Alert archive / Massachusetts / Severe Thunderstorm Warnings in 2021
Severe Thunderstorm Warning 105, NWS Boston/Norton, MA
NWS Boston/Norton, MA issued this severe thunderstorm warning at Aug 19, 2021, 12:32 PM EDT for 4 counties in Massachusetts. It was in force for 58 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
- Aug 19, 2021, 12:32 PM EDT (16:32 UTC)
- Expired
- Aug 19, 2021, 1:30 PM EDT
- In force
- 58 min
- Issued by
- NWS Boston/Norton, MA
- Area
- Storm-based polygon
- Tornado
- Possible
- Hail
- 0.75 in
- Wind
- 60.0 mph
Counties Essex County, MA, Middlesex County, MA, Norfolk County, MA, Suffolk County, MA
The radar
The Boston radar (KBOX), 56 km from the middle of the area, began a volume at 16:36 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 |
|---|---|---|---|
| Aug 19, 12:42 PM EDT | TSTM WND DMG | Somerville, MA | TREE DOWN AT 40 BLOCK OF DERBY STREET. RELAYED BY AMATEUR RADIO. |
| Aug 19, 1:00 PM EDT | TSTM WND DMG | Lynnfield, MA | TREE DOWN ON POWER LINES AT HEATH CIRCLE |
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 12:00Z, 4.5 hours before the alert went out and 171 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
- 110 J/kg
- Mixed-layer CIN
- -40 J/kg
- Mixed-layer LCL
- 884 m above ground
- 0-6 km bulk shear
- 13 kt
- 0-1 km storm-relative helicity
- 36 m²/s²
- 0-3 km storm-relative helicity
- 68 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
860
WUUS51 KBOX 191632
SVRBOX
MAC009-017-021-025-191730-
/O.NEW.KBOX.SV.W.0105.210819T1632Z-210819T1730Z/
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Boston/Norton MA
1232 PM EDT Thu Aug 19 2021
The National Weather Service in Boston/Norton has issued a
* Severe Thunderstorm Warning for...
Suffolk County in eastern Massachusetts...
Northeastern Norfolk County in eastern Massachusetts...
Southeastern Essex County in northeastern Massachusetts...
East central Middlesex County in northeastern Massachusetts...
* Until 130 PM EDT.
* At 1231 PM EDT, a severe thunderstorm was located over Cambridge,
moving northeast at 25 mph.
HAZARD...60 mph wind gusts and penny size hail.
SOURCE...Radar indicated.
IMPACT...Expect damage to trees and power lines.
* Locations impacted include...
Boston, Cambridge, Quincy, Lynn, Newton, Somerville, Waltham,
Malden, Brookline, Medford, Revere, Peabody, Arlington, Everett,
Salem, Beverly, Woburn, Chelsea, Watertown and Gloucester.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.
&&
LAT...LON 4258 7065 4254 7090 4254 7087 4250 7085
4246 7094 4242 7091 4243 7092 4241 7099
4236 7097 4237 7099 4232 7096 4238 7105
4230 7103 4230 7101 4225 7114 4237 7125
4273 7082
TIME...MOT...LOC 1631Z 232DEG 20KT 4235 7109
TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
$$
Chai2 follow-up statements
572
WWUS51 KBOX 191713
SVSBOX
Severe Weather Statement
National Weather Service Boston/Norton MA
113 PM EDT Thu Aug 19 2021
MAC021-025-191723-
/O.CAN.KBOX.SV.W.0105.000000T0000Z-210819T1730Z/
Suffolk MA-Norfolk MA-
113 PM EDT Thu Aug 19 2021
...THE SEVERE THUNDERSTORM WARNING FOR SUFFOLK AND NORTHEASTERN
NORFOLK COUNTIES IS CANCELLED...
The severe thunderstorm which prompted the warning has moved out of
the warned area. Therefore, the warning has been cancelled.
LAT...LON 4258 7065 4254 7090 4254 7087 4250 7085
4248 7089 4250 7110 4273 7082
TIME...MOT...LOC 1713Z 232DEG 20KT 4249 7084
$$
MAC009-017-191730-
/O.CON.KBOX.SV.W.0105.000000T0000Z-210819T1730Z/
Essex MA-Middlesex MA-
113 PM EDT Thu Aug 19 2021
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 130 PM EDT
FOR SOUTHEASTERN ESSEX AND EASTERN MIDDLESEX COUNTIES...
At 113 PM EDT, a severe thunderstorm was located over Marblehead, or
over Salem, moving northeast at 25 mph.
HAZARD...60 mph wind gusts and penny size hail.
SOURCE...Radar indicated.
IMPACT...Expect damage to trees and power lines.
Locations impacted include...
Lynn, Peabody, Salem, Beverly, Gloucester, Saugus, Danvers,
Wakefield, Stoneham, Marblehead, Swampscott, Ipswich, Lynnfield,
Middleton, Hamilton, Topsfield, Manchester, Wenham and Essex.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
For your protection move to an interior room on the lowest floor of a
building.
Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.
&&
LAT...LON 4258 7065 4254 7090 4254 7087 4250 7085
4248 7089 4250 7110 4273 7082
TIME...MOT...LOC 1713Z 232DEG 20KT 4249 7084
TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
$$
Chai879
WWUS51 KBOX 191729
SVSBOX
Severe Weather Statement
National Weather Service Boston/Norton MA
129 PM EDT Thu Aug 19 2021
MAC009-017-191739-
/O.EXP.KBOX.SV.W.0105.000000T0000Z-210819T1730Z/
Essex MA-Middlesex MA-
129 PM EDT Thu Aug 19 2021
...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN ESSEX AND EASTERN
MIDDLESEX COUNTIES WILL EXPIRE AT 130 PM EDT...
The storm which prompted the warning has weakened below severe
limits, and has exited the warned area. Therefore, the warning will
be allowed to expire. However heavy rain is still possible with this
thunderstorm.
LAT...LON 4258 7065 4254 7090 4254 7087 4250 7085
4248 7089 4250 7110 4273 7082
TIME...MOT...LOC 1729Z 232DEG 20KT 4254 7075
$$
ChaiThe office that day
Everything else NWS Boston/Norton, MA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 19, 8:14 AM EDT | Flash Flood Warning | BOX | Hampden, Worcester | 3 hr |
| Aug 19, 9:18 AM EDT | Flash Flood Warning | BOX | Hampden, Hampshire, Worcester | 3 hr |
| Aug 19, 10:14 AM EDT | Severe Thunderstorm Warning | BOX | Middlesex, Worcester | 44 min |
| Aug 19, 10:21 AM EDT | Tornado Warning | BOX | Middlesex, Worcester | 29 min |
| Aug 19, 10:46 AM EDT | Flash Flood Warning | BOX | Essex, Middlesex, Norfolk, Suffolk, Worcester | 3 hr |
| Aug 19, 11:36 AM EDT | Severe Thunderstorm Warning | BOX | Essex, Middlesex, Norfolk, Suffolk, Worcester | 54 min |
| Aug 19, 11:40 AM EDT | Flash Flood Warning | BOX | Essex, Middlesex | 3 hr |
| Aug 19, 12:33 PM EDT | Special Marine Warning | BOX | 57 min | |
| Aug 19, 12:49 PM EDT | Tornado Warning | BOX | Essex, Middlesex, Suffolk | 39 min |
| Aug 19, 1:18 PM EDT | Tornado Warning | BOX | Middlesex, Worcester | 27 min |
| Aug 19, 1:37 PM EDT | Special Weather Statement | BOX | Essex | 38 min |
| Aug 19, 1:38 PM EDT | Special Marine Warning | BOX | 67 min | |
| Aug 19, 1:46 PM EDT | Special Weather Statement | BOX | Barnstable | 59 min |
| Aug 19, 1:48 PM EDT | Special Marine Warning | BOX | 57 min | |
| Aug 19, 1:54 PM EDT | Special Weather Statement | BOX | Middlesex | 51 min |
| Aug 19, 2:23 PM EDT | Severe Thunderstorm Warning | BOX | Middlesex | 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.