"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/media\/5621"}],"wp:attachment":[{"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/media?parent=5619"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/categories?post=5619"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ialert.com\/blog\/wp-json\/wp\/v2\/tags?post=5619"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}