Alert archive / Massachusetts / Flash Flood Warnings in 2018

Flash Flood Warning 2, NWS Boston/Norton, MA

April 16, 2018Middlesex County, Worcester County, Massachusetts

NWS Boston/Norton, MA issued this flash flood warning at Apr 16, 2018, 1:56 PM EDT for Middlesex County, Worcester County, Massachusetts. It was in force for 3 hr. 6 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: Apr 16, 2018, 1:56 PM EDT (17:56 UTC)
Expired: Apr 16, 2018, 4:45 PM EDT
In force: 3 hr
Issued by: NWS Boston/Norton, MA
Area: Storm-based polygon
Flood severity: None

Counties Middlesex County, MA, Worcester County, MA

The radar

The Boston radar (KBOX), 57 km from the middle of the area, began a volume at 17:57 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
Apr 16, 3:33 PM EDT	FLOOD	Shrewsbury, MA	CAR STUCK IN FLOOD WATERS ON OAK STREET
Apr 16, 4:02 PM EDT	FLOOD	Shrewsbury, MA	ROUTE 9 WESTBOUND FLOODED AND IMPASSABLE
Apr 16, 4:24 PM EDT	HEAVY RAIN 2.27	Webster, MA
Apr 16, 4:35 PM EDT	FLOOD	Westborough, MA	SECTIONS OF ROUTE 9 ARE FLOODED AND IMPASSABLE
Apr 16, 4:40 PM EDT	FLOOD	Hopkinton, MA	SECTION OF WOODS STREET FLOODED AND IMPASSABLE
Apr 16, 4:47 PM EDT	HEAVY RAIN 2.25	North Grafton, MA

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Chatham, MA (KCHH), launched 12:00Z, 5.9 hours before the alert went out and 157 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: 514 m above ground
0-6 km bulk shear: 57 kt
0-1 km storm-relative helicity: 551 m²/s²
0-3 km storm-relative helicity: 630 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

441 
WGUS51 KBOX 161756
FFWBOX
MAC017-027-162045-
/O.NEW.KBOX.FF.W.0002.180416T1756Z-180416T2045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Boston/Norton MA
156 PM EDT MON APR 16 2018

The National Weather Service in Boston/Norton has issued a

* Flash Flood Warning for...
  Southeastern Worcester County in central Massachusetts...
  South central Middlesex County in northeastern Massachusetts...

* Until 445 PM EDT.

* At 155 PM EDT Doppler radar indicated that showers and 
  thunderstorms producing heavy rainfall were moving into the 
  Worcester area. These showers and thunderstorms will be capable of 
  producing a quick 1 to 2 inches of rain. As a result, urban flash 
  flooding is expected. Significant ponding of water is expected in 
  urban and other poor drainage areas in Worcester and surrounding 
  communities. In addition, some flashy small streams may produce 
  minor flooding.

* Some locations that will experience flooding include...
  Worcester, Marlborough, Shrewsbury, Milford, Westborough, Grafton,
  Holden, Webster, Southbridge, Ashland, Auburn, Northbridge,
  Hopkinton, Northborough, Oxford, Uxbridge, Millbury, Charlton,
  Spencer and Dudley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Flooding will occur quickly and could pose a significant hazard to 
those who try to drive through flooded roads or underpasses. Find 
alternate routes and avoid flooded areas.

&&

LAT...LON 4236 7150 4202 7150 4203 7205 4237 7204

$$

NMB

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 16, 9:51 AM EDT	Wind Advisory	BOX	Barnstable, Bristol, Dukes, Nantucket, Norfolk, Plymouth	10 hr
Apr 16, 11:15 AM EDT	Areal Flood Advisory	BOX	Hampden, Hampshire	4 hr
Apr 16, 12:57 PM EDT	Areal Flood Advisory	BOX	Franklin, Worcester	4 hr
Apr 16, 1:24 PM EDT	Special Weather Statement	BOX	Worcester	36 min
Apr 16, 1:26 PM EDT	Areal Flood Warning	BOX	Hampden, Hampshire	6 hr
Apr 16, 3:41 PM EDT	Small Craft Advisory	BOX		60 hr
Apr 16, 3:42 PM EDT	Coastal Flood Advisory	BOX	Bristol	7 hr
Apr 16, 5:14 PM EDT	Special Weather Statement	BOX	Bristol, Norfolk, Suffolk	46 min
Apr 16, 6:07 PM EDT	River Flood Warning	BOX	Middlesex	9 hr
Apr 16, 6:35 PM EDT	River Flood Warning	BOX	Norfolk, Suffolk	7 hr

Nearby

Flash Flood Warnings in Massachusetts, 2018 Every flash flood warning in 2018

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.