Alert archive / Maryland / Mesoscale Discussions in 2011

Mesoscale Discussion 554

April 24, 20115 states

The Storm Prediction Center issued this mesoscale discussion at Apr 24, 2011, 6:10 PM EDT for 5 states. It was in force for 65 min.

The area

The outline as issued.

The facts

Issued: Apr 24, 2011, 6:10 PM EDT (22:10 UTC)
Expired: Apr 24, 2011, 7:15 PM EDT
In force: 65 min
Issued by: the Storm Prediction Center

All 44 counties

Kent County, DE, New Castle County, DE, Anne Arundel County, MD, Baltimore County, MD, Caroline County, MD, Carroll County, MD, Cecil County, MD, Charles County, MD, City of Baltimore, 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, Talbot County, MD, Atlantic County, NJ, Burlington County, NJ, Camden County, NJ, Cape May County, NJ, Cumberland County, NJ, Gloucester County, NJ, Mercer County, NJ, Monmouth County, NJ, Ocean County, NJ, Salem County, NJ, Adams County, PA, Chester County, PA, Delaware County, PA, Lancaster County, PA, Montgomery County, PA, Philadelphia County, PA, York County, PA, Arlington County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, VA, City of Manassas, VA, City of Manassas Park, VA, Fairfax County, VA, Loudoun County, VA, Prince William County, VA, Stafford County, VA

The radar

The Dover AFB radar (KDOX), 74 km from the middle of the area, began a volume at 22:11 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

Washington/Dulle, VA (KIAD), launched 12:00Z, 10.2 hours before the alert went out and 114 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: 1135 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: -16 m²/s²
0-3 km storm-relative helicity: 32 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.

361 
ACUS11 KWNS 242210
SWOMCD
SPC MCD 242210 
NJZ000-PAZ000-DEZ000-MDZ000-DCZ000-VAZ000-WVZ000-242315-

MESOSCALE DISCUSSION 0554
NWS STORM PREDICTION CENTER NORMAN OK
0510 PM CDT SUN APR 24 2011

AREAS AFFECTED...FAR NERN VA...MUCH OF MD...DELMARVA PENINSULA...SRN
NJ...SERN PA

CONCERNING...SEVERE THUNDERSTORM WATCH 195...

VALID 242210Z - 242315Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 195
CONTINUES.

SMALL MCS CONTINUES TO PROGRESS EWD ACROSS THE DELMARVA
PENINSULA...WITH THE APEX MOVING INTO SRN NJ. A STRONGER CELL HAS
DEVELOPED ON THE SRN END OF THE LINE...WHICH LIKELY WILL HAVE THE
POTENTIAL TO PRODUCE SOME SVR HAIL AND DMGG WINDS. CURRENT
EXTRAPOLATION OF THE LINE SHOULD HAVE IT MOVING OFFSHORE BTWN
2300-2330Z. MEANWHILE...UPSTREAM AREAS IN THE WAKE OF THE CONVECTION
HAVE COOLED SUBSTANTIALLY...BUT SFC TEMPERATURES APPEAR TO BE
RECOVERING SOMEWHAT WITH BREAKS IN THE CLOUDINESS. AN OUTFLOW
BOUNDARY /EVIDENT ON KLWX RADAR REFLECTIVITY/ CURRENTLY IS
POSITIONED E-W THROUGH SRN PORTIONS OF THE WASHINGTON DC METRO AREA.
MODERATELY STEEP MIDLEVEL LAPSE RATES WILL STILL MAINTAIN AN
ENVIRONMENT SUPPORTIVE FOR ADDITIONAL ISOLATED THUNDERSTORM
DEVELOPMENT...BUT THE SVR THREAT APPEARS TO BE QUITE MARGINAL IN THE
WAKE OF THE MCS DUE TO BOUNDARY LAYER MODIFICATION.

..ROGERS.. 04/24/2011

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

ATTN...WFO...PHI...CTP...LWX...

LAT...LON   38337772 39777774 40557376 39137371 38337772

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 24, 2:12 PM EDT	Mesoscale Discussion	SPC	Kent, New Castle	93 min
Apr 24, 3:40 PM EDT	Severe Thunderstorm Watch	SPC	Kent, New Castle, Sussex	5 hr
Apr 23, 8:16 PM EDT	Mesoscale Discussion	SPC	Garrett	59 min

Nearby

Mesoscale Discussions in Maryland, 2011 Mesoscale Discussions in New Jersey, 2011 Mesoscale Discussions in Virginia, 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.