Alert archive / Massachusetts / Flash Flood Watches in 2020

Flash Flood Watch 1, NWS Boston/Norton, MA

July 9, 202013 counties in Massachusetts; 5 counties in Rhode Island; Capitol Planning Region, Northeastern Connecticut Planning Region, Connecticut

NWS Boston/Norton, MA issued this flash flood watch at Jul 9, 2020, 4:06 PM EDT for 13 counties in Massachusetts; 5 counties in Rhode Island; Capitol Planning Region, Northeastern Connecticut Planning Region, Connecticut. It took effect at Jul 10, 2020, 12:00 PM EDT. It was in force for 9 hr.

The area

The counties it named.

The facts

Issued: Jul 9, 2020, 4:06 PM EDT (20:06 UTC)
In effect from: Jul 10, 2020, 12:00 PM EDT
Expired: Jul 10, 2020, 8:39 PM EDT
In force: 9 hr
Issued by: NWS Boston/Norton, MA
Flood severity: None

Counties Capitol Planning Region, CT, Northeastern Connecticut Planning Region, CT, Barnstable County, MA, Bristol County, MA, Dukes County, MA, Essex County, MA, Franklin County, MA, Hampden County, MA, Hampshire County, MA, Middlesex County, MA, Nantucket County, MA, Norfolk County, MA, Plymouth County, MA, Suffolk County, MA, Worcester County, MA, Bristol County, RI, Kent County, RI, Newport County, RI, Providence County, RI, Washington County, RI

The radar

The Boston radar (KBOX), 26 km from the middle of the area, began a volume at 20:07 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 nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 8.1 hours before the alert went out and 168 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: 119 J/kg
Mixed-layer CIN: -57 J/kg
Mixed-layer LCL: 858 m above ground
0-6 km bulk shear: 8 kt
0-1 km storm-relative helicity: 5 m²/s²
0-3 km storm-relative helicity: 12 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood watch went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Boston/Norton, MA wrote its last area forecast discussion before this flash flood watch went out at Jul 9, 10:47 AM EDT, 5 hours 19 minutes earlier.

Area forecast discussion, Jul 9, 10:47 AM EDT, 5 hours 19 minutes before

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Hazardous weather outlook, Jul 9, 4:22 AM EDT, 11 hours 44 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 9, 4:20 PM EDT	Special Weather Statement	BOX	Franklin	40 min
Jul 9, 4:58 PM EDT	Special Weather Statement	BOX	Franklin	47 min
Jul 9, 5:49 PM EDT	Special Weather Statement	BOX	Franklin	41 min
Jul 9, 6:44 PM EDT	Special Weather Statement	BOX	Franklin	46 min
Jul 9, 7:31 PM EDT	Special Weather Statement	BOX	Hampshire	59 min

Nearby

Flash Flood Watches in Massachusetts, 2020 Flash Flood Watches in Rhode Island, 2020 Flash Flood Watches in Connecticut, 2020 Every flash flood watch 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.