Alert archive / Virginia / Mesoscale Discussions in 2012
Mesoscale Discussion 970
The Storm Prediction Center issued this mesoscale discussion at May 29, 2012, 7:48 PM EDT for 4 counties in Maryland; 8 counties in Virginia. It was in force for 57 min.
The area
The outline as issued.
The facts
- Issued
- May 29, 2012, 7:48 PM EDT (23:48 UTC)
- Expired
- May 29, 2012, 8:45 PM EDT
- In force
- 57 min
- Issued by
- the Storm Prediction Center
Counties Anne Arundel County, MD, Charles County, MD, Kent County, MD, Prince George's County, MD, Caroline County, VA, City of Alexandria, VA, City of Fredericksburg, VA, Goochland County, VA, King George County, VA, Louisa County, VA, Spotsylvania County, VA, Stafford County, VA
The radar
The Sterling radar (KLWX), 65 km from the middle of the area, began a volume at 23:48 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, 11.8 hours before the alert went out and 60 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.
- Mixed-layer CAPE
- 601 J/kg
- Mixed-layer CIN
- -150 J/kg
- Mixed-layer LCL
- 1156 m above ground
- 0-6 km bulk shear
- 8 kt
- 0-1 km storm-relative helicity
- -68 m²/s²
- 0-3 km storm-relative helicity
- -33 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
836 ACUS11 KWNS 292349 SWOMCD SPC MCD 292348 MDZ000-VAZ000-DCZ000-300045- MESOSCALE DISCUSSION 0970 NWS STORM PREDICTION CENTER NORMAN OK 0648 PM CDT TUE MAY 29 2012 AREAS AFFECTED...NERN VA INTO NRN MD CONCERNING...SEVERE THUNDERSTORM WATCH 316... VALID 292348Z - 300045Z THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 316 CONTINUES. SUMMARY...AT LEAST A MODEST THREAT FOR ISOLATED STRONG WIND GUSTS WILL PERSIST FROM NERN VA INTO NRN MD NEXT HOUR OR TWO. OVERALL THREAT EXPECTED TO BECOME INCREASINGLY MARGINAL. DISCUSSION...EXPANSIVE SQUALL LINE EXTENDS FROM NEW ENGLAND SWWD THROUGH NRN AND SWRN VA. THE VA/MA PORTION OF THE LINE IS MOVING EAST AT AROUND 25 KT AND IS EMBEDDED WITHIN AN ENVIRONMENT CHARACTERIZED BY WEAK VERTICAL SHEAR AND 1000-1500 J/KG MLCAPE. A MODEST THREAT FOR ISOLATED DAMAGING WIND WILL PERSIST NEXT HOUR OR TWO AS THE LINE CONTINUES THROUGH REMAINING PORTION OF WW 316...BUT OVERALL TREND SHOULD BE FOR SEVERE THREAT TO UNDERGO A GRADUAL DECREASE AS THE BOUNDARY LAYER BEGINS TO COOL. ..DIAL.. 05/29/2012 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...PHI...AKQ...LWX...RNK... LAT...LON 37667845 39017694 39477582 38997625 37747758 37667845
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 29, 4:22 PM EDT | Mesoscale Discussion | SPC | Frederick, Washington | 53 min |
| May 29, 4:33 PM EDT | Severe Thunderstorm Watch | SPC | Baltimore, Carroll, Charles, Frederick, Harford, Howard and 4 more | 4 hr |
Nearby
Mesoscale Discussions in Virginia, 2012Mesoscale Discussions in Maryland, 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.