Alert archive / Massachusetts / Dense Fog Advisories in 2021

Dense Fog Advisory 6, NWS Boston/Norton, MA

July 14, 202110 counties in Massachusetts; 5 counties in Rhode Island

NWS Boston/Norton, MA issued this dense fog advisory at Jul 14, 2021, 12:32 AM EDT for 10 counties in Massachusetts; 5 counties in Rhode Island. It was in force for 9 hr.

The area

The counties it named.

The facts

Issued
Jul 14, 2021, 12:32 AM EDT (04:32 UTC)
Expired
Jul 14, 2021, 10:00 AM EDT
In force
9 hr
Issued by
NWS Boston/Norton, MA

Counties Barnstable County, MA, Bristol County, MA, Dukes County, MA, Essex 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), 9 km from the middle of the area, began a volume at 04:32 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 00:00Z, 4.5 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-pSkew-T log-p diagram, Brookhaven, NY at 00:00Z on 2021-07-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 64 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Brookhaven, NY at 00:00Z on 2021-07-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 108 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
64 J/kg
Mixed-layer CIN
-315 J/kg
Mixed-layer LCL
438 m above ground
0-6 km bulk shear
19 kt
0-1 km storm-relative helicity
108 m²/s²
0-3 km storm-relative helicity
110 m²/s²
Significant tornado parameter
0.0
Supercell composite
2.8

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this dense fog advisory 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 dense fog advisory went out at Jul 13, 10:42 PM EDT, 1 hour 50 minutes earlier.

Area forecast discussion, Jul 13, 10:42 PM EDT, 1 hour 50 minutes before
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Hazardous weather outlook, Jul 13, 4:34 PM EDT, 7 hours 58 minutes before
Hazardous Weather Outlook
National Weather Service Boston/Norton MA
434 PM EDT Tue Jul 13 2021

CTZ002>004-MAZ002>024-026-RIZ001>007-142045-
Hartford CT-Tolland CT-Windham CT-Western Franklin MA-
Eastern Franklin MA-Northern Worcester MA-Central Middlesex MA-
Western Essex MA-Eastern Essex MA-Western Hampshire MA-
Western Hampden MA-Eastern Hampshire MA-Eastern Hampden MA-
Southern Worcester MA-Western Norfolk MA-Southeast Middlesex MA-
Suffolk MA-Eastern Norfolk MA-Northern Bristol MA-
Western Plymouth MA-Eastern Plymouth MA-Southern Bristol MA-
Southern Plymouth MA-Barnstable MA-Dukes MA-Nantucket MA-
Northern Middlesex MA-Northwest Providence RI-
Southeast Providence RI-Western Kent RI-Eastern Kent RI-Bristol RI-
Washington RI-Newport RI-
434 PM EDT Tue Jul 13 2021

This Hazardous Weather Outlook is for northern Connecticut, all of
Massachusetts east of Berkshire County, northern Rhode
Island and southern Rhode Island.

.DAY ONE...Tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

ANZ230>237-250-251-254>256-142045-
Boston Harbor-Cape Cod Bay-Nantucket Sound-Vineyard Sound-
Buzzards Bay-Rhode Island Sound-Narragansett Bay-Block Island Sound-
Coastal waters east of Ipswich Bay and the Stellwagen Bank National
Marine Sanctuary-Massachusetts Bay and Ipswich Bay-
Coastal waters from Provincetown MA to Chatham MA to Nantucket MA
out 20 nm-
Coastal Waters extending out to 25 nm South of Marthas Vineyard and
Nantucket-
Coastal Waters from Montauk NY to Marthas Vineyard extending out to
20 nm South of Block Island-
434 PM EDT Tue Jul 13 2021

This Hazardous Weather Outlook is for Massachusetts and Rhode
Island coastal waters.

