Alert archive / Massachusetts / Flash Flood Warnings in 2021

Flash Flood Warning 21, NWS Boston/Norton, MA

August 19, 2021Essex County, Middlesex County, Massachusetts

NWS Boston/Norton, MA issued this flash flood warning at Aug 19, 2021, 11:40 AM EDT for Essex County, Middlesex County, Massachusetts. It was in force for 3 hr. 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, 11:40 AM EDT (15:40 UTC)
Expired
Aug 19, 2021, 2:45 PM EDT
In force
3 hr
Issued by
NWS Boston/Norton, MA
Area
Storm-based polygon
Flood severity
None

Counties Essex County, MA, Middlesex County, MA

The radar

The Boston radar (KBOX), 90 km from the middle of the area, began a volume at 15:38 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

TimeReportWhereRemark
Aug 19, 1:00 PM EDTFLOODPeabody, MAPIERMONT STREET FLOODED AND IMPASSABLE
Aug 19, 2:02 PM EDTFLOOD2 Ese Peabody, MASOCIAL MEDIA IMAGE OF FLOODING ON MAIN ST IN PEABODY.

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, 3.7 hours before the alert went out and 140 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.

Skew-T log-pSkew-T log-p diagram, Gray, ME at 12:00Z on 2021-08-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 110 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Gray, ME at 12:00Z on 2021-08-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 36 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
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

Open this sounding in Storm Lab

The text

As transmitted.

467 
WGUS51 KBOX 191540
FFWBOX
MAC009-017-191845-
/O.NEW.KBOX.FF.W.0021.210819T1540Z-210819T1845Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Boston/Norton MA
1140 AM EDT Thu Aug 19 2021

The National Weather Service in Norton has issued a

* Flash Flood Warning for...
  Essex County in northeastern Massachusetts...
  Northeastern Middlesex County in northeastern Massachusetts...

* Until 245 PM EDT.

* At 1140 AM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Up to 1.5 inches of rain have 
  fallen. The expected rainfall rate is 1.5 inches in 1 hour. Flash 
  flooding is ongoing or expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Lowell, Lynn, Lawrence, Haverhill, Peabody, Methuen, Salem, 
  Billerica, Beverly, Woburn, Chelmsford, Andover, Lexington, 
  Dracut, Tewksbury, Gloucester, North Andover, Saugus, Danvers and 
  Wakefield.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 4274 7125 4274 7118 4279 7119 4281 7117
      4282 7113 4281 7107 4286 7103 4288 7093
      4286 7085 4287 7082 4281 7081 4282 7082
      4280 7083 4281 7071 4267 7054 4248 7076
      4249 7147 4270 7147 4270 7129

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...1.5 INCHES IN 1 HOUR

$$

AL
3 follow-up statements
103 
WGUS71 KBOX 191729
FFSBOX

Flash Flood Statement
National Weather Service Boston/Norton MA
129 PM EDT Thu Aug 19 2021

MAC009-017-191845-
/O.CON.KBOX.FF.W.0021.000000T0000Z-210819T1845Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Essex MA-Middlesex MA-
129 PM EDT Thu Aug 19 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 245 PM EDT THIS 
AFTERNOON FOR ESSEX AND NORTHEASTERN MIDDLESEX COUNTIES...

At 129 PM EDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. While no significant reports of 
flooding have been reported, Hamilton Police Dept reports many roads 
in Hamilton have 1 to 3 inches of standing water on them. Between 1 
and 3 inches of rain have fallen. The expected rainfall rate is 1.25 
inches in 1 hour. Flash flooding is ongoing or expected to begin 
shortly as torrential rainfall moves across the warned area.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Radar.

IMPACT...Flash flooding of small creeks and streams, urban areas,
         highways, streets and underpasses as well as other poor
         drainage and low-lying areas.

Some locations that will experience flash flooding include...
  Lowell, Lynn, Lawrence, Haverhill, Peabody, Methuen, Salem, 
  Billerica, Beverly, Woburn, Chelmsford, Andover, Lexington, 
  Dracut, Tewksbury, Gloucester, North Andover, Saugus, Danvers and 
  Wakefield.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 4274 7125 4274 7118 4279 7119 4281 7117
      4282 7113 4281 7107 4286 7103 4288 7093
      4286 7085 4287 7082 4281 7081 4282 7082
      4280 7083 4281 7071 4267 7054 4248 7076
      4249 7147 4270 7147 4270 7129

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...1.25 INCHES IN 1 HOUR

$$

AL
755 
WGUS71 KBOX 191754
FFSBOX

Flash Flood Statement
National Weather Service Boston/Norton MA
154 PM EDT Thu Aug 19 2021

MAC009-017-191845-
/O.CON.KBOX.FF.W.0021.000000T0000Z-210819T1845Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Essex MA-Middlesex MA-
154 PM EDT Thu Aug 19 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 245 PM EDT THIS 
AFTERNOON FOR ESSEX AND NORTHEASTERN MIDDLESEX COUNTIES...

