Alert archive / Oklahoma / Mesoscale Discussions in 2017
Mesoscale Discussion 883
The Storm Prediction Center issued this mesoscale discussion at May 27, 2017, 8:07 PM CDT for 39 counties in Oklahoma. It was in force for 83 min.
The area
The outline as issued.
The facts
- Issued
- May 27, 2017, 8:07 PM CDT (01:07 UTC)
- Expired
- May 27, 2017, 9:30 PM CDT
- In force
- 83 min
- Issued by
- the Storm Prediction Center
All 39 counties
Caddo County, OK, Canadian County, OK, Carter County, OK, Cherokee County, OK, Cleveland County, OK, Coal County, OK, Comanche County, OK, Cotton County, OK, Craig County, OK, Creek County, OK, Delaware County, OK, Garvin County, OK, Grady County, OK, Hughes County, OK, Johnston County, OK, Lincoln County, OK, Logan County, OK, Marshall County, OK, Mayes County, OK, McClain County, OK, McIntosh County, OK, Murray County, OK, Muskogee County, OK, Nowata County, OK, Okfuskee County, OK, Oklahoma County, OK, Okmulgee County, OK, Pawnee County, OK, Payne County, OK, Pittsburg County, OK, Pontotoc County, OK, Pottawatomie County, OK, Rogers County, OK, Seminole County, OK, Stephens County, OK, Tillman County, OK, Tulsa County, OK, Wagoner County, OK, Washington County, OK
The radar
The Norman radar (KTLX), 49 km from the middle of the area, began a volume at 01:06 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 00:00Z, 1.1 hours before the alert went out and 53 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
- 5174 J/kg
- Mixed-layer CIN
- -10 J/kg
- Mixed-layer LCL
- 1475 m above ground
- 0-6 km bulk shear
- 56 kt
- 0-1 km storm-relative helicity
- 91 m²/s²
- 0-3 km storm-relative helicity
- 119 m²/s²
- Significant tornado parameter
- 1.2
- Supercell composite
- 8.1
The text
As transmitted.
147
ACUS11 KWNS 280108
SWOMCD
SPC MCD 280107
OKZ000-280230-
Mesoscale Discussion 0883
NWS Storm Prediction Center Norman OK
0807 PM CDT Sat May 27 2017
Areas affected...Central and eastern OK
Concerning...Tornado Watch 279...
Valid 280107Z - 280230Z
The severe weather threat for Tornado Watch 279 continues.
SUMMARY...The threat for all severe hazards continues across Tornado
Watch 279. The coverage of potentially severe thunderstorms is
expected to increase this evening as a cold front moves into the
area.
DISCUSSION...Explosive thunderstorm development has recently
occurred across portions of northeast and southern OK, with
additional development underway across central and southwest OK.
Regional ASOS and OK Mesonet obs, along with radar data, show
several boundaries across the region, with two notable features of
interest being a cold front moving southward into central OK, and a
pre-frontal wind shift near the I-44 corridor, where recent
development has been noted.
In the short term, the primary convective mode is expected to be
semi-discrete supercells. Extreme instability and sufficient
effective shear (as noted on the 00Z OUN sounding) will support a
threat of all convective hazards. Steep tropospheric lapse rates
will support the potential for very large hail with any discrete
cell. The tornado threat will be limited to some extent by
relatively weak low-level flow, though as the low-level jet
increases this evening from south-central into northeast OK, the
tornado threat will increase with any remaining discrete cells. The
cells currently developing across Lincoln into Creek County and also
Stephens County may also have some increased tornado potential as
they interact with the pre-frontal boundary.
Later this evening, an increase in convective coverage is expected
along the cold front as it advances southeastward. A transition to
more of a linear or QLCS mode is expected as that occurs, though all
severe hazards will continue to be possible given the magnitude of
instability and shear across the region.
..Dean.. 05/28/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...TSA...OUN...
LAT...LON 34389909 35339842 36469674 36859582 36929499 36539472
35859493 34659584 34199620 33939656 33979701 34019739
34169781 34219822 34389909SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 27, 7:12 PM CDT | Mesoscale Discussion | SPC | Beaver, Cimarron, Texas | 2 hr |
| May 27, 9:07 PM CDT | Mesoscale Discussion | SPC | Beaver, Dewey, Ellis, Harper, Roger Mills, Woodward | 53 min |
| May 27, 9:39 PM CDT | Severe Thunderstorm Watch | SPC | Beckham, Blaine, Custer, Dewey, Ellis, Garfield and 9 more | 4 hr |
| May 27, 10:43 PM CDT | Mesoscale Discussion | SPC | Kingfisher, Major, Woodward | 32 min |
| May 27, 11:47 PM CDT | Mesoscale Discussion | SPC | Adair, Atoka, Bryan, Carter, Cherokee, Choctaw and 17 more | 58 min |
| May 28, 12:06 AM CDT | Severe Thunderstorm Watch | SPC | Adair, Cherokee, Choctaw, Delaware, Haskell, Latimer and 10 more | 5 hr |
| May 28, 12:52 AM CDT | Mesoscale Discussion | SPC | McCurtain | 23 min |
| May 28, 2:53 AM CDT | Mesoscale Discussion | SPC | Atoka, Bryan, Choctaw, Haskell, Latimer, LeFlore and 6 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.