An upper level trough moved east-southeast from the Southern Rockies and into the Plains and Four-State Region during the evening hours on April 21st. Isolated thunderstorms developed near a cold front across Northcentral Texas before spreading into Southeast Oklahoma and Northeast Texas.
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 SHV wrote it up.
An upper level trough moved east-southeast from the Southern Rockies and into the Plains and Four-State Region during the evening hours on April 21st. Isolated thunderstorms developed near a cold front across Northcentral Texas before spreading into Southeast Oklahoma and Northeast Texas. More than adequate frontogenetical forcing coupled with ample low level moisture and increased upper level support led to some of the thunderstorms becoming strong to severe, with large hail having fallen throughout McCurtain County, with damaging winds also having downed trees blocking roadways near Valiant. These storms weakened late as instability diminished.
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 Shreveport, LA wrote its last area forecast discussion before the first event at Apr 21, 6:10 PM CST, 2 hours 50 minutes earlier.
Area Forecast Discussion National Weather Service Shreveport LA 710 PM CDT Fri Apr 21 2017 .AVIATION... For the 22/00Z terminal forecast will prevail VFR flight categories until around 2204Z-2209Z when lowering clouds ahead of an approaching cold front with a band of showers and thunderstorms. The cold front will continue to push across the Four State Region with the convection shining Southeast with it. In and near the thunderstorms IFR ceilings and visibilities will develop as well out ahead and just behind the frontal boundary. Conditions will slowly return from IFR to MVFR during the mid morning with a gradual return to VFR near mid day to early afternoon. Surface winds will be South to Southwest overnight 7-14 knots increasing during the mid evening for the Northwest sections of the region. As winds shift to the West and Northwest with and in wake of the frontal passage expect an increase in speeds to 15-20 knots with higher gusts. /06/ && .PREV DISCUSSION... /issued 458 PM CDT Fri Apr 21 2017/ UPDATE... Sent out a quick update to headline Tornado watch 155 which will be in affect until 1 AM for northeast Texas, southeast Oklahoma, and portions of southwest Arkansas. Discrete supercells across the red river valley into eastern Oklahoma to increase in coverage along frontal boundary as upper disturbance migrates east bringing increased instability to the watch area. Very large hail, damaging winds, and isolated tornadoes will be possible. /05/ PREV DISCUSSION... /issued 409 PM CDT Fri Apr 21 2017/ DISCUSSION... As expected, the morning/early afternoon MCS has diminished across Ncntrl AR, having outrun the best forcing aloft ahead of the compact upper closed low now entering SW KS, while also shifting N into the cooler/more stable air mass N of a stationary front extending across Srn OK/Cntrl AR. This early MCV has left behind an extensive mesoscale bndry just S of the stationary front, which is well noted in the visible satellite imagery per the somewhat agitated cu field from just NE of SWW, to GLE, to ADR and across Srn LeFlore County OK to MEZ and HOT. We continue to await this small closed low as it enters Nrn OK this evening, with sct convection expected to develop soon across Nrn TX, before building NE into Srn OK. A rather expansive warm/moist sector remains in place across much of N TX into N LA/Srn AR S of the stationary front, although strong capping noted on the 20Z KFWD capping and the struggling cu field along the remnant mesoscale bndry may delay the onset of convection until late afternoon/early evening once better diffluence aloft overspreads this area and this cap is able to erode. MLCapes between 1500-2500 J/Kg is common attm over extreme Srn OK/N TX, with frontal convergence expected to increase once a 30-40kt SSW low level jet develops by early evening. Thus, convection should rapidly grow/become severe as steep H700-500 lapse rates advect in beneath the Nrn OK closed low, resulting in the convection to build E into SE OK/extreme NE TX/Wrn AR by mid to late evening. Have maintained likely pops for the I-30 corridor tonight with severe mention, with this convection possibly maintaining svr intensity in some areas even after 06Z Saturday as they possibly gust ESE into Srn AR/the I-20 corridor of E TX and extreme NW LA. Did increase pops late for the I-20 corridor of E TX, but the general trend for the convection is for it to weaken late as the low level instability diminishes and the convection outruns the attendant cold front and diminished frontal convergence. The GFS has slowed the frontal progress and is about 3-4 hours slower than the NAM/ECMWF/HRRR blends, but should this convection gust out late, then this may actually reinforce the front ESE a tad faster than the GFS. However, still expecting cooler and drier air to begin spilling SE into NE TX/SE OK/adjacent SW AR late, with the front expected to clear the remainder of E TX/N LA by Saturday afternoon. Still can't rule out isolated to sct convection Saturday on both sides of the front, but the lack of sfc frontal forcing and forcing aloft should be minimal with a secondary shortwave developing behind the compact closed low Saturday afternoon before digging into the Red River Valley by early evening. Have maintained chance pops over E TX/N LA/Scntrl AR Saturday, although convection should begin to diminish by afternoon over Lower E TX/NW LA/Scntrl AR as the H850 front sinks farther SE in wake of the sfc fropa. The short term progs are now suggesting postfrontal stratocu spilling S Saturday evening/night in wake of the aforementioned shortwave passage, with this cloud cover gradually scattering out