Alert archive / Virginia / Mesoscale Discussions in 2016
Mesoscale Discussion 1739
The Storm Prediction Center issued this mesoscale discussion at Sep 28, 2016, 2:44 PM EDT for 30 counties in North Carolina; 43 counties in Virginia. It was in force for 91 min.
The area
The outline as issued.
The facts
- Issued
- Sep 28, 2016, 2:44 PM EDT (18:44 UTC)
- Expired
- Sep 28, 2016, 4:15 PM EDT
- In force
- 91 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 80%
All 73 counties
Alamance County, NC, Caswell County, NC, Chatham County, NC, Davidson County, NC, Davie County, NC, Durham County, NC, Edgecombe County, NC, Forsyth County, NC, Franklin County, NC, Gates County, NC, Granville County, NC, Guilford County, NC, Halifax County, NC, Harnett County, NC, Hertford County, NC, Iredell 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, Rockingham County, NC, Rowan County, NC, Vance County, NC, Wake County, NC, Warren County, NC, Amelia County, VA, Appomattox County, VA, Brunswick County, VA, Campbell County, VA, Charles City County, VA, Charlotte County, VA, Chesterfield County, VA, City of Colonial Heights, VA, City of Danville, VA, City of Emporia, VA, City of Franklin, VA, City of Hampton, VA, City of Hopewell, VA, City of Newport News, VA, City of Petersburg, VA, City of Poquoson, VA, City of Richmond, VA, City of Suffolk, VA, City of Williamsburg, VA, Cumberland County, VA, Dinwiddie County, VA, Gloucester County, VA, Goochland County, VA, Greensville County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Isle of Wight County, VA, James City County, VA, King and Queen County, VA, King William County, VA, Lunenburg County, VA, Mecklenburg County, VA, New Kent County, VA, Nottoway County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Southampton County, VA, Surry County, VA, Sussex County, VA, York County, VA
The radar
The Raleigh/Durham radar (KRAX), 100 km from the middle of the area, began a volume at 18:43 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
Roanoke, VA (KRNK), launched 12:00Z, 6.7 hours before the alert went out and 116 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 2684 m above ground
- 0-6 km bulk shear
- 16 kt
- 0-1 km storm-relative helicity
- 13 m²/s²
- 0-3 km storm-relative helicity
- 19 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
812
ACUS11 KWNS 281845
SWOMCD
SPC MCD 281844
VAZ000-NCZ000-282015-
MESOSCALE DISCUSSION 1739
NWS STORM PREDICTION CENTER NORMAN OK
0144 PM CDT WED SEP 28 2016
AREAS AFFECTED...PORTIONS OF SRN/ERN VA AND NC
CONCERNING...SEVERE POTENTIAL...WATCH LIKELY
VALID 281844Z - 282015Z
PROBABILITY OF WATCH ISSUANCE...80 PERCENT
SUMMARY...THE SEVERE THREAT...INCLUDING A RISK FOR STRONG TO LOCALLY
DAMAGING WINDS AND ISOLATED TORNADOES...IS INCREASING. WW ISSUANCE
IS LIKELY.
DISCUSSION...RECENT VISIBLE SATELLITE AND RADAR IMAGERY INDICATE AN
INCREASE IN CONVECTION ACROSS THE MCD AREA AS FILTERED DIURNAL
HEATING HAS OCCURRED ALONG/S OF A FRONTAL BOUNDARY EXTENDING FROM
WRN NC NNEWD INTO PARTS OF SRN/ERN VA. WHILE SLY LOW-LEVEL WINDS ARE
RELATIVELY WEAK ATTM PER 18Z SFC OBSERVATIONS AND AREA VWPS...THEY
ARE FORECAST TO STRENGTHEN SOMEWHAT THROUGH THE REMAINDER OF THE
AFTERNOON INTO THIS EVENING AS AN UPPER LOW OVER IND CONTINUES
MOVING SWD. WINDS DO STRENGTHEN/VEER WITH HEIGHT AT MID-LEVELS...
WITH LATEST RAP MESOANALYSIS SUGGESTING EFFECTIVE BULK SHEAR VALUES
GENERALLY RANGE FROM 35-45 KT. A VERY MOIST LOW-LEVEL AIRMASS ALONG
WITH SOME SFC HEATING HAS ALLOWED MLCAPE TO INCREASE BETWEEN
1000-1500 J/KG. THIS COMBINATION OF INSTABILITY AND SHEAR WILL BE
SUPPORTIVE OF SOME SUPERCELL STRUCTURES AND PERHAPS BOWING
SEGMENTS...WITH STRONG TO LOCALLY DAMAGING WINDS AND ISOLATED
TORNADOES POSSIBLE.
..GLEASON/HART.. 09/28/2016
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...AKQ...RAH...RNK...GSP...
LAT...LON 35758112 37157921 37837801 37827709 37497631 37067627
36527656 35097895 35187998 35758112SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 28, 12:09 PM EDT | Mesoscale Discussion | SPC | Caswell, Durham, Franklin, Granville, Halifax, Nash and 5 more | 66 min |
| Sep 28, 3:13 PM EDT | Severe Thunderstorm Watch | SPC | Alamance, Alexander, Alleghany, Anson, Ashe, Avery and 52 more | 7 hr |
| Sep 28, 4:41 PM EDT | Mesoscale Discussion | SPC | Alamance, Alexander, Alleghany, Anson, Ashe, Avery and 56 more | 2 hr |
| Sep 28, 7:02 PM EDT | Mesoscale Discussion | SPC | Alamance, Alexander, Alleghany, Ashe, Cabarrus, Caldwell and 32 more | 88 min |
Nearby
Mesoscale Discussions in Virginia, 2016Mesoscale Discussions in North 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.