Alert archive / Pennsylvania / Mesoscale Discussions in 2011
Mesoscale Discussion 2121
The Storm Prediction Center issued this mesoscale discussion at Sep 4, 2011, 1:33 PM EDT for 19 counties in New York; 34 counties in Pennsylvania. It was in force for 87 min.
The area
The outline as issued.
The facts
- Issued
- Sep 4, 2011, 1:33 PM EDT (17:33 UTC)
- Expired
- Sep 4, 2011, 3:00 PM EDT
- In force
- 87 min
- Issued by
- the Storm Prediction Center
All 53 counties
Broome County, NY, Chemung County, NY, Chenango County, NY, Cortland County, NY, Delaware County, NY, Fulton County, NY, Hamilton County, NY, Herkimer County, NY, Madison County, NY, Montgomery County, NY, Oneida County, NY, Onondaga County, NY, Otsego County, NY, Schoharie County, NY, Schuyler County, NY, Steuben County, NY, Sullivan County, NY, Tioga County, NY, Tompkins County, NY, Bedford County, PA, Blair County, PA, Bradford County, PA, Cambria County, PA, Cameron County, PA, Centre County, PA, Clearfield County, PA, Clinton County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Indiana County, PA, Juniata County, PA, Lackawanna County, PA, Luzerne County, PA, Lycoming County, PA, Mifflin County, PA, Montour County, PA, Northumberland County, PA, Perry County, PA, Potter County, PA, Schuylkill County, PA, Snyder County, PA, Somerset County, PA, Sullivan County, PA, Susquehanna County, PA, Tioga County, PA, Union County, PA, Wayne County, PA, Westmoreland County, PA, Wyoming County, PA
The radar
The Binghamton radar (KBGM), 110 km from the middle of the area, began a volume at 17:36 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
Buffalo Intl Airport, NY (KBUF), launched 12:00Z, 5.6 hours before the alert went out and 223 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
- 220 J/kg
- Mixed-layer CIN
- -162 J/kg
- Mixed-layer LCL
- 963 m above ground
- 0-6 km bulk shear
- 34 kt
- 0-1 km storm-relative helicity
- 162 m²/s²
- 0-3 km storm-relative helicity
- 96 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.2
The text
As transmitted, in the capitals the NWS used until 2016.
631
ACUS11 KWNS 041733
SWOMCD
SPC MCD 041733
NYZ000-PAZ000-041900-
MESOSCALE DISCUSSION 2121
NWS STORM PREDICTION CENTER NORMAN OK
1233 PM CDT SUN SEP 04 2011
AREAS AFFECTED...PORTIONS OF NY AND PA
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 041733Z - 041900Z
THE THREAT FOR SEVERE STORMS CAPABLE OF DAMAGING WINDS AND HAIL IS
EXPECTED TO INCREASE THIS AFTERNOON AND CONVECTIVE TRENDS ARE BEING
MONITORED FOR A POSSIBLE WATCH.
THOUGH THE SYNOPTIC COLD FRONT REMAINS WEST OF REGIONAL...SURFACE
ANALYSIS AND VISIBLE SATELLITE INDICATE A NUMBER OF WEAK WIND
SHIFTS/OUTFLOW BOUNDARIES PRESENT ACROSS THE DISCUSSION AREA. ONE
OF WHICH APPEARS TO BE SUPPORTING THE DEEPENING OF CUMULUS ACROSS
PARTS OF S-CNTRL NY /N AND E OF BGM/ INTO CNTRL PA /E OF UNV/.
HERE...BREAKS IN THE CLOUDS HAVE ALLOWED TEMPERATURES TO WARM INTO
THE LOW-MID 80S...WHICH WHEN COUPLED WITH DEW POINTS IN THE UPPER
70S-LOWER 80S IS RESULTING IN MLCAPE VALUES OF AROUND 2000 J/KG AND
A WEAKENING CAP.
CURRENT THINKING IS THAT LOW-LEVEL ASCENT ALONG EXISTING SURFACE
BOUNDARIES AND GRADUAL INCREASE IN LARGE-SCALE FORCING AHEAD OF
UPSTREAM TROUGH WILL FOSTER MULTIPLE BANDS/CLUSTERS OF TSTMS THIS
AFTERNOON. THE COMBINATION OF THE MODERATE INSTABILITY AND STEADILY
STRENGTHENING DEEP-LAYER WIND FIELD WILL BE SUPPORTIVE OF ORGANIZED
LINE SEGMENTS/BOWS CAPABLE OF DAMAGING WINDS AND HAIL.
..MEAD.. 09/04/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...ALY...PHI...BGM...BUF...CTP...PBZ...
LAT...LON 40407957 42657695 43987474 43407381 41917443 40587635
39917736 39887898 40407957SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 4, 3:07 AM EDT | Mesoscale Discussion | SPC | Allegany, Cattaraugus, Cayuga, Erie, Genesee, Livingston and 8 more | 83 min |
| Sep 4, 3:26 AM EDT | Severe Thunderstorm Watch | SPC | Allegany, Cattaraugus, Cayuga, Chautauqua, Erie, Genesee and 16 more | 4 hr |
| Sep 4, 6:22 AM EDT | Mesoscale Discussion | SPC | Cayuga, Jefferson, Lewis, Oneida, Onondaga, Ontario and 4 more | 83 min |
| Sep 4, 2:43 PM EDT | Severe Thunderstorm Watch | SPC | Albany, Broome, Cayuga, Chemung, Chenango, Clinton and 30 more | 8 hr |
| Sep 4, 6:06 PM EDT | Mesoscale Discussion | SPC | Albany, Broome, Cayuga, Chemung, Chenango, Clinton and 30 more | 54 min |
Nearby
Mesoscale Discussions in Pennsylvania, 2011Mesoscale Discussions in New York, 2011Every mesoscale discussion in 2011
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.