Alert archive / Oklahoma / Mesoscale Discussions in 2017
Mesoscale Discussion 694
The Storm Prediction Center issued this mesoscale discussion at May 11, 2017, 11:44 AM CDT for 12 counties in Kansas; 44 counties in Oklahoma. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- May 11, 2017, 11:44 AM CDT (16:44 UTC)
- Expired
- May 11, 2017, 2:15 PM CDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 80%
All 56 counties
Barber County, KS, Butler County, KS, Chautauqua County, KS, Comanche County, KS, Cowley County, KS, Elk County, KS, Harper County, KS, Kingman County, KS, Labette County, KS, Montgomery County, KS, Sedgwick County, KS, Sumner County, KS, Adair County, OK, Alfalfa County, OK, Blaine County, OK, Canadian County, OK, Cherokee County, OK, Craig County, OK, Creek County, OK, Delaware County, OK, Dewey County, OK, Garfield County, OK, Grant County, OK, Harper County, OK, Haskell County, OK, Hughes County, OK, Kay County, OK, Kingfisher County, OK, Latimer County, OK, LeFlore County, OK, Lincoln County, OK, Logan County, OK, Major County, OK, Mayes County, OK, McIntosh County, OK, Muskogee County, OK, Noble County, OK, Nowata County, OK, Okfuskee County, OK, Oklahoma County, OK, Okmulgee County, OK, Osage County, OK, Ottawa County, OK, Pawnee County, OK, Payne County, OK, Pittsburg County, OK, Pottawatomie County, OK, Pushmataha County, OK, Rogers County, OK, Seminole County, OK, Sequoyah County, OK, Tulsa County, OK, Wagoner County, OK, Washington County, OK, Woods County, OK, Woodward County, OK
The radar
The Norman radar (KTLX), 85 km from the middle of the area, began a volume at 16:47 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
Norman, OK (KOUN), launched 12:00Z, 4.7 hours before the alert went out and 101 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
- 592 J/kg
- Mixed-layer CIN
- -121 J/kg
- Mixed-layer LCL
- 1262 m above ground
- 0-6 km bulk shear
- 49 kt
- 0-1 km storm-relative helicity
- 106 m²/s²
- 0-3 km storm-relative helicity
- 91 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 1.8
The text
As transmitted.
785
ACUS11 KWNS 111644
SWOMCD
SPC MCD 111644
OKZ000-KSZ000-111915-
Mesoscale Discussion 0694
NWS Storm Prediction Center Norman OK
1144 AM CDT Thu May 11 2017
Areas affected...Northern and Eastern Oklahoma...Southern Kansas
Concerning...Severe potential...Watch likely
Valid 111644Z - 111915Z
Probability of Watch Issuance...80 percent
SUMMARY...A severe threat is expected to develop across northern and
eastern Oklahoma over the next couple of hours. The storms should
expand in coverage affecting southern Kansas as well. Large hail and
wind damage will be the primary threats initially but an isolated
tornado threat may also develop as storm coverage expands. Weather
watch issuance will likely be needed across the region over the next
hour or so.
DISCUSSION...The latest surface analysis shows a 1008 mb low over
north-central Oklahoma with a boundary extending east-southeastward
from the surface low across northern and eastern Oklahoma. Surface
dewpoints along this boundary are in the mid to upper 60s F and
moderate instability is in place with MLCAPE values estimated by the
RAP in the 1500 to 2500 J/kg range. As surface temperatures continue
to increase into the mid to upper 70s F and as low-level convergence
becomes more focused along the boundary, convective initiation is
expected to take place across northern Oklahoma over the next hour
or two.
At mid-levels, an upper-level low is located across far northwest
Oklahoma according to water vapor imagery with a 60 to 75 kt
mid-level jet over southern Oklahoma. The mid-level jet was helping
to enhance lift and create strong deep-layer shear profiles across
Oklahoma which will support supercell development. Cold air aloft
(500 mb temperatures of -16 to -18C) along with 700-500 mb lapse
rates near 8.0 C/km will be favorable for large hail with rotating
updrafts. As cells increase in coverage and downdrafts mature early
this afternoon, a wind damage threat is also expected to develop.
Although low-level shear is relatively weak across northern
Oklahoma, a brief tornado can not be ruled out mainly with any
supercell that becomes dominant.
..Broyles.. 05/11/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...SGF...SHV...TSA...ICT...OUN...DDC...
LAT...LON 34299567 34829629 35349745 35649834 36159956 36679989
37439941 37799818 37799663 37269524 36739469 35589449
34499459 34299567SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 11, 12:56 PM CDT | Severe Thunderstorm Watch | SPC | Chautauqua, Cherokee, Cowley, Crawford, Labette, Montgomery and 1 more | 8 hr |
| May 11, 2:49 PM CDT | Mesoscale Discussion | SPC | Cherokee | 116 min |
| May 11, 6:07 PM CDT | Mesoscale Discussion | SPC | Chautauqua, Cherokee, Crawford, Labette, Montgomery, Neosho | 83 min |
| May 11, 1:37 PM CDT | Mesoscale Discussion | SPC | McCurtain | 2 hr |
| May 11, 2:43 PM CDT | Severe Thunderstorm Watch | SPC | McCurtain | 9 hr |
Nearby
Mesoscale Discussions in Oklahoma, 2017Mesoscale Discussions in Kansas, 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.