Alert archive / Arkansas / Mesoscale Discussions in 2017
Mesoscale Discussion 593
The Storm Prediction Center issued this mesoscale discussion at Apr 29, 2017, 1:11 PM CDT for 21 counties in Arkansas; 7 counties in Oklahoma. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 29, 2017, 1:11 PM CDT (18:11 UTC)
- Expired
- Apr 29, 2017, 3:15 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 20%
All 28 counties
Benton County, AR, Conway County, AR, Crawford County, AR, Franklin County, AR, Garland County, AR, Hot Spring County, AR, Johnson County, AR, Logan County, AR, Madison County, AR, Montgomery County, AR, Newton County, AR, Perry County, AR, Polk County, AR, Pope County, AR, Saline County, AR, Scott County, AR, Searcy County, AR, Sebastian County, AR, Van Buren County, AR, Washington County, AR, Yell County, AR, Adair County, OK, Haskell County, OK, Latimer County, OK, LeFlore County, OK, McCurtain County, OK, Pushmataha County, OK, Sequoyah County, OK
The radar
The Western Arkansas radar (KSRX), 29 km from the middle of the area, began a volume at 18:16 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 nearest sounding before it
Springfield, MO (KSGF), launched 12:00Z, 6.2 hours before the alert went out and 173 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 704 m above ground
- 0-6 km bulk shear
- 72 kt
- 0-1 km storm-relative helicity
- 318 m²/s²
- 0-3 km storm-relative helicity
- 413 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 3.6
The text
As transmitted.
806
ACUS11 KWNS 291811
SWOMCD
SPC MCD 291811
ARZ000-OKZ000-292015-
Mesoscale Discussion 0593
NWS Storm Prediction Center Norman OK
0111 PM CDT Sat Apr 29 2017
Areas affected...Far eastern OK...Western/central AR
Concerning...Severe potential...Watch unlikely
Valid 291811Z - 292015Z
Probability of Watch Issuance...20 percent
SUMMARY...Some isolated hail and damaging wind gusts are possible
across the region over the next few hours. Limited severe coverage
is expected to preclude the need for a watch until possibly later
this afternoon/early evening.
DISCUSSION...Strong low-level flow continues to advect moisture
northward into eastern OK and western AR. Recent radar imagery has
shown an increase in convective coverage over the past hour or so,
likely a result of ongoing moist isentropic ascent within the
continually destabilizing airmass. Moisture advection and isentropic
ascent are expected to persist throughout the afternoon with
thunderstorms expected to continue throughout the time frame as
well.
This area is on the edge of the stronger flow aloft and current
mesoanalysis indicates a gradient in the effective shear from 50 kt
across central OK to less than 30 kt across central AR, which is
sufficient enough to support updraft organization. Elevated nature
of the convection and continual storm interactions will make robust
updraft organization difficult but, given the strength of the
instability and adequate shear, some hail is still possible. A wet
downburst or two may also occur.
..Mosier/Weiss.. 04/29/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LZK...SHV...TSA...
LAT...LON 35489533 36399433 36209296 35669218 34209277 34089547
35489533SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 28, 10:01 PM CDT | Severe Thunderstorm Watch | SPC | Baxter, Benton, Boone, Carroll, Crawford, Franklin and 8 more | 9 hr |
| Apr 28, 10:49 PM CDT | Mesoscale Discussion | SPC | Johnson, Logan, Pope, Searcy, Van Buren | 56 min |
| Apr 28, 11:55 PM CDT | Mesoscale Discussion | SPC | Baxter, Benton, Boone, Carroll, Clay, Crawford and 12 more | 95 min |
| Apr 29, 3:39 AM CDT | Mesoscale Discussion | SPC | Benton, Boone, Carroll, Madison, Washington | 96 min |
| Apr 29, 5:36 PM CDT | Severe Thunderstorm Watch | SPC | Baxter, Boone, Carroll, Crawford, Franklin, Fulton and 9 more | 4 hr |
| Apr 29, 6:21 PM CDT | Mesoscale Discussion | SPC | Arkansas, Bradley, Calhoun, Chicot, Cleveland, Craighead and 20 more | 54 min |
| Apr 28, 10:18 PM CDT | Mesoscale Discussion | SPC | Beckham, Blaine, Caddo, Canadian, Cleveland, Comanche and 18 more | 117 min |
| Apr 28, 10:35 PM CDT | Severe Thunderstorm Watch | SPC | Beckham, Blaine, Caddo, Canadian, Cleveland, Comanche and 21 more | 8 hr |
| Apr 29, 2:45 AM CDT | Mesoscale Discussion | SPC | Beckham, Blaine, Caddo, Canadian, Cleveland, Comanche and 21 more | 2 hr |
| Apr 29, 4:04 AM CDT | Mesoscale Discussion | SPC | Cimarron | 6 hr |
| Apr 29, 2:10 PM CDT | Mesoscale Discussion | SPC | Bryan, Marshall | 2 hr |
Nearby
Mesoscale Discussions in Arkansas, 2017Mesoscale 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.