Alert archive / Massachusetts / Mesoscale Discussions in 2021

Mesoscale Discussion 1875

October 16, 2021Bristol County, Plymouth County, Massachusetts; Bristol County, Newport County, Rhode Island

The Storm Prediction Center issued this mesoscale discussion at Oct 16, 2021, 11:21 PM EDT for Bristol County, Plymouth County, Massachusetts; Bristol County, Newport County, Rhode Island. It was in force for 54 min.

The area

The outline as issued.

The facts

Issued
Oct 16, 2021, 11:21 PM EDT (03:21 UTC)
Expired
Oct 17, 2021, 12:15 AM EDT
In force
54 min
Issued by
the Storm Prediction Center
Concerning
Severe potential...watch unlikely
Chance of a watch
5%

Counties Bristol County, MA, Plymouth County, MA, Bristol County, RI, Newport County, RI

The radar

The Boston radar (KBOX), 13 km from the middle of the area, began a volume at 03:18 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, 3.4 hours before the alert went out and 198 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 2021-10-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 107 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 2021-10-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 245 square meters per square second.1939587897117Sfc1 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
107 J/kg
Mixed-layer CIN
-20 J/kg
Mixed-layer LCL
736 m above ground
0-6 km bulk shear
60 kt
0-1 km storm-relative helicity
245 m²/s²
0-3 km storm-relative helicity
384 m²/s²
Significant tornado parameter
0.1
Supercell composite
2.4

Open this sounding in Storm Lab

The text

As transmitted.

362 
ACUS11 KWNS 170321
SWOMCD
SPC MCD 170321 
MAZ000-RIZ000-170415-

Mesoscale Discussion 1875
NWS Storm Prediction Center Norman OK
1021 PM CDT Sat Oct 16 2021

Areas affected...southeast MA

Concerning...Severe potential...Watch unlikely 

Valid 170321Z - 170415Z

Probability of Watch Issuance...5 percent

SUMMARY...Localized damaging gusts cannot be ruled out.  The
expected coverage and magnitude of the potential severe risk will
preclude a severe thunderstorm watch issuance.

DISCUSSION...A cold front continues to progress eastward across
southern New England.  A frontal-forced convective band has
developed over RI and is moving east-northeastward into southeastern
MA.  With the negatively tilted mid-upper trough over the region,
expecting at least a maintenance of convection due in large part to
strong forcing for ascent.  Buoyancy will remain scant but downdraft
potential in the form of stronger gusts is not entirely out of the
question.  As a result, some limited risk for a damaging gust could
materialize, especially if convection intensifies.

..Smith/Guyer.. 10/17/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...BOX...

LAT...LON   42087123 42347096 42297067 41947054 41547084 41387141
            42087123

Nearby

Mesoscale Discussions in Massachusetts, 2021Mesoscale Discussions in Rhode Island, 2021Every mesoscale discussion 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.