Alert archive / Pennsylvania / Mesoscale Discussions in 2012
Mesoscale Discussion 959
The Storm Prediction Center issued this mesoscale discussion at May 29, 2012, 2:13 PM EDT for 10 counties in New Jersey; 16 counties in New York; 41 counties in Pennsylvania. It was in force for 62 min.
The area
The outline as issued.
The facts
- Issued
- May 29, 2012, 2:13 PM EDT (18:13 UTC)
- Expired
- May 29, 2012, 3:15 PM EDT
- In force
- 62 min
- Issued by
- the Storm Prediction Center
All 67 counties
Bergen County, NJ, Essex County, NJ, Hunterdon County, NJ, Mercer County, NJ, Morris County, NJ, Passaic County, NJ, Somerset County, NJ, Sussex County, NJ, Union County, NJ, Warren County, NJ, Broome County, NY, Chemung County, NY, Chenango County, NY, Cortland County, NY, Delaware County, NY, Dutchess County, NY, Madison County, NY, Orange County, NY, Otsego County, NY, Putnam County, NY, Rockland County, NY, Sullivan County, NY, Tioga County, NY, Tompkins County, NY, Ulster County, NY, Westchester County, NY, Adams County, PA, Bedford 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
The radar
The Binghamton radar (KBGM), 120 km from the middle of the area, began a volume at 18:16 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
Albany, NY (KALY), launched 12:00Z, 6.2 hours before the alert went out and 204 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
- 1908 J/kg
- Mixed-layer CIN
- -96 J/kg
- Mixed-layer LCL
- 1026 m above ground
- 0-6 km bulk shear
- 42 kt
- 0-1 km storm-relative helicity
- 123 m²/s²
- 0-3 km storm-relative helicity
- 141 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 0.7
The text
As transmitted, in the capitals the NWS used until 2016.
408
ACUS11 KWNS 291813
SWOMCD
SPC MCD 291813
CTZ000-NYZ000-NJZ000-PAZ000-DEZ000-MDZ000-291915-
MESOSCALE DISCUSSION 0959
NWS STORM PREDICTION CENTER NORMAN OK
0113 PM CDT TUE MAY 29 2012
AREAS AFFECTED...CNTRL/ERN PA...S CNTRL NY/SERN NY...SRN NEW ENGLAND
CONCERNING...SEVERE THUNDERSTORM WATCH 314...
VALID 291813Z - 291915Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 314
CONTINUES.
SUMMARY...SEVERAL ROUNDS OF SEVERE THUNDERSTORMS APPEAR LIKELY
ACROSS THE WW AREA. WITH NEW DEVELOPMENT NOW NOTED ACROSS THE
POCONOS AND CATSKILLS...AN ADDITIONAL WW WILL LIKELY BE NEEDED EAST
OF WW314.
DISCUSSION...SEVERAL LINES OF PRE-FRONTAL CONVECTION FORMED THIS
MORNING IN RESPONSE TO FORCING FOR ASCENT ATTENDANT TO AN
APPROACHING UPPER TROUGH. A LEADING SURGING OUTFLOW HAS BEEN NOTED
ON 18Z VISIBLE IMAGERY...AND WILL LIKELY INITIATE NEW SEVERE
CONVECTION IN ADVANCE OF THE PRIMARY LINE OF CONVECTION. THIS NEW
CONVECTIVE DEVELOPMENT WILL LIKELY OVERTAKE THE ONGOING ACTIVITY
ALONG THE ALLEGHENIES. GIVEN AMPLE SURFACE-BASED DESTABILIZATION AND
INCREASING HEIGHT FALLS...THE ACTIVITY WILL LIKELY CONTINUE TO
PRODUCE DMGG WINDS AND HAIL. DMGG WINDS ARE ESPECIALLY POSSIBLE
ACROSS CNTRL NY...WHERE LOW-LEVEL SHEAR REMAINS STRONGER THAN TO THE
S.
FARTHER E...A FEW STRONGER CELLS HAVE BEEN NOTED ALONG THE POCONOS
AND CATSKILLS. ALTHOUGH MORE VIGOROUS AND WIDESPREAD ACTIVITY MAY BE
SOMEWHAT DELAYED UNTIL HEIGHTS FALL MORE RAPIDLY...SBCAPE NEAR
2000-2500 J/KG PER MESOANALYSIS AND MODEST EFFECTIVE SHEAR OF 30 KTS
OVER SERN NY MAY SUPPORT A FEW SEVERE STORMS IN THE MEANTIME. WITH
THE NEW ACTIVITY AND AN INCREASE IN CONVECTION FROM THE W...A NEW WW
EAST OF WW314 MAY BE NEEDED.
..HURLBUT.. 05/29/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...OKX...ALY...PHI...BGM...CTP...LWX...
LAT...LON 39687878 41807754 43047577 42637469 42187449 41977339
41827305 41347339 40847406 40097480 39757529 39687878SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 29, 12:26 PM EDT | Tornado Watch | SPC | Northwest Hills Planning Region | 8 hr |
| May 29, 3:44 PM EDT | Severe Thunderstorm Watch | SPC | Capitol Planning Region | 5 hr |
| May 29, 5:54 PM EDT | Severe Thunderstorm Watch | SPC | Greater Bridgeport Planning Region, Naugatuck Valley Planning Region | 3 hr |
| May 29, 7:01 PM EDT | Mesoscale Discussion | SPC | 89 min | |
| May 29, 7:21 PM EDT | Mesoscale Discussion | SPC | 54 min | |
| May 29, 4:40 PM EDT | Mesoscale Discussion | SPC | Hunterdon, Morris, Sussex, Warren | 65 min |
| May 29, 10:27 AM EDT | Severe Thunderstorm Watch | SPC | Allegany, Cattaraugus, Cayuga, Chautauqua, Jefferson, Lewis and 11 more | 5 hr |
| May 29, 11:43 AM EDT | Mesoscale Discussion | SPC | Albany, Broome, Cayuga, Chemung, Chenango, Columbia and 26 more | 62 min |
| May 29, 12:01 PM EDT | Mesoscale Discussion | SPC | Albany, Broome, Chemung, Chenango, Columbia, Cortland and 19 more | 59 min |
| May 29, 1:03 PM EDT | Severe Thunderstorm Watch | SPC | Broome, Chemung, Chenango, Cortland, Delaware, Madison and 5 more | 8 hr |
| May 29, 1:25 PM EDT | Mesoscale Discussion | SPC | Allegany, Cattaraugus, Cayuga, Chautauqua, Erie, Genesee and 13 more | 65 min |
| May 29, 1:52 PM EDT | Mesoscale Discussion | SPC | Albany, Clinton, Columbia, Essex, Franklin, Fulton and 8 more | 53 min |
| May 29, 3:12 PM EDT | Mesoscale Discussion | SPC | Broome, Cayuga, Chemung, Chenango, Cortland, Delaware and 12 more | 63 min |
| May 29, 3:26 PM EDT | Mesoscale Discussion | SPC | Albany, Clinton, Columbia, Essex, Franklin, Fulton and 11 more | 64 min |
| May 29, 9:48 AM EDT | Mesoscale Discussion | SPC | Allegheny, Armstrong, Beaver, Butler, Clarion, Clearfield and 8 more | 87 min |
Nearby
Mesoscale Discussions in Pennsylvania, 2012Mesoscale Discussions in New York, 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.