Alert archive / Maryland / Mesoscale Discussions in 2003
Mesoscale Discussion 2339
The Storm Prediction Center issued this mesoscale discussion at Sep 1, 2003, 7:17 PM EDT for 10 counties in Maryland; Adams County, York County, Pennsylvania; 6 counties in Virginia. It was in force for 88 min.
The area
The outline as issued.
The facts
- Issued
- Sep 1, 2003, 7:17 PM EDT (23:17 UTC)
- Expired
- Sep 1, 2003, 8:45 PM EDT
- In force
- 88 min
- Issued by
- the Storm Prediction Center
Counties Anne Arundel County, MD, Baltimore County, MD, Carroll County, MD, Charles County, MD, City of Baltimore, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Montgomery County, MD, Prince George's County, MD, Adams County, PA, York County, PA, Arlington County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, VA, Fairfax County, VA, King George County, VA
The radar
The Sterling radar (KLWX), 45 km from the middle of the area, began a volume at 23:21 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, 11.3 hours before the alert went out and 40 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
- 16 J/kg
- Mixed-layer CIN
- -177 J/kg
- Mixed-layer LCL
- 593 m above ground
- 0-6 km bulk shear
- 23 kt
- 0-1 km storm-relative helicity
- 72 m²/s²
- 0-3 km storm-relative helicity
- 91 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
578 ACUS11 KWNS 012318 SWOMCD SPC MCD 012317 PAZ000-MDZ000-VAZ000-DCZ000-020045- MESOSCALE DISCUSSION 2339 NWS STORM PREDICTION CENTER NORMAN OK 0617 PM CDT MON SEP 01 2003 AREAS AFFECTED...SRN PA...MD...DC....EXTREME NRN VA CONCERNING...SEVERE THUNDERSTORM POTENTIAL VALID 012317Z - 020045Z A FEW STRONG TO ISOLD SEVERE STORMS WILL REMAIN POSSIBLE ACROSS PORTIONS OF THE POTOMAC BASIN INTO SRN PA AND NRN MD OVER THE NEXT HOUR OR SO. LIMITED GEOGRAPHIC EXTENT OF THE SEVERE WEATHER THREAT AND UNFAVORABLE DIURNAL FORCING SHOULD PRECLUDE THE NEED FOR A WATCH. ONE CLUSTER OF POORLY ORGANIZED LINEAR CONVECTION HAS MOVED EAST ACROSS NRN VA OVER THE PAST 2 HOURS AND WAS BRIEFLY INTENSIFYING WITHIN LOW LEVEL INSTABILITY AXIS FROM NERN VA/DC AREA INTO MD. ISOLD DOWNBURST WINDS HAVE OCCURRED WITH THIS ACTIVITY AND LEADING EDGE SHOULD MOVE INTO DC AREA WITHIN THE HOUR. SLIGHTLY GREATER STORM ORGANIZATION AND A COUPLE OF SPLITTING SUPERCELLS WERE NOTED ON THE SRN BORDER OF PA THIS EVENING WHERE CELLS WERE TRACKING EWD ALONG WELL-DEFINED WARM FRONT. DEEP LAYER SHEAR WAS STRONGER ACROSS THIS REGION THAN FURTHER SOUTH AND LOW LEVEL DIRECTIONAL SHEAR NEAR AND NORTH OF THE FRONT WILL FAVOR MESOCYCLONES. HOWEVER...INSTABILITY WAS LESS ACROSS THE AREA AND STORMS SO FAR APPEAR TO BE SLIGHTLY ELEVATED ABOVE THE FRONTAL SURFACE. NONETHELESS...THIS ACTIVITY WILL NEED TO BE MONITORED CLOSELY FOR DEVIANT RIGHTWARD MOTION NEAR THE BOUNDARY WHERE ENVIRONMENT COULD SUPPORT AN ISOLD WIND/TORNADO EVENT. CONTINUED BOUNDARY LAYER COOLING AND SMALL AREA AFFECTED SUGGESTS THAT A WATCH IS NOT NEEDED AT THIS TIME. ..CARBIN.. 09/01/2003 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...PHI...AKQ...CTP...LWX... 39787765 40097694 39877582 39257646 38557658 38287669 38167740 38787744 38967754
Nearby
Mesoscale Discussions in Maryland, 2003Mesoscale Discussions in Virginia, 2003Mesoscale Discussions in Pennsylvania, 2003Every mesoscale discussion in 2003
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.