Alert archive / South Carolina / Mesoscale Discussions in 2003

Mesoscale Discussion 484

April 18, 20035 counties in Georgia; 7 counties in South Carolina

The Storm Prediction Center issued this mesoscale discussion at Apr 18, 2003, 1:20 PM EDT for 5 counties in Georgia; 7 counties in South Carolina. It was in force for 115 min.

The area

The outline as issued.

The facts

Issued: Apr 18, 2003, 1:20 PM EDT (17:20 UTC)
Expired: Apr 18, 2003, 3:15 PM EDT
In force: 115 min
Issued by: the Storm Prediction Center

Counties Bulloch County, GA, Candler County, GA, Emanuel County, GA, Jenkins County, GA, Screven County, GA, Allendale County, SC, Bamberg County, SC, Barnwell County, SC, Colleton County, SC, Dorchester County, SC, Hampton County, SC, Orangeburg County, SC

The radar

The Charleston,SC radar (KCLX), 52 km from the middle of the area, began a volume at 17:22 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, 5.3 hours before the alert went out and 133 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: 379 J/kg
Mixed-layer CIN: -11 J/kg
Mixed-layer LCL: 679 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 53 m²/s²
0-3 km storm-relative helicity: 71 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.

217 
ACUS11 KWNS 181721
SWOMCD
SPC MCD 181720 
SCZ000-GAZ000-181915-

MESOSCALE DISCUSSION 0484
NWS STORM PREDICTION CENTER NORMAN OK
1220 PM CDT FRI APR 18 2003

AREAS AFFECTED...SRN SC...PARTS OF ERN GA

CONCERNING...CONVECTIVE TRENDS 

VALID 181720Z - 181915Z

ISOLATED STRONG STORMS ARE POSSIBLE THIS AFTERNOON.

COLD FRONT CONTINUES TO SURGE SOUTHWESTWARD IN THE IMMEDIATE LEE
OF THE SOUTHERN APPALACHIANS...INTO NORTHWEST GEORGIA...WHILE
ADVANCING MORE SLOWLY SOUTHWARD ACROSS THE COASTAL PLAINS OF
SOUTH CAROLINA.  MOIST SOUTHEASTERLY ACROSS THE SOUTH ATLANTIC
COAST...AND DAYTIME HEATING...ARE CONTRIBUTING TO MODERATELY
UNSTABLE ENVIRONMENT ALONG AND SOUTH OF FRONTAL ZONE...WITH
LATEST OBJECTIVE GUIDANCE SUGGESTING MOST UNSTABLE CAPE IN EXCESS
OF 1000 J/KG.  DESTABILIZATION AND WEAK LOW-LEVEL WARM ADVECTION
REGIME IS SUPPORTING CONVECTIVE DEVELOPMENT IN WARM SECTOR SOUTH
OF COLUMBIA...AND ALONG SURFACE FRONT NEAR/WEST NORTHWEST OF
COLUMBIA.  

WHILE LOW-LEVEL FORCING WILL REMAIN SUFFICIENT FOR DEEP
CONVECTIVE DEVELOPMENT ALONG FRONT AS IT PROGRESSES SOUTHWARD
INTO PARTS OF EAST CENTRAL/SOUTHEAST GEORGIA...MID-LEVEL
SUBSIDENCE WEST OF UPPER TROUGH AXIS SHIFTING INTO THE MID
ATLANTIC COAST MAY SUPPRESS MORE EXTENSIVE ACTIVITY. 
HOWEVER...AN ISOLATED STRONG STORM OR TWO APPEARS POSSIBLE.  IF
THIS OCCURS...WEAK BUT VEERING WIND PROFILES WITH HEIGHT BENEATH
NORTHWESTERLY MID-LEVEL FLOW MAY SUPPORT UPDRAFT ROTATION...WHICH
WOULD ENHANCE POTENTIAL FOR SOME HAIL/GUSTY WINDS.

..KERR.. 04/18/2003

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

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

32958238 33128176 33458148 33668118 33668069 33527986
32908030 32738081 32258154 32188222 32538246

Nearby

Mesoscale Discussions in South Carolina, 2003 Mesoscale Discussions in Georgia, 2003 Every mesoscale discussion in 2003

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.