Alert archive / Virginia / Mesoscale Discussions in 2012

Mesoscale Discussion 1606

July 26, 20124 states

The Storm Prediction Center issued this mesoscale discussion at Jul 26, 2012, 3:08 PM EDT for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Jul 26, 2012, 3:08 PM EDT (19:08 UTC)
Expired
Jul 26, 2012, 5:15 PM EDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
40%
All 109 counties

Kent County, DE, Sussex County, DE, Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Caroline County, MD, Carroll County, MD, Charles County, MD, City of Baltimore, MD, Dorchester County, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Kent 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, Wicomico County, MD, Worcester County, MD, Accomack County, VA, Albemarle County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Arlington County, VA, Augusta County, VA, Buckingham County, VA, Campbell County, VA, Caroline County, VA, Charles City County, VA, Charlotte County, VA, Chesterfield County, VA, City of Alexandria, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Colonial Heights, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Hampton, VA, City of Harrisonburg, VA, City of Hopewell, VA, City of Lexington, VA, City of Lynchburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Newport News, VA, City of Petersburg, VA, City of Poquoson, VA, City of Richmond, VA, City of Staunton, VA, City of Waynesboro, 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, 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, Middlesex County, VA, Nelson 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, Rockbridge County, VA, Rockingham County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Surry County, VA, Sussex County, VA, Warren County, VA, Westmoreland County, VA, York County, VA, Hampshire County, WV, Hardy County, WV, Jefferson County, WV

The radar

The Sterling radar (KLWX), 94 km from the middle of the area, began a volume at 19:09 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, 7.1 hours before the alert went out and 90 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-pSkew-T log-p diagram, Washington/Dulle, VA at 12:00Z on 2012-07-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1172 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 12:00Z on 2012-07-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 180 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
1172 J/kg
Mixed-layer CIN
-226 J/kg
Mixed-layer LCL
985 m above ground
0-6 km bulk shear
29 kt
0-1 km storm-relative helicity
180 m²/s²
0-3 km storm-relative helicity
170 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.

012 
ACUS11 KWNS 261908
SWOMCD
SPC MCD 261908 
DEZ000-MDZ000-VAZ000-DCZ000-WVZ000-262115-

MESOSCALE DISCUSSION 1606
NWS STORM PREDICTION CENTER NORMAN OK
0208 PM CDT THU JUL 26 2012

AREAS AFFECTED...PORTIONS VA...ERN WV...DC...MD...DE.

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 261908Z - 262115Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...TSTM POTENTIAL IS INCREASING OVER THIS AREA...AS AIR MASS
CONTINUES TO DESTABILIZE SE OF WW 524.  BEING NEAR SRN PERIPHERY OF
FAVORABLE MIDLEVEL WINDS AND DEEP SHEAR...POTENTIAL EXISTS FOR
SUFFICIENT TSTM ORGANIZATION TO WARRANT WW...AND CONVECTIVE TRENDS
WILL BE MONITORED ACCORDINGLY. DAMAGING GUSTS ARE PRIMARY
CONCERN...AND MRGL SVR HAIL IS POSSIBLE.

DISCUSSION...18Z SFC MESOANALYSIS SHOWED QUASISTATIONARY LEE TROUGH
WITH WEAK CONFLUENCE NEAR FDK-LYH-MTV LINE.  FARTHER
E...BETTER-DEFINED  CONFLUENCE BAND WAS EVIDENT BETWEEN RDU-RIC-DCA
THEN NEWD OVER HARFORD COUNTY MD.  AIR MASS BETWEEN THESE BOUNDARIES
HAS HEATED QUITE STRONGLY...WITH SFC TEMPS MID-UPPER 90S AND DEW
POINTS UPPER 60S TO 70S F CONTRIBUTING TO MLCAPE 3000-4500 J/KG. 
THIS IS DERIVED FROM MODIFIED 12Z AND 18Z RAOBS AND FCST
SOUNDINGS...DISCOUNTING SITES WITH ANOMALOUSLY HIGH/80S F SFC DEW
POINTS.  18Z IAD RAOB INDICATED WEAK CINH STILL REMAINING...AS WELL
AS STABLE LAYER BETWEEN 500-650 MB...EACH OF WHICH MAY BE MITIGATING
DEEP CONVECTIVE DEVELOPMENT SO FAR.  HOWEVER...CONTINUED
HEATING/DESTABILIZATION SHOULD SUPPORT TSTM INITIATION/GROWTH DURING
NEXT FEW HOURS INVOF EITHER BOUNDARY.  VIS IMAGERY ACCORDINGLY
DEPICTS PATCHES OF DEEPENING CU/TCU BETWEEN I-95 CORRIDOR AND BLUE
RIDGE...ESPECIALLY NEAR RIC.  VWP AND OBSERVED/FCST SOUNDINGS
SUGGEST 25-35 KT EFFECTIVE SHEAR MAGNITUDES IN SUPPORT OF ORGANIZED
MULTICELLULAR POTENTIAL.

..EDWARDS/HART.. 07/26/2012

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

ATTN...WFO...PHI...AKQ...LWX...RNK...

LAT...LON   37697971 39297878 39717650 39467559 38747510 37997528
            37167589 36747685 37017924 37697971

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 26, 3:37 PM EDTMesoscale DiscussionSPCNew Castle113 min
Jul 26, 5:54 PM EDTSevere Thunderstorm WatchSPCKent, New Castle, Sussex6 hr
Jul 26, 1:16 PM EDTSevere Thunderstorm WatchSPCGarrett9 hr
Jul 26, 6:06 PM EDTMesoscale DiscussionSPCGarrett84 min
Jul 26, 6:26 PM EDTSevere Thunderstorm WatchSPCBuchanan, Dickenson7 hr
Jul 26, 4:31 AM EDTMesoscale DiscussionSPCBrooke, Doddridge, Hancock, Harrison, Marion, Marshall and 8 more89 min
Jul 26, 12:26 PM EDTMesoscale DiscussionSPCBrooke, Hancock, Ohio2 hr
Jul 26, 4:57 PM EDTMesoscale DiscussionSPCBoone, Logan, Mingo, Wayne2 hr

Nearby

Mesoscale Discussions in Virginia, 2012Mesoscale Discussions in Maryland, 2012Mesoscale Discussions in West Virginia, 2012Every 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.