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3840 Views Tornado then Snow Reports

Link: https://mesonet.agron.iastate.edu/sites/obhistory.php?network=IA_ASOS&station=DSM&year=2015&month=11&day=11

The Des Moines Airport weather station reported a very unique combination of weather phenomena on Wednesday, 11 November 2015. At 3:36 PM, a tornado was sighted near the airport and an augmented METAR report was generated:

KDSM 112136Z 24016G46KT 10SM R31/2800VP6000FT +FC TSRA FEW014 
BKN034 OVC070 16/13 A2924 RMK TORNADO B35
AO2 PK WND 17046/2130 WSHFT 2119 TSB09 TORNADO B30 VC NE MOV
NE OCNL LTGICCG NE-SE TS NE-SE MOV NE P0018 T01560128 $

and just 6 hours and 1 minute later, a rain snow mix was reported
KDSM 120337Z 28027G41KT 5SM -RASN OVC017 04/01 A2926
RMK AO2 PK WND 28041/0331 SNB35 P0002 T00390011 $

Has such a close combination of such events been recorded before?For the Des Moines Airport, the answer appears to be "no". Based on IEM archives, just four other dates have had a tornado reported by the METAR report for the Airport, those include:

  1. 10 Jun 1976
  2. 20 Apr 1977
  3. 2 Jul 1983
  4. 11 Apr 1996

For those dates, snowfall was not reported later that day.

At this point, it would be a good time to point out a few caveats to this news story.
  1. The author of this news item is by no means an expert in METAR reporting standards and how supplemented reports work.
  2. The IEM archives of METAR data are not complete and may contain observations without supplemented reports that would have included tornados.
  3. The number of observation locations that have supplemental observations is a small fraction of the total automated stations these days. Such supplemental obs were more common a few decades ago.
  4. Waterspouts are included in this analysis as well.
  5. A more formal treatment of this topic may already exist in the literature!

So I wrote a script looking back through my METAR archives looking for combinations of tornado reports (either +FC or TORNADO denoted in the report) and then a subsequent (SN) report within 24 hours of the original tornado report. This search was done for archives over the continental United States.

My script found 4,930 observations with a tornado or waterspout reported and first being back in 1971. Here is an Excel file with these observations included. Note that this total includes duplicate reports as a single tornado observation is repeated with followup reports. These reports were not filtered as it is impossible to know if two tornadoes were reported or just the same one reported multiple times.

Here is a listing of combinations of Tornado reports and subsequent snow reports within 24 hours of the tornado report. You will see that there are a few other instances of this combination within a single calendar day. The times tamps shown are local to the reporting station.

