Alert archive / New York / Mesoscale Discussions in 2021

Mesoscale Discussion 1127

June 29, 20215 states

The Storm Prediction Center issued this mesoscale discussion at Jun 29, 2021, 7:17 PM EDT for 5 states. It was in force for 88 min.

The area

The outline as issued.

The facts

Issued: Jun 29, 2021, 7:17 PM EDT (23:17 UTC)
Expired: Jun 29, 2021, 8:45 PM EDT
In force: 88 min
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch unlikely
Chance of a watch: 5%

All 27 counties

Berkshire County, MA, Franklin County, MA, Hampden County, MA, Hampshire County, MA, Middlesex County, MA, Norfolk County, MA, Suffolk County, MA, Worcester County, MA, Cheshire County, NH, Hillsborough County, NH, Sullivan County, NH, Albany County, NY, Columbia County, NY, Fulton County, NY, Greene County, NY, Montgomery County, NY, Rensselaer County, NY, Saratoga County, NY, Schenectady County, NY, Schoharie County, NY, Washington County, NY, Kent County, RI, Providence County, RI, Bennington County, VT, Rutland County, VT, Windham County, VT, Windsor County, VT

The radar

The Albany radar (KENX), 81 km from the middle of the area, began a volume at 23:20 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

Albany, NY (KALY), launched 12:00Z, 11.3 hours before the alert went out and 60 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 333 J/kg
Mixed-layer CIN: -97 J/kg
Mixed-layer LCL: 1057 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 72 m²/s²
0-3 km storm-relative helicity: 80 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.4

Open this sounding in Storm Lab

The text

As transmitted.

258 
ACUS11 KWNS 292317
SWOMCD
SPC MCD 292317 
MAZ000-NHZ000-RIZ000-CTZ000-VTZ000-NYZ000-300045-

Mesoscale Discussion 1127
NWS Storm Prediction Center Norman OK
0617 PM CDT Tue Jun 29 2021

Areas affected...Eastern New York into portions of New England

Concerning...Severe potential...Watch unlikely 

Valid 292317Z - 300045Z

Probability of Watch Issuance...5 percent

SUMMARY...Isolated strong thunderstorms will pose a risk for a few
damaging wind gusts into this evening. Weak shear and limited storm
organization suggests the severe threat will remain marginal.

DISCUSSION...2300z observations showed isolated thunderstorms
ongoing along and south of a diffuse frontal zone from eastern New
York through portions of New England. In the past half hour, a few
of these storms have produced occasional tree damage suggesting a
low-end severe threat may continue for a few more hours. From SPC
mesoanalysis, moderate instability (1500-2500 J/kg of MLCAPE) is in
place, with weak vertical shear less than 25 kts. The
instability/shear overlap will favor a multicellular storm mode with
the potential for a few marginally severe gusts through this evening
as storms continue east. As sunset approaches and nocturnal
inhibition begins to increase, storm coverage and the resulting
severe threat should dwindle. Given convective trends and coverage,
a weather watch is unlikely.

..Lyons/Guyer.. 06/29/2021

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

ATTN...WFO...GYX...BOX...BTV...OKX...ALY...BGM...

LAT...LON   43367445 43657328 43577212 42487068 41767119 41447249
            42117458 43007463 43367445

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 29, 2:33 PM EDT	Mesoscale Discussion	SPC	Allegany, Cattaraugus, Cayuga, Chautauqua, Chemung, Cortland and 14 more	117 min

Nearby

Mesoscale Discussions in New York, 2021 Mesoscale Discussions in Massachusetts, 2021 Mesoscale Discussions in Vermont, 2021 Every 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.