Alert archive / Massachusetts / Severe Thunderstorm Warnings in 2021
Severe Thunderstorm Warning 86, NWS Boston/Norton, MA
NWS Boston/Norton, MA issued this severe thunderstorm warning at Jul 21, 2021, 8:30 PM EDT for Norfolk County, Plymouth County, Suffolk County, Massachusetts. It was in force for 30 min. 2 reports came from inside the area while it was in force.
The area
The outline as issued, with what was reported inside it.
The facts
- Issued
- Jul 21, 2021, 8:30 PM EDT (00:30 UTC)
- Expired
- Jul 21, 2021, 9:00 PM EDT
- In force
- 30 min
- Issued by
- NWS Boston/Norton, MA
- Area
- Storm-based polygon
- Hail
- 1.0 in
- Wind
- 60.0 mph
Counties Norfolk County, MA, Plymouth County, MA, Suffolk County, MA
The radar
The Boston radar (KBOX), 37 km from the middle of the area, began a volume at 00:29 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.
What was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| Jul 21, 8:35 PM EDT | TSTM WND DMG | Randolph, MA | LARGE LIMB DOWN ON DOOR STREET AT VINTON STREET. THE TIME IS APPROXIMATE. |
| Jul 21, 8:35 PM EDT | TSTM WND DMG | Randolph, MA | POWER LINES DOWN ON DOOR STREET AT RUSS STREET. TIME APPROXIMATE. |
Local storm reports filed while the alert was in force, from inside its polygon or its counties.
The nearest sounding before it
Gray, ME (KGYX), launched 00:00Z, 0.5 hours before the alert went out and 192 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
- 445 J/kg
- Mixed-layer CIN
- -27 J/kg
- Mixed-layer LCL
- 843 m above ground
- 0-6 km bulk shear
- 23 kt
- 0-1 km storm-relative helicity
- -15 m²/s²
- 0-3 km storm-relative helicity
- 42 m²/s²
- Significant tornado parameter
- -0.0
- Supercell composite
- -0.2
The text
As transmitted.
051
WUUS51 KBOX 220030
SVRBOX
MAC021-023-025-220130-
/O.NEW.KBOX.SV.W.0086.210722T0030Z-210722T0130Z/
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Boston/Norton MA
830 PM EDT Wed Jul 21 2021
The National Weather Service in Boston/Norton has issued a
* Severe Thunderstorm Warning for...
South central Suffolk County in eastern Massachusetts...
Northeastern Norfolk County in eastern Massachusetts...
Northern Plymouth County in southeastern Massachusetts...
* Until 930 PM EDT.
* At 828 PM EDT, a severe thunderstorm was located over Braintree,
moving east at 20 mph.
HAZARD...60 mph wind gusts and quarter size hail.
SOURCE...Radar indicated.
IMPACT...Expect wind damage to trees and power lines. Minor hail
damage to vehicles is possible.
* Locations impacted include...
Boston, Brockton, Quincy, Weymouth, Braintree, Randolph, Milton,
Stoughton, Marshfield, Hingham, Canton, Scituate, Pembroke,
Rockland, Abington, Duxbury, Whitman, Hanover, Holbrook and
Norwell.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
&&
LAT...LON 4206 7065 4210 7109 4228 7110 4229 7102
4226 7097 4229 7095 4225 7096 4227 7093
4225 7088 4228 7090 4230 7088 4226 7087
4227 7083 4224 7077 4225 7077 4220 7071
4217 7073 4208 7064
TIME...MOT...LOC 0028Z 270DEG 17KT 4219 7101
HAIL...1.00IN
WIND...60MPH
$$
Chai1 follow-up statement
710
WWUS51 KBOX 220100
SVSBOX
Severe Weather Statement
National Weather Service Boston/Norton MA
900 PM EDT Wed Jul 21 2021
MAC021-023-025-220108-
/O.CAN.KBOX.SV.W.0086.000000T0000Z-210722T0130Z/
Suffolk MA-Norfolk MA-Plymouth MA-
900 PM EDT Wed Jul 21 2021
...THE SEVERE THUNDERSTORM WARNING FOR SOUTH CENTRAL SUFFOLK...
NORTHEASTERN NORFOLK AND NORTHERN PLYMOUTH COUNTIES IS CANCELLED...
The storm which prompted the warning has weakened below severe
limits, and has exited the warned area. Therefore, the warning has
been cancelled. However heavy rain is still possible with this
thunderstorm.
LAT...LON 4206 7065 4210 7109 4228 7110 4229 7102
4226 7097 4229 7095 4225 7096 4227 7093
4225 7088 4228 7090 4230 7088 4226 7087
4227 7083 4224 7077 4225 7077 4220 7071
4217 7073 4208 7064
TIME...MOT...LOC 0057Z 270DEG 17KT 4219 7081
$$
ChaiThe office that day
Everything else NWS Boston/Norton, MA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 21, 8:20 PM EDT | Special Weather Statement | BOX | Norfolk | 40 min |
| Jul 21, 8:27 PM EDT | Special Marine Warning | BOX | 63 min | |
| Jul 21, 8:42 PM EDT | Special Marine Warning | BOX | 63 min | |
| Jul 21, 8:46 PM EDT | Special Weather Statement | BOX | Plymouth | 44 min |
| Jul 21, 9:29 PM EDT | Special Weather Statement | BOX | Plymouth | 46 min |
| Jul 21, 9:51 PM EDT | Special Marine Warning | BOX | 54 min | |
| Jul 21, 9:53 PM EDT | Special Weather Statement | BOX | Barnstable | 37 min |
Nearby
Severe Thunderstorm Warnings in Massachusetts, 2021Every severe thunderstorm warning in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.