Alert archive / Virginia / Mesoscale Discussions in 2011
Mesoscale Discussion 455
The Storm Prediction Center issued this mesoscale discussion at Apr 16, 2011, 12:52 PM EDT for 16 counties in Maryland; 57 counties in Virginia; 6 counties in West Virginia. It was in force for 113 min.
The area
The outline as issued.
The facts
- Issued
- Apr 16, 2011, 12:52 PM EDT (16:52 UTC)
- Expired
- Apr 16, 2011, 2:45 PM EDT
- In force
- 113 min
- Issued by
- the Storm Prediction Center
All 79 counties
Anne Arundel County, MD, Calvert County, MD, Caroline County, MD, Charles County, MD, City of Baltimore, MD, Dorchester County, MD, Frederick County, MD, Howard County, MD, Montgomery County, MD, Prince George's County, MD, Queen Anne's County, MD, Saint Mary's County, MD, Somerset County, MD, Talbot County, MD, Washington County, MD, Wicomico County, MD, Accomack County, VA, Albemarle County, VA, Amherst County, VA, Arlington County, VA, Augusta County, VA, Botetourt County, VA, Caroline County, VA, City of Alexandria, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Harrisonburg, VA, City of Lexington, VA, City of Manassas, VA, City of Manassas Park, VA, City of Staunton, VA, City of Waynesboro, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Essex County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Frederick County, VA, Gloucester County, VA, Goochland County, VA, Greene County, VA, Hanover County, VA, Highland County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Lancaster County, VA, Loudoun County, VA, Louisa County, VA, Madison County, VA, Mathews County, VA, Middlesex County, VA, Nelson County, VA, New Kent County, VA, Northampton County, VA, Northumberland County, VA, Orange County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Richmond County, VA, Rockbridge County, VA, Rockingham County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Westmoreland County, VA, Berkeley County, WV, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, Morgan County, WV, Pendleton County, WV
The radar
The Sterling radar (KLWX), 87 km from the middle of the area, began a volume at 16:53 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
Washington/Dulle, VA (KIAD), launched 12:00Z, 4.9 hours before the alert went out and 84 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
- 533 m above ground
- 0-6 km bulk shear
- 56 kt
- 0-1 km storm-relative helicity
- 473 m²/s²
- 0-3 km storm-relative helicity
- 699 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
335
ACUS11 KWNS 161652
SWOMCD
SPC MCD 161652
DEZ000-MDZ000-VAZ000-DCZ000-WVZ000-161845-
MESOSCALE DISCUSSION 0455
NWS STORM PREDICTION CENTER NORMAN OK
1152 AM CDT SAT APR 16 2011
AREAS AFFECTED...DC...PORTIONS VA...MD...DE...ERN PANHANDLE OF WV.
CONCERNING...SEVERE POTENTIAL...WATCH LIKELY
VALID 161652Z - 161845Z
SVR THREAT....INCLUDING TORNADO/DAMAGING GUST RISK...IS FCST TO
INCREASE THROUGH LATE AFTERNOON OVER AREAS N OF WW 150. WHILE NOT
AS BUOYANT AS FARTHER S...AIR MASS IS FCST TO DESTABILIZE AT LEAST
MRGL LEVELS THROUGH 21Z. GIVEN ALREADY FAVORABLE DEEP-LAYER
KINEMATIC PROFILES THAT ARE FCST TO STRENGTHEN WITH TIME AS
MID-UPPER TROUGH APCHS...WW IS ANTICIPATED.
16Z SFC MESOANALYSIS DEPICTS COLD FRONT MOVING EWD ACROSS
CENTRAL/NRN WV AND WRN VA...JUST BEHIND INCREASING
COVERAGE/INTENSITY OF TSTMS WITHIN CONVECTIVE BAND NEAR MWK-ROA-EKN
LINE. WARM FRONT WAS REDEVELOPING NWD ACROSS NC TO NEAR VA BORDER
AND WILL MOVE NWD ACROSS SRN/CENTRAL VA AND SRN MD...PERHAPS AS FAR
N AS DC AREA PRIOR TO ARRIVAL OF MAIN TSTM BAND. CLOUD
BREAKS...EVIDENT IN 1615Z VIS IMAGE OVER CENTRAL NC...WERE SPREADING
NWD INTO S-CENTRAL VA. THIS WILL COMBINE WITH THETAE ADVECTION
ACCOMPANYING WARM FROPA TO RENDER SFC-BASED EFFECTIVE INFLOW
PARCELS...MINIMAL CINH AND AT LEAST WEAK MLCAPE OVER MUCH OF
CENTRAL/ERN VA...WHILE THERMODYNAMIC PROFILES OVER WRN/NRN VA WILL
REMAIN NEARLY NEUTRAL. BY 20Z...EXPECT 200-500 J/KG MLCAPE INTO
PORTIONS SWRN-CENTRAL VA AHEAD OF CONVECTIVE
BAND...SPREADING/EXPANDING NEWD TOWARD MD BY LATE AFTERNOON. AS
BUOYANT PROFILE DEVELOPS/DEEPENS...EFFECTIVE SHEAR 60-75 KT WILL
DEVELOP. MEANWHILE EFFECTIVE SRH NEAR 500 J/KG WILL OCCUR INVOF
WARM FRONT.
EXPECT MORE MERIDIONALLY ALIGNED MEAN WIND VECTORS WITH NWD
EXTENT...WHICH WILL BE LESS ORTHOGONAL TO CORRIDOR OF CONVECTIVE
FORCING. THIS WILL CONTRIBUTE TO MORE LINEAR MODAL TENDENCIES
ACROSS WRN/NWRN VA AND NWRN MD. HOWEVER...STG SFC ISALLOBARIC
FORCING WILL MAINTAIN RELATIVELY BACKED SFC WINDS AND ENLARGED
LOW-LEVEL HODOGRAPHS. THIS INDICATES POTENTIAL FOR EMBEDDED
BOW/LEWP FEATURES TO ENHANCE WIND DAMAGE THREAT LOCALLY...AS WELL AS
TORNADOES RELATED TO BOTH EMBEDDED MESOCIRCULATIONS AND LEADING-EDGE
QUASI-LINEAR CONVECTIVE FORCING.
..EDWARDS.. 04/16/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...PHI...AKQ...LWX...RNK...
LAT...LON 37487984 38707956 39597841 39677732 39317637 38817549
37957531 37827547 37157590 37327609 37697811 37547934
37487984SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 16, 1:29 PM EDT | Tornado Watch | SPC | Allegany, Anne Arundel, Baltimore, Calvert, Carroll, Charles and 8 more | 8 hr |
| Apr 16, 4:29 PM EDT | Mesoscale Discussion | SPC | Allegany, Anne Arundel, Baltimore, Calvert, Carroll, Cecil and 13 more | 31 min |
| Apr 16, 4:41 PM EDT | Tornado Watch | SPC | Caroline, Cecil, Kent, Queen Anne's, Talbot | 6 hr |
| Apr 16, 6:38 PM EDT | Mesoscale Discussion | SPC | Anne Arundel, Baltimore, Calvert, Caroline, Carroll, Cecil and 13 more | 97 min |
| Apr 16, 10:39 AM EDT | Mesoscale Discussion | SPC | Brunswick, Charles City, Chesterfield, Dinwiddie, Gloucester, Greensville and 25 more | 2 hr |
| Apr 16, 12:02 PM EDT | Tornado Watch | SPC | Amelia, Amherst, Appomattox, Bedford, Brunswick, Buckingham and 62 more | 11 hr |
| Apr 16, 2:28 PM EDT | Mesoscale Discussion | SPC | Amelia, Brunswick, Charles City, Charlotte, Chesterfield, Cumberland and 43 more | 92 min |
| Apr 16, 4:49 PM EDT | Mesoscale Discussion | SPC | Brunswick, Caroline, Charles City, Chesterfield, Dinwiddie, Essex and 33 more | 86 min |
| Apr 16, 6:59 PM EDT | Mesoscale Discussion | SPC | Greensville, Isle of Wight, Prince George, Southampton, Surry, Sussex and 9 more | 91 min |
| Apr 16, 10:43 AM EDT | Mesoscale Discussion | SPC | Barbour, Braxton, Doddridge, Gilmer, Harrison, Lewis and 13 more | 62 min |
| Apr 16, 1:34 PM EDT | Mesoscale Discussion | SPC | Brooke, Hancock, Marshall, Ohio, Wetzel | 116 min |
Nearby
Mesoscale Discussions in Virginia, 2011Mesoscale Discussions in Maryland, 2011Mesoscale Discussions in West Virginia, 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.