Alert archive / Pennsylvania / Mesoscale Discussions in 2012
Mesoscale Discussion 913
The Storm Prediction Center issued this mesoscale discussion at May 26, 2012, 6:04 PM EDT for 12 counties in New Jersey; 9 counties in New York; 19 counties in Pennsylvania. It was in force for 56 min.
The area
The outline as issued.
The facts
- Issued
- May 26, 2012, 6:04 PM EDT (22:04 UTC)
- Expired
- May 26, 2012, 7:00 PM EDT
- In force
- 56 min
- Issued by
- the Storm Prediction Center
All 40 counties
Bergen County, NJ, Essex County, NJ, Hudson County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Morris County, NJ, Passaic County, NJ, Somerset County, NJ, Sussex County, NJ, Union County, NJ, Warren County, NJ, Bronx County, NY, Kings County, NY, Nassau County, NY, New York County, NY, Queens County, NY, Richmond County, NY, Rockland County, NY, Suffolk County, NY, Westchester County, NY, Adams County, PA, Berks County, PA, Bucks County, PA, Carbon County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Juniata County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Monroe County, PA, Montgomery County, PA, Northampton County, PA, Northumberland County, PA, Perry County, PA, Schuylkill County, PA, Snyder County, PA, York County, PA
The radar
The Philadelphia radar (KDIX), 132 km from the middle of the area, began a volume at 22:05 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, 10.1 hours before the alert went out and 229 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
- 225 J/kg
- Mixed-layer CIN
- -140 J/kg
- Mixed-layer LCL
- 809 m above ground
- 0-6 km bulk shear
- 16 kt
- 0-1 km storm-relative helicity
- 74 m²/s²
- 0-3 km storm-relative helicity
- 75 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
168
ACUS11 KWNS 262205
SWOMCD
SPC MCD 262204
CTZ000-NYZ000-NJZ000-PAZ000-262300-
MESOSCALE DISCUSSION 0913
NWS STORM PREDICTION CENTER NORMAN OK
0504 PM CDT SAT MAY 26 2012
AREAS AFFECTED...PA...NY...NJ...CT
CONCERNING...SEVERE THUNDERSTORM WATCH 300...
VALID 262204Z - 262300Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 300
CONTINUES.
SUMMARY...ISOLATED SEVERE POTENTIAL WILL CONTINUE ACROSS THE WATCH
AREA FOR THE NEXT 1 TO 2 HOURS.
DISCUSSION...CONVECTIVE TRENDS HAVE DECREASED CONSIDERABLY OVER THE
PAST HOUR. ADDITIONALLY...COLD FRONT IS BECOMING MORE DIFFUSE AND
VEERING WIND PROFILES AHEAD OF THE FRONT HAVE DECREASED MASS
CONVERGENCE. 21Z MESOANALYSIS HAS MLCAPE VALUES AOA 2500 J/KG AHEAD
OF THE FRONT ACROSS PORTIONS OF WRN PA AND NRN NJ. THIS APPEARS TO
BE SIGNIFICANTLY TOO HIGH...LIKELY CAUSED BY ERRONEOUS RAP FORECAST
LOW-LEVEL MOISTURE PROFILE. MORE REASONABLE MLCAPE VALUES ARE LIKELY
HALF THOSE VALUES...CLOSER TO 1500 J/KG. THESE INSTABILITY VALUES
COMBINED WITH WEAK SHEAR PROFILES WILL FAVOR SHORT-LIVED PULSE
CONVECTION WITH A LOW-END HAIL/WIND THREAT. ISOLATED SEVERE
POTENTIAL WILL CONTINUE FOR THE NEXT 1-2 HOURS AS STORMS DEVELOP
ALONG OUTFLOW BOUNDARIES FROM PREVIOUS STORMS OR THE COLD FRONT BUT
AN OVERALL DOWNWARD TREND IN CONVECTIVE ACTIVITY IS EXPECTED.
..MOSIER.. 05/26/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...BOX...OKX...ALY...PHI...BGM...CTP...
LAT...LON 39807740 40247747 40687744 40987698 41437365 41607245
40647248 39937636 39807740SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 26, 1:17 PM EDT | Mesoscale Discussion | SPC | 88 min | |
| May 26, 2:08 PM EDT | Mesoscale Discussion | SPC | 37 min | |
| May 26, 2:29 PM EDT | Severe Thunderstorm Watch | SPC | Greater Bridgeport Planning Region, Naugatuck Valley Planning Region | 6 hr |
| May 25, 9:18 PM EDT | Mesoscale Discussion | SPC | Cayuga, Franklin, Hamilton, Herkimer, Jefferson, Lewis and 5 more | 117 min |
Nearby
Mesoscale Discussions in Pennsylvania, 2012Mesoscale Discussions in New Jersey, 2012Mesoscale Discussions in New York, 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.