A very anomalous storm system produced winter weather across the Rockies, Upper Midwest, and Great Lakes region and severe weather across the mid-Mississippi and Ohio Valley regions. The combination of a warm and moist environment in place across the Ohio Valley region and a cold front that moved in from the west led to widespread thunderstorm development as the cold front pushed eastward…
Every event with a place to put it; 14 filed by county or forecast zone are drawn at its center, in a lighter ring. 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 JKL wrote it up.
A very anomalous storm system produced winter weather across the Rockies, Upper Midwest, and Great Lakes region and severe weather across the mid-Mississippi and Ohio Valley regions. The combination of a warm and moist environment in place across the Ohio Valley region and a cold front that moved in from the west led to widespread thunderstorm development as the cold front pushed eastward through Missouri, Illinois and Kentucky. Additionally, a strong low level jet and low level wind shear contributed to strong thunderstorms developing that were favorable for tornadoes.
As the storms moved across western and central Kentucky during the overnight hours, they produced a tornado outbreak of historic proportions. However, as they reached eastern Kentucky during the early morning hours on the 11th, they began to lose strength, continuing to push away from the area of best instability, highest low level winds, and with temperatures continuing to cool. Several tornado warnings were issued as the rotating and once tornadic storms moved across the Jackson CWA border, along with multiple severe thunderstorm warnings. Thankfully, no tornadoes impacted eastern Kentucky, though there were numerous reports of strong thunderstorm wind gusts and trees down across portions of the area.
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, KY wrote its last area forecast discussion before the first event at Dec 11, 1:25 AM EST, 1 hour 5 minutes earlier.
AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 125 AM EST Sat Dec 11 2021 .UPDATE... Issued at 100 AM EST SAT DEC 11 2021 One thunderstorm is lifting quickly northeast through western Fleming County but the rest of the area remains in a lull with triggers lacking and low to non-existent instability. We continue to await the approach of the cold front with the latest CAMs guidance keeping activity minimal for the JKL CWA through at least 4 or 5 am. Have tweaked the PoPs through dawn with this in mind and also incorporated the latest obs and trends for the T/Td grids. These updates have been sent to the NDFD and web servers. UPDATE Issued at 1132 PM EST FRI DEC 10 2021 Overall, a few showers can be seen in our far southeast, but things generally remain fairly quiet for now as the better activity remains to our west. There's still the question of how much in the way of scattered showers and storms make it into some of our northern counties over the next few hours, but the CAMs still suggest a possibility. Have tweaked the PoPs again for the next few hours, but the timing of the more widespread activity reaching our area remains largely unchanged. Have also incorporated recent obs. UPDATE Issued at 857 PM EST FRI DEC 10 2021 Some showers made their way north through the area earlier in the evening, but behind these showers, our area has continued to sit in a lull, with only weak activity seen on radar, at least over east Kentucky. However, this is not the case nearer to west Kentucky and towards to the Middle Mississippi Valley, where storms are ongoing in the warm sector of a deepening system centered roughly over the Missouri/Iowa border. Back in east Kentucky, the lull is not expected to continue for too much longer with CAMs still suggesting the development of more showers with possible thunderstorms late in the evening ahead of the strongest portion of the intensifying low level jet, especially in areas near and north of I-64. Have massaged PoPs slightly based on recent trends, but the timing of the more widespread showers and storms has not changed significantly. So, still expect the more widespread and impactful storms to begin reaching into our area early Saturday morning. Temperatures across the area sit in the upper 50s to around 60 currently, and are expected to warm through the night as advection increases ahead of the approaching cold front. The current forecast has this in hand though and mainly blended in obs. && .SHORT TERM...