Alert archive / South Carolina / Mesoscale Discussions in 2018

Mesoscale Discussion 2

January 3, 2018Brunswick County, North Carolina; Beaufort County, Charleston County, Georgetown County, South Carolina

The Storm Prediction Center issued this mesoscale discussion at Jan 3, 2018, 11:09 AM EST for Brunswick County, North Carolina; Beaufort County, Charleston County, Georgetown County, South Carolina. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued: Jan 3, 2018, 11:09 AM EST (16:09 UTC)
Expired: Jan 3, 2018, 3:15 PM EST
In force: 4 hr
Issued by: the Storm Prediction Center

Counties Brunswick County, NC, Beaufort County, SC, Charleston County, SC, Georgetown County, SC

The radar

The Charleston,SC radar (KCLX), 142 km from the middle of the area, began a volume at 16:12 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, 4.2 hours before the alert went out and 42 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1142 m above ground
0-6 km bulk shear: 57 kt
0-1 km storm-relative helicity: 163 m²/s²
0-3 km storm-relative helicity: 144 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

609 
ACUS11 KWNS 031609
SWOMCD
SPC MCD 031609 
NCZ000-SCZ000-032015-

Mesoscale Discussion 0002
NWS Storm Prediction Center Norman OK
1009 AM CST Wed Jan 03 2018

Areas affected...Coastal Carolina

Concerning...Freezing rain 

Valid 031609Z - 032015Z

SUMMARY...Freezing rain will spread/develop northeast along the
South Carolina coast into southern North Carolina into the early
afternoon.  Freezing rain rates on the order of .10" per hour will
be common.

DISCUSSION...Surface low is beginning to deepen off the FL coast and
will lift north-northeast during the day in response to strong
mid-level short-wave trough. Precip shield is expanding ahead of
this feature across southeast GA and southern SC within intensifying
warm advection corridor. Current surface observations support the
strengthening warm advection and freezing rain is the predominant
precip type along the immediate SC coast. 12z sounding from CHS
exhibits a significant warm layer between 950mb-800mb and the latest
3km NAM guidance suggests further warming is possible around 900mb
through 16z-17z at CHS before the column cools enough for a
transition to ice pellets and snow later this afternoon. While ice
pellets and snow will be noted a few counties inland, it appears the
heaviest precipitation over the next 2-4hr will be near the coast
and primarily freezing rain.

..Darrow.. 01/03/2018

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

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

LAT...LON   32548100 33847888 34077818 33717804 32068070 32548100

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jan 3, 4:13 PM EST	Mesoscale Discussion	SPC	Beaufort, Bertie, Camden, Chowan, Currituck, Duplin and 16 more	4 hr

Nearby

Mesoscale Discussions in South Carolina, 2018 Mesoscale Discussions in North Carolina, 2018 Every mesoscale discussion in 2018

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.