Alert archive / North Carolina / Mesoscale Discussions in 2011

Mesoscale Discussion 993

May 27, 201133 counties in North Carolina; 12 counties in South Carolina; 7 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at May 27, 2011, 11:26 AM EDT for 33 counties in North Carolina; 12 counties in South Carolina; 7 counties in Virginia. It was in force for 94 min.

The area

The outline as issued.

The facts

Issued: May 27, 2011, 11:26 AM EDT (15:26 UTC)
Expired: May 27, 2011, 1:00 PM EDT
In force: 94 min
Issued by: the Storm Prediction Center

All 52 counties

Alamance County, NC, Anson County, NC, Caswell County, NC, Chatham County, NC, Cumberland County, NC, Durham County, NC, Edgecombe County, NC, Franklin County, NC, Granville County, NC, Greene County, NC, Halifax County, NC, Harnett County, NC, Hoke County, NC, Johnston County, NC, Lee County, NC, Montgomery County, NC, Moore County, NC, Nash County, NC, Northampton County, NC, Orange County, NC, Person County, NC, Randolph County, NC, Richmond County, NC, Robeson County, NC, Sampson County, NC, Scotland County, NC, Stanly County, NC, Union County, NC, Vance County, NC, Wake County, NC, Warren County, NC, Wayne County, NC, Wilson County, NC, Chesterfield County, SC, Clarendon County, SC, Darlington County, SC, Dillon County, SC, Florence County, SC, Kershaw County, SC, Lancaster County, SC, Lee County, SC, Marion County, SC, Marlboro County, SC, Sumter County, SC, Williamsburg County, SC, Brunswick County, VA, City of Emporia, VA, Dinwiddie County, VA, Greensville County, VA, Lunenburg County, VA, Mecklenburg County, VA, Nottoway County, VA

The radar

The Raleigh/Durham radar (KRAX), 44 km from the middle of the area, began a volume at 15:26 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 387May 27, 12:10 PM EDT

The nearest sounding before it

Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 3.4 hours before the alert went out and 101 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: 31 J/kg
Mixed-layer CIN: -292 J/kg
Mixed-layer LCL: 831 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 93 m²/s²
0-3 km storm-relative helicity: 106 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.

982 
ACUS11 KWNS 271527
SWOMCD
SPC MCD 271526
NCZ000-VAZ000-SCZ000-271700-

MESOSCALE DISCUSSION 0993
NWS STORM PREDICTION CENTER NORMAN OK
1026 AM CDT FRI MAY 27 2011

AREAS AFFECTED...SRN SC...CNTRL NC...SRN VA

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 271526Z - 271700Z

A SEVERE THREAT IS EXPECTED TO DEVELOP OVER THE NEXT FEW HOURS
ACROSS NE SC...CNTRL NC AND SRN VA AS CELLS GRADUALLY INTENSIFY.
WIND DAMAGE AND ISOLATED LARGE HAIL SHOULD BE THE PRIMARY THREATS.
WW ISSUANCE APPEARS LIKELY BY EARLY AFTERNOON ACROSS THE REGION.

SFC ANALYSIS SHOWS AN AXIS OF ABUNDANT LOW-LEVEL MOISTURE WITH SFC
DEWPOINTS IN THE MID TO UPPER 60S F FROM SC NNEWD INTO ERN VA. SFC
TEMPS ALONG THIS AXIS WILL CONTINUE TO WARM REACHING THE MID TO
UPPER 80S F RESULTING IN STRONG INSTABILITY ALONG THE MOIST AXIS.
FORECAST SOUNDINGS SUGGEST THAT SBCAPE VALUES WILL REACH THE 2000 TO
3000 J/KG RANGE BY EARLY AFTERNOON. AT THE MID TO UPPER LEVELS...JET
MAX IS ANALYZED FROM WRN SC NNEWD ACROSS CNTRL AND WRN NC WHICH WILL
CREATE MODERATE DEEP LAYER SHEAR PROFILE FAVORABLE FOR ORGANIZED
STORMS. STEEPENING LOW-LEVEL LAPSE RATES AND THE STRONG INSTABILITY
WILL SUPPORT A THREAT FOR DAMAGING WIND GUSTS AS THE CELLS GRADUALLY
INTENSIFY OVER THE NEXT FEW HOURS. IN ADDITION...MID-LEVEL LAPSE
RATES ARE ALSO STEEP ESPECIALLY OVER CNTRL NC AND SRN VA SUGGESTING
A THREAT FOR LARGE HAIL WILL ALSO BE POSSIBLE.

..BROYLES.. 05/27/2011

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

ATTN...WFO...AKQ...MHX...RAH...ILM...RNK...CAE...GSP...

LAT...LON   37027853 36697901 35598025 34808077 34188089 33868076
            33487980 33987911 34817834 35947713 36567699 37077739
            37217797 37027853

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 26, 11:22 PM EDT	Mesoscale Discussion	SPC	Caswell, Forsyth, Rockingham, Stokes, Yadkin	113 min
May 27, 12:06 PM EDT	Severe Thunderstorm Watch	SPC	Alamance, Anson, Cabarrus, Caswell, Chatham, Cumberland and 34 more	7 hr
May 27, 3:29 PM EDT	Mesoscale Discussion	SPC	Alamance, Anson, Bertie, Bladen, Caswell, Chatham and 37 more	91 min
May 27, 6:24 PM EDT	Mesoscale Discussion	SPC	Alamance, Anson, Bladen, Caswell, Chatham, Columbus and 29 more	66 min
May 27, 12:24 PM EDT	Mesoscale Discussion	SPC	Arlington, Caroline, Clarke, Culpeper, Fairfax, Fauquier and 24 more	96 min
May 27, 12:57 PM EDT	Severe Thunderstorm Watch	SPC	Albemarle, Arlington, Augusta, Clarke, Culpeper, Fairfax and 28 more	9 hr
May 27, 6:14 PM EDT	Mesoscale Discussion	SPC	Arlington, Clarke, Culpeper, Fairfax, Fauquier, Frederick and 12 more	2 hr

Nearby

Mesoscale Discussions in North Carolina, 2011 Mesoscale Discussions in South Carolina, 2011 Mesoscale Discussions in Virginia, 2011 Every mesoscale discussion in 2011

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.