Alert archive / Virginia / Mesoscale Discussions in 2012

Mesoscale Discussion 1241

June 22, 20125 states

The Storm Prediction Center issued this mesoscale discussion at Jun 22, 2012, 4:10 PM EDT for 5 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jun 22, 2012, 4:10 PM EDT (20:10 UTC)
Expired: Jun 22, 2012, 6:15 PM EDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 110 counties

Kent County, DE, Sussex County, DE, Anne Arundel County, MD, Calvert County, MD, Caroline County, MD, Charles County, MD, Dorchester 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, Worcester County, MD, Alamance County, NC, Bertie County, NC, Cabarrus County, NC, Camden County, NC, Caswell County, NC, Chatham County, NC, Chowan County, NC, Cumberland County, NC, Durham County, NC, Edgecombe County, NC, Franklin County, NC, Gates County, NC, Granville County, NC, Greene County, NC, Guilford County, NC, Halifax County, NC, Harnett County, NC, Hertford County, NC, Hoke County, NC, Johnston County, NC, Lee County, NC, Martin County, NC, Montgomery County, NC, Moore County, NC, Nash County, NC, Northampton County, NC, Orange County, NC, Pasquotank County, NC, Perquimans County, NC, Person County, NC, Pitt County, NC, Randolph County, NC, Richmond County, NC, Stanly County, NC, Vance County, NC, Wake County, NC, Warren County, NC, Washington County, NC, Wayne County, NC, Wilson County, NC, Cape May County, NJ, Cumberland County, NJ, Accomack County, VA, Amelia County, VA, Brunswick County, VA, Caroline County, VA, Charles City County, VA, Charlotte County, VA, Chesterfield County, VA, City of Chesapeake, VA, City of Colonial Heights, VA, City of Emporia, VA, City of Franklin, VA, City of Hampton, VA, City of Hopewell, 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, 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 George County, VA, King William County, VA, Lancaster County, VA, Lunenburg County, VA, Mathews County, VA, Mecklenburg County, VA, Middlesex County, VA, New Kent County, VA, Northampton County, VA, Northumberland County, VA, Nottoway County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Richmond County, VA, Southampton County, VA, Surry County, VA, Sussex County, VA, Westmoreland County, VA, York County, VA

The radar

The Norfolk radar (KAKQ), 37 km from the middle of the area, began a volume at 20:12 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, 8.2 hours before the alert went out and 147 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: 1404 J/kg
Mixed-layer CIN: -75 J/kg
Mixed-layer LCL: 1490 m above ground
0-6 km bulk shear: 19 kt
0-1 km storm-relative helicity: -16 m²/s²
0-3 km storm-relative helicity: 36 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.

250 
ACUS11 KWNS 222011
SWOMCD
SPC MCD 222010
NJZ000-DEZ000-MDZ000-VAZ000-NCZ000-DCZ000-222215-

MESOSCALE DISCUSSION 1241
NWS STORM PREDICTION CENTER NORMAN OK
0310 PM CDT FRI JUN 22 2012

AREAS AFFECTED...PORTIONS VA...MD...DE...SRN NJ...DC...WRN/CENTRAL
NC.

CONCERNING...SEVERE THUNDERSTORM WATCH 418...

VALID 222010Z - 222215Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 418
CONTINUES.

SUMMARY...MAIN CONCERN WILL REMAIN DAMAGING GUSTS THREAT WITH
LOOSELY ORGANIZED BAND OF TSTMS EVIDENT AT 20Z FROM NRN CHESAPEAKE
BAY REGION SWWD ACROSS DAN AREA AND INTO WRN NC.  ISOLATED LARGE
HAIL ALSO IS POSSIBLE.  FARTHER S ACROSS NC...CONVECTION IN WEAKER
SHEAR REGIME IS FORMING AGGREGATED COLD POOL AND MAY POSE LOCALLY
ENHANCED THREAT FOR DAMAGING WINDS.

CONVECTION FARTHER W OVER WV MOSTLY IS BEHIND ITS OWN GUST
FRONTS...AND MAY POSE MRGL SVR THREAT AS IT MOVES INTO WRN VA.  A
FEW COUNTIES MAY BE ADDED PER COORD W/WFO LWX.

DISCUSSION...REMAINING INSOLATION...BOUNDARY-LAYER MIXING AND
LOW-LEVEL MOISTURE BETWEEN PRIMARY CONVECTIVE BAND AND COASTAL
TIDEWATER AREAS WILL SUPPORT CONTINUED THREAT FOR STG-SVR GUSTS IN
MOST INTENSE CELLS.  DEEP-LAYER SHEAR WEAKENS SUBSTANTIALLY WITH
SSWWD EXTENT FROM CENTRAL/NRN VA...WITH EFFECTIVE SHEAR MAGNITUDES
20 KT OR LESS OVER MOST OF SRN VA AND NC.  STILL...OCNL SVR GUSTS
ARE POSSIBLE WHERE COLD POOLS FROM EXISTING CONVECTION FORCE
ADDITIONAL DEVELOPMENT INTO PRECONVECTIVE ENVIRONMENT CHARACTERIZED
BY RICH LOW-LEVEL MOISTURE AND 1500-2500 J/KG MLCAPE.
HOWEVER...REFLECTIVITY IMAGERY AND OCNL...FORTUITOUSLY PLACED SFC
OBS INDICATE GUST FRONTS ARE OUTPACING REFLECTIVITY ECHOES
CORRESPONDING TO THEIR SOURCES.  ADDITIONAL WW IS NOT ANTICIPATED
ATTM.

..EDWARDS.. 06/22/2012

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

ATTN...WFO...PHI...AKQ...MHX...LWX...RAH...ILM...RNK...GSP...

LAT...LON   35308071 36297968 37847777 38997695 39467591 39437436
            38907490 38787510 38277509 37697556 37107588 37117594
            36947599 36327602 35507689 34827917 35308071

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 22, 12:18 PM EDT	Mesoscale Discussion	SPC	Kent, New Castle, Sussex	2 hr
Jun 22, 2:12 PM EDT	Severe Thunderstorm Watch	SPC	Kent, New Castle, Sussex	7 hr
Jun 22, 6:42 PM EDT	Mesoscale Discussion	SPC	Kent, New Castle, Sussex	63 min
Jun 22, 1:41 PM EDT	Severe Thunderstorm Watch	SPC	Bergen, Burlington, Camden, Essex, Hudson, Hunterdon and 10 more	7 hr
Jun 22, 4:33 PM EDT	Mesoscale Discussion	SPC	Bergen, Burlington, Camden, Essex, Gloucester, Hudson and 11 more	87 min

Nearby

Mesoscale Discussions in Virginia, 2012 Mesoscale Discussions in North Carolina, 2012 Mesoscale Discussions in Maryland, 2012 Every mesoscale discussion in 2012

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.