Alert archive / Massachusetts / Severe Thunderstorm Watches in 2003
Severe Thunderstorm Watch 794
The Storm Prediction Center issued this severe thunderstorm watch at Jul 21, 2003, 8:40 PM EDT for 4 states. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 21, 2003, 8:40 PM EDT (00:40 UTC)
- Expired
- Jul 22, 2003, 1:00 AM EDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
Counties Franklin County, MA, Hampden County, MA, Hampshire County, MA, Worcester County, MA, Cheshire County, NH, Hillsborough County, NH, Kent County, RI, Providence County, RI, Windham County, VT
The radar
The Boston radar (KBOX), 103 km from the middle of the area, began a volume at 00:41 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
2 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 21, 9:24 PM EDT | Severe Thunderstorm Warning | BOX | Franklin | 36 min |
| Jul 21, 9:37 PM EDT | Severe Thunderstorm Warning | ALY | Windham | 53 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 00:00Z, 0.7 hours before the alert went out and 143 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
- 1765 J/kg
- Mixed-layer CIN
- -13 J/kg
- Mixed-layer LCL
- 601 m above ground
- 0-6 km bulk shear
- 56 kt
- 0-1 km storm-relative helicity
- 347 m²/s²
- 0-3 km storm-relative helicity
- 418 m²/s²
- Significant tornado parameter
- 4.6
- Supercell composite
- 21.6
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 21, 10:33 PM EDT | Mesoscale Discussion | SPC | 87 min | |
| Jul 22, 1:45 PM EDT | Severe Thunderstorm Watch | SPC | 5 hr |
Nearby
Severe Thunderstorm Watches in Massachusetts, 2003Severe Thunderstorm Watches in Connecticut, 2003Severe Thunderstorm Watches in New Hampshire, 2003Every severe thunderstorm watch in 2003
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.