Hail, Knox
- When
- May 21, 7:02 PM CST
- Where
- Knox County, Knox City
- Measured
- 1 in hail
- Reported by
- State Official
- Coordinates
- 33.420, -99.820
Isolated storms produced a severe hail reports during the evening of the 21st.
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 OUN wrote it up.
Isolated storms produced a severe hail reports during the evening of the 21st.
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 Norman, OK wrote its last area forecast discussion before the first event at May 21, 2:38 PM CST, 4 hours 24 minutes earlier.
Area Forecast Discussion National Weather Service Norman OK 338 PM CDT Thu May 21 2020 ...New LONG TERM... .SHORT TERM... (This evening through Friday) Issued at 240 PM CDT Thu May 21 2020 The showers/thunderstorms that existed over western Oklahoma and western north Texas have since diminished. As seen in the radar and satellite loops, an MCV has lifted northeast across Oklahoma today. As of 19Z, a surface low was centered near the CO/KS border with a dryline extending southward across the OK and TX panhandles. Trends in the CAMS suggest a later arrival of a shower/thunderstorm complex into our area, which is now forecast to enter NW Oklahoma after 06Z Friday. A few severe storms capable of producing up to golf ball size hail and damaging wind gusts are possible across far NW Oklahoma tonight. The showers/thunderstorms are forecast to linger into tomorrow morning as the upper wave progresses east. For tomorrow afternoon/evening, latest thinking is thunderstorms may develop and intensify along an outflow boundary across southern Oklahoma. && .LONG TERM... (Friday night through next Wednesday) Issued at 338 PM CDT Thu May 21 2020 Showers and thunderstorms are expected to continue across southeast/south central Oklahoma and north Texas. These thunderstorms may grow upscale into another MCS with a threat for severe weather through the overnight hours. For Saturday, most locations will likely remain dry. Isolated thunderstorms may develop along the dryline during the late afternoon and could move eastward into western Oklahoma in the evening. Forecast soundings indicate a strong cap (+17 C at ~770 mb), so coverage of storms should be isolated at best. In addition, mid-level heights are progged to rise during the evening hours (which would also temper the risk of convection). For Sunday, the eastward progression of the longwave trough has slowed down. Therefore, opted to decrease the probabilities of showers/storms across western/central Oklahoma during the daytime. There are indications a subtle wave may lift across southeast/eastern Oklahoma, so maintained higher probabilities in this area. With respect to the trough, thunderstorms may initially develop along the dryline in the Texas/Oklahoma panhandles late afternoon. Widespread showers and thunderstorms would be delayed to Sunday night into early Monday as synoptic-scale ascent spreads eastward. For Monday and beyond, the forecast confidence remains low as there remains high uncertainty on the evolution of the shortwave trough. Model consensus continues to indicate the shortwave trough will close-off, but the location is still uncertain. The 21/12Z guidance indicates the low may close off to the west (New Mexico or the Oklahoma/Texas panhandles). This will keep us in a favorable pattern for at least a moderate chance of showers/storms with deep, southerly flow through the middle part of the week. Heavy rainfall/flooding will become a hazard if this occurs. Mahale && .AVIATION... (18Z TAFS) Issued at 1251 PM CDT Thu May 21 2020 Showers/thunderstorms are possible late this evening near KWWR with storms progressing southeast overnight into the early morning hours. Confidence is low on timing, however, as the models have trended slower with the progression of the precipitation. Winds are forecast to shift to the north over KWWR, KCSM, KPNC after 12Z Friday. && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 66 85 67 84 / 40 50 20 10 Hobart OK 65 89 67 88 / 30 10 20 10 Wichita Falls TX 68 91 67 87 / 20 40 40 10 Gage OK 58 85 63 93 / 60 10 0 10 Ponca City OK 64 80 65 85 / 70 70 20 10 Durant OK 66 85 69 84 / 30 40 50 20 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...None. TX...None. && SHORT TERM...01 LONG TERM....10 AVIATION...01
Hazardous Weather Outlook...UPDATED National Weather Service Norman OK 352 PM CDT Thu May 21 2020 OKZ004>048-050>052-TXZ083>090-222100- Harper-Woods-Alfalfa-Grant-Kay-Ellis-Woodward-Major-Garfield- Noble-Roger Mills-Dewey-Custer-Blaine-Kingfisher-Logan-Payne- Beckham-Washita-Caddo-Canadian-Oklahoma-Lincoln-Grady-McClain- Cleveland-Pottawatomie-Seminole-Hughes-Harmon-Greer-Kiowa-Jackson- Tillman-Comanche-Stephens-Garvin-Murray-Pontotoc-Coal-Cotton- Jefferson-Carter-Johnston-Atoka-Love-Marshall-Bryan-Hardeman- Foard-Wilbarger-Wichita-Knox-Baylor-Archer-Clay- 352 PM CDT Thu May 21 2020 This hazardous weather outlook is for portions of northern... western...central...and southern Oklahoma...and western north Texas. .DAY ONE...Tonight... .Thunderstorms... There is a risk of severe thunderstorms tonight. The greatest risk of severe storms will be across northern Oklahoma. Thunderstorms moving southeast from the High Plains are expected to move into northwest Oklahoma later this evening into the overnight. Hail up to the size up golf balls and wind gusts up to 75 mph are the primary hazards. Heavy rainfall may also lead to localized flooding. Storms are expected to continue into the early morning, with a decreasing risk of severe weather as the storms move southeastward. .SPOTTER AND EMERGENCY MANAGEMENT STATEMENT... Storm spotter groups and emergency management personnel across northwest Oklahoma should prepare for severe weather operations tonight. .DAYS TWO THROUGH SEVEN...Friday through Wednesday... .Thunderstorms... Thunderstorms are expected to continue off and on through next Wednesday. On Friday, a Slight Risk of severe storms thunderstorms covers southeast and south central Oklahoma and adjacent parts of north Texas. Severe storms will be most likely in the afternoon and evening. A Marginal Risk covers the area west of Enid to Lawton to Seymour Texas on Saturday, mainly during the evening. Severe thunderstorms will also be possible on Sunday, but details are still uncertain regarding timing and location. .Heavy rain... Heavy rainfall is possible, particularly on Friday, and again Sunday night into Monday. Heavy rainfall may lead to flooding. Get graphics and more details at weather.gov/norman...and follow our weather forecast office on Twitter and Facebook. Mahale
The Dyess AFB radar (KDYX), 111 km away, was scanning. The volume nearest the first event began at 01:02 UTC.
1 hail. Local standard time, as filed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Texas in 2020Every state in 2020This day in weather historyWarnings in Texas, May 2020
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: 897470.