Alert archive / Massachusetts / Flash Flood Warnings in 2021

Flash Flood Warning 5, NWS Boston/Norton, MA

July 9, 20216 counties in Massachusetts

NWS Boston/Norton, MA issued this flash flood warning at Jul 9, 2021, 9:32 AM EDT for 6 counties in Massachusetts. It was in force for 6 hr. 8 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 9, 2021, 9:32 AM EDT (13:32 UTC)
Expired: Jul 9, 2021, 3:24 PM EDT
In force: 6 hr
Issued by: NWS Boston/Norton, MA
Area: Storm-based polygon
Flood severity: None

Counties Bristol County, MA, Essex County, MA, Middlesex County, MA, Norfolk County, MA, Plymouth County, MA, Suffolk County, MA

The radar

The Boston radar (KBOX), 42 km from the middle of the area, began a volume at 13:31 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 9, 10:16 AM EDT	FLOOD	Winthrop, MA	FRANKLIN STREET CLOSED DUE TO FLOODING.
Jul 9, 12:03 PM EDT	FLOOD	Newton, MA	ALBERMARLE ROAD FROM CRAFTS STREET TO WATERTOWN STREET IS CLOSED DUE TO FLOODING. REPORTED BY AMATEUR RADIO.
Jul 9, 12:05 PM EDT	FLOOD	Lynn, MA	CARS STUCK IN STREET FLOODING ON THE ROUTE 107 BRIDGE. REPORTED BY AMATEUR RADIO.
Jul 9, 12:09 PM EDT	FLOOD	Sharon, MA	CANTON STREET UNDERPASS IS BEING CLOSED DUE TO FLOODING. REPORTED BY AMATEUR RADIO.
Jul 9, 12:15 PM EDT	FLOOD	Melrose, MA	SYLVAN STREET FROM MAIN TO MOUNT VERNON STREET CLOSED DUE TO FLOODING. REPORTED BY AMATEUR RADIO.
Jul 9, 12:34 PM EDT	FLOOD	Peabody, MA	WALNUT STREET CLOSED DUE TO FLOODING.
Jul 9, 2:19 PM EDT	FLOOD	Hyde Park, MA	TRUMAN PARKWAY CLOSED DUE TO FLOODING BETWEEN BRUSH HILL RD AND WARREN ST.
Jul 9, 2:53 PM EDT	FLOOD	Boston, MA	CAR STUCK IN STREET FLOODING ON FRANKLIN PARK AVE NEAR AMERICAN LEGION HWY.

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, 1.5 hours before the alert went out and 185 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 638 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 101 m²/s²
0-3 km storm-relative helicity: 384 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

As transmitted.

653 
WGUS51 KBOX 091332
FFWBOX
MAC005-009-017-021-023-025-091930-
/O.NEW.KBOX.FF.W.0005.210709T1332Z-210709T1930Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Boston/Norton MA
932 AM EDT Fri Jul 9 2021

The National Weather Service in Norton has issued a

* Flash Flood Warning for...
  Norfolk County in eastern Massachusetts...
  Suffolk County in eastern Massachusetts...
  South Central Essex County in northeastern Massachusetts...
  East Central Middlesex County in northeastern Massachusetts...
  Northwestern Bristol County in southeastern Massachusetts...
  Northern Plymouth County in southeastern Massachusetts...

* Until 330 PM EDT.

* At 932 AM EDT, Doppler radar indicated bands of moderate to heavy 
  rain crossing through greater Boston area. Between 0.5 and 1 inch 
  of rain has fallen in communities south of Boston. Additional 
  rainfall amounts of 1 to 3 inches are possible in the warned area 
  during the next several hours. Flash flooding is expected to begin 
  shortly.

  HAZARD...Flash flooding caused by heavy rain.

  SOURCE...Radar.

  IMPACT...Flash flooding of small 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...
  Boston, Cambridge, Brockton, Quincy, Lynn, Newton, Somerville, 
  Waltham, Malden, Brookline, Medford, Weymouth, Revere, Peabody, 
  Arlington, Everett, Salem, Billerica, Beverly and Woburn.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 4239 7133 4250 7130 4260 7103 4254 7088
      4251 7080 4244 7091 4243 7091 4234 7088
      4229 7086 4227 7076 4206 7063 4206 7065
      4199 7132 4206 7133 4227 7130

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...0.5-1.5 INCHES IN 1 HOUR

$$

NB

1 follow-up statement

166 
WGUS71 KBOX 091924
FFSBOX

Flash Flood Statement
National Weather Service Boston/Norton MA
324 PM EDT Fri Jul 9 2021

MAC005-009-017-021-023-025-091934-
/O.CAN.KBOX.FF.W.0005.000000T0000Z-210709T1930Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Bristol MA-Essex MA-Middlesex MA-Norfolk MA-Plymouth MA-Suffolk MA-
324 PM EDT Fri Jul 9 2021

...FLASH FLOOD WARNING FOR NORFOLK, SUFFOLK, SOUTH CENTRAL ESSEX, 
EAST CENTRAL MIDDLESEX, NORTHWESTERN BRISTOL AND NORTHERN PLYMOUTH 
COUNTIES HAS BEEN REPLACED WITH A FLOOD WARNING...

The heavy rains from Tropical Storm Elsa are ending. However, a 
widespread 2 to 4 inches of rain fell across the region. While the 
significant flash flood threat is ending, areas of stream flooding 
are likely into this evening. Poor drainage floodwaters may take a 
few more hours to fully recede. Please continue to heed any road 
closures.


LAT...LON 4239 7133 4250 7130 4260 7103 4254 7088
      4251 7080 4244 7091 4243 7091 4234 7088
      4229 7086 4227 7076 4206 7063 4206 7065
      4199 7132 4206 7133 4227 7130

$$

NB

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 9, 8:19 AM EDT	Flash Flood Warning	BOX	Hampden, Hampshire	6 hr
Jul 9, 9:11 AM EDT	Flash Flood Warning	BOX	Bristol, Middlesex, Norfolk, Worcester	7 hr
Jul 9, 12:19 PM EDT	River Flood Warning	BOX	Norfolk, Suffolk	4 hr
Jul 9, 12:19 PM EDT	River Flood Warning	BOX	Essex	8 hr
Jul 9, 12:19 PM EDT	River Flood Warning	BOX	Middlesex	37 hr
Jul 9, 2:24 PM EDT	Areal Flood Warning	BOX	Hampden, Worcester	8 hr
Jul 9, 3:24 PM EDT	Areal Flood Warning	BOX	Bristol, Essex, Middlesex, Norfolk, Plymouth, Suffolk	5 hr
Jul 9, 3:41 PM EDT	Areal Flood Warning	BOX	Bristol, Middlesex, Norfolk, Worcester	5 hr
Jul 9, 4:52 PM EDT	Small Craft Advisory	BOX		22 hr
Jul 9, 7:50 PM EDT	Special Weather Statement	BOX	Hampden	40 min

Nearby

Flash Flood Warnings in Massachusetts, 2021 Every 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.