At 154 PM EDT, thunderstorms producing heavy rain continued across 
the warned area. Public reported that Main St in Peabody near the 
Eagan Place intersection is flooded. In addition, portions of Route 
1 in Saugus are flooded with high water flowing over both lanes. 
Between 1 and 3 inches of rain have fallen. The expected rainfall 
rate is 1.25 inches in 1 hour. Flash flooding is already occurring 
and additional rains may worsen or trigger new areas of flooding.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Public reported.

IMPACT...Flash flooding of small creeks and streams, urban areas,
         highways, streets and underpasses as well as other poor
         drainage and low-lying areas.

Some locations that will experience flash flooding include...
  Lowell, Lynn, Lawrence, Haverhill, Peabody, Methuen, Salem, 
  Billerica, Beverly, Woburn, Chelmsford, Andover, Lexington, 
  Dracut, Tewksbury, Gloucester, North Andover, Saugus, Danvers and 
  Wakefield.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 4274 7125 4274 7118 4279 7119 4281 7117
      4282 7113 4281 7107 4286 7103 4288 7093
      4286 7085 4287 7082 4281 7081 4282 7082
      4280 7083 4281 7071 4267 7054 4248 7076
      4249 7147 4270 7147 4270 7129

FLASH FLOOD...OBSERVED
EXPECTED RAINFALL...1.25 INCHES IN 1 HOUR

$$

AL
468 
WGUS71 KBOX 191843
FFSBOX

Flash Flood Statement
National Weather Service Boston/Norton MA
243 PM EDT Thu Aug 19 2021

MAC009-017-191853-
/O.EXP.KBOX.FF.W.0021.000000T0000Z-210819T1845Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Essex MA-Middlesex MA-
243 PM EDT Thu Aug 19 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 245 PM EDT THIS AFTERNOON FOR 
ESSEX AND NORTHEASTERN MIDDLESEX COUNTIES...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 4274 7125 4274 7118 4279 7119 4281 7117
      4282 7113 4281 7107 4286 7103 4288 7093
      4286 7085 4287 7082 4281 7081 4282 7082
      4280 7083 4281 7071 4267 7054 4248 7076
      4249 7147 4270 7147 4270 7129

$$

AL

The office that day

Everything else NWS Boston/Norton, MA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 19, 8:14 AM EDTFlash Flood WarningBOXHampden, Worcester3 hr
Aug 19, 9:18 AM EDTFlash Flood WarningBOXHampden, Hampshire, Worcester3 hr
Aug 19, 10:14 AM EDTSevere Thunderstorm WarningBOXMiddlesex, Worcester44 min
Aug 19, 10:21 AM EDTTornado WarningBOXMiddlesex, Worcester29 min
Aug 19, 10:46 AM EDTFlash Flood WarningBOXEssex, Middlesex, Norfolk, Suffolk, Worcester3 hr
Aug 19, 11:36 AM EDTSevere Thunderstorm WarningBOXEssex, Middlesex, Norfolk, Suffolk, Worcester54 min
Aug 19, 12:32 PM EDTSevere Thunderstorm WarningBOXEssex, Middlesex, Norfolk, Suffolk58 min
Aug 19, 12:33 PM EDTSpecial Marine WarningBOX57 min
Aug 19, 12:49 PM EDTTornado WarningBOXEssex, Middlesex, Suffolk39 min
Aug 19, 1:18 PM EDTTornado WarningBOXMiddlesex, Worcester27 min
Aug 19, 1:37 PM EDTSpecial Weather StatementBOXEssex38 min
Aug 19, 1:38 PM EDTSpecial Marine WarningBOX67 min
Aug 19, 1:46 PM EDTSpecial Weather StatementBOXBarnstable59 min
Aug 19, 1:48 PM EDTSpecial Marine WarningBOX57 min
Aug 19, 1:54 PM EDTSpecial Weather StatementBOXMiddlesex51 min
Aug 19, 2:23 PM EDTSevere Thunderstorm WarningBOXMiddlesex37 min

Nearby

Flash Flood Warnings in Massachusetts, 2021Every flash flood 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.