Alert archive / North Carolina / Mesoscale Discussions in 2012

Mesoscale Discussion 1871

September 3, 201225 counties in North Carolina; 22 counties in South Carolina; 5 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Sep 3, 2012, 1:52 PM EDT for 25 counties in North Carolina; 22 counties in South Carolina; 5 counties in Virginia. It was in force for 53 min.

The area

The outline as issued.

The facts

Issued
Sep 3, 2012, 1:52 PM EDT (17:52 UTC)
Expired
Sep 3, 2012, 2:45 PM EDT
In force
53 min
Issued by
the Storm Prediction Center
Chance of a watch
20%
All 52 counties

Alamance County, NC, Anson County, NC, Cabarrus County, NC, Caswell County, NC, Chatham County, NC, Cumberland County, NC, Davidson County, NC, Davie County, NC, Forsyth County, NC, Guilford County, NC, Harnett County, NC, Hoke County, NC, Lee County, NC, Montgomery County, NC, Moore County, NC, Orange County, NC, Randolph County, NC, Richmond County, NC, Robeson County, NC, Rockingham County, NC, Rowan County, NC, Scotland County, NC, Stanly County, NC, Stokes County, NC, Union County, NC, Allendale County, SC, Bamberg County, SC, Berkeley County, SC, Calhoun County, SC, Chesterfield County, SC, Clarendon County, SC, Colleton County, SC, Darlington County, SC, Dillon County, SC, Dorchester County, SC, Florence County, SC, Hampton County, SC, Jasper County, SC, Kershaw County, SC, Lancaster County, SC, Lee County, SC, Marion County, SC, Marlboro County, SC, Orangeburg County, SC, Richland County, SC, Sumter County, SC, Williamsburg County, SC, City of Danville, VA, City of Martinsville, VA, Franklin County, VA, Henry County, VA, Patrick County, VA

The radar

The Columbia radar (KCAE), 107 km from the middle of the area, began a volume at 17:52 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

Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 5.9 hours before the alert went out and 173 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, Greensboro/Hi Pt, NC at 12:00Z on 2012-09-03Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 576 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, Greensboro/Hi Pt, NC at 12:00Z on 2012-09-03The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 57 square meters per square second.1939Sfc1 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
576 J/kg
Mixed-layer CIN
-44 J/kg
Mixed-layer LCL
801 m above ground
0-6 km bulk shear
17 kt
0-1 km storm-relative helicity
57 m²/s²
0-3 km storm-relative helicity
44 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.

105 
ACUS11 KWNS 031753
SWOMCD
SPC MCD 031752
NCZ000-SCZ000-VAZ000-031845-

MESOSCALE DISCUSSION 1871
NWS STORM PREDICTION CENTER NORMAN OK
1252 PM CDT MON SEP 03 2012

AREAS AFFECTED...CNTRL/ERN NC/SC AND S CNTRL VA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 031752Z - 031845Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...ISOLD DMGG WINDS AND HEAVY RAINFALL WILL OCCUR ACROSS THE
COASTAL PLAINS THIS AFTERNOON. A WW IS NOT CURRENTLY ANTICIPATED.

DISCUSSION...THUNDERSTORMS ARE BEGINNING TO INCREASE IN COVERAGE
ALONG A BROAD AREA OF SURFACE CONFLUENCE EXTENDING ROUGHLY FROM
APALACHEE BAY NNEWD TO ROANOKE VA. WEAKLY DIFFLUENT FLOW ALOFT AND
HIGH MOISTURE CONTENT WILL LIKELY ALLOW A REGENERATION OF STORMS
ALONG OUTFLOW BOUNDARIES OF QUICKLY COLLAPSING STORMS. WEAK DEEP
LAYER WINDS WILL GENERALLY LIMIT ORGANIZATION...WITH
SHORT-LIVED...CHAOTIC CLUSTERS AND PULSE-STORMS OCCASIONALLY CAPABLE
OF DMGG WINDS GIVEN A STRONGER CORE.

..HURLBUT/CORFIDI.. 09/03/2012

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

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

LAT...LON   32848142 34348084 35278073 36738060 37097984 36487910
            35767877 34887862 33467967 32648044 32228095 32848142

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 2, 9:43 PM EDTMesoscale DiscussionSPCCherokee, Graham62 min

Nearby

Mesoscale Discussions in North Carolina, 2012Mesoscale Discussions in South Carolina, 2012Mesoscale Discussions in Virginia, 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.