Alert archive / Pennsylvania / Mesoscale Discussions in 2012
Mesoscale Discussion 1708
The Storm Prediction Center issued this mesoscale discussion at Aug 5, 2012, 2:49 PM EDT for 7 states. It was in force for 86 min.
The area
The outline as issued.
The facts
- Issued
- Aug 5, 2012, 2:49 PM EDT (18:49 UTC)
- Expired
- Aug 5, 2012, 4:15 PM EDT
- In force
- 86 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 40%
All 120 counties
Kent County, DE, New Castle 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, 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, Washington County, MD, Bergen County, NJ, Burlington County, NJ, Camden County, NJ, Cumberland County, NJ, Essex County, NJ, Gloucester County, NJ, Hudson County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Monmouth County, NJ, Morris County, NJ, Passaic County, NJ, Salem County, NJ, Somerset County, NJ, Sussex County, NJ, Union County, NJ, Warren County, NJ, Bronx County, NY, Broome County, NY, Chemung County, NY, Chenango County, NY, Delaware County, NY, Dutchess County, NY, Kings County, NY, New York County, NY, Orange County, NY, Putnam County, NY, Queens County, NY, Richmond County, NY, Rockland County, NY, Sullivan County, NY, Tioga County, NY, Ulster County, NY, Adams County, PA, Berks County, PA, Bradford County, PA, Bucks County, PA, Carbon County, PA, Centre County, PA, Chester County, PA, Clinton County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Delaware County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Juniata County, PA, Lackawanna County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Luzerne County, PA, Lycoming County, PA, Mifflin County, PA, Monroe County, PA, Montgomery County, PA, Montour County, PA, Northampton County, PA, Northumberland County, PA, Perry County, PA, Philadelphia County, PA, Pike County, PA, Schuylkill County, PA, Snyder County, PA, Sullivan County, PA, Susquehanna County, PA, Tioga County, PA, Union County, PA, Wayne County, PA, Wyoming County, PA, York County, PA, Arlington County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, King George County, VA, Loudoun County, VA, Madison County, VA, Orange County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Berkeley County, WV, Jefferson County, WV, Morgan County, WV
The radar
The State College radar (KCCX), 145 km from the middle of the area, began a volume at 18:50 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Washington/Dulle, VA (KIAD), launched 12:00Z, 6.8 hours before the alert went out and 156 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
- 809 J/kg
- Mixed-layer CIN
- -82 J/kg
- Mixed-layer LCL
- 1048 m above ground
- 0-6 km bulk shear
- 5 kt
- 0-1 km storm-relative helicity
- 48 m²/s²
- 0-3 km storm-relative helicity
- 57 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
140
ACUS11 KWNS 051850
SWOMCD
SPC MCD 051849 COR
NYZ000-NJZ000-PAZ000-DEZ000-MDZ000-VAZ000-DCZ000-WVZ000-052015-
MESOSCALE DISCUSSION 1708
NWS STORM PREDICTION CENTER NORMAN OK
0149 PM CDT SUN AUG 05 2012
AREAS AFFECTED...PORTIONS OF SRN NY...CENTRAL/ERN PA...NJ...MD...ERN
WV...NRN VA AND NRN DE
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 051849Z - 052015Z
CORRECTED FOR GEOGRAPHIC REFERENCES
PROBABILITY OF WATCH ISSUANCE...40 PERCENT
SUMMARY...TSTMS DEVELOPING IN CLUSTERS/LINE SEGMENTS WILL LIKELY
CONTINUE TO INTENSIFY THROUGH REMAINDER OF AFTN WITH A SVR WIND AND
ISOLATED HAIL THREAT. AREA IS BEING MONITORED FOR A POSSIBLE WW.
DISCUSSION...TSTMS CONTINUE TO DEVELOP ACROSS CENTRAL/ERN PA SWD
INTO WRN VA IN DIFFERENTIAL HEATING ZONE AND AIDED BY OROGRAPHIC
FORCING. OBJECTIVE ANALYSIS INDICATED MLCAPE VALUES OF 1500 TO
LOCALLY 2500 J/KG. AREA IS ON THE SRN FRINGE OF STRONGER MID-LEVEL
FLOW ASSOCIATED WITH UPPER TROUGH ROTATING THROUGH ERN GREAT
LAKES/WRN NEW ENGLAND...HOWEVER SHEAR SHOULD BE SUFFICIENT FOR
MULTICELL STORMS/CLUSTERS CAPABLE OF PRODUCING DAMAGING WINDS. POOR
LAPSE RATES SHOULD LIMIT LARGE HAIL THREAT...BUT AN ISOLATED LARGE
HAIL REPORT IS POSSIBLE. CONVECTIVE TRENDS WILL CONTINUE TO BE
MONITORED AND A WW IS POSSIBLE IN THE NEXT FEW HOURS.
..BUNTING/THOMPSON.. 08/05/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...OKX...ALY...PHI...BGM...AKQ...CTP...LWX...
LAT...LON 40767804 42127746 42507629 42607508 41987366 40627381
39407499 38727607 38217698 38017780 38267841 38687886
40767804SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 5, 3:36 PM EDT | Severe Thunderstorm Watch | SPC | Kent, New Castle | 5 hr |
| Aug 5, 6:38 PM EDT | Mesoscale Discussion | SPC | Kent, New Castle | 2 hr |
| Aug 5, 12:06 PM EDT | Mesoscale Discussion | SPC | Allegany, Cattaraugus, Cayuga, Chautauqua, Erie, Genesee and 10 more | 84 min |
| Aug 5, 12:42 PM EDT | Severe Thunderstorm Watch | SPC | Allegany, Cattaraugus, Cayuga, Chautauqua, Chemung, Cortland and 20 more | 6 hr |
| Aug 5, 4:21 PM EDT | Mesoscale Discussion | SPC | Cayuga, Clinton, Cortland, Essex, Franklin, Fulton and 13 more | 84 min |
| Aug 4, 10:46 PM EDT | Mesoscale Discussion | SPC | Mercer | 119 min |
Nearby
Mesoscale Discussions in Pennsylvania, 2012Mesoscale Discussions in Virginia, 2012Mesoscale Discussions in New Jersey, 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.