Alert archive / Maryland / Mesoscale Discussions in 2012
Mesoscale Discussion 1812
The Storm Prediction Center issued this mesoscale discussion at Aug 25, 2012, 4:46 PM EDT for Somerset County, Wicomico County, Worcester County, Maryland; Accomack County, Virginia. It was in force for 89 min.
The area
The outline as issued.
The facts
- Issued
- Aug 25, 2012, 4:46 PM EDT (20:46 UTC)
- Expired
- Aug 25, 2012, 6:15 PM EDT
- In force
- 89 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 20%
Counties Somerset County, MD, Wicomico County, MD, Worcester County, MD, Accomack County, VA
The radar
The Dover AFB radar (KDOX), 83 km from the middle of the area, began a volume at 20:48 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
Wallops Is Stn, VA (KWAL), launched 12:00Z, 8.8 hours before the alert went out and 21 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
- 86 J/kg
- Mixed-layer CIN
- -59 J/kg
- Mixed-layer LCL
- 860 m above ground
- 0-6 km bulk shear
- 21 kt
- 0-1 km storm-relative helicity
- -37 m²/s²
- 0-3 km storm-relative helicity
- 64 m²/s²
- Significant tornado parameter
- -0.0
- Supercell composite
- -0.0
The text
As transmitted, in the capitals the NWS used until 2016.
728 ACUS11 KWNS 252046 SWOMCD SPC MCD 252046 DEZ000-MDZ000-VAZ000-252215- MESOSCALE DISCUSSION 1812 NWS STORM PREDICTION CENTER NORMAN OK 0346 PM CDT SAT AUG 25 2012 AREAS AFFECTED...ERN VA THROUGH SRN MD AND EXTREME SRN DE CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY VALID 252046Z - 252215Z PROBABILITY OF WATCH ISSUANCE...20 PERCENT SUMMARY...THE THREAT FOR A COUPLE OF ISOLATED TORNADOES IS EXPECTED TO PERSIST INTO THE EARLY EVENING OVER EXTREME ERN VA INTO SRN MD AND EXTREME SRN DE. OVERALL THREAT DOES NOT APPEAR SUFFICIENT FOR A WW AT THIS TIME...AND HEAVY RAIN REMAINS THE PRIMARY CONCERN. DISCUSSION...SFC LOW HAS DEVELOPED INTO SERN VA IN ASSOCIATION WITH A SLOW NWD MOVING UPPER LOW CIRCULATION. WARM FRONT EXTENDS NEWD FROM THE LOW INTO THE CHESAPEAKE BAY AREA. DESPITE CLEARING AND HEATING OF THE BOUNDARY LAYER IN THE WARM SECTOR...INSTABILITY REMAINS LIMITED TO AOB 500 J/KG DUE TO POOR MID LEVEL LAPSE RATES...POSSIBLY EXACERBATED BY WHAT APPEARS TO BE WEAK SUBSIDENCE IN NWD EXPANDING MID LEVEL DRY SLOT REGION. THE GREATEST POTENTIAL FOR AN ISOLATED TORNADO SHOULD PERSIST FROM ERN VA INTO SRN MD AND SRN DE THIS EVENING AS STORMS INTERACT WITH FRONT AND LIFT IS MAXIMIZED WHERE MOIST INFLOW FROM MODEST SELY LLJ INTERSECTS THIS QUASI-STATIONARY BOUNDARY. THE ZONE OF STRONGER MESOSCALE ASCENT WILL SHIFT SLOWLY NWD THROUGH MID EVENING WITH HEAVY RAIN LIKELY PROMOTED BY 1.5-2 INCH PW AND TRAINING CELLS ALONG WARM CONVEYOR BELT. ..DIAL/WEISS.. 08/25/2012 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...PHI...AKQ... LAT...LON 38337509 37707559 37457639 38627554 38337509
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 25, 11:22 AM EDT | Mesoscale Discussion | SPC | Somerset, Worcester | 113 min |
| Aug 25, 6:12 AM EDT | Mesoscale Discussion | SPC | Accomack, Gloucester, Isle of Wight, James City, Mathews, Middlesex and 15 more | 3 hr |
Nearby
Mesoscale Discussions in Maryland, 2012Mesoscale Discussions in 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.