----------------------------
ID: POB Date: 03 Mar 1971 Name: POPE_AFB State: NC Interval: 11h 0m
03 Mar 1971 03:00 PM => METAR KPOB 032000Z 07004KT 15/8SM -RA FG CLR 13/12 A2940 RMK F2 CIG 2V5 PIREP CONFIROMED TORNADO 20E FAY MOVMT UNKN WET RWY 1015 SLPNO 8/935 T01280117
04 Mar 1971 02:00 AM => METAR KPOB 040700Z 30006KT 1SM -SN CLR 02/M02 A2949 RMK R22VR60+ S6 CIG 14V16 PRESRR WET RWY SLPNO 8/015 T00171022
----------------------------
ID: PRC Date: 20 Apr 1973 Name: PRESCOTT/LOVE FLD State: AZ Interval: 7h 0m
20 Apr 1973 01:00 PM => KPRC 202000Z 21010KT 40SM BKN030 09/M08 A2977 RMK RWU ALQDS MTNS OBSCD S-W/UUA TORNADO SIGHTED 10SW P14 B52.20N INW MDT RIME ICG 130 BE36PRC4/18 SLP064 8/950 T00881077
20 Apr 1973 08:00 PM => KPRC 210300Z 12008KT 10SM -SHSN OVC013 01/M03 A2993 RMK RE09 SB10 SLP138 T00111033 52034
----------------------------
ID: GAG Date: 19 Nov 1973 Name: GAGE/SHATTUCK State: OK Interval: 12h 47m
19 Nov 1973 05:13 PM => KGAG 192313Z 19020G30KT 7SM TSRA OVC010 A2950 RMK TB11 OVHD-S MOVG N FQT LTGICCG S PRESRR/ PUBLIC REPORTS TORNADO ON GND BETWEEN ARNETT AND VICI SLPNO
20 Nov 1973 06:00 AM => KGAG 201200Z 30018KT 3SM RASN OVC002 02/M01 A2959 RMK SLP023 70030 T00161005 52003
----------------------------
ID: IAB Date: 21 Feb 1974 Name: MCCONNELL_AFB State: KS Interval: 5h 0m
21 Feb 1974 06:00 PM => METAR KIAB 212300Z 32030G42KT 8SM BKN016 OVC050 01/M02 A2976 RMK RCD 140/PK WND WET RWY M147 067/75/68/1828/974/PK WND 18/45/UA 2250 DURGD BFM 6 HND AND BLO SVR TURBC BE35 UA 2255 PSBL TORNADO 25 SW M SLPNO T00111021 5302/
21 Feb 1974 11:00 PM => METAR KIAB 220400Z 31024G37KT 4SM -SN -BLSN OVC022 01/M04 A2990 RMK RCD130/PK WND WET RWY SLPNO T00061043 5301/
----------------------------
ID: HTS Date: 03 Apr 1974 Name: HUNTINGTON/TRI STAT State: WV Interval: 17h 0m
03 Apr 1974 07:00 PM => KHTS 032300Z 18012G18KT 15SM SCT050 OVC200 28/14 A2956 RMK TORNADO 10E OF HUNTINGTON BY PUBLIC AT 2140 SLP005 T02780139
04 Apr 1974 12:00 PM => KHTS 041600Z 16012G17KT 10SM BKN040 OVC200 22/17 A2962 RMK UA DCA-CSN MDT CHOP AFT CSN IN CLR NO TURBC. 15E CRW LGT CHOP 100 C131 SLP022 8/543 T02220172
----------------------------
ID: OTM Date: 10 Jan 1975 Name: OTTUMWA State: IA Interval: 7h 0m
10 Jan 1975 03:00 PM => METAR KOTM 102100Z 21018G23KT 7SM OVC006 09/06 A2885 RMK UNCFM TORNADO RPTD BY PUBLIC AT 2005 OVR OTM MOVMT UNK SLP774 P0001 T00890061 55027
10 Jan 1975 10:00 PM => METAR KOTM 110400Z 24024G30KT 7SM -SN OVC010 M03/M04 A2893 RMK SB33 CIG RGD SLP803 T10331044
----------------------------
ID: CVS Date: 21 Feb 1975 Name: CANNON AFB/CLOVIS State: NM Interval: 1h 0m
