Alert archive / North Carolina / Mesoscale Discussions in 2016

Mesoscale Discussion 1621

September 2, 201611 counties in North Carolina; Georgetown County, Horry County, Williamsburg County, South Carolina

The Storm Prediction Center issued this mesoscale discussion at Sep 2, 2016, 3:29 PM EDT for 11 counties in North Carolina; Georgetown County, Horry County, Williamsburg County, South Carolina. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued
Sep 2, 2016, 3:29 PM EDT (19:29 UTC)
Expired
Sep 2, 2016, 6:00 PM EDT
In force
3 hr
Issued by
the Storm Prediction Center
Chance of a watch
95%

Counties Brunswick County, NC, Carteret County, NC, Columbus County, NC, Craven County, NC, Dare County, NC, Hyde County, NC, Jones County, NC, New Hanover County, NC, Onslow County, NC, Pamlico County, NC, Pender County, NC, Georgetown County, SC, Horry County, SC, Williamsburg County, SC

The radar

The Wilmington radar (KLTX), 72 km from the middle of the area, began a volume at 19:29 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.

The nearest sounding before it

Newport, NC (KMHX), launched 12:00Z, 7.5 hours before the alert went out and 95 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, Newport, NC at 12:00Z on 2016-09-02Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 403 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Newport, NC at 12:00Z on 2016-09-02The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 33 square meters per square second.193958Sfc1 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
403 J/kg
Mixed-layer CIN
-11 J/kg
Mixed-layer LCL
534 m above ground
0-6 km bulk shear
32 kt
0-1 km storm-relative helicity
33 m²/s²
0-3 km storm-relative helicity
89 m²/s²
Significant tornado parameter
0.1
Supercell composite
0.7

Open this sounding in Storm Lab

The text

As transmitted.

106 
ACUS11 KWNS 021929
SWOMCD
SPC MCD 021929 
NCZ000-SCZ000-022200-

MESOSCALE DISCUSSION 1621
NWS STORM PREDICTION CENTER NORMAN OK
0229 PM CDT FRI SEP 02 2016

AREAS AFFECTED...NRN COASTAL SC...COASTAL NC

CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY 

VALID 021929Z - 022200Z

PROBABILITY OF WATCH ISSUANCE...95 PERCENT

SUMMARY...THE THREAT FOR TORNADOES IS EXPECTED TO CONTINUE ACROSS
COASTAL PORTIONS OF NE SC AND MUCH OF NC.

DISCUSSION...TROPICAL STORM HERMINE IS CURRENTLY CENTERED JUST N OF
SAV AND IS MOVING NEWD AT ABOUT 16 TO 18 KT. GENERALLY NEWD MOTION
IS EXPECTED TO CONTINUE WITH THE CENTER OF THE STORM EXPECTED TO
REACH CNTRL COASTAL SC /APPROX. 45 NNE OF CHS/ BY 00Z. MUCH OF THE
AREA DOWNSTREAM OF THE STORM IS CURRENTLY STABLE WITH SURFACE
TEMPERATURES AND DEWPOINTS IN THE LOW TO MID 70S. HOWEVER...SOME
MODEST INSTABILITY EXISTS IMMEDIATELY NE OF THE CENTER WHERE
TEMPERATURES ARE IN THE UPPER 70S/LOW 80S AND DEWPOINTS ARE IN THE
UPPER 70S. WARM ADVECTION AHEAD OF THE SYSTEM IS EXPECTED TO
DESTABILIZE AREAS ALONG THE COAST DURING THE NEXT SEVERAL HOURS.
STRONG LOW-LEVEL SHEAR PROFILES WILL PERSIST AND THE THREAT FOR
TRANSIENT LOW-LEVEL ROTATION AND A TORNADO OR TWO WILL EXIST ACROSS
COASTAL PORTIONS OF NC AND NE SC. A TORNADO WATCH WILL BE ISSUED
SOON TO COVER THIS THREAT.

..MOSIER/HART.. 09/02/2016

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

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

LAT...LON   33608005 34767821 36027567 35287529 34957588 33927787
            32957942 33608005

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 2, 7:51 AM EDTTornado WatchSPCBrunswick, Columbus8 hr
Sep 2, 12:55 PM EDTMesoscale DiscussionSPCBladen, Brunswick, Columbus, Robeson2 hr
Sep 2, 3:45 PM EDTTornado WatchSPCBrunswick, Carteret, Columbus, Craven, Dare, Hyde and 5 more11 hr
Sep 1, 10:01 PM EDTMesoscale DiscussionSPCBeaufort, Jasper2 hr
Sep 1, 10:47 PM EDTTornado WatchSPCAllendale, Beaufort, Hampton, Jasper9 hr
Sep 2, 12:45 AM EDTMesoscale DiscussionSPCAllendale, Beaufort, Hampton, Jasper4 hr
Sep 2, 5:05 AM EDTMesoscale DiscussionSPCBeaufort, Berkeley, Charleston, Colleton, Dorchester, Georgetown and 5 more2 hr

Nearby

Mesoscale Discussions in North Carolina, 2016Mesoscale Discussions in South Carolina, 2016Every mesoscale discussion in 2016

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.