Alert archive / Arkansas / Mesoscale Discussions in 2011
Mesoscale Discussion 429
The Storm Prediction Center issued this mesoscale discussion at Apr 14, 2011, 7:33 PM CDT for 40 counties in Arkansas. It was in force for 117 min.
The area
The outline as issued.
The facts
- Issued
- Apr 14, 2011, 7:33 PM CDT (00:33 UTC)
- Expired
- Apr 14, 2011, 9:30 PM CDT
- In force
- 117 min
- Issued by
- the Storm Prediction Center
All 40 counties
Boone County, AR, Calhoun County, AR, Carroll County, AR, Clark County, AR, Cleburne County, AR, Cleveland County, AR, Conway County, AR, Crawford County, AR, Dallas County, AR, Faulkner County, AR, Franklin County, AR, Garland County, AR, Grant County, AR, Hempstead County, AR, Hot Spring County, AR, Howard County, AR, Jefferson County, AR, Johnson County, AR, Logan County, AR, Lonoke County, AR, Madison County, AR, Marion County, AR, Montgomery County, AR, Nevada County, AR, Newton County, AR, Ouachita County, AR, Perry County, AR, Pike County, AR, Polk County, AR, Pope County, AR, Pulaski County, AR, Saline County, AR, Scott County, AR, Searcy County, AR, Sebastian County, AR, Sevier County, AR, Stone County, AR, Van Buren County, AR, Washington County, AR, Yell County, AR
The radar
The Western Arkansas radar (KSRX), 90 km from the middle of the area, began a volume at 00:36 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Springfield, MO (KSGF), launched 00:00Z, 0.6 hours before the alert went out and 230 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
- 2194 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km storm-relative helicity
- 81 m²/s²
- 0-3 km storm-relative helicity
- 249 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.3
The text
As transmitted, in the capitals the NWS used until 2016.
611
ACUS11 KWNS 150034
SWOMCD
SPC MCD 150033
ARZ000-150230-
MESOSCALE DISCUSSION 0429
NWS STORM PREDICTION CENTER NORMAN OK
0733 PM CDT THU APR 14 2011
AREAS AFFECTED...CNTRL/WRN AR
CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY
VALID 150033Z - 150230Z
SEVERE THUNDERSTORMS WITH A HISTORY OF PRODUCING TORNADOES OVER ERN
OK...MOVING EWD AT 25 TO 35 KT...WILL CROSS THE OK/AR BORDER AFTER
02Z AND MARCH ACROSS AR DURING THE MID/LATE EVENING AND OVERNIGHT
HOURS. A TORNADO WATCH WILL LIKELY BE ISSUED.
SFC DEWPOINTS IN THE LOWER 60S AHEAD OF THE DRYLINE WILL SHIFT EWD
INTO AR AS A PACIFIC COLD FRONT OVER CNTRL OK OVERTAKES THE DRYLINE
AND THE MOIST AXIS SHIFTS EWD. WITH STEEP MID-LEVEL LAPSE RATES IN
PLACE...MLCAPE VALUES OF 1000 TO 2000 J/KG WILL OVERSPREAD AR INVOF
THE MOIST AXIS. STRONG DEEP-LAYER WIND SHEAR /EFFECTIVE BULK SHEAR
MAGNITUDES AROUND 60 KT/ WILL SUSTAIN THE ONGOING SEVERE CONVECTION
INTO AR. WHILE THE ANTICIPATED CONVECTIVE MODE IS SOMEWHAT
UNCERTAIN...HIGH-RESOLUTION WRF GUIDANCE CONTINUES TO SUGGEST
UPSCALE GROWTH INTO A QLCS...ESPECIALLY ACROSS CNTRL AND NRN AR.
THIS WILL LIKELY OCCUR AS DEEP-LAYER ASCENT STRENGTHENS IN RESPONSE
TO THE APPROACH OF THE LEFT-EXIT REGION OF A 100-125-KT 250-MB JET
STREAK. DAMAGING WINDS AND LARGE HAIL ARE EXPECTED TO ACCOMPANY
THESE STORMS. EMBEDDED SUPERCELLS AND MESOVORTICES WILL BE
ASSOCIATED WITH A TORNADO THREAT GIVEN INCREASING LOW-LEVEL
CLOCKWISE CURVATURE IN HODOGRAPHS PER RUC FORECAST SOUNDINGS
SUPPORTING EFFECTIVE STORM-RELATIVE HELICITY VALUES BETWEEN 300 AND
500 M2 PER S2. THIS WILL OCCUR AS A S-SWLY LOW LEVEL JET BECOMES
ESTABLISHED AFTER SUNSET. A TORNADO THREAT WILL ALSO BE ASSOCIATED
WITH ANY DISCRETE SUPERCELLS LEADING OR SOUTH OF THE QLCS. WHILE THE
THREAT FOR A STRONG TORNADO WILL EXIST ACROSS WRN AR PRIOR TO 05Z
WITH MORE DISCRETE CONVECTION...THE CONVECTIVE EVOLUTION TOWARD A
MORE LINEAR SYSTEM WILL LIKELY MITIGATE THIS POTENTIAL LATER IN THE
NIGHT.
..COHEN.. 04/15/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LZK...SHV...TSA...
LAT...LON 33859422 34629438 35639440 36219428 36429333 36069180
33639186 33289334 33859422SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 14, 9:06 PM CDT | Tornado Watch | SPC | Baxter, Benton, Boone, Bradley, Calhoun, Carroll and 45 more | 6 hr |
| Apr 14, 11:11 PM CDT | Mesoscale Discussion | SPC | Baxter, Benton, Boone, Carroll, Clark, Cleburne and 35 more | 94 min |
| Apr 15, 1:27 AM CDT | Mesoscale Discussion | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Cleburne and 33 more | 93 min |
| Apr 15, 2:19 AM CDT | Tornado Watch | SPC | Arkansas, Ashley, Baxter, Bradley, Calhoun, Chicot and 38 more | 8 hr |
| Apr 15, 12:29 PM CDT | Mesoscale Discussion | SPC | Clay, Crittenden, Mississippi | 61 min |
| Apr 15, 2:09 PM CDT | Tornado Watch | SPC | Clay, Craighead, Crittenden, Cross, Greene, Lee and 3 more | 7 hr |
| Apr 15, 3:32 PM CDT | Mesoscale Discussion | SPC | Clay, Greene | 58 min |
| Apr 15, 5:57 PM CDT | Mesoscale Discussion | SPC | Mississippi | 2 hr |
Nearby
Mesoscale Discussions in Arkansas, 2011Every mesoscale discussion in 2011
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.