21 Feb 1975 11:00 PM => KCVS 220600Z 09020KT 5SM -BLSN BKN005 OVC015 01/M02 A2985 RMK LSR02 90402 NZY NUC 0700Z 15 230/53/38/0811/021 TIK LTS 0635 TORNADO AT LTS MOVG N 3/4 INCH HAIL WND W50KNTS GUST TO 82KNTS PRESRR BY TIK SLP097 60020 8/6// T00061016 50000
22 Feb 1975 12:00 AM => KCVS 220700Z 06018G24KT 5SM -BLSN BKN005 OVC015 00/M02 A2985 RMK PS02 SLPNO T00001021
----------------------------
ID: CDS Date: 22 Feb 1975 Name: CHILDRESS MUNICIPAL State: TX Interval: 1h 0m
22 Feb 1975 02:00 AM => METAR KCDS 220800Z 31015G23KT 1SM SN FG OVC003 01/00 A2996 RMK PRESRR TORNADO F01 ABT 0600 RPRTD BY PUBLIC SLP151 T00060000
22 Feb 1975 03:00 AM => METAR KCDS 220900Z 02020G27KT 5SM -SN FG BKN005 OVC043 01/M01 A2984 RMK PRESFR SLP112 T00061005 57044
----------------------------
ID: LZK Date: 22 Feb 1975 Name: NORTH LITTLE ROCK State: AR Interval: 22h 0m
22 Feb 1975 05:00 PM => KLZK 222300Z 22009KT 3SM TSRA BKN009 OVC025 22/18 A2963 RMK TORNADO 10N LIFTD MOVD NNE TORNADO ENDED RB42/ PK WND 18/22 28 SLP034 T02170178
23 Feb 1975 04:00 PM => KLZK 232100Z 29011KT 7SM -SN BKN015 OVC025 03/M01 A2970 RMK RE20SB35 / SLP060 8/7// T00331005 56020
----------------------------
ID: MTC Date: 24 Mar 1975 Name: SELFRIDGE ANGB State: MI Interval: 13h 0m
24 Mar 1975 07:00 PM => METAR KMTC 250000Z 23030G48KT 10SM -SHRA BKN030 BKN200 11/00 A2940 RMK UNCONFIRMED TORNADO 10S 2 MOVNT UNKN 2343 UNCONFIRMED FUNNEL CLOUD 15W MOVG E 33600 1903 SLP958 6002/ 7352/ T01060000 52035
25 Mar 1975 08:00 AM => METAR KMTC 251300Z 26010G18KT 7SM -SHSN SCT016 OVC026 M01/M07 A2954 RMK LSR14P SLPNO T10101066
----------------------------
ID: PIA Date: 29 Nov 1975 Name: PEORIA State: IL Interval: 12h 0m
29 Nov 1975 11:00 PM => METAR KPIA 300500Z 24018G29KT 5SM TSRA OVC005 14/13 A2956 RMK 10SE PIA UNCONFIRMED TORNADO BY PUBLIC 0450 T B33 ALQDS MOVG E FQT LTGICCCCG ALQDS RB32 PK WND 1841/04 PRJMP 6/0425/31 SLP012 P0028 T01390128
30 Nov 1975 11:00 AM => METAR KPIA 301700Z 26018G24KT 9SM -SN OVC019 M01/M03 A2983 RMK PK WND 07 UA 1650 12 N PIA OVC58 CLR ABV SLP105 7728/ T10061033 52072
----------------------------
ID: PIA Date: 04 Mar 1976 Name: PEORIA State: IL Interval: 13h 0m
04 Mar 1976 06:00 PM => METAR KPIA 050000Z 17024G32KT 15SM BKN080 OVC220 20/16 A2953 RMK TORNADO S LONDON MILLS MOVG NE BY CIVIL DEFENSE PK WND 1832/51 SLP001 8/057 T02000156 57024
05 Mar 1976 07:00 AM => METAR KPIA 051300Z 26020G30KT 10SM -SHSN OVC020 M02/M06 A2994 RMK CIG RGD PK WND 2630/45 SB50 SLP143 T10171061
----------------------------
ID: ACB Date: 30 Mar 1977 Name: BELLAIRE State: MI Interval: 5h 0m
30 Mar 1977 05:00 PM => METAR KACB 302200Z 20005KT 25SM SCT020 BKN035 OVC120 06/02 A2954 RMK UA /OV IMT160015 2135 /RM RADAR SHOWS POSBL TORNADO UA /OV ESC 270020 2140 /CV58 /RM HOOKS ON CLDS;MQT3/14 SLP017 T00610017
