Alert archive / Pennsylvania / Mesoscale Discussions in 2012
Mesoscale Discussion 1303
The Storm Prediction Center issued this mesoscale discussion at Jun 29, 2012, 3:41 AM EDT for 10 counties in New Jersey; 25 counties in Pennsylvania. It was in force for 94 min.
The area
The outline as issued.
The facts
- Issued
- Jun 29, 2012, 3:41 AM EDT (07:41 UTC)
- Expired
- Jun 29, 2012, 5:15 AM EDT
- In force
- 94 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 40%
All 35 counties
Burlington County, NJ, Camden County, NJ, Gloucester County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Morris County, NJ, Ocean County, NJ, Somerset County, NJ, Warren County, NJ, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Delaware County, PA, Juniata County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Luzerne County, PA, Monroe County, PA, Montgomery County, PA, Montour County, PA, Northampton County, PA, Northumberland County, PA, Perry County, PA, Philadelphia County, PA, Schuylkill County, PA, Snyder County, PA, Sullivan County, PA, Union County, PA, York County, PA
The radar
The State College radar (KCCX), 152 km from the middle of the area, began a volume at 07:43 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 00:00Z, 7.7 hours before the alert went out and 207 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 2494 m above ground
- 0-6 km bulk shear
- 56 kt
- 0-1 km storm-relative helicity
- 132 m²/s²
- 0-3 km storm-relative helicity
- 317 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
272
ACUS11 KWNS 290742
SWOMCD
SPC MCD 290741
NJZ000-PAZ000-DEZ000-MDZ000-290915-
MESOSCALE DISCUSSION 1303
NWS STORM PREDICTION CENTER NORMAN OK
0241 AM CDT FRI JUN 29 2012
AREAS AFFECTED...CENTRAL/EASTERN PA TO NJ
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 290741Z - 290915Z
PROBABILITY OF WATCH ISSUANCE...40 PERCENT
SUMMARY...AT LEAST LOCALIZED WIND DAMAGE/SOME HAIL WILL REMAIN
POSSIBLE OVERNIGHT ESPECIALLY ACROSS CENTRAL/SOUTHEAST PA INTO
PORTIONS OF NJ.
DISCUSSION...A RELATIVELY WELL-ORGANIZED MCS/COMPACT BOW
ECHO...INCLUDING PARENT MCV CHARACTERISTICS...WILL CONTINUE TO
STEADILY ADVANCE EAST-SOUTHEASTWARD OVERNIGHT /POTENTIALLY THROUGH
09Z-10Z/ ESPECIALLY ACROSS SOUTHEAST PA INTO NJ. LIKELY ATTRIBUTABLE
TO POST-BOW REAR INFLOW...RECENT WSR-88D DATA FROM CENTRAL PA
SAMPLES 50+ KT WINDS WITHIN THE LOWEST 2-6 KM. WHILE THE BOUNDARY
LAYER CONTINUES TO COOL/REMAINS STABLE AHEAD OF THIS MCS...A
WEST-NORTHWESTERLY INSTABILITY FEED/PLUME OF RELATIVELY STEEP LAPSE
RATES CONTINUES TO OCCUR ABOVE THE SURFACE PER DERIVED REGIONAL WIND
PROFILES/EARLIER 00Z OBSERVED SOUNDINGS. THIS FACTOR...IN
CONJUNCTION WITH A BELT OF MODERATELY STRONG LOW-MID TROPOSPHERIC
FLOW/FAST FORWARD MCS MOTION...WILL MAINTAIN AT LEAST LOCALIZED WIND
DAMAGE/SOME HAIL POTENTIAL EVEN WHILE THE NEAR-SURFACE LAYER WILL
TEND TO REMAIN STABLE.
..GUYER/MEAD.. 06/29/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...OKX...PHI...BGM...CTP...
LAT...LON 41047706 41557651 40917442 39657404 39577549 40257819
40767729 41047706SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 29, 4:34 AM EDT | Severe Thunderstorm Watch | SPC | Atlantic, Burlington, Camden, Cape May, Cumberland, Gloucester and 3 more | 3 hr |
| Jun 28, 8:53 PM EDT | Mesoscale Discussion | SPC | Erie | 97 min |
| Jun 29, 12:45 AM EDT | Mesoscale Discussion | SPC | Armstrong, Blair, Butler, Cambria, Cameron, Centre and 18 more | 90 min |
| Jun 29, 3:07 PM EDT | Mesoscale Discussion | SPC | Greene, Washington | 53 min |
| Jun 29, 6:03 PM EDT | Mesoscale Discussion | SPC | Fayette, Greene, Somerset, Washington | 87 min |
| Jun 29, 6:34 PM EDT | Severe Thunderstorm Watch | SPC | Allegheny, Bedford, Fayette, Franklin, Fulton, Greene and 3 more | 6 hr |
| Jun 29, 7:51 PM EDT | Mesoscale Discussion | SPC | Adams, Bedford, Fayette, Franklin, Fulton, Greene and 2 more | 114 min |
Nearby
Mesoscale Discussions in Pennsylvania, 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.