Alert archive / Massachusetts / Severe Thunderstorm Warnings in 2004

Severe Thunderstorm Warning 39, NWS Boston/Norton, MA

August 20, 2004Middlesex County, Worcester County, Massachusetts

NWS Boston/Norton, MA issued this severe thunderstorm warning at Aug 20, 2004, 2:28 PM EDT for Middlesex County, Worcester County, Massachusetts. It was in force for 32 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 20, 2004, 2:28 PM EDT (18:28 UTC)
Expired
Aug 20, 2004, 3:00 PM EDT
In force
32 min
Issued by
NWS Boston/Norton, MA
Area
Counties, with a storm outline in the text

Counties Middlesex County, MA, Worcester County, MA

The radar

The Boston radar (KBOX), 80 km from the middle of the area, began a volume at 18:28 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Aug 20, 1:05 PM EDTSevere Thunderstorm WatchSPC6 hr

The nearest sounding before it

Chatham, MA (KCHH), launched 12:00Z, 6.5 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-pSkew-T log-p diagram, Chatham, MA at 12:00Z on 2004-08-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1264 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, Chatham, MA at 12:00Z on 2004-08-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 115 square meters per square second.193958Sfc1 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
1264 J/kg
Mixed-layer CIN
-82 J/kg
Mixed-layer LCL
795 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
115 m²/s²
0-3 km storm-relative helicity
130 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.6

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
WUUS51 KBOX 201828
SVRBOX
MAC017-027-201900-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE TAUNTON MA
228 PM EDT FRI AUG 20 2004

THE NATIONAL WEATHER SERVICE IN TAUNTON HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHEASTERN WORCESTER COUNTY IN CENTRAL MASSACHUSETTS
  THIS INCLUDES THE CITY OF FITCHBURG
  NORTHERN MIDDLESEX COUNTY IN EASTERN MASSACHUSETTS

* UNTIL 300 PM EDT

* AT 224 PM EDT...TRAINED WEATHER SPOTTERS REPORTED A SEVERE   
THUNDERSTORM PRODUCING LARGE DAMAGING HAIL UP TO GOLF BALL SIZE.  
THIS STORM WAS LOCATED NEAR ASHBURNHAM...OR ABOUT NEAR   
FITCHBURG...AND MOVING EAST AT 20 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  FITCHBURG AND ASHBY BY 235 PM EDT
  LUNENBURG BY 245 PM EDT
  TOWNSEND BY 250 PM EDT
  SHIRLEY BY 255 PM EDT
  GROTON...PEPPERELL...AYER AND 8 MILES SOUTHWEST OF DUNSTABLE BY 300
  PM EDT

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE
IMMEDIATELY FOR DAMAGING WINDS...DESTRUCTIVE HAIL...AND DEADLY CLOUD
TO GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...
PREFERABLY INSIDE A STRONG BUILDING BUT AWAY FROM WINDOWS.

LAT...LON 4251 7138 4251 7158 4252 7159 4253 7198
      4271 7200 4270 7194 4270 7145 4269 7144
      4269 7134 4251 7134

$$

NMB/AED

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 20, 1:59 PM EDTSevere Thunderstorm WarningBOXWorcester31 min
Aug 20, 2:07 PM EDTTornado WarningBOXWorcester23 min
Aug 20, 2:58 PM EDTSevere Thunderstorm WarningBOXMiddlesex, Worcester47 min
Aug 20, 3:25 PM EDTSevere Thunderstorm WarningBOXEssex, Middlesex50 min
Aug 20, 3:51 PM EDTSpecial Marine WarningBOX84 min
Aug 20, 4:29 PM EDTSevere Thunderstorm WarningBOXEssex, Middlesex46 min
Aug 20, 4:33 PM EDTSevere Thunderstorm WarningBOXFranklin, Hampshire27 min
Aug 20, 5:27 PM EDTSpecial Marine WarningBOX48 min
Aug 20, 6:03 PM EDTSevere Thunderstorm WarningBOXMiddlesex, Worcester42 min
Aug 20, 6:41 PM EDTSevere Thunderstorm WarningBOXMiddlesex, Norfolk, Suffolk49 min
Aug 20, 6:46 PM EDTSpecial Marine WarningBOX89 min
Aug 20, 6:46 PM EDTSpecial Marine WarningBOX89 min

Nearby

Severe Thunderstorm Warnings in Massachusetts, 2004Every severe thunderstorm warning in 2004

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.