Mesoscale Discussion 1722

Issued

Sep 9, 2021, 4:12 AM EDT (08:12 UTC)

Expired

Sep 9, 2021, 6:45 AM EDT

In force

3 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

20%

Counties Bristol County, MA, Essex County, MA, Middlesex County, MA, Norfolk County, MA, Plymouth County, MA, Suffolk County, MA, Worcester County, MA, Hillsborough County, NH, Rockingham County, NH, Bristol County, RI, Kent County, RI, Newport County, RI, Providence County, RI, Washington County, RI

The Boston radar (KBOX), 28 km from the middle of the area, began a volume at 08:15 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.

444 
ACUS11 KWNS 090813
SWOMCD
SPC MCD 090812 
MAZ000-NHZ000-RIZ000-CTZ000-NYZ000-091045-

Mesoscale Discussion 1722
NWS Storm Prediction Center Norman OK
0312 AM CDT Thu Sep 09 2021

Areas affected...Portions of eastern CT...RI...central/eastern
MA...and southern NH

Concerning...Severe potential...Watch unlikely 

Valid 090812Z - 091045Z

Probability of Watch Issuance...20 percent

SUMMARY...An isolated threat for strong to damaging winds and
perhaps a brief tornado may continue through the early morning.
Watch issuance appears unlikely at this time.

DISCUSSION...A small cluster of storms has recently strengthened
over central/eastern CT ahead of a cold front. The thermodynamic
environment across southern New England may be marginally suitable
for surface-based storms, with low to mid 70s surface temperatures
and mid to upper 60s dewpoints supporting around 250-500 J/kg of
MLCAPE. About 35-40 kt of deep-layer shear is present across this
region in association with an upper trough extending across much of
the eastern CONUS. Multicells and marginal supercells may occur as
storms move eastward early this morning. Enhanced southwesterly
low-level winds attendant to a low-level jet appear to be fairly
well sampled by the KBOX VWP, and strong to locally damaging winds
may occur. Given current storm motion, around 100-150 m2/s2 of
0-1-km SRH is present, which could support occasional low-level
rotation and perhaps a brief tornado. Current expectations are for
the stronger winds associated with the low-level jet to gradually
shift northeastward and away from the better low-level moisture
across southern New England over the next few hours. Accordingly,
the overall severe threat should remain too isolated/marginal to
justify watch issuance.

..Gleason/Edwards.. 09/09/2021

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

ATTN...WFO...GYX...BOX...OKX...

LAT...LON   41247253 42127232 43147156 43217109 42967059 42777070
            42637051 42427076 42087056 41807049 41487102 41257198
            41247253

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

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.