Alert archive / Pennsylvania / Severe Thunderstorm Watches in 2004
Severe Thunderstorm Watch 771
The Storm Prediction Center issued this severe thunderstorm watch at Aug 20, 2004, 6:10 PM EDT for 8 states. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 20, 2004, 6:10 PM EDT (22:10 UTC)
- Expired
- Aug 20, 2004, 11:00 PM EDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
All 66 counties
Berkshire County, MA, Bristol County, MA, Essex County, MA, Franklin County, MA, Hampden County, MA, Hampshire County, MA, Middlesex County, MA, Norfolk County, MA, Plymouth County, MA, Suffolk County, MA, Worcester County, MA, York County, ME, Cheshire County, NH, Hillsborough County, NH, Rockingham County, NH, Strafford County, NH, Passaic County, NJ, Sussex County, NJ, Warren County, NJ, Albany County, NY, Broome County, NY, Chemung County, NY, Columbia County, NY, Delaware County, NY, Dutchess County, NY, Greene County, NY, Orange County, NY, Putnam County, NY, Rensselaer County, NY, Rockland County, NY, Schoharie County, NY, Sullivan County, NY, Tioga County, NY, Ulster County, NY, Westchester County, NY, Bradford County, PA, Cameron County, PA, Carbon County, PA, Centre County, PA, Clinton County, PA, Columbia County, PA, Huntingdon County, PA, Juniata County, PA, Lackawanna County, PA, Luzerne County, PA, Lycoming County, PA, Mifflin County, PA, Monroe County, PA, Montour County, PA, Northampton County, PA, Northumberland County, PA, Perry County, PA, Pike County, PA, Potter 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, Bristol County, RI, Kent County, RI, Providence County, RI, Windham County, VT
The radar
The Binghamton radar (KBGM), 78 km from the middle of the area, began a volume at 22:11 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.
Warnings issued inside it
13 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 20, 6:23 PM EDT | Severe Thunderstorm Warning | ALY | Berkshire | 52 min |
| Aug 20, 6:25 PM EDT | Severe Thunderstorm Warning | PHI | Northampton | 50 min |
| Aug 20, 6:41 PM EDT | Severe Thunderstorm Warning | BOX | Middlesex, Norfolk, Suffolk | 49 min |
| Aug 20, 6:54 PM EDT | Severe Thunderstorm Warning | ALY | Albany | 36 min |
| Aug 20, 7:20 PM EDT | Severe Thunderstorm Warning | ALY | Greene | 25 min |
| Aug 20, 7:22 PM EDT | Severe Thunderstorm Warning | BOX | Cheshire | 23 min |
| Aug 20, 7:27 PM EDT | Severe Thunderstorm Warning | ALY | Columbia, Rensselaer | 63 min |
| Aug 20, 7:30 PM EDT | Flash Flood Warning | CTP | Union | 6 hr |
| Aug 20, 7:56 PM EDT | Severe Thunderstorm Warning | OKX | Rockland | 34 min |
| Aug 20, 8:01 PM EDT | Severe Thunderstorm Warning | OKX | Orange | 44 min |
| Aug 20, 8:04 PM EDT | Severe Thunderstorm Warning | OKX | Westchester | 26 min |
| Aug 20, 8:19 PM EDT | Severe Thunderstorm Warning | OKX | Putnam | 41 min |
| Aug 20, 8:31 PM EDT | Severe Thunderstorm Warning | BOX | Middlesex | 29 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Albany, NY (KALY), launched 12:00Z, 10.2 hours before the alert went out and 149 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
- 244 J/kg
- Mixed-layer CIN
- -24 J/kg
- Mixed-layer LCL
- 569 m above ground
- 0-6 km bulk shear
- 51 kt
- 0-1 km storm-relative helicity
- 77 m²/s²
- 0-3 km storm-relative helicity
- 142 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.2
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 20, 11:56 AM EDT | Mesoscale Discussion | SPC | 2 hr | |
| Aug 20, 1:05 PM EDT | Severe Thunderstorm Watch | SPC | 6 hr | |
| Aug 20, 3:41 PM EDT | Mesoscale Discussion | SPC | 2 hr | |
| Aug 20, 2:05 PM EDT | Severe Thunderstorm Watch | SPC | Morris, Sussex, Warren | 5 hr |
| Aug 19, 8:28 PM EDT | Mesoscale Discussion | SPC | Adams | 92 min |
| Aug 20, 4:03 PM EDT | Mesoscale Discussion | SPC | Adams, Bedford, Berks, Cumberland, Franklin, Fulton and 4 more | 2 hr |
| Aug 20, 4:25 PM EDT | Severe Thunderstorm Watch | SPC | Allegheny, Armstrong, Beaver, Butler, Cambria, Clearfield and 7 more | 5 hr |
| Aug 20, 7:15 PM EDT | Mesoscale Discussion | SPC | Cambria, Clearfield, Indiana, Somerset, Westmoreland | 90 min |
Nearby
Severe Thunderstorm Watches in Pennsylvania, 2004Severe Thunderstorm Watches in New York, 2004Severe Thunderstorm Watches in Massachusetts, 2004Every severe thunderstorm watch in 2004
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.