Alert archive / Oklahoma / Mesoscale Discussions in 2017
Mesoscale Discussion 770
The Storm Prediction Center issued this mesoscale discussion at May 18, 2017, 7:43 PM CDT for 6 counties in Oklahoma. It was in force for 62 min.
The area
The outline as issued.
The facts
- Issued
- May 18, 2017, 7:43 PM CDT (00:43 UTC)
- Expired
- May 18, 2017, 8:45 PM CDT
- In force
- 62 min
- Issued by
- the Storm Prediction Center
Counties Carter County, OK, Jefferson County, OK, Johnston County, OK, Love County, OK, Murray County, OK, Pontotoc County, OK
The radar
The Norman radar (KTLX), 119 km from the middle of the area, began a volume at 00:44 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Fort Worth, TX (KFWD), launched 00:00Z, 0.7 hours before the alert went out and 160 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 1519 J/kg
- Mixed-layer CIN
- -36 J/kg
- Mixed-layer LCL
- 1729 m above ground
- 0-6 km bulk shear
- 50 kt
- 0-1 km storm-relative helicity
- 154 m²/s²
- 0-3 km storm-relative helicity
- 211 m²/s²
- Significant tornado parameter
- 0.5
- Supercell composite
- 16.4
The text
As transmitted.
380 ACUS11 KWNS 190044 SWOMCD SPC MCD 190043 OKZ000-TXZ000-190145- Mesoscale Discussion 0770 NWS Storm Prediction Center Norman OK 0743 PM CDT Thu May 18 2017 Areas affected...south-central OK Concerning...Tornado Watch 235...240... Valid 190043Z - 190145Z The severe weather threat for Tornado Watch 235, 240 continues. SUMMARY...Scattered severe gusts 60-80 mph are possible with a bowing MCS across south-central OK. DISCUSSION...Radar imagery shows a developing MCS across the Red River Valley in between the I-44 and I-35 corridors. The transition to a linear mode will likely result in mainly a wind risk as it progresses eastward across south-central OK this evening. Surface observations ahead of the storm complex show temperatures in the lower 80s degrees F and dewpoints around 70 F. The 00Z FWD raob showed steep 0-2 km lapse rates and 4100 J/kg SBCAPE with a veering and strengthening wind profile with height. A strong moist influx and 40-kt south-southeasterly 925-850 mb flow at KFWS, steep 700-500 lapse rates (7.5 degrees C/km), and strong 0-6 km shear (50-kt) all strongly favor a severe-wind producing MCS across southern OK. Expecting scattered 60-80 mph winds with the stronger downdrafts. ..Smith.. 05/19/2017 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FWD...OUN... LAT...LON 33949711 33999822 34609772 34969636 34189635 33949711
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 18, 7:19 PM CDT | Mesoscale Discussion | SPC | Alfalfa, Garfield, Grant, Major, Woods | 26 min |
| May 18, 7:47 PM CDT | Severe Thunderstorm Watch | SPC | Alfalfa, Atoka, Bryan, Canadian, Carter, Cleveland and 26 more | 6 hr |
| May 18, 9:41 PM CDT | Mesoscale Discussion | SPC | Adair, Cherokee, Craig, Delaware, Haskell, Latimer and 4 more | 94 min |
| May 19, 10:41 AM CDT | Mesoscale Discussion | SPC | Carter, Jefferson, Love, Marshall | 94 min |
| May 19, 2:13 PM CDT | Mesoscale Discussion | SPC | Adair, Ottawa, Sequoyah | 92 min |
| May 19, 3:26 PM CDT | Tornado Watch | SPC | Adair, Atoka, Bryan, Carter, Cherokee, Choctaw and 19 more | 11 hr |
| May 19, 3:28 PM CDT | Mesoscale Discussion | SPC | Grant, Kay | 92 min |
| May 19, 4:47 PM CDT | Tornado Watch | SPC | Alfalfa, Grant, Kay | 4 hr |
| May 19, 6:56 PM CDT | Mesoscale Discussion | SPC | Adair, Atoka, Bryan, Carter, Cherokee, Choctaw and 24 more | 2 hr |
Nearby
Mesoscale Discussions in Oklahoma, 2017Every mesoscale discussion in 2017
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.