Alert archive / South Carolina / Mesoscale Discussions in 2017

Mesoscale Discussion 385

March 31, 20177 counties in North Carolina; 23 counties in South Carolina

The Storm Prediction Center issued this mesoscale discussion at Mar 31, 2017, 12:53 AM EDT for 7 counties in North Carolina; 23 counties in South Carolina. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Mar 31, 2017, 12:53 AM EDT (04:53 UTC)
Expired
Mar 31, 2017, 3:00 AM EDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
40%
All 30 counties

Bladen County, NC, Brunswick County, NC, Columbus County, NC, New Hanover County, NC, Pender County, NC, Robeson County, NC, Scotland County, NC, Bamberg County, SC, Berkeley County, SC, Calhoun County, SC, Charleston County, SC, Chesterfield County, SC, Clarendon County, SC, Darlington County, SC, Dillon County, SC, Dorchester County, SC, Fairfield County, SC, Florence County, SC, Georgetown County, SC, Horry County, SC, Kershaw County, SC, Lee County, SC, Lexington County, SC, Marion County, SC, Marlboro County, SC, Orangeburg County, SC, Richland County, SC, Saluda County, SC, Sumter County, SC, Williamsburg County, SC

The radar

The Wilmington radar (KLTX), 123 km from the middle of the area, began a volume at 04:54 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 00:00Z, 4.9 hours before the alert went out and 109 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 00:00Z on 2017-03-31Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 10 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 00:00Z on 2017-03-31The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 119 square meters per square second.1939587897Sfc1 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
10 J/kg
Mixed-layer CIN
-124 J/kg
Mixed-layer LCL
966 m above ground
0-6 km bulk shear
32 kt
0-1 km storm-relative helicity
119 m²/s²
0-3 km storm-relative helicity
201 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

333 
ACUS11 KWNS 310453
SWOMCD
SPC MCD 310453 
NCZ000-SCZ000-310700-

Mesoscale Discussion 0385
NWS Storm Prediction Center Norman OK
1153 PM CDT Thu Mar 30 2017

Areas affected...Portions of South Carolina and far southern North
Carolina

Concerning...Severe potential...Watch possible 

Valid 310453Z - 310700Z

Probability of Watch Issuance...40 percent

SUMMARY...Thunderstorms will gradually organize across coastal South
Carolina over the next 2-3 hours, with a potential threat for a few
damaging-wind gusts and perhaps a tornado or two.

DISCUSSION...As large-scale ascent related to the main
upper/mid-level trough overspreads the southeast U.S. coast tonight,
thunderstorms should increase in coverage over parts of
central/coastal South Carolina. Over the next several hours, a weak
frontal boundary, currently stretching from the SC/GA border
east/southeastward to the central SC coast, will slowly advance
northeast in tandem with a strengthening low-level mass response. To
the south of this boundary, modest surface moistening (e.g., dew
points rising into the mid/upper 60s) across eastern SC will combine
with cooling aloft to produce MLCAPE values upwards of 500-1000
J/kg. In addition, as the trough approaches from the west,
south/southwesterly low/mid-level flow will strengthen and veer with
height, enhancing effective storm-relative helicity, especially in
the vicinity of the front/confluence boundary. Considering the
relatively moist and weakly unstable nature of the environment, more
vigorous/organized convection late tonight may support spotty
damaging winds and/or a couple tornadoes. While uncertainty remains
with regards to the timing and overall coverage of stronger
convection, enough potential exists that trends will be monitored
for possible watch issuance within the next 2-3 hours.

..Picca/Edwards.. 03/31/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...MHX...RAH...ILM...CHS...CAE...GSP...

LAT...LON   32897914 32697982 33008077 33678181 33918195 34368129
            34938021 35027931 34807824 34357760 33747778 32897914

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Mar 31, 9:57 AM EDTMesoscale DiscussionSPCBeaufort, Bertie, Bladen, Brunswick, Camden, Carteret and 31 more2 hr
Mar 31, 2:08 PM EDTMesoscale DiscussionSPCAlamance, Caswell, Davidson, Davie, Durham, Forsyth and 13 more67 min
Mar 31, 3:54 PM EDTTornado WatchSPCBertie, Camden, Chowan, Currituck, Gates, Granville and 8 more6 hr
Mar 31, 6:11 PM EDTMesoscale DiscussionSPCBertie, Camden, Chowan, Currituck, Gates, Hertford and 3 more94 min

Nearby

Mesoscale Discussions in South Carolina, 2017Mesoscale Discussions in North Carolina, 2017Every mesoscale discussion in 2017

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.