(This evening through Saturday night) Issued at 515 PM EST FRI DEC 10 2021 At 21z, the latest analysis showed a warm front situated north of the forecast area. This front extended westward to a rapidly intensifying lower pressure was centered over central Colorado. Another, nearly stationary boundary was located from central Kentucky and arced south and east around the southern foothills of the Appalachians. Across eastern Kentucky, persistent cloud cover and and light showers have kept temperatures mainly in the 50s while dew points have risen into the 50s. Further upstream across western Tennessee and northeast Mississippi, temperatures are in the mid to upper 70s with unseasonably sultry dew points in the mid to upper 60s. The latest radar imagery shows a band of showers, with a little embedded thunder, lifting northeastward across the CWA but with very quiet conditions upstream, at least for now. The surface low will rapidly lift northeastward to near/over Lake Michigan by 12z Saturday and then further deepen into a sub-970 mb low across Quebec Saturday night. This rapid deepening will be in response a favorably coupled and intense upper level jet structure and deep positively tilting upper level trough moving eastward from the central CONUS. As a result, the system’s warm conveyor belt jet will rapidly intensify to 55-70 knots at 850 mb overnight and will lift the currently stationary boundary back to the northeast. The system’s cold front will sweep through between 14-19z on Saturday, likely preceded and/or accompanied by one or more QLCS. The 850mb winds will turn northwesterly behind the front causing temperatures at that level, which will start the Saturday morning around +10-12C, to tumble to between -3 and -7C by 6z Sunday. This dynamic system will bring multiple hazards to eastern Kentucky: Severe Thunderstorms: Unusually warm surface dew points in the lower 60s and near moist adiabatic low to mid-level lapse rates will lead to skinny and weak surface-based instability late tonight into Saturday morning. The CAMs are still suggesting 100-600 J/kg, highest amounts west. While these values are minimal compared to the summer months, strong dynamic forcing with the front, along with this weak instability and 45-55 knots of largely speed shear between 0-3 km AGL suggest that the primary threat will be for QLCS convective modes. The primary timeframe for severe weather concern is between 5 AM and 2 PM Saturday and the primary threat with these lines will be damaging straight-line wind gusts. However, the presence of 35-50 knots of sfc-1 km layer shear and subtle veering in the hodograph are suggesting ESRH values in the 100-400m2s-2 range. These helicity values are sufficient for isolated tornadogenesis. The CAMs are also showing a subtle moisture boundary lifting from Central Kentucky to the Bluegrass/Northeast Kentucky earlier in the night, between 10 PM this evening and 2 AM Saturday, ahead of the most intense low-level jet core. While surface-based instability will be minimal with this boundary, a stray severe storm cannot be ruled out closer to Lake Cumberland or the Bluegrass. Through this event, the greater threat for severe winds and tornadoes should remain near/west of a Sandy Hook to Jackson to Williamsburg line although a severe storm is possible anywhere in the CWA. Strong Wind Gusts: Outside of convection, strong environmental wind gusts are expected ahead of and behind the front. The southerly warm conveyor belt will quickly intensify tonight. This will leading strengthening winds across the ridges, higher mountains, and Bluegrass, likely gusting into the 35 to 45 mph range by sunrise. A moderately stable but shallow nocturnal boundary layer will probably try to set up in the valley, keeping the wind gusts weaker there; but the combination of a tightening surface pressure gradient, plentiful cloud cover, and turbulent mixing could still cause blustery and erratic gusts of 15 to 30 mph at times – sufficient to wreak havoc on holiday décor. Behind the front on Saturday, strong CAA will cause low-level lapse rates to steepen to near dry adiabatic, which will be much more conducive to efficient momentum transfer. Thus anticipate a few hours of gusty northwest winds reaching 35 to 45 mph behind the cold front later Saturday morning and early afternoon. Locally stronger wind gusts to 50 mph or higher cannot be ruled out across the most exposed ridgelines (eg. Flatwoods and Black Mountain). A wind advisory has been issued for all of eastern Kentucky to account for these strong environmental winds. Flash Flooding: While a few isolated high water concerns cannot be ruled out, this threat will be minimized by extremely fast storm motions on the order of 60-75 knots. Significant cell training would be necessary for any notable issues. Storm total amounts should range from 0.5 to 1.0 inches at most locations although the HREF PMM suggests the potential for isolated 1.5-2.0 inch amounts. The 1-hr FFG is mostly in the 1.0-2.0 inch range while the 3-hr FFG is in the 1.5-3.0 inch range – both of which will be hard to attain due to the fast storm motions. Sensibly, look for tonight’s lows to occur this evening before