30 Mar 1977 10:00 PM => METAR KACB 310300Z 01014G21KT 1SM -FZDZSN FG OVC003 M02/M03 A2966 RMK SB UA /OV MQT 0245 ;FL50 /TP PA23 /SK 17 OVC 50 /TA -5C /IC TRACE/ 224;MQT3/14 SLP064 T10211032
----------------------------
ID: BOI Date: 26 Oct 1984 Name: BOISE MUNICIPAL State: ID Interval: 17h 40m
26 Oct 1984 10:20 AM => KBOI 261620Z 33010KT 4SM -SHRA SCT015 BKN035 OVC060 A2966 RMK T E18 MOVD E VSBY LWR E/OFF DUTY WEA SVC PERSONNEL TORNADO 6W BOI SHORT DURATION MOVD E SLPNO 8/535
27 Oct 1984 04:00 AM => KBOI 271000Z 23003KT 15SM -SHSN BKN050 OVC070 03/M03 A2993 RMK SB38 SLP143 T00331028
----------------------------
ID: HMN Date: 06 Jan 1986 Name: HOLLOMAN AFB State: NM Interval: 8h 45m
06 Jan 1986 07:00 PM => KHMN 070200Z 27008KT 1SM FG OVC002 M/M A2982 RMK UNCONFIRMED TORNADO 20NNE HMN 0139 MOVMT UNKN SLP091 T////////
07 Jan 1986 03:45 AM => KHMN 071045Z 34016KT 30SM -SHSN SCT050 BKN100 A3000 RMK PCPN VRY LGT SLPNO
----------------------------
ID: RKS Date: 30 May 1989 Name: ROCK SPRINGS State: WY Interval: 11h 0m
30 May 1989 01:00 PM => KRKS 301900Z 05012KT 15SM -TSRA SCT010 BKN020 07/00 A2995 RMK TORNADO B20E25 SE DSIPD TB18RB18 E MOVG E SLP110 T00720000
31 May 1989 12:00 AM => KRKS 310600Z 22004KT 1SM -SN FG OVC008 01/00 A3013 RMK RE20SB25/ SLP189 P0010 60014 T00060000 53019
----------------------------
ID: CMX Date: 18 Sep 1991 Name: HANCOCK State: MI Interval: 19h 0m
18 Sep 1991 11:00 AM => METAR KCMX 181500Z 23012G22KT 10SM -RA OVC012 07/06 A2965 RMK TORNADO AND WATERSPOUT MVD NE/ SLP049 T00720056 51003
19 Sep 1991 06:00 AM => METAR KCMX 191000Z 27010KT 3SM -SN OVC015 03/01 A3016 RMK SB40 SLP226 T00280011
----------------------------
ID: NIP Date: 12 Mar 1993 Name: JACKSONVILLE NAS State: FL Interval: 19h 0m
12 Mar 1993 10:00 PM => METAR KNIP 130300Z 15020G27KT 7SM SCT050 SCT080 OVC250 21/13 A2959 RMK PRESFR/ /SVR T2/TORNADO T2 SLP019 8/557 T02110127 58046
13 Mar 1993 05:00 PM => METAR KNIP 132200Z 27028G40KT 7SM -SN OVC030 04/M07 A2967 RMK SLP046 T00441067
----------------------------
ID: NKT Date: 13 Mar 1993 Name: CHERRY_POINT_MCAS State: NC Interval: 9h 0m
13 Mar 1993 11:00 AM => METAR KNKT 131600Z 13012G20KT 3SM -SHRA FG SCT002 OVC005 17/16 A2886 RMK TORNADO CONDITION 2 PRESFR SLP774 T01660155
13 Mar 1993 08:00 PM => METAR KNKT 140100Z 23029G42KT 5SM -SN OVC015 03/M02 A2899 RMK PK WND 2345/05 SLP818 T00331017
----------------------------
ID: FCS Date: 25 Apr 1994 Name: FORT CARSON/BUTTS State: CO Interval: 2h 22m
25 Apr 1994 01:03 PM => KFCS 251903Z /////KT 6SM CLR A//// RMK TORNADOTORNADO 3E MOVG S; SLPNO
