Alert archive / Massachusetts / Areal Flood Warnings in 2017

Areal Flood Warning 20, NWS Boston/Norton, MA

September 15, 2017Essex County, Massachusetts

NWS Boston/Norton, MA issued this areal flood warning at Sep 15, 2017, 5:18 PM EDT for Essex County, Massachusetts. It was in force for 117 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Sep 15, 2017, 5:18 PM EDT (21:18 UTC)
Expired
Sep 15, 2017, 7:15 PM EDT
In force
117 min
Issued by
NWS Boston/Norton, MA
Area
Storm-based polygon
Flood severity
None

County Essex County, MA

The radar

The Boston radar (KBOX), 79 km from the middle of the area, began a volume at 21:19 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

Chatham, MA (KCHH), launched 12:00Z, 9.3 hours before the alert went out and 131 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 2017-09-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 226 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, Chatham, MA at 12:00Z on 2017-09-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 72 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
226 J/kg
Mixed-layer CIN
-109 J/kg
Mixed-layer LCL
790 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
72 m²/s²
0-3 km storm-relative helicity
102 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.5

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this areal flood warning 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 areal flood warning went out at Sep 15, 4:24 PM EDT, 54 minutes earlier.

Area forecast discussion, Sep 15, 4:24 PM EDT, 54 minutes before
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Hazardous weather outlook, Sep 15, 4:19 PM EDT, 59 minutes before
Hazardous Weather Outlook
National Weather Service Taunton MA
419 PM EDT Fri Sep 15 2017

CTZ002>004-MAZ002>024-026-RIZ001>008-162030-
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-Block Island RI-
419 PM EDT Fri Sep 15 2017

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

.DAY ONE...Tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Tropical Cyclone Jose will likely bring high surf and dangerous rip
currents to some ocean-exposed beaches later this weekend into the
middle of next week. There is the potential for significant erosion
along ocean-exposed beaches early to mid next week. There is also a
risk for minor to moderate coastal flooding if Jose passes close
enough to southern New England.

It remains uncertain if Jose will get close enough to southern New
England for any other impacts during the first half of next week.
There is a possibility of tropical storm force winds reaching
portions of Rhode Island and southeast Massachusetts with the Cape
and Islands most at risk. If this should happen, then scattered
power
outages would be possible given full foliage at this time of year.
There could also be pockets of heavy rain.

We need to stress that there remains considerable uncertainty in how
close Jose will get.  People in southern New England are urged to
monitor the latest forecasts through this weekend.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed.

ANZ230>237-250-251-254>256-162030-
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-
419 PM EDT Fri Sep 15 2017

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...Saturday through Thursday.

Tropical Cyclone Jose will likely bring high seas and possibly
significant wind to portions of the coastal waters early next week.
It remains uncertain how close Jose will get to Southern New
England. Mariners are urged to monitor the latest forecasts through
this weekend. Now would be a good time to check moorings.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed.

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, Sep 15, 3:38 PM EDT, 1 hour 40 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE Taunton MA
338 PM EDT FRI SEP 15 2017

MAZ006-007-152000-
Eastern Essex MA-Western Essex MA-
338 PM EDT FRI SEP 15 2017

...Thunderstorms with locally heavy rain in northern Essex County...

At 336 PM EDT, Doppler radar was tracking a strong thunderstorm near
Amesbury, or near Exeter, moving east at 10 mph. Locally heavy
downpours could produce one-half to one inch of rain.

Locations impacted include...
Haverhill, Newburyport, Amesbury, Ipswich, Salisbury, Georgetown,
Newbury, Groveland, Merrimac, Rowley, West Newbury, Seabrook, South
Hampton and Plaistow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Do not drive through flooded roads or underpasses. Avoid low lying
areas near small streams.  When thunder roars, go indoors.

&&

LAT...LON 4286 7085 4287 7082 4283 7081 4281 7087
      4280 7083 4271 7085 4280 7111 4281 7110
      4281 7107 4286 7103 4287 7097 4289 7093
      4289 7090
TIME...MOT...LOC 1936Z 287DEG 8KT 4289 7099

Field
Special weather statement, Sep 15, 4:00 PM EDT, 1 hour 18 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE Taunton MA
400 PM EDT FRI SEP 15 2017

MAZ005-014-152030-
Central Middlesex County MA-Southeast Middlesex MA-
400 PM EDT FRI SEP 15 2017

...Thunderstorm with heavy rain in east central Middlesex County ...

At 358 PM EDT, Doppler radar was tracking a strong thunderstorm over
Carlisle, or near Chelmsford, moving southeast at 10 mph.

Locally heavy downpours and pea size hail will accompany this storm.

Locations impacted include...
Billerica, Chelmsford, Lexington, Acton, Concord, Bedford, Lincoln
and Carlisle.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Do not drive through flooded roads or underpasses. Avoid low lying
areas near small streams. When thunder roars, go indoors.

&&

LAT...LON 4249 7141 4257 7137 4255 7122 4243 7126
TIME...MOT...LOC 1958Z 294DEG 11KT 4252 7135

FIELD
Special weather statement, Sep 15, 4:21 PM EDT, 57 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE Taunton MA
421 PM EDT FRI SEP 15 2017

MAZ006-007-152115-
Eastern Essex MA-Western Essex MA-
421 PM EDT FRI SEP 15 2017

...Torrential Rainfall Affecting northwestern Essex County ...

At 418 PM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from Merrimac Massachusetts to Salem New Hampshire.
Movement was slowly east at 5 to 10 mph. Up to 1 to 1.5 inches of
rain is likely with these storms through 515 PM.

Locations impacted include...
Haverhill, Methuen, Newburyport, Amesbury, Salisbury, Groveland,
Merrimac, West Newbury and Plaistow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Do not drive through flooded roads or underpasses. Avoid low lying
areas near small streams. Remember that when thunder roars, go
indoors.

&&

LAT...LON 4284 7081 4274 7107 4275 7118 4279 7118
      4282 7110 4281 7107 4283 7105 4285 7100
      4285 7082
TIME...MOT...LOC 2018Z 275DEG 8KT 4286 7100 4279 7120

FIELD
Special weather statement, Sep 15, 4:58 PM EDT, 20 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Sep 15, 9:58 AM EDTSpecial Marine WarningBOX62 min
Sep 15, 12:05 PM EDTSpecial Marine WarningBOX85 min
Sep 15, 1:28 PM EDTSpecial Marine WarningBOX62 min
Sep 15, 3:38 PM EDTSpecial Weather StatementBOXEssex22 min
Sep 15, 4:00 PM EDTSpecial Weather StatementBOXMiddlesex30 min
Sep 15, 4:21 PM EDTSpecial Weather StatementBOXEssex54 min
Sep 15, 4:58 PM EDTSpecial Weather StatementBOXMiddlesex32 min
Sep 15, 5:02 PM EDTAreal Flood AdvisoryBOXEssex58 min
Sep 15, 5:34 PM EDTAreal Flood WarningBOXEssex, Middlesex116 min
Sep 15, 6:39 PM EDTAreal Flood AdvisoryBOXSuffolk66 min

Nearby

Areal Flood Warnings in Massachusetts, 2017Every areal flood warning in 2017

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.