Alert archive / Virginia / Mesoscale Discussions in 2011
Mesoscale Discussion 668
The Storm Prediction Center issued this mesoscale discussion at Apr 28, 2011, 8:27 PM EDT for 4 counties in Maryland; 9 counties in North Carolina; 21 counties in Virginia. It was in force for 33 min.
The area
The outline as issued.
The facts
- Issued
- Apr 28, 2011, 8:27 PM EDT (00:27 UTC)
- Expired
- Apr 28, 2011, 9:00 PM EDT
- In force
- 33 min
- Issued by
- the Storm Prediction Center
All 34 counties
Saint Mary's County, MD, Somerset County, MD, Wicomico County, MD, Worcester County, MD, Camden County, NC, Carteret County, NC, Currituck County, NC, Dare County, NC, Hyde County, NC, Pamlico County, NC, Pasquotank County, NC, Perquimans County, NC, Tyrrell County, NC, Accomack County, VA, Charles City County, VA, City of Chesapeake, VA, City of Hampton, VA, City of Newport News, VA, City of Norfolk, VA, City of Poquoson, VA, City of Portsmouth, VA, City of Suffolk, VA, City of Virginia Beach, VA, City of Williamsburg, VA, Gloucester County, VA, Isle of Wight County, VA, James City County, VA, Lancaster County, VA, Mathews County, VA, Middlesex County, VA, Northampton County, VA, Northumberland County, VA, Surry County, VA, York County, VA
The radar
The Norfolk radar (KAKQ), 114 km from the middle of the area, began a volume at 00:27 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
Newport, NC (KMHX), launched 00:00Z, 0.5 hours before the alert went out and 167 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
- 2654 J/kg
- Mixed-layer CIN
- -5 J/kg
- Mixed-layer LCL
- 459 m above ground
- 0-6 km bulk shear
- 49 kt
- 0-1 km storm-relative helicity
- 449 m²/s²
- 0-3 km storm-relative helicity
- 435 m²/s²
- Significant tornado parameter
- 5.6
- Supercell composite
- 32.4
The text
As transmitted, in the capitals the NWS used until 2016.
774
ACUS11 KWNS 290027
SWOMCD
SPC MCD 290027
MDZ000-VAZ000-NCZ000-290100-
MESOSCALE DISCUSSION 0668
NWS STORM PREDICTION CENTER NORMAN OK
0727 PM CDT THU APR 28 2011
AREAS AFFECTED...SERN VA...SRN DELMARVA PENINSULA...AND ERN NC
CONCERNING...TORNADO WATCH 255...
VALID 290027Z - 290100Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 255 CONTINUES.
SEVERE WEATHER THREAT WILL CONTINUE TO AFFECT THE ERN PARTS OF WW
255 BEYOND THE EXPIRATION TIME OF 01Z. LIMITED SPATIAL AND TEMPORAL
THREAT SHOULD PRECLUDE THE NEED FOR A NEW WATCH. HOWEVER...LOCAL
WFO EXTENSION OF THIS WATCH IS POSSIBLE DUE TO A CONTINUED SEVERE
WEATHER THREAT THROUGH 02-03Z.
THE AIR MASS ACROSS WW 255 REMAINS SUPPORTIVE FOR SEVERE STORMS
/MODERATE INSTABILITY AND EFFECTIVE BULK SHEAR 45-60 KT/...
INCLUDING A TORNADO THREAT PER EFFECTIVE SRH OF 200-300 M2/S2.
EARLY EVENING RADAR TRENDS SUGGEST STORMS WILL CONTINUE TO AFFECT
FAR ERN NC INCLUDING THE OUTER BANKS THROUGH 02Z. FARTHER
N...WEAKER LOW LEVEL SHEAR SUGGESTS A GREATER THREAT FOR ISOLATED
DAMAGING WINDS AND HAIL WITH STORMS TRACKING NEWD FROM SERN VA
TOWARD THE SRN CHESAPEAKE BAY TO SRN DELMARVA THROUGH 02-03Z.
..PETERS.. 04/29/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...AKQ...MHX...LWX...
LAT...LON 34387624 34607714 35417660 36267653 36657684 37047729
37787678 38427648 38387468 36827558 35377508 34907531
34387624Nearby
Mesoscale Discussions in Virginia, 2011Mesoscale Discussions in North Carolina, 2011Mesoscale Discussions in Maryland, 2011Every 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.