from NW to SE Sunday. Given this cloud cover and NW winds, have made minor upward adjustments to min temps Saturday night, with the coldest night still expected Sunday night with ideal radiational cooling expected as the clouds clear and winds diminish once sfc ridging builds into the region. A warming trend will commence Monday with above normal temps returning, with afternoon RH's expected to gradually increase through midweek. Dry conditions will persist as well as a zonal flow is established in wake of the shortwave passage, before a WSW flow aloft is established as the next shortwave digs SE through the Rockies late Wednesday and into the Plains Thursday. Have maintained slight chance pops for extreme NE TX/SE OK/adjacent SW AR Thursday, although the more organized convection may await until just after the end of the forecast period (next weekend) as the next longwave trough digs through the Rockies and Srn Plains. /15/ && .PRELIMINARY POINT TEMPS/POPS... SHV 67 75 49 70 / 40 30 10 0 MLU 69 78 51 67 / 30 40 10 10 DEQ 56 65 43 70 / 70 20 10 0 TXK 59 67 48 70 / 60 20 10 0 ELD 66 72 49 68 / 60 30 10 10 TYR 59 68 47 71 / 60 30 10 0 GGG 63 71 47 70 / 60 30 10 0 LFK 68 76 48 72 / 20 30 10 0 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && 06/05/15
Hazardous Weather Outlook National Weather Service Shreveport LA 1224 PM CDT Fri Apr 21 2017 ARZ050-051-059>061-070>073-LAZ001>004-006-OKZ077-TXZ096-097- 108>112-124>126-136>138-221100- Sevier-Howard-Little River-Hempstead-Nevada-Miller-Lafayette- Columbia-Union-Caddo-Bossier-Webster-Claiborne-McCurtain- Red River-Bowie-Franklin-Titus-Camp-Morris-Cass-Wood-Upshur- Marion-Smith-Gregg-Harrison- 1224 PM CDT Fri Apr 21 2017 This Hazardous Weather Outlook is for portions of south central Arkansas, southwest Arkansas, north central Louisiana, northwest Louisiana, southeast Oklahoma and northeast Texas. .DAY ONE...This Afternoon and Tonight... A complex of strong to severe thunderstorms over Eastern Oklahoma will move into Western Arkansas early this afternoon, but should remain just north of the region. However, convective boundaries associated with this system should linger across Southeast Oklahoma and the northern sections of Southwest Arkansas, and will help focus scattered to numerous showers and thunderstorms late this afternoon through this evening over these areas as a strong upper level disturbance moves across Northern Oklahoma. These storms are expected to build farther south this evening and overnight into Northeast Texas, Southern Arkansas, and possibly extreme Northern Louisiana along and ahead of an associated cold front before weakening late. Given the strong instability, wind shear, and frontal forcing expected to be in place, some of these storms will become severe, with damaging winds, large hail, and even an isolated tornado possible. .DAYS TWO THROUGH SEVEN...Saturday through Thursday... Isolated showers and a few thunderstorms will be possible Saturday near and behind the cold front. However, no hazardous weather is expected. Afterwards, much cooler and drier air will spill south in wake of the frontal passage Saturday, before a warmup commences Monday. Dry conditions will continue across much of the region through at least Thursday. .SPOTTER INFORMATION STATEMENT... Activation of emergency managers, storm spotters, and amateur radio operators, will be needed this evening and tonight across extreme Northeast Texas, Southeast Oklahoma, and Southwest Arkansas. LAZ005-010>014-017>022-TXZ149>153-165>167-221100- Lincoln-De Soto-Red River-Bienville-Jackson-Ouachita-Sabine- Natchitoches-Winn-Grant-Caldwell-La Salle-Cherokee-Rusk-Panola- Nacogdoches-Shelby-Angelina-San Augustine- 1224 PM CDT Fri Apr 21 2017 This Hazardous Weather Outlook is for portions of north central Louisiana, northwest Louisiana, east Texas and northeast Texas. .DAY ONE...This Afternoon and Tonight... Isolated showers and thunderstorms will be possible this afternoon across portions of Deep East Texas and Northcentral Louisiana before diminishing this evening with the loss of heating. However, additional isolated to scattered showers and thunderstorms will be possible late over the area as a complex of strong to severe thunderstorms gradually sinks southeast and weakens late. Strong gusty winds will be possible late should any convective boundaries accelerate southeast ahead of the complex of showers and thunderstorms. .DAYS TWO THROUGH SEVEN...Saturday through Thursday... Isolated to scattered showers and thunderstorms will be possible Saturday near and behind the cold front especially over portions of Lower East Texas and North Louisiana, with the front expected to exit the region Saturday afternoon. However, the threat for hazardous weather is low. Afterwards, much cooler and drier air will spill south in wake of the frontal passage Saturday, before a warmup commences Monday. Dry conditions will continue across much of the region through at least Thursday. .SPOTTER INFORMATION STATEMENT... Activation of emergency managers, spotter networks, and amateur radio operators, should not be needed this afternoon or tonight. 15
The Western Arkansas radar (KSRX), 150 km away, was scanning. The volume nearest the first event began at 02:59 UTC.
3 hail, 2 thunderstorm wind. Local standard time, as filed.
Trees and power lines were blown down. Roads were blocked.
Quarter size hail fell in the Millerton Community. Report from a Sheriff's Deputy via Facebook.
Tree down across old Highway 98. Report from Facebook.
Penny size hail fell in Valliant.
Quarter size hail fell and damaged a Sheriff's vehicle.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Oklahoma in 2017Every state in 2017This day in weather historyWarnings in Oklahoma, April 2017
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: 684703, 684704, 684705, 684706, 684707.