Alert archive / Virginia / Mesoscale Discussions in 2011

Mesoscale Discussion 793

May 15, 20114 states

The Storm Prediction Center issued this mesoscale discussion at May 15, 2011, 1:38 PM EDT for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: May 15, 2011, 1:38 PM EDT (17:38 UTC)
Expired: May 15, 2011, 3:45 PM EDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 95 counties

Kent County, DE, Anne Arundel County, MD, Calvert County, MD, Caroline County, MD, Charles County, MD, City of Baltimore, MD, Dorchester County, MD, Howard County, MD, Kent County, MD, Prince George's County, MD, Queen Anne's County, MD, Saint Mary's County, MD, Somerset County, MD, Talbot County, MD, Wicomico County, MD, Beaufort County, NC, Bertie County, NC, Camden County, NC, Chowan County, NC, Edgecombe County, NC, Gates County, NC, Greene County, NC, Halifax County, NC, Hertford County, NC, Lenoir County, NC, Martin County, NC, Nash County, NC, Northampton County, NC, Pasquotank County, NC, Perquimans County, NC, Pitt County, NC, Warren County, NC, Washington County, NC, Wilson County, NC, Accomack County, VA, Amelia County, VA, Arlington County, VA, Brunswick County, VA, Caroline County, VA, Charles City County, VA, Chesterfield County, VA, City of Alexandria, 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, Dinwiddie County, VA, Essex County, VA, Fairfax County, VA, Gloucester County, VA, Goochland 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, Louisa County, VA, Lunenburg County, VA, Mathews County, VA, Middlesex County, VA, New Kent County, VA, Northampton County, VA, Northumberland County, VA, Nottoway County, VA, Powhatan County, VA, Prince George County, VA, Prince William County, VA, Richmond County, VA, Southampton County, VA, Spotsylvania County, VA, Stafford County, VA, Surry County, VA, Sussex County, VA, Westmoreland County, VA, York County, VA

The radar

The Norfolk radar (KAKQ), 14 km from the middle of the area, began a volume at 17:39 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

Wallops Is Stn, VA (KWAL), launched 12:00Z, 5.6 hours before the alert went out and 164 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1144 m above ground
0-6 km bulk shear: 29 kt
0-1 km storm-relative helicity: -15 m²/s²
0-3 km storm-relative helicity: 10 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

517 
ACUS11 KWNS 151738
SWOMCD
SPC MCD 151738 
DEZ000-MDZ000-VAZ000-NCZ000-DCZ000-151945-

MESOSCALE DISCUSSION 0793
NWS STORM PREDICTION CENTER NORMAN OK
1238 PM CDT SUN MAY 15 2011

AREAS AFFECTED...ERN NC...ERN VA...MD AND DE

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 151738Z - 151945Z

A FEW STORMS DEVELOPING FROM ERN NC INTO THE MID ATLANTIC REGION MAY
BECOME CAPABLE OF PRODUCING LOCALLY STRONG WIND GUSTS AND MARGINALLY
SEVERE HAIL. DUE TO LIMITING FACTORS FOR A MORE ROBUST SEVERE
EVENT...WW ISSUANCE IS UNCERTAIN...BUT AREA WILL CONTINUE TO BE
MONITORED.

THIS AFTERNOON A COLD FRONT EXTENDS FROM A SURFACE LOW IN CNTRL PA
THROUGH WRN VA...CNTRL NC AND ERN SC. WARM FRONT EXTENDS FROM SRN NJ
WWD THROUGH NRN MD WHERE IT INTERSECTS THE COLD FRONT. NUMEROUS
STORMS ARE DEVELOPING ALONG THE FRONT AND IN WARM SECTOR INCLUDING
SEA BREEZE BOUNDARIES FROM ERN NC THROUGH CNTRL AND ERN VA WHERE THE
ATMOSPHERE IS UNCAPPED AND MARGINALLY UNSTABLE WITH 800-1200 J/KG
MLCAPE. CIRCULATION AROUND UPPER LOW CENTERED OVER THE OH VALLEY IS
RESULTING IN MODEST FLOW ALOFT OVER THE WARM SECTOR WITH 20-30 KT
SWLY UNIDIRECTIONAL SHEAR SUPPORTIVE OF MULTICELLS. THE MODEST
VERTICAL SHEAR AND WEAK LAPSE RATES WILL PROBABLY SERVE TO LIMIT
DEGREE OF ANY SEVERE THREAT. HOWEVER...A FEW STORMS MAY BECOME
CAPABLE OF PRODUCING ISOLATED STRONG WIND GUSTS AS THEY DEVELOP
NEWD...ESPECIALLY ONCE THEY BEGIN TO ORGANIZE INTO SMALL CLUSTERS OR
LINE SEGMENTS.

..DIAL.. 05/15/2011

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

ATTN...WFO...PHI...AKQ...MHX...LWX...RAH...

LAT...LON   35157684 35167786 37087831 38727779 39367677 39207522
            37417586 35867624 35157684

Nearby

Mesoscale Discussions in Virginia, 2011 Mesoscale Discussions in North Carolina, 2011 Mesoscale Discussions in Maryland, 2011 Every 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.