Alert archive / South Carolina / Mesoscale Discussions in 2012

Mesoscale Discussion 604

April 27, 201218 counties in Georgia; 21 counties in South Carolina

The Storm Prediction Center issued this mesoscale discussion at Apr 27, 2012, 11:34 AM EDT for 18 counties in Georgia; 21 counties in South Carolina. It was in force for 56 min.

The area

The outline as issued.

The facts

Issued
Apr 27, 2012, 11:34 AM EDT (15:34 UTC)
Expired
Apr 27, 2012, 12:30 PM EDT
In force
56 min
Issued by
the Storm Prediction Center
All 39 counties

Barrow County, GA, Clarke County, GA, Columbia County, GA, Elbert County, GA, Glascock County, GA, Greene County, GA, Jackson County, GA, Lincoln County, GA, Madison County, GA, McDuffie County, GA, Morgan County, GA, Oconee County, GA, Oglethorpe County, GA, Richmond County, GA, Taliaferro County, GA, Walton County, GA, Warren County, GA, Wilkes County, GA, Abbeville County, SC, Aiken County, SC, Allendale County, SC, Bamberg County, SC, Barnwell County, SC, Berkeley County, SC, Calhoun County, SC, Charleston County, SC, Clarendon County, SC, Colleton County, SC, Dorchester County, SC, Edgefield County, SC, Georgetown County, SC, Greenwood County, SC, Lexington County, SC, McCormick County, SC, Orangeburg County, SC, Richland County, SC, Saluda County, SC, Sumter County, SC, Williamsburg County, SC

The radar

The Columbia radar (KCAE), 67 km from the middle of the area, began a volume at 15:38 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, 3.6 hours before the alert went out and 174 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, Charleston AFB, SC at 12:00Z on 2012-04-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 75 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, Charleston AFB, SC at 12:00Z on 2012-04-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 120 square meters per square second.19395878Sfc1 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
75 J/kg
Mixed-layer CIN
-239 J/kg
Mixed-layer LCL
1255 m above ground
0-6 km bulk shear
33 kt
0-1 km storm-relative helicity
120 m²/s²
0-3 km storm-relative helicity
179 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.

750 
ACUS11 KWNS 271535
SWOMCD
SPC MCD 271534
SCZ000-GAZ000-271630-

MESOSCALE DISCUSSION 0604
NWS STORM PREDICTION CENTER NORMAN OK
1034 AM CDT FRI APR 27 2012

AREAS AFFECTED...CNTRL/SRN SC...NERN GA

CONCERNING...OUTLOOK UPGRADE

VALID 271534Z - 271630Z

THERE WILL BE A CATEGORICAL UPGRADE TO SLIGHT RISK IN THE UPCOMING
1630Z DAY 1 CONVECTIVE OUTLOOK. CONFIDENCE HAS INCREASED REGARDING A
GREATER THREAT FOR TSTMS FORMING THIS AFTERNOON WITHIN A
QUASI-STATIONARY FRONTAL ZONE...POTENTIALLY PRODUCING SEVERE HAIL
AND DAMAGING WINDS.

..GRAMS.. 04/27/2012

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

ATTN...WFO...ILM...CHS...CAE...GSP...FFC...

LAT...LON   32598002 33328307 33808404 34248397 34338376 34358237
            33837875 33137923 32598002

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 27, 2:42 PM EDTMesoscale DiscussionSPCColumbia, Elbert, Hart, Lincoln, Richmond, Wilkes2 hr
Apr 27, 5:36 PM EDTSevere Thunderstorm WatchSPCColumbia, Elbert, Franklin, Hart, Lincoln, McDuffie and 2 more6 hr

Nearby

Mesoscale Discussions in South Carolina, 2012Mesoscale Discussions in Georgia, 2012Every 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.