Alert archive / New York / Mesoscale Discussions in 2021
Mesoscale Discussion 1719
The Storm Prediction Center issued this mesoscale discussion at Sep 8, 2021, 9:25 PM EDT for 4 states. It was in force for 95 min.
The area
The outline as issued.
The facts
- Issued
- Sep 8, 2021, 9:25 PM EDT (01:25 UTC)
- Expired
- Sep 8, 2021, 11:00 PM EDT
- In force
- 95 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 491
All 22 counties
Berkshire County, MA, Hunterdon County, NJ, Morris County, NJ, Passaic County, NJ, Somerset County, NJ, Sussