Showers and thunderstorms developed each day in a warm, moist, and unstable air mass. Some of these storms produced damaging wind gusts and hail.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS JAN wrote it up.
Showers and thunderstorms developed each day in a warm, moist, and unstable air mass. Some of these storms produced damaging wind gusts and hail.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Jackson, MS wrote its last area forecast discussion before the first event at May 20, 11:41 AM CST, 9 minutes earlier.
Area Forecast Discussion...UPDATED National Weather Service Jackson MS 1241 PM CDT Sun May 20 2018 .UPDATE... Updated for 18Z aviation discussion && .AVIATION... 18Z TAF discussion: Mostly VFR conditions will dominate through the remainder of the day and into the evening. Scattered showers and thunderstorms will be spread out over the region through this time period and TAF sites that experience any of these will see a brief lowering of ceilings/visibilities to MVFR/IFR. The convection will diminish by late evening/after midnight. MVFR ceilings and visibilities in fog look to develop at MEI and HBG after 21/09Z and linger until 21/15Z./26/ && .DISCUSSION... Current forecast on track with scattered convection expected this afternoon/evening. Wet microburst checklist indicated a slight chance/chance category highlighted by DCAPEs of 1300 J/kg, upper 20s vertical totals and theta-e difference over 30. The HRRR is also indicating some wind potential as max wind gusts grids locally exceed 40 knots with some of the convection this afternoon. Will, thus, maintain the marginal severe risk in the HWO. A slight delay in convective onset will allow maximums to reach a little higher than previously expected. This will also modulate a more robust convective potential this afternoon./26/ Prior discussion below: Today and tonight: There was quite a bit thunderstorm activity overnight in portions of southeastern MS as the slow evolution toward a wetter pattern waited until sundown yesterday to begin in our region. Above average warmth and humidity, combined with relatively chilly temperatures aloft, created a good deal of instability that only required subtle convergence to "break the lid" that has been largely keeping most of the convection at bay the last few days. Today the "lid" holding down deep convection is expected to give way across the entire region (not just in southeastern MS) during the afternoon and evening hours. Since our early transition into a summer-like pattern (devoid of major synoptic forcing mechanisms and wind shear) has occurred, we only expect subtle factors to help tip the scales toward lots of thunderstorm activity, especially since moisture continues to gradually increase. Not to get into the weeds over much, but the main weak positive factors for convective development (aside from lots of instability) look to be favorable divergence in jet-level wind fields and minor lower level wind and moisture convergence as easterly flow impinges from AL. HREF guidance suggests peak working CAPE levels by early afternoon should range from at least 2500 to 3500 j/kg with surface temperatures ranging from 88 to 92 degrees. Relatively steep lapse rates and some dry air available well aloft will increase the risk for some microbursts and larger scale downbursts with slightly organized line segments. Given the ingredients available it would be surprising if there were not at least several severe storms this afternoon so we have gone ahead and included a local MARGINAL severe risk in our HWO and graphics. The main risk will be damaging wind gusts, although some hail certainly cannot be ruled out. Some convection will almost certainly linger well into the evening, with CAMS guidance suggesting this is more likely across portions of eastern MS. But by late tonight we anticipate conditions will be mainly dry with maybe a bit of patchy fog in areas where downpours are received today. Lows by daybreak Monday may be a touch cooler than this morning, consider the influence of latter day cooling precipitation. /BB/ Monday through next Saturday: The summer-type pattern will be the norm across the forecast area throughout this portion of the forecast. Off and on periods of weak troughing and ridging aloft, weak flow aloft, warm temperatures, and plenty of moisture, will result in mainly diurnal chances for showers and storms in the 30- 50% range each afternoon. Convection each day looks scattered in nature. Where the best chances for convection each day continues to look to largely depend upon where any lingering outflow boundaries from the previous day's convection resides. Although these better rain chances will again fall during the heat of the day, some convection will likely linger a few hours into the evening periods. While confidence is currently quite low in any organized severe storms, an isolated strong to potentially severe storm cannot be ruled out each afternoon. Gusty winds will be the primary concern with such storms. Locally heavy downpours and frequent lightning can also be expected. As eluded to above, warm conditions will persist areawide through the period. Highs each day look to peak to around the 90 degree mark, but scattered convection each afternoon could have a large bearing on whether temperatures warm that much. Again, while most of the convection each day will dissipate during the evening hours as daytime heating is lost, some lingering clouds will be present across the region during the overnight hours. Lows will remain mild as they range from the mid 60s to lower 70s. /19/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 89 67 89 68 / 41 50 51 22 Meridian 92 66 88 65 / 44 36 47 23 Vicksburg 90 68 90 68 / 33 33 51 23 Hattiesburg 91 65 89 67 / 42 37 52 26 Natchez 90 67 89 69 / 36 35 51 24 Greenville 92 70 89 70 / 24 39 50 22 Greenwood 90 69 90 68 / 28 31 52 19 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. &&
Hazardous Weather Outlook National Weather Service Jackson MS 326 AM CDT Sun May 20 2018 ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074- 210830- Ashley-Chicot-Morehouse-West Carroll-East Carroll-Richland- Madison LA-Franklin LA-Catahoula-Tensas-Concordia-Bolivar- Sunflower-Leflore-Grenada-Carroll-Montgomery-Webster-Clay-Lowndes- Choctaw-Oktibbeha-Washington-Humphreys-Holmes-Attala-Winston- Noxubee-Issaquena-Sharkey-Yazoo-Madison MS-Leake-Neshoba-Kemper- Warren-Hinds-Rankin-Scott-Newton-Lauderdale-Claiborne-Copiah- Simpson-Smith-Jasper-Clarke-Jefferson-Adams-Franklin MS-Lincoln- Lawrence-Jefferson Davis-Covington-Jones-Marion-Lamar-Forrest- 326 AM CDT Sun May 20 2018 This hazardous weather outlook is for portions of southeast Arkansas, northeast Louisiana, central Mississippi, north central Mississippi, and south central Mississippi. .DAY ONE...Today and Tonight SEVERE THUNDERSTORMS THREAT...Marginal TIMING...Early afternoon into the evening Isolated severe thunderstorms will be possible, mainly this afternoon, across the region. The main risk will be damaging wind gusts although hail be also be possible. (https://www.weather.gov/images/jan/graphicast/image1.png) .DAYS TWO THROUGH SEVEN...Monday through Saturday The probability for widespread hazardous weather is low. .SPOTTER CALL TO ACTION STATEMENT... The activation of storm spotters, HAM radio operators, and emergency management personnel in support of severe weather operations may be needed for portions of the region today. 50 && ...HAZARD LEGEND... *SEVERE THUNDERSTORMS* High...Significant severe thunderstorms are expected. Moderate...Severe storms expected with significant severe weather possible. Enhanced...Severe storms expected. Slight...Severe storms possible. Marginal...Isolated severe storms possible. ...USEFUL WEATHER WEB PAGES (URLS)... NWS JAN Home page... https://www.weather.gov/jan Stay Aware, Stay Safe NWS JAN Briefing Page... https://www.weather.gov/jan/safe Latest Weather Briefing... https://www.weather.gov/jan/weather_briefing Find NWS JAN on Facebook... https://www.facebook.com/NWSJacksonMS Follow NWS JAN on Twitter... @NWSJacksonMS Follow NWS JAN on Youtube... https://www.youtube.com/user/NWSJacksonMiss ...ADDITIONAL URLS FOR SEVERE WEATHER ISSUES... Storm Prediction Center (SPC)... www.spc.noaa.gov/ Meso Analysis... www.spc.noaa.gov/exper/mesoanalysis/ Day 1 through 3 Outlooks... www.spc.noaa.gov/products/outlook/ Storm Reports... www.spc.noaa.gov/climo/online/
The Columbus AFB radar (KGWX), 103 km away, was scanning. The volume nearest the first event began at 17:49 UTC.
8 thunderstorm wind, 1 hail. Local standard time, as filed.
A tree was blown down on Highway 15 at South Louisville Street.
A tree was blown down near Stamp Bridge and Mount Pilgrim roads near Camden.
A tree was blown down on Highway 433 West near the Tri Community Fire Department.
Tin roofing was torn off of a barn and several trees were blown down around the intersection of Ira G. Odom and Pecan Grove roads.
A couple of trees were blown down in Bentonia.
A tree was blown down across Raymond Road between Plummer Circle and Maddox Road.
Quarter size hail fell near the intersection of McCluer Street and Rainey Road as well as near the intersection of Spryfield Road and Tifton Drive.
A few trees and large limbs were blown down in the Highway 471 area.
A tree was down across Old Highway 43.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Mississippi in 2018Every state in 2018This day in weather historyWarnings in Mississippi, May 2018
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 748126, 748127, 748128, 748129, 748130, 748131, 748132, 748133, 748134.