Alert archive / Arkansas / Mesoscale Discussions in 2018
Mesoscale Discussion 1306
The Storm Prediction Center issued this mesoscale discussion at Aug 17, 2018, 9:23 AM CDT for 17 counties in Arkansas; Haskell County, LeFlore County, Sequoyah County, Oklahoma. It was in force for 97 min.
The area
The outline as issued.
The facts
- Issued
- Aug 17, 2018, 9:23 AM CDT (14:23 UTC)
- Expired
- Aug 17, 2018, 11:00 AM CDT
- In force
- 97 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 40%
Counties Cleburne County, AR, Conway County, AR, Crawford County, AR, Faulkner County, AR, Franklin County, AR, Johnson County, AR, Logan County, AR, Madison County, AR, Newton County, AR, Perry County, AR, Pope County, AR, Scott County, AR, Searcy County, AR, Sebastian County, AR, Van Buren County, AR, Washington County, AR, Yell County, AR, Haskell County, OK, LeFlore County, OK, Sequoyah County, OK
The radar
The Western Arkansas radar (KSRX), 80 km from the middle of the area, began a volume at 14:24 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, 2.4 hours before the alert went out and 159 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
- 52 J/kg
- Mixed-layer CIN
- -247 J/kg
- Mixed-layer LCL
- 1481 m above ground
- 0-6 km bulk shear
- 23 kt
- 0-1 km storm-relative helicity
- 72 m²/s²
- 0-3 km storm-relative helicity
- 103 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
986
ACUS11 KWNS 171424
SWOMCD
SPC MCD 171423
ARZ000-OKZ000-171600-
Mesoscale Discussion 1306
NWS Storm Prediction Center Norman OK
0923 AM CDT Fri Aug 17 2018
Areas affected...East-Central OK...Northwest/West-Central AR
Concerning...Severe potential...Watch possible
Valid 171423Z - 171600Z
Probability of Watch Issuance...40 percent
SUMMARY...Isolated damaging wind gusts and hail are possible for the
next hour or two. Higher severe thunderstorm coverage is expected by
midday as the convective line becomes more surface-based.
DISCUSSION...Recent regional radar imagery shows a convective
cluster moving through northeast OK and northwest AR. Based on KSRX
imagery, outflow associated with this cluster remains ahead of the
stronger cores, suggesting storms are currently elevated and likely
sustained primarily by warm-air advection amidst moderate elevated
instability (as sampled by the 12Z LZK sounding). These inferences
are further confirmed by additional thunderstorm development well
behind the line in southeast KS.
Expectation is for the cluster to remain elevated as it continues
southeastward for the next two hours or so. Thereafter, daytime
heating and rich low-level moisture will aid in the development of a
more surface-based character to the convective line. Damaging wind
gusts or hail are expected to remain more isolated before this
transition to more surface-based updrafts occurs. Even so, trends
will be monitored closely and a watch may be needed if trends
suggest the line is becoming surface-based.
..Mosier/Dial.. 08/17/2018
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LZK...TSA...
LAT...LON 36139380 36249316 36209272 35689196 35229194 34689253
34629361 34739483 35059519 35689508 36139380SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 17, 3:39 PM CDT | Mesoscale Discussion | SPC | Ashley, Bradley, Calhoun, Chicot, Cleveland, Desha and 4 more | 2 hr |
| Aug 17, 5:13 PM CDT | Mesoscale Discussion | SPC | Atoka, Bryan, Carter, Choctaw, Coal, Comanche and 20 more | 92 min |
Nearby
Mesoscale Discussions in Arkansas, 2018Mesoscale Discussions in Oklahoma, 2018Every mesoscale discussion in 2018
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.