.DAY ONE...Tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

For more information on upcoming hazardous weather, please see the
Area Forecast Discussion on our webpage for the latest forecast
thinking. There is also our Enhanced Hazardous Weather Outlook at
www.weather.gov/box/ehwo

For the latest updates...please visit our webpage at
www.weather.gov/boston

You can follow us on Facebook at
www.facebook.com/nwsboston

You can follow us on Twitter at
@NWSBoston

In the hours before

Special weather statement, Jul 13, 10:09 PM EDT, 2 hours 23 minutes before
Special Weather Statement
National Weather Service Boston/Norton MA
1009 PM EDT Tue Jul 13 2021

CTZ004-MAZ004>007-012>024-026-RIZ001>008-140700-
Windham CT-Northern Worcester MA-Central Middlesex MA-
Western Essex MA-Eastern Essex MA-Southern Worcester MA-
Western Norfolk MA-Southeast Middlesex MA-Suffolk MA-
Eastern Norfolk MA-Northern Bristol MA-Western Plymouth MA-
Eastern Plymouth MA-Southern Bristol MA-Southern Plymouth MA-
Barnstable MA-Dukes MA-Nantucket MA-Northern Middlesex MA-
Northwest Providence RI-Southeast Providence RI-Western Kent RI-
Eastern Kent RI-Bristol RI-Washington RI-Newport RI-
Block Island RI-
Including the cities of Putnam, Willimantic, Barre, Fitchburg,
Framingham, Lowell, Lawrence, Gloucester, Milford, Worcester,
Foxborough, Norwood, Cambridge, Boston, Quincy, Taunton,
Brockton, Plymouth, Fall River, New Bedford, Mattapoisett,
Chatham, Falmouth, Provincetown, Vineyard Haven, Nantucket, Ayer,
Foster, Smithfield, Providence, Coventry, West Greenwich,
East Greenwich, Warwick, West Warwick, Bristol, Narragansett,
Westerly, Newport, and New Shoreham
1009 PM EDT Tue Jul 13 2021

...AREAS OF FOG, LOCALLY DENSE, WILL CONTINUE TO DEVELOP
THROUGH OVERNIGHT...

Areas of fog have developed across central and eastern
Massachusetts, Rhode Island into eastern Connecticut late this
evening. While visibilities have been commonly between one-half
and 2 statute miles, intervals of dense fog with visibilities of
less than one-quarter mile are possible. If visibilities continue
to lower to the point where dense fog becomes more common, a
Dense Fog Advisory may be needed for parts of the area.

Motorists driving overnight are advised to drive with low-beam
headlights and drive at reduced speeds in areas of fog.

Loconto

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 14, 3:36 AM EDTSpecial Weather StatementBOXHampden, Hampshire39 min
Jul 14, 4:15 AM EDTSpecial Weather StatementBOXHampden, Hampshire45 min
Jul 14, 4:46 PM EDTSpecial Weather StatementBOXWorcester44 min
Jul 14, 4:53 PM EDTSevere Thunderstorm WarningBOXFranklin, Worcester52 min
Jul 14, 5:30 PM EDTSevere Thunderstorm WarningBOXFranklin, Hampshire, Worcester45 min
Jul 14, 6:05 PM EDTSevere Thunderstorm WarningBOXFranklin, Hampden, Hampshire, Worcester40 min
Jul 14, 6:38 PM EDTSevere Thunderstorm WarningBOXFranklin, Hampden, Hampshire, Worcester52 min
Jul 14, 7:16 PM EDTFlash Flood WarningBOXHampshire53 min
Jul 14, 7:31 PM EDTSpecial Weather StatementBOXWorcester44 min
Jul 14, 7:33 PM EDTSpecial Weather StatementBOXHampden42 min
Jul 14, 7:46 PM EDTSevere Thunderstorm WarningBOXFranklin, Hampden, Hampshire, Worcester26 min
Jul 14, 4:37 AM EDTSpecial Weather StatementBOX38 min
Jul 14, 5:46 AM EDTSpecial Weather StatementBOX44 min

Nearby

Dense Fog Advisories in Massachusetts, 2021Dense Fog Advisories in Rhode Island, 2021Every dense fog advisory 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.