Alert archive / South Carolina / Mesoscale Discussions in 2012

Mesoscale Discussion 871

May 22, 2012Chatham County, Georgia; 8 counties in South Carolina

The Storm Prediction Center issued this mesoscale discussion at May 22, 2012, 6:58 PM EDT for Chatham County, Georgia; 8 counties in South Carolina. It was in force for 62 min.

The area

The outline as issued.

The facts

Issued: May 22, 2012, 6:58 PM EDT (22:58 UTC)
Expired: May 22, 2012, 8:00 PM EDT
In force: 62 min
Issued by: the Storm Prediction Center

Counties Chatham County, GA, Beaufort County, SC, Berkeley County, SC, Charleston County, SC, Clarendon County, SC, Colleton County, SC, Dorchester County, SC, Georgetown County, SC, Williamsburg County, SC

The radar

The Charleston,SC radar (KCLX), 81 km from the middle of the area, began a volume at 23:01 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, 11.0 hours before the alert went out and 22 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: 831 J/kg
Mixed-layer CIN: -73 J/kg
Mixed-layer LCL: 1209 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: 34 m²/s²
0-3 km storm-relative helicity: 49 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.

182 
ACUS11 KWNS 222258
SWOMCD
SPC MCD 222258 
SCZ000-GAZ000-230000-

MESOSCALE DISCUSSION 0871
NWS STORM PREDICTION CENTER NORMAN OK
0558 PM CDT TUE MAY 22 2012

AREAS AFFECTED...FAR SERN GA...SRN SC

CONCERNING...SEVERE THUNDERSTORM WATCH 288...

VALID 222258Z - 230000Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 288
CONTINUES.

SUMMARY...THREAT FOR DMGG WIND/HAIL NOW PRIMARILY CONFINED TO SRN
SC...WHILE THE AIR MASS HAS STABILIZED OVER MOST OF FAR SERN GA WITH
A SUBSEQUENT REDUCED SVR THREAT. WW CAN BE CLEARED BY WFO CHS FROM
SW-NE IN WAKE OF CONVECTION.

DISCUSSION...SFC OBS SHOW WINDS VEERING IN WAKE OF ENEWD MOVING
CONVECTION ALONG PRE-FRONTAL WEAK SFC TROUGH. AIR MASS APPEARS TO
HAVE STABILIZED OVER MOST OF FAR SERN GA AND INTO FAR SWRN SC...WITH
PRIMARY THREAT NOW FOCUSED NE OF BEAUFORT/HAMPTON COUNTIES SC.
POCKETS OF ENHANCED INSTABILITY /MLCAPE VALUES NEAR 1500 J/KG PER
RECENT OBJECTIVE ANALYSIS DATA/ WHERE TEMPERATURES HAVE REACHED THE
LOWER 80S SHOULD SUPPORT CONTINUED DEVELOPMENT OF MULTICELL CLUSTERS
CAPABLE OF PRODUCING ISOLATED DMGG WIND/HAIL. THE THREAT COULD
EXTEND TO THE N/E OF THE ONGOING WW AREA FOR THE NEXT 1-2 HRS...BUT
WITH THE ONSET OF DIURNAL COOLING...A GENERAL DOWNTREND IN TSTM
INTENSITY IS EXPECTED TO OCCUR AS WATCH EXPIRATION TIME OF 01Z
APPROACHES. THUS...AN ADDITIONAL WW IS NOT ANTICIPATED BEYOND THIS
TIME.

..ROGERS.. 05/22/2012

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

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

LAT...LON   32757965 32337997 31948061 31808097 31768115 32038124
            32438095 32938104 33178107 33668050 33828028 33977992
            33947949 33697911 33427909 33097930 32757965

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 22, 1:46 PM EDT	Mesoscale Discussion	SPC	Appling, Atkinson, Bacon, Brantley, Bulloch, Burke and 38 more	59 min
May 22, 3:32 PM EDT	Severe Thunderstorm Watch	SPC	Bryan, Bulloch, Candler, Chatham, Effingham, Evans and 6 more	5 hr
May 22, 4:43 PM EDT	Severe Thunderstorm Watch	SPC	Baker, Ben Hill, Berrien, Brooks, Calhoun, Colquitt and 18 more	4 hr
May 22, 2:29 PM EDT	Mesoscale Discussion	SPC	Dillon, Georgetown, Horry, Marion, Marlboro, Williamsburg	91 min

Nearby

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