temperatures rise into the mid 60s to lower 70s by Saturday morning on increasingly gusty winds. Other that a stray shower, most of the forecast area will remain dry through the night. The notable exception will be closer to the I-64 and Lake Cumberland where there could be period of more organized convection around midnight. One or more gusty lines of showers and storms are expected on Saturday. The primary window for severe storms is from 5 AM to 2 PM although an isolated severe storm cannot be ruled out closer to the Bluegrass or Lake Cumberland overnight. Once the front passes, look for the winds to to shift northwesterly and gust to between 35 and 45 mph across most of the area. Conditions will dry out quickly Saturday afternoon and night while temperatures crash back into the 40s by early Saturday evening and will continue falling into the mid 20s to lower 30s by sunrise on Sunday. .LONG TERM...(Sunday through Friday) Issued at 505 PM EST FRI DEC 10 2021 A quasi zonal pattern is expected to began the period with west to west southwest flow aloft across much of the Conus to begin the period. There will be a lingering trough extending into the Northeast and down along or near the eastern seaboard from Quebec with another upper level low west of BC with an associated upper level trough over portions of the eastern seaboard. Meanwhile, the period is expected to begin with a ridge of sfc high pressure extending from the Appalachians southwest to east TX. The zonal pattern across much of the Conus will continue into Monday at about which time the pattern is expected to amplify with a deep upper low off the northwest US coast and an associated trough nearing the west coast of the Conus and an upper level ridge building from the Gulf of Mexico north into the lower to mid MS Valley. The upper level ridge should build into the southeastern Conus Mon night to Tue as the upper level trough is expected to move into the western Conus. Tue to Wed, a weak shortwave trough should pass through the OH Valley around the Tue night to early Wed period. Otherwise, the upper level ridge should extend from the western Gulf of Mexico into the southeast while the upper level trough is expected evolve over the western Conus to Plains. The center of sfc high pressure should shift gradually east and southeast of the area to southwest VA through Tuesday. A weak warm front may lift into the region with the shortwave trough during the Tue night to early Wed period, but moisture and any forcing with that will be best north and west of East KY, and should not be more than a cloud producer in eastern KY. During the second half of the week, the ridge over the Gulf into the southeast Conus should shift to the east and off the eastern seaboard by around Thursday as a weak shortwave trough should near and then move east of the MS River. Although that shortwave trough should move east of the area by late Thu night, the axis of the upper ridge should remain from the Gulf of Mexico and into the Atlantic with southwest flow aloft in the OH Valley between it and some degree of troughing over the central to southwestern Conus. Low pressure should develop to the lee of the Rockies at midweek in response to the evolving upper trough from the western Conus into the Plains and reach Ontario rather quickly by Wed night and early Thu and then into the Maritimes by the end of the period. A trailing cold front should become increasingly sheared with southeast extent int the Thu to Fri period as it nears the region and with the degree of ridging in the Gulf to the western Atlantic and southwest flow appears destined to become stationary at least for a time near or just south of the area at the end of the period. Uncertainty in timing and strength of individual features increases during this time. After temperatures are near normal for highs on Sunday, then moderate above normal for Monday and Tuesday as the ridge gradually builds into the southeast and the sfc high moves and return flow begins. Further warming will occur Wednesday and Thursday ahead of the front, and temperatures could approach and even reach or exceed record levels for highs on the 15th to 16th. The records for Jackson/KJKL for these dates are 73 (1984) and 70 (2015), respectively. Meanwhile for London/KLOZ, the records are 72 (1969) and 69 (2015) for the 15th and 16th respectively. During this period, the forecast max T was increased above the NBM 50th percentile and trends in temperatures for this period will be monitored. For now, widespread mid to upper 60s are forecast. Temperatures during this period may be somewhat contingent on soil moisture conditions following rain over the next 24 to 30 hours followed by a few days of drying. Some there is some uncertainty. Chances for rain should return during the second half of the week toward the end of the period, as one or more shortwave troughs moves across the region as a sfc cold front moves into the region. At this point, with forcing potentially not all the strong, QPF form WPC is minimal and this seems reasonable at this time. An extended period of slight chance to chance pops from the NBM seemed reasonable during that period, especially with the potential for the boundary to stall by Thu night to Fri. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) ISSUED AT 125 AM EST SAT DEC 11 2021 Most of the TAF sites are currently seeing low-end MVFR CIGs, with possibly an occasional dip down to IFR as a lull in activity locally continues. More scattered showers, with possible thunderstorms, are expected to develop as we head deeper through the overnight hours. Early this morning and into the start of the afternoon, a strong cold front will bring more definitive lines of showers and strong storms. Expect reductions in visibility along with erratic strong wind gusts as the storms impact the TAF sites. Winds will continue to increase through the early morning hours out of the southwest at 10 to 20 kts with gusts to 30 kts or higher, at times, before shifting to out of the west/northwest at around 10 to 15 kts late this afternoon after the front passes. A strengthening low level jet will contribute to strong low level wind shear across all TAF sites through mid morning. Improving conditions then follow into the evening with CIGs likely becoming VFR or SKC while the winds start to settle. && .JKL WATCHES/WARNINGS/ADVISORIES... Wind Advisory until 3 PM EST this afternoon for KYZ044-050>052- 058>060-068-069-079-080-083>088-104-106>120. && UPDATE...GREIF SHORT TERM...GEERTSON LONG TERM...JP AVIATION...HAS/GREIF
Hazardous Weather Outlook National Weather Service Jackson KY 421 PM EST Fri Dec 10 2021 KYZ044-050>052-058>060-068-069-079-080-083>088-104-106>120-120030- Fleming-Montgomery-Bath-Rowan-Estill-Powell-Menifee-Rockcastle- Jackson-Pulaski-Laurel-Wayne-McCreary-Whitley-Knox-Bell-Harlan- Elliott-Morgan-Johnson-Wolfe-Magoffin-Floyd-Lee-Breathitt-Knott- Owsley-Perry-Clay-Leslie-Letcher-Martin-Pike- Including the cities of Flemingsburg, Camargo, Jeffersonville, Mount Sterling, Owingsville, Morehead, Irvine, Ravenna, Clay City, Stanton, Frenchburg, Brodhead, Mount Vernon, McKee, Annville, Burnside, Somerset, London, Monticello, Stearns, Whitley City, Corbin, Williamsburg, Barbourville, Middlesboro, Pineville, Cumberland, Harlan, Sandy Hook, West Liberty, Paintsville, Campton, Salyersville, Prestonsburg, Wheelwright, Beattyville, Jackson, Hindman, Pippa Passes, Booneville, Hazard, Manchester, Hyden, Jenkins, Whitesburg, Inez, Coal Run, Elkhorn City, Pikeville, and South Williamson 421 PM EST Fri Dec 10 2021 ...WIND ADVISORY IN EFFECT FROM 1 AM TO 3 PM EST SATURDAY... This hazardous weather outlook is for portions of eastern Kentucky. .DAY ONE...Tonight. Thunderstorms are possible tonight and some could become strong to severe. The chances for severe thunderstorms is mainly along and west of a Sandy Hook to Jackson to Barbourville to Williamsburg line. The strongest of these could bring damaging wind gusts and times of heavy rainfall. In addition, an isolated tornado cannot be ruled out late tonight. Outside of the thunderstorms, strong wind gusts, in excess of 40 mph, are possible at times, mainly late tonight. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. Strong to severe thunderstorms are possible Saturday as a potent cold front moves through the area. The highest threat of severe thunderstorms is generally along and west of a Sandy Hook to Jackson to Barbourville to Williamsburg line. Thunderstorms could produce damaging wind gusts and times of heavy rainfall. In addition, an isolated tornado cannot be ruled out on Saturday morning. Outside of the thunderstorms, strong wind gusts, in excess of 40 mph, are possible at times on Saturday. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report any instances of wind damage or heavy rain that occur tonight and on Saturday. GEERTSON/JP
The Jackson,KY radar (KJKL), 72 km away, was scanning. The volume nearest the first event began at 09:45 UTC.
38 thunderstorm wind, 9 strong wind, 5 high wind, 2 flood. Local standard time, as filed.
A 42 mph gust was measured at the Bath County Mesonet station near the community of Preston.
A 46 mph wind gust was recorded at the Pike County Mesonet station on Dorton Mountain at an elevation of 2774 feet.
A tree was reported down across KY-805.
A 48 mph wind gust was recorded at the Harlan County Mesonet station on Black Mountain at an elevation of 4031 feet.
A tree was down on a powerline along Brush Creek Road north of Clay City.
Power line downed along Pottersville Road near the communities of Hope and Means.
A 40 mph wind gusts was measured at the Morgan County Mesonet station near the community of Index.
