Alert archive / Pennsylvania / Mesoscale Discussions in 2017
Mesoscale Discussion 623
The Storm Prediction Center issued this mesoscale discussion at May 1, 2017, 1:41 PM EDT for 8 counties in New York; 21 counties in Pennsylvania. It was in force for 64 min.
The area
The outline as issued.
The facts
- Issued
- May 1, 2017, 1:41 PM EDT (17:41 UTC)
- Expired
- May 1, 2017, 2:45 PM EDT
- In force
- 64 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 95%
All 29 counties
Allegany County, NY, Cattaraugus County, NY, Genesee County, NY, Livingston County, NY, Ontario County, NY, Steuben County, NY, Wyoming County, NY, Yates County, NY, Bedford County, PA, Blair County, PA, Cambria County, PA, Cameron County, PA, Centre County, PA, Clearfield County, PA, Clinton County, PA, Cumberland County, PA, Elk County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Juniata County, PA, Lycoming County, PA, McKean County, PA, Mifflin County, PA, Perry County, PA, Potter County, PA, Snyder County, PA, Tioga County, PA, Union County, PA
The radar
The State College radar (KCCX), 42 km from the middle of the area, began a volume at 17:43 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
Buffalo Intl Airport, NY (KBUF), launched 12:00Z, 5.7 hours before the alert went out and 189 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
- 1242 m above ground
- 0-6 km bulk shear
- 48 kt
- 0-1 km storm-relative helicity
- 306 m²/s²
- 0-3 km storm-relative helicity
- 318 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
841
ACUS11 KWNS 011742
SWOMCD
SPC MCD 011741
PAZ000-NYZ000-011845-
Mesoscale Discussion 0623
NWS Storm Prediction Center Norman OK
1241 PM CDT Mon May 01 2017
Areas affected...western New York through central Pennsylvania
Concerning...Severe potential...Tornado Watch likely
Valid 011741Z - 011845Z
Probability of Watch Issuance...95 percent
SUMMARY...Severe storm threat with damaging wind and a few tornadoes
should continue to expand eastward into western NY and central PA
this afternoon. A tornado watch will likely be issued soon.
DISCUSSION...Organized line of storms with embedded mesovortices and
bowing segments from Lake Erie through extreme eastern OH is moving
east at around 40 kt. VWP data and special Pittsburg RAOB show very
favorable wind profiles for embedded supercells with large 0-1 km
hodographs. Latest visible imagery also show numerous cloud breaks
which will promote further destabilization of the boundary layer
with 500-1000 J/kg MLCAPE this afternoon.
..Dial/Grams.. 05/01/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BGM...BUF...CTP...PBZ...
LAT...LON 41077867 42167927 43067828 42867709 40577680 39797736
39757878 41077867SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 1, 2:12 PM EDT | Tornado Watch | SPC | Allegany, Broome, Cattaraugus, Cayuga, Chautauqua, Chemung and 23 more | 8 hr |
| May 1, 4:36 PM EDT | Mesoscale Discussion | SPC | Broome, Cayuga, Chemung, Chenango, Cortland, Madison and 11 more | 84 min |
| May 1, 6:29 PM EDT | Mesoscale Discussion | SPC | Albany, Chenango, Clinton, Columbia, Delaware, Dutchess and 20 more | 61 min |
| May 1, 6:52 PM EDT | Severe Thunderstorm Watch | SPC | Albany, Columbia, Delaware, Dutchess, Essex, Franklin and 15 more | 4 hr |
| May 1, 7:16 PM EDT | Mesoscale Discussion | SPC | New York, Richmond, Rockland, Westchester | 2 hr |
| May 1, 11:59 AM EDT | Mesoscale Discussion | SPC | Allegheny, Armstrong, Beaver, Butler, Clarion, Fayette and 8 more | 2 hr |
| May 1, 12:32 PM EDT | Tornado Watch | SPC | Allegheny, Armstrong, Beaver, Butler, Clarion, Crawford and 11 more | 4 hr |
| May 1, 5:54 PM EDT | Severe Thunderstorm Watch | SPC | Adams, Cumberland, Dauphin, Franklin, Lancaster, Lebanon and 3 more | 5 hr |
Nearby
Mesoscale Discussions in Pennsylvania, 2017Mesoscale Discussions in New York, 2017Every mesoscale discussion in 2017
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.