Alert archive / Virginia / Mesoscale Discussions in 2010

Mesoscale Discussion 1908

September 30, 20105 states

The Storm Prediction Center issued this mesoscale discussion at Sep 30, 2010, 8:25 AM EDT for 5 states. It was in force for 95 min.

The area

The outline as issued.

The facts

Issued
Sep 30, 2010, 8:25 AM EDT (12:25 UTC)
Expired
Sep 30, 2010, 10:00 AM EDT
In force
95 min
Issued by
the Storm Prediction Center
All 116 counties

Kent County, DE, New Castle County, DE, Sussex County, DE, Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Caroline County, MD, Carroll County, MD, Cecil County, MD, Charles County, MD, City of Baltimore, MD, Dorchester 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, Beaufort County, NC, Bertie County, NC, Bladen County, NC, Brunswick County, NC, Camden County, NC, Carteret County, NC, Chowan County, NC, Columbus County, NC, Craven County, NC, Cumberland County, NC, Currituck County, NC, Dare County, NC, Duplin County, NC, Edgecombe County, NC, Franklin County, NC, Gates County, NC, Granville County, NC, Greene County, NC, Halifax County, NC, Hertford County, NC, Hyde County, NC, Johnston County, NC, Jones County, NC, Lenoir County, NC, Martin County, NC, Nash County, NC, New Hanover County, NC, Northampton County, NC, Onslow County, NC, Pamlico County, NC, Pasquotank County, NC, Pender County, NC, Perquimans County, NC, Pitt County, NC, Sampson County, NC, Tyrrell County, NC, Vance County, NC, Wake County, NC, Warren County, NC, Washington County, NC, Wayne County, NC, Wilson County, NC, Atlantic County, NJ, Camden County, NJ, Cape May County, NJ, Cumberland County, NJ, Gloucester County, NJ, Salem County, NJ, Accomack County, VA, Arlington County, VA, Caroline County, VA, Charles City County, VA, City of Alexandria, VA, City of Chesapeake, VA, City of Colonial Heights, VA, City of Emporia, VA, City of Falls Church, 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, Essex County, VA, Fairfax County, VA, Gloucester 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, Mathews County, VA, Middlesex County, VA, New Kent County, VA, Northampton County, VA, Northumberland 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), 74 km from the middle of the area, began a volume at 12:25 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, 0.4 hours before the alert went out and 138 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, Wallops Is Stn, VA at 12:00Z on 2010-09-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 511 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, Wallops Is Stn, VA at 12:00Z on 2010-09-30The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 267 square meters per square second.19395878Sfc1 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
511 J/kg
Mixed-layer CIN
-23 J/kg
Mixed-layer LCL
619 m above ground
0-6 km bulk shear
45 kt
0-1 km storm-relative helicity
267 m²/s²
0-3 km storm-relative helicity
282 m²/s²
Significant tornado parameter
0.7
Supercell composite
3.3

Open this sounding in Storm Lab

The text

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

881 
ACUS11 KWNS 301225
SWOMCD
SPC MCD 301225 
NJZ000-PAZ000-DEZ000-MDZ000-VAZ000-NCZ000-DCZ000-SCZ000-301400-

MESOSCALE DISCUSSION 1908
NWS STORM PREDICTION CENTER NORMAN OK
0725 AM CDT THU SEP 30 2010

AREAS AFFECTED...PORTIONS NC-VA TIDEWATER AND COASTAL
PLAIN...DC/MD...TO DELMARVA REGION AND SRN NJ.

CONCERNING...TORNADO WATCH 688...

VALID 301225Z - 301400Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 688 CONTINUES.

POTENTIAL CONTINUES FOR SUPERCELLS EMBEDDED WITHIN BANDS IN ERN
PORTION OF PRECIP SHIELD ACROSS WW AREA.  INTERMITTENT/STG
HORIZONTAL SHEAR COUPLETS HAVE BEEN OBSERVED WITHIN SEVERAL CELLS
ACROSS NERN NC/SERN VA...AND THIS REGIME SHOULD SHIFT GENERALLY NWD
THROUGH REMAINDER FORENOON HOURS.

SFC MESOANALYSIS SHOWS PRIMARY LOW OVER N-CENTRAL NC...EXPECTED TO
CONTINUE LIFTING NWD INTO SRN VA.  WARM FRONTAL ZONE IS ANALYZED
NEWD FROM LOW ACROSS SERN VA NEAR RIC...TO NRN CHESAPEAKE BAY...NRN
DE AND NRN NJ.  FRONT SHOULD CONTINUE TO MOVE SLOWLY WWD...SOMEWHAT
POORLY DEFINED BENEATH PRECIP SHIELD.  AIR MASS E OF FRONT GRADUALLY
BECOMES MORE UNSTABLE EWD TOWARD COAST AND AWAY FROM MOST PERSISTENT
AREAS OF PRECIP...AS AIR MASS BECOMES MORE UNDISTURBED AND
MARITIME/TROPICAL IN CHARACTER.  RELATED HIGH BOUNDARY-LAYER THETAE
AND RICH MOISTURE YIELD LOW LCL AND MLCAPE 500-1000 J/KG NEAR
COAST...AMIDST BACKED SFC WINDS THAT CONTRIBUTE TO 0-1 KM SRH OF
200-400 J/KG...PER REGIONAL VWPS AND 12Z WAL RAOB.  ALTHOUGH
GREATEST ISALLOBARIC DEFICITS ARE ANALYZED W OF FRONT...FALLS
ALONG/E OF FRONT SHOULD CONTINUE AND HELP TO MAINTAIN BACKED
WINDS...AND SUITABLE LOW-LEVEL SHEAR...TO ITS E.

..EDWARDS.. 09/30/2010

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

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

LAT...LON   34157892 36407872 36667771 39677714 39737578 39947501
            39487434 39007477 38937486 38947498 39177490 39187518
            39227540 38987531 38787508 38427504 37927529 37867542
            37337570 37107591 37077599 36917601 36337579 35687542
            35127554 35227557 35117582 34837630 34477654 34647660
            34687694 34397756 33747795 33877802 33857842 34157892

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 30, 4:02 AM EDTMesoscale DiscussionSPCKent, Sussex118 min
Sep 30, 4:55 AM EDTTornado WatchSPCKent, New Castle, Sussex8 hr
Sep 30, 10:49 AM EDTMesoscale DiscussionSPCKent, New Castle, Sussex116 min
Sep 30, 12:39 PM EDTTornado WatchSPCKent, New Castle, Sussex6 hr
Sep 30, 3:16 PM EDTMesoscale DiscussionSPCKent, New Castle, Sussex119 min
Sep 30, 5:43 PM EDTMesoscale DiscussionSPCSomerset92 min
Sep 29, 8:42 PM EDTMesoscale DiscussionSPCBeaufort, Bertie, Bladen, Brunswick, Camden, Carteret and 28 more93 min
Sep 29, 9:39 PM EDTTornado WatchSPCBeaufort, Bertie, Bladen, Brunswick, Camden, Carteret and 31 more7 hr
Sep 30, 12:47 AM EDTMesoscale DiscussionSPCBeaufort, Bertie, Bladen, Brunswick, Camden, Carteret and 31 more88 min
Sep 30, 3:07 PM EDTMesoscale DiscussionSPCBeaufort, Camden, Carteret, Chowan, Craven, Currituck and 10 more113 min

Nearby

Mesoscale Discussions in Virginia, 2010Mesoscale Discussions in North Carolina, 2010Mesoscale Discussions in Maryland, 2010Every mesoscale discussion in 2010

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.