Alert archive / Arkansas / Mesoscale Discussions in 2017
Mesoscale Discussion 608
The Storm Prediction Center issued this mesoscale discussion at Apr 30, 2017, 3:36 AM CDT for 16 counties in Arkansas; 9 parishes in Louisiana. It was in force for 84 min.
The area
The outline as issued.
The facts
- Issued
- Apr 30, 2017, 3:36 AM CDT (08:36 UTC)
- Expired
- Apr 30, 2017, 5:00 AM CDT
- In force
- 84 min
- Issued by
- the Storm Prediction Center
All 25 counties
Arkansas County, AR, Bradley County, AR, Calhoun County, AR, Cleveland County, AR, Desha County, AR, Drew County, AR, Independence County, AR, Jackson County, AR, Jefferson County, AR, Lincoln County, AR, Lonoke County, AR, Monroe County, AR, Prairie County, AR, Union County, AR, White County, AR, Woodruff County, AR, Caldwell Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Union Parish, LA, Winn Parish, LA
The radar
The Little Rock radar (KLZK), 148 km from the middle of the area, began a volume at 08:36 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
Shreveport, LA (KBAD), launched 00:00Z, 8.6 hours before the alert went out and 202 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
- 1748 J/kg
- Mixed-layer CIN
- -53 J/kg
- Mixed-layer LCL
- 772 m above ground
- 0-6 km bulk shear
- 31 kt
- 0-1 km storm-relative helicity
- 251 m²/s²
- 0-3 km storm-relative helicity
- 454 m²/s²
- Significant tornado parameter
- 3.0
- Supercell composite
- 19.0
The text
As transmitted.
816
ACUS11 KWNS 300837
SWOMCD
SPC MCD 300836
ARZ000-MSZ000-LAZ000-301000-
Mesoscale Discussion 0608
NWS Storm Prediction Center Norman OK
0336 AM CDT Sun Apr 30 2017
Areas affected...Southern and eastern AR...and northern LA
Concerning...Severe Thunderstorm Watch 178...
Valid 300836Z - 301000Z
The severe weather threat for Severe Thunderstorm Watch 178
continues.
SUMMARY...Severe weather threat continues across WW 178, along and
east of the cold front as it advances east across AR and
northern/western LA overnight to early this morning. Meanwhile,
counties and parishes can be cleared in the wake of the cold front
passage.
DISCUSSION...08Z surface analysis indicated a synoptic low centered
near the border of northeast OK and southeast KS, with a secondary
low located in south-central AR, while the cold front trailed
southward through northwest and west-central LA to extreme southeast
TX/upper TX coast area.
Water vapor imagery indicated an apparent midlevel shortwave trough
currently tracking to the north/northeast across LA toward southern
and eastern AR and western MS by 12Z. Forcing for ascent attendant
to this midlevel trough and low-level confluence along the cold
front and a pre-frontal trough has resulted in an increase in
thunderstorm coverage across southern into central LA thus far.
This activity with further development is expected to spread across
northern LA into southern and eastern AR within the valid portions
of WW 178. Strengthening deep-layer winds is supporting an increase
in low-level shear (surface-1 km of 40-50 kt) and effective bulk
shear of 40-50 kt within a moderately unstable environment suggests
damaging winds and some tornado threat remains possible across
northern LA into southern and eastern AR.
..Peters.. 04/30/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MEG...JAN...LZK...LCH...SHV...
LAT...LON 33049204 31999206 31519217 31419281 31429320 32779292
33809279 34549210 35379193 35909159 35869111 34919099
34059098 33639110 33239184 33049204SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 29, 9:38 PM CDT | Mesoscale Discussion | SPC | Clark, Columbia, Hempstead, Hot Spring, Howard, Lafayette and 5 more | 67 min |
| Apr 29, 10:23 PM CDT | Severe Thunderstorm Watch | SPC | Arkansas, Bradley, Calhoun, Clark, Cleburne, Cleveland and 36 more | 8 hr |
| Apr 29, 11:37 PM CDT | Mesoscale Discussion | SPC | Bradley, Calhoun, Clark, Cleveland, Columbia, Conway and 23 more | 53 min |
| Apr 30, 12:54 AM CDT | Mesoscale Discussion | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Clay and 26 more | 96 min |
| Apr 30, 1:10 AM CDT | Severe Thunderstorm Watch | SPC | Clay, Craighead, Crittenden, Cross, Greene, Lee and 4 more | 6 hr |
| Apr 30, 1:49 AM CDT | Tornado Watch | SPC | Ashley, Chicot | 7 hr |
| Apr 30, 2:58 AM CDT | Mesoscale Discussion | SPC | Crittenden, Cross, Lee, Mississippi, Phillips, Poinsett and 1 more | 92 min |
| Apr 30, 5:41 AM CDT | Mesoscale Discussion | SPC | Arkansas, Bradley, Clay, Cleveland, Craighead, Crittenden and 19 more | 64 min |
| Apr 30, 6:12 AM CDT | Mesoscale Discussion | SPC | Ashley, Chicot | 93 min |
| Apr 30, 1:14 AM CDT | Mesoscale Discussion | SPC | Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Caldwell and 20 more | 91 min |
| Apr 30, 6:59 AM CDT | Mesoscale Discussion | SPC | Ascension, Assumption, East Baton Rouge, East Feliciana, Jefferson, Lafourche and 12 more | 2 hr |
| Apr 30, 7:32 AM CDT | Tornado Watch | SPC | Ascension, Assumption, East Baton Rouge, East Feliciana, Iberville, Jefferson and 14 more | 7 hr |
Nearby
Mesoscale Discussions in Arkansas, 2017Mesoscale Discussions in Louisiana, 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.