A tree was blown down in the Kendall Springs community.
Trees were blown down along Heights Avenue in Morehead. Nearby, scaffolding was also blown down near 200 Flemingsburg Road.
A tree was downed along the 7200 block of Hardwicks Creek Road south of Stanton.
A tree is on a 3-phase powerline along Spout Springs Road. The road is closed and repairs are ongoing.
A tree was downed and over Paint Creek Road in the 2500 block north of Stanton.
Trees were reported down along Muri Road near the community of Cabell.
A 51 mph wind gust was recorded at the Pike County Mesonet station on Dorton Mountain at an elevation of 2774 feet.
A tree was reported down along Hwy 200 near the community of Hidalgo.
Tree is reported across KY-858 in the 1000 block near the community of Bethesda.
A very large tree was reported down and across Adair Street in Monticello.
Trees were reported down along Highway 3284.
Trees were reported across powerlines in the vicinity of Bertram Hollow Road near the community of Cooper.
A tree was reported down on Hwy-1009.
A tree was reported down across Hwy-1619.
A tree was downed and blocking Hwy-761 near the community of Nancy.
A tree was downed on power lines, both of which were laying across and blocking both lanes of Hwy-1674 just northeast of Somerset.
Power lines are downed in the community of Burnside at the intersection of Cliffside and Cumberland Drives.
A tree was reported down on Hwy-167 near the community of Cooper.
A tree was reported down along Hwy-92 West near the Wayne/McCreary county line.
A member of the public relayed a report from the 911 dispatch, in which they had received a complaint that a tree was down on South Puncheon Fork Road (Route 1766) near the 1 mile marker, blocking the roadway.
A tree was reported down on Round Top Road west of Pine Knot.
A tree was reported down across Murphy Ridge Road near the community of Strunk.
A tree is down and blocking Laurel Cemetery Road near the McCreary County Airport.
The Pulaski County Mesonet station in the community of Dabney reported a 56 mph gust.
Trees have fallen onto powerlines along Hightop Road just south of Laurel River Lake.
A tree was blown down along Possum Kingdom Road in the Brodhead community.
Two trees were blown down in the community of Keavy.
A tree was reported to have been blown down in the East Bernstadt community.
Two trees were blown down on Scaffold Cane Road near the Madison County line.
A tree is down on a power line and blocking Furnace Junction Road.
A tree was downed and is blocking KY-715 in the Red River Gorge.
A tree was blown down blocking Hwy-52W in the 2000 block near the community of Mount Olive.
Large branches have been broken off and blocked the road in the 4000 block of KY-715 near the Red River Gorge.
Two trees were reported down across Sandy Ridge Road, blocking the road, near the community of Booth.
An 8-inch tree was reported down blocking Flat Mary Road near the community of Mary.
Maple Street (Pompeii Road) is closed and flooded by water of an unknown depth.
A 57 mph wind gust was measured at the Pike County Mesonet Station on Dorton Mountain at an elevation of 2774 feet.
Flooding was reported via MPing in low lying areas along creeks near the community of Clio.
Trees were reported to have been blown down in the Lick Creek (Lickburg) community.
A 49 mph wind gust was measured at the Harlan County Mesonet on Black Mountain at an elevation of 4031 feet.
Trees were reported having fallen on power lines along Kensee Hollow Road.
A tree was blown down along US-119N.
The AWOS near Monticello (KEKQ) measured a wind gusts of 44mph.
The Rowan County Mesonet near Morehead measured a wind gust of 40 mph.
A tree was reported having been blown down onto an electric line at 5290 Red Lick Road near the community of Jinks.
A tree was blown down in along US-119N.
A 44 mph wind gust was measured at the Morgan County Mesonet station near the community of Index.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Kentucky in 2021Every state in 2021This day in weather historyWarnings in Kentucky, December 2021
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: 997785, 997776, 997765, 997780, 997743, 997751, 997778, 997773, 997718, 997744, 997745, 997746, 997701, 997777, 997702, 997703, 997704, 997705, 997714, 997715, 997716, 997724, 997726, 997734, 997717, 997755, 997762, 997756, 997759, 997761, 997739, 997697, 997719, 997769, 997770, 997721, 997747, 997753, 997768, 997693, and more.