25 Apr 1994 03:25 PM => KFCS 252125Z 01007KT 3SM -SHRASN SCT010 OVC015 A2944 RMK T MOVD SE; SLPNO
----------------------------
ID: NHK Date: 08 Mar 1995 Name: PATUXENT RIVER NAS State: MD Interval: 8h 0m
08 Mar 1995 05:00 PM => KNHK 082200Z 16011G22KT 11/4SM FG SCT003 BKN006 OVC012 12/11 A2971 RMK F BNK NW-N WR// WR// LLWS ALERT T2 SET TORNADO COND II TWR VSBY PRESFR; SLP061 8/1/2 T01220111
09 Mar 1995 01:00 AM => KNHK 090600Z 34018G27KT 6SM -RASN SCT014 OVC017 02/M01 A2998 RMK RCRNR LLWS ALERT 52037 6009/ 10043 20035 WND 30V01 PK WND 3429/29; SLP151 600// T00171011 580/8
----------------------------
ID: NMM Date: 18 Jan 1996 Name: MERIDIAN NAS/MCCAIN State: MS Interval: 12h 0m
18 Jan 1996 10:00 AM => METAR KNMM 181600Z 15009KT 7SM SCT011 BKN018 BKN025 21/18 A2969 RMK TORNADO COND 2; SLP063 T02060183
18 Jan 1996 10:00 PM => METAR KNMM 190400Z 29016G21KT 6SM -SN OVC031 M02/M08 A3001 RMK SLP172 T10221078
----------------------------
ID: NMM Date: 30 Jan 1996 Name: MERIDIAN NAS/MCCAIN State: MS Interval: 15h 0m
30 Jan 1996 06:00 PM => METAR KNMM 310000Z 22003KT 3SM TSRA BKN029 BKN050 OVC090 19/17 A2989 RMK CB OVHD MOVG NE TORNADO S MOVMT UKN SVR T1 SET/ 55007 6001/ 10071 20066; SLP130 6006/ T01890167 580/3
31 Jan 1996 09:00 AM => METAR KNMM 311500Z 34008KT 5SM -SN OVC005 M02/M03 A3014 RMK 52030; SLP219 T10221033 580/6
----------------------------
ID: ROW Date: 02 Dec 1997 Name: ROSWELL/INDUSTRIAL State: NM Interval: 7h 51m
02 Dec 1997 03:01 PM => KROW 022201Z 35011KT 10SM +FC FEW033 OVC075 09/04 A2981 RMK TORNADO B00 AO2
02 Dec 1997 10:52 PM => KROW 030552Z AUTO 34009KT 7SM -SN OVC004 01/01 A3003 RMK AO2 RAE32SNB32 CIG 003V007 SLP159 P0002 60002 T00110006 10056 20011 51021 TSNO
----------------------------
ID: AKO Date: 17 May 2000 Name: AKRON/WASHINGTON CO State: CO Interval: 11h 59m
17 May 2000 12:54 PM => KAKO 171854Z 07023G34KT 10SM +FC TS FEW026 SCT034 SCT085 19/12 A2927 RMK FUNNEL CLOUD B47EAST MOVING WEST FUNNEL CLOUD E51 TORNADO B52 EAST MOVING WEST
18 May 2000 12:53 AM => KAKO 180653Z 34028G34KT 2SM -SN BR BKN007 OVC012 03/02 A2984 RMK AO2 PK WND 34041/0606 RAE13SNB20 CIG 004V010 SLP083 P0004 T00330022 402390033 $
----------------------------
ID: STK Date: 17 May 2000 Name: Sterling State: CO Interval: 11h 59m
17 May 2000 12:54 PM => KAKO 171854Z 07023G34KT 10SM +FC TS FEW026 SCT034 SCT085 19/12 A2927 RMK FUNNEL CLOUD B47EAST MOVING WEST FUNNEL CLOUD E51 TORNADO B52 EAST MOVING WEST AO2 PK WND 06028/1854
18 May 2000 12:53 AM => KAKO 180653Z 34028G34KT 2SM -SN BR BKN007 OVC012 03/02 A2984 RMK AO2 PK WND 34041/0606 RAE13SNB20 CIG 004V010 SLP083 P0004 T00330022 402390033 $
----------------------------
ID: BOI Date: 24 Jan 2004 Name: BOISE MUNICIPAL State: ID Interval: 0h 1m
24 Jan 2004 06:46 PM => KBOI 250146Z 36005KT 2SM +FC -SN BR FEW010 BKN049 OVC060 M02/M03 A2971 RMK WATERSPOUT B40 WATERSPOUT E46 AO2 WSHFT 0040 P0002
24 Jan 2004 06:47 PM => KBOI 250147Z 01005KT 2SM -SN BR FEW010 BKN049 OVC060 M02/M03 A2970 RMK WATERSPOUT B40 WATERSPOUT E46 AO2 WSHFT 0040 SLP081 P0002 T10221033
----------------------------
ID: CEY Date: 26 Feb 2008 Name: Murray State: KY Interval: 0h 30m
26 Feb 2008 02:23 PM => KPAH 262023Z 31011G22KT 7SM +FC OVC019 01/M03 A2996 RMK WATERSPOUT B22 AO2 PK WND 32029/1959
26 Feb 2008 02:53 PM => KPAH 262053Z 31020G25KT 4SM -SN BKN021 OVC026 01/M04 A2997 RMK WATERSPOUT B22 WATERSPOUT E23 AO2 PK WND 32029/1959 SNB48 SLP150 TEST P0000 60000 T00111039 53017
----------------------------
ID: IDA Date: 18 Jan 2012 Name: IDAHO FALLS/FANNING State: ID Interval: 0h 1m
18 Jan 2012 12:55 PM => KIDA 181955Z 19014G22KT 8SM +FC -SN BLSN BKN012 OVC022 M02/M04 A2988 RMK TORNADO B54 AO2 P0000
18 Jan 2012 12:56 PM => KIDA 181956Z 18014G22KT 9SM -SN BKN012 OVC022 M02/M04 A2988 RMK TORNADO B54 TORNADO E55 AO2 P0000
----------------------------
ID: PVU Date: 10 Nov 2012 Name: PROVO MUNI (AWOS) State: UT Interval: 18h 54m
10 Nov 2012 12:53 PM => KPVU 101953Z 32009KT 15SM +FC FEW024 BKN070 00/M06 A2982 RMK WATERSPOUT 1953 8 SW MOV SE
11 Nov 2012 07:47 AM => KPVU 111447Z VRB05KT 10SM -SN SCT014 BKN021 BKN030 M03/M04 A3018
----------------------------
ID: FCM Date: 24 Mar 2014 Name: MNPLS/FLYING CLD State: MN Interval: 0h 2m
24 Mar 2014 07:45 AM => KFCM 241245Z 00000KT 10SM +FC -SN BKN042 M07/M10 A3027 RMK WATERSPOUT B44 AO2 SNB38 P0000
24 Mar 2014 07:47 AM => KFCM 241247Z 00000KT 10SM -SN BKN042 M07/M10 A3027 RMK WATERSPOUT B44 WATERSPOUT E46 AO2 SNB38 P0000
----------------------------
ID: FAR Date: 28 Oct 2015 Name: FARGO State: ND Interval: 0h 46m
28 Oct 2015 09:21 AM => KFAR 281421Z 30018G24KT 7SM +FC -RA SCT022 BKN038 OVC050 03/00 A2962 RMK WATERSPOUT B20 AO2 RAB18 P0000 T00280000
28 Oct 2015 10:07 AM => KFAR 281507Z 32014KT 2 1/2SM -SN BR FEW010 BKN014 OVC028 02/01 A2961 RMK AO2 RAE1458SNB1458 P0000 T00220006
----------------------------
ID: DSM Date: 11 Nov 2015 Name: DES MOINES State: IA Interval: 6h 1m
11 Nov 2015 03:36 PM => KDSM 112136Z 24016G46KT 10SM R31/2800VP6000FT +FC TSRA FEW014 BKN034 OVC070 16/13 A2924 RMK TORNADO B35 AO2 PK WND 17046/2130 WSHFT 2119 TSB09 TORNADO B30 VC NE MOV NE OCNL LTGICCG NE-SE TS NE-SE MOV NE P0018 T01560128 $
11 Nov 2015 09:37 PM => KDSM 120337Z 28027G41KT 5SM -RASN OVC017 04/01 A2926 RMK AO2 PK WND 28041/0331 SNB35 P0002 T00390011 $