Alert archive / South Carolina / Mesoscale Discussions in 2012

Mesoscale Discussion 1576

July 24, 20127 counties in South Carolina

The Storm Prediction Center issued this mesoscale discussion at Jul 24, 2012, 6:46 PM EDT for 7 counties in South Carolina. It was in force for 89 min.

The area

The outline as issued.

The facts

Issued: Jul 24, 2012, 6:46 PM EDT (22:46 UTC)
Expired: Jul 24, 2012, 8:15 PM EDT
In force: 89 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

Counties Calhoun County, SC, Clarendon County, SC, Lee County, SC, Lexington County, SC, Richland County, SC, Saluda County, SC, Sumter County, SC

The radar

The Columbia radar (KCAE), 12 km from the middle of the area, began a volume at 22:48 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

Charleston AFB, SC (KCHS), launched 12:00Z, 10.8 hours before the alert went out and 148 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1348 J/kg
Mixed-layer CIN: -111 J/kg
Mixed-layer LCL: 977 m above ground
0-6 km bulk shear: 11 kt
0-1 km storm-relative helicity: 55 m²/s²
0-3 km storm-relative helicity: 76 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.

180 
ACUS11 KWNS 242246
SWOMCD
SPC MCD 242246 
SCZ000-250015-

MESOSCALE DISCUSSION 1576
NWS STORM PREDICTION CENTER NORMAN OK
0546 PM CDT TUE JUL 24 2012

AREAS AFFECTED...CNTRL SOUTH CAROLINA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 242246Z - 250015Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...THE NEED FOR A WATCH IS NOT CURRENTLY ANTICIPATED...BUT A
SHORT TERM SEVERE THREAT MAY DEVELOP ACROSS COLUMBIA/SUMTER AND
ADJACENT PORTIONS OF THE CENTRAL SOUTH CAROLINA PIEDMONT DURING THE
NEXT COUPLE OF HOURS.  AND TRENDS WILL CONTINUE TO BE MONITORED FOR
THE POSSIBILITY OF AN INCREASING THREAT THAT COULD REQUIRE A WW.

DISCUSSION...AN INCREASE IN THUNDERSTORM ACTIVITY IS ONGOING ACROSS
THE HIGHER TERRAIN OF WESTERN SOUTH CAROLINA INTO THE LEE SURFACE
TROUGH ACROSS THE PIEDMONT.  WITH BOUNDARY LAYER CAPE REMAINING
MODERATELY LARGE...AND CAPPING WEAK...POTENTIAL FOR FURTHER
DEVELOPMENT WILL CONTINUE INTO THE 00-02Z TIME FRAME.  SOME
CONSOLIDATION OF ACTIVITY APPEARS POSSIBLE ACROSS THE COLUMBIA AND
SUMTER AREAS...WHERE THE BOUNDARY LAYER REMAINS DEEPLY MIXED WITH
TEMPERATURES IN THE MID/UPPER 90S AND DEW POINTS NEAR 70F.  HEAVY
PRECIPITATION LOADING AND SIZABLE SUB-CLOUD TEMPERATURE DEW POINT
SPREADS MAY SUPPORT ONE OR TWO DOWNBURSTS WITH POTENTIALLY DAMAGING
SURFACE GUSTS.  IF COLD POOLS ARE ABLE TO MERGE...LIGHT
NORTHWESTERLY MID-LEVEL FLOW MAY CONTRIBUTE TO SOUTHWARD PROPAGATION
TOWARD THE COASTAL PLAIN THEREAFTER...BUT WEAK LARGE-SCALE FORCING
FOR UPWARD VERTICAL MOTION AND SLOW BOUNDARY LAYER
COOLING/STABILIZATION MAY LIMIT THE EXTENT OF THE SEVERE THREAT.

..KERR/MEAD.. 07/24/2012

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

ATTN...WFO...ILM...CAE...

LAT...LON   34238180 34118088 34248015 33987980 33578013 33488092
            33728154 33998184 34238180

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 24, 1:12 PM EDT	Mesoscale Discussion	SPC	Cherokee, Chester, Greenville, Lancaster, Laurens, Pickens and 3 more	93 min
Jul 24, 2:36 PM EDT	Severe Thunderstorm Watch	SPC	Cherokee, Chester, York	5 hr
Jul 24, 3:46 PM EDT	Mesoscale Discussion	SPC	Darlington, Dillon, Florence, Horry, Marion, Marlboro and 1 more	89 min
Jul 24, 4:24 PM EDT	Severe Thunderstorm Watch	SPC	Dillon, Horry, Marion, Marlboro	4 hr

Nearby

Mesoscale Discussions in South Carolina, 2012 Every mesoscale discussion in 2012

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.