Alert archive / Virginia / Mesoscale Discussions in 2017
Mesoscale Discussion 839
The Storm Prediction Center issued this mesoscale discussion at May 25, 2017, 12:59 PM EDT for 4 states. It was in force for 61 min.
The area
The outline as issued.
The facts
- Issued
- May 25, 2017, 12:59 PM EDT (16:59 UTC)
- Expired
- May 25, 2017, 2:00 PM EDT
- In force
- 61 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 20%
All 123 counties
Anne Arundel County, MD, Calvert County, MD, Charles County, MD, City of Baltimore, MD, Dorchester 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, Beaufort County, NC, Bertie County, NC, Camden County, NC, Chowan County, NC, Craven County, NC, Duplin County, NC, Edgecombe County, NC, Franklin County, NC, Gates County, NC, Granville County, NC, Greene County, NC, Halifax County, NC, Harnett County, NC, Hertford County, NC, Johnston County, NC, Jones County, NC, Lenoir County, NC, Martin County, NC, Nash County, NC, Northampton County, NC, Pasquotank County, NC, Perquimans County, NC, Pitt County, NC, Tyrrell County, NC, Vance County, NC, Wake County, NC, Warren County, NC, Washington County, NC, Wayne County, NC, Wilson County, NC, Albemarle County, VA, Amelia County, VA, Arlington County, VA, Brunswick County, VA, Buckingham County, VA, Caroline County, VA, Charles City County, VA, Chesterfield County, VA, City of Alexandria, VA, City of Charlottesville, VA, City of Chesapeake, VA, City of Colonial Heights, VA, City of Emporia, VA, City of Fairfax, VA, City of Falls Church, VA, City of Franklin, VA, City of Fredericksburg, VA, City of Hampton, VA, City of Hopewell, VA, City of Manassas, VA, City of Manassas Park, VA, City of Newport News, VA, City of Norfolk, VA, City of Petersburg, VA, City of Poquoson, VA, City of Portsmouth, VA, City of Richmond, VA, City of Suffolk, VA, City of Virginia Beach, VA, City of Williamsburg, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Cumberland County, VA, Dinwiddie 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, Greensville County, VA, Hanover County, VA, Henrico County, VA, Isle of Wight County, VA, James City County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Lancaster County, VA, Loudoun County, VA, Louisa County, VA, Lunenburg County, VA, Madison County, VA, Mathews County, VA, Mecklenburg County, VA, Middlesex County, VA, New Kent County, VA, Northampton County, VA, Northumberland County, VA, Nottoway County, VA, Orange County, VA, Page County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Prince William County, VA, Rappahannock County, VA, Richmond County, VA, Shenandoah County, VA, Southampton County, VA, Spotsylvania County, VA, Stafford County, VA, Surry County, VA, Sussex County, VA, Warren County, VA, Westmoreland County, VA, York County, VA, Jefferson County, WV
The radar
The Norfolk radar (KAKQ), 72 km from the middle of the area, began a volume at 16:59 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
Roanoke, VA (KRNK), launched 12:00Z, 5.0 hours before the alert went out and 159 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
- 8 J/kg
- Mixed-layer CIN
- -118 J/kg
- Mixed-layer LCL
- 1058 m above ground
- 0-6 km bulk shear
- 63 kt
- 0-1 km storm-relative helicity
- -48 m²/s²
- 0-3 km storm-relative helicity
- 116 m²/s²
- Significant tornado parameter
- -0.0
- Supercell composite
- -0.3
The text
As transmitted.
594
ACUS11 KWNS 251659
SWOMCD
SPC MCD 251659
VAZ000-MDZ000-NCZ000-DCZ000-WVZ000-251800-
Mesoscale Discussion 0839
NWS Storm Prediction Center Norman OK
1159 AM CDT Thu May 25 2017
Areas affected...Southern Maryland...central/eastern Virginia...and
central/eastern North Carolina
Concerning...Severe potential...Watch unlikely
Valid 251659Z - 251800Z
Probability of Watch Issuance...20 percent
SUMMARY...Scattered thunderstorms should gradually increase in
intensity over the course of the afternoon, although any severe
threat is expected to remain isolated. A weather watch issuance is
not currently anticipated for this activity.
DISCUSSION...The combination of continued pockets of surface heating
and forcing for ascent aloft with approach of a mid-level
disturbance over southern Ohio will foster a gradual increase in
convective coverage and intensity across the discussion area this
afternoon. 500-1500 J/kg MUCAPE and 40-50 knot deep shear could
foster organized, sustained updrafts with some threat for 1-1.5"
hail stones and damaging wind gusts in/near the strongest activity.
Weak low-level shear profiles will foster more
outflow-dominant/forward propagating storms initially although
low-level flow will increase some later in the afternoon. Any
severe threat should be too isolated to necessitate a severe
thunderstorm watch issuance.
..Cook/Kerr.. 05/25/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...PHI...AKQ...MHX...LWX...RAH...RNK...
LAT...LON 39207862 39387816 39417704 39247620 38757586 37967578
37077582 36267599 35527630 34967694 34867762 35037848
35177890 35507912 36167876 36697865 37427859 38167874
38667887 38927880 39207862Nearby
Mesoscale Discussions in Virginia, 2017Mesoscale Discussions in North Carolina, 2017Mesoscale Discussions in Maryland, 2017Every mesoscale discussion in 2017
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.