Alert archive / Massachusetts / Mesoscale Discussions in 2020
Mesoscale Discussion 1396
The Storm Prediction Center issued this mesoscale discussion at Aug 4, 2020, 11:34 AM EDT for 4 states. It was in force for 86 min.
The area
The outline as issued.
The facts
- Issued
- Aug 4, 2020, 11:34 AM EDT (15:34 UTC)
- Expired
- Aug 4, 2020, 1:00 PM EDT
- In force
- 86 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...tornado watch likely
- Chance of a watch
- 95%
Counties Bristol County, MA, Dukes 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, Cheshire County, NH, Bristol County, RI, Kent County, RI, Newport County, RI, Providence County, RI, Windham County, VT
The radar
The Boston radar (KBOX), 58 km from the middle of the area, began a volume at 15:34 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
Brookhaven, NY (KOKX), launched 12:00Z, 3.6 hours before the alert went out and 153 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
- 1593 J/kg
- Mixed-layer CIN
- -3 J/kg
- Mixed-layer LCL
- 570 m above ground
- 0-6 km bulk shear
- 53 kt
- 0-1 km storm-relative helicity
- 150 m²/s²
- 0-3 km storm-relative helicity
- 245 m²/s²
- Significant tornado parameter
- 1.5
- Supercell composite
- 7.4
The text
As transmitted.
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</html>SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 4, 6:45 AM EDT | Mesoscale Discussion | SPC | 3 hr | |
| Aug 4, 7:23 AM EDT | Tornado Watch | SPC | Greater Bridgeport Planning Region, Lower Connecticut River Valley Planning Region, Naugatuck Valley Planning Region, Southeastern Connecticut Planning Region | 9 hr |
| Aug 4, 11:13 AM EDT | Mesoscale Discussion | SPC | 92 min | |
| Aug 4, 12:43 PM EDT | Tornado Watch | SPC | Capitol Planning Region, Northwest Hills Planning Region, Northeastern Connecticut Planning Region | 6 hr |
| Aug 4, 3:05 PM EDT | Mesoscale Discussion | SPC | 85 min | |
| Aug 4, 5:44 PM EDT | Mesoscale Discussion | SPC | Essex, Middlesex, Suffolk | 2 hr |
Nearby
Mesoscale Discussions in Massachusetts, 2020Mesoscale Discussions in Rhode Island, 2020Mesoscale Discussions in Connecticut, 2020Every mesoscale discussion in 2020
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.