Alert archive / Arkansas / Mesoscale Discussions in 2014

Mesoscale Discussion 1721

September 16, 201410 counties in Arkansas

The Storm Prediction Center issued this mesoscale discussion at Sep 16, 2014, 5:16 PM CDT for 10 counties in Arkansas. It was in force for 119 min.

The area

The outline as issued.

The facts

Issued
Sep 16, 2014, 5:16 PM CDT (22:16 UTC)
Expired
Sep 16, 2014, 7:15 PM CDT
In force
119 min
Issued by
the Storm Prediction Center
Chance of a watch
5%

Counties Cleveland County, AR, Dallas County, AR, Garland County, AR, Grant County, AR, Hot Spring County, AR, Jefferson County, AR, Perry County, AR, Pulaski County, AR, Saline County, AR, Yell County, AR

The radar

The Little Rock radar (KLZK), 67 km from the middle of the area, began a volume at 22:16 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

Shreveport, LA (KBAD), launched 12:00Z, 10.3 hours before the alert went out and 241 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.

Skew-T log-pSkew-T log-p diagram, Shreveport, LA at 12:00Z on 2014-09-16Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 239 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Shreveport, LA at 12:00Z on 2014-09-16The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 19 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
239 J/kg
Mixed-layer CIN
-149 J/kg
Mixed-layer LCL
1123 m above ground
0-6 km bulk shear
20 kt
0-1 km storm-relative helicity
19 m²/s²
0-3 km storm-relative helicity
40 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

324 
ACUS11 KWNS 162216
SWOMCD
SPC MCD 162216 
ARZ000-170015-

MESOSCALE DISCUSSION 1721
NWS STORM PREDICTION CENTER NORMAN OK
0516 PM CDT TUE SEP 16 2014

AREAS AFFECTED...PORTIONS OF CNTRL AR

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 162216Z - 170015Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...AN ISOLATED/MARGINAL SVR-TSTM POTENTIAL WILL EXIST INTO
THE EVENING HOURS...THOUGH WW ISSUANCE WILL NOT BE NEEDED.

DISCUSSION...WEAK LOW/MID-LEVEL ASCENT AND DIURNAL DESTABILIZATION
HAVE CONTRIBUTED TO THE MAINTENANCE OF ONGOING STORMS ACROSS
PORTIONS OF NRN/CNTRL AR. THIS ACTIVITY LIES N OF A WAVY STATIONARY
BOUNDARY ANALYZED FROM GREENVILLE MS TO HOT SPRINGS AR TO FORT SMITH
AR. THE PRESENCE OF SFC DEWPOINTS FROM THE MIDDLE 60S TO AROUND 70F
IS AIDING MLCAPE AROUND 1000-1500 J/KG...WHICH MAY SUPPORT A FEW
INTENSE UPDRAFTS. AND...WITH 30-35 KT OF EFFECTIVE BULK
SHEAR...SUSTAINED/ORGANIZED CONVECTIVE ELEMENTS MAY CONTINUE TO
ADVANCE SEWD/SSEWD DURING THE NEXT FEW HOURS AS THEY MOVE TOWARD THE
WARM SIDE OF THE BOUNDARY. MARGINALLY SVR HAIL AND PERHAPS A DMGG
WIND GUST MAY OCCUR. HOWEVER...THE LACK OF STRONGER BUOYANCY AND THE
LACK OF STRONGER DEEP-LAYER ASCENT WILL LIKELY PREVENT A MORE
SUBSTANTIAL SVR-TSTM RISK FROM OCCURRING.

..COHEN/HART.. 09/16/2014

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...LZK...

LAT...LON   34169321 34999386 35339351 35029241 34279185 33769219
            34169321

Nearby

Mesoscale Discussions in Arkansas, 2014Every mesoscale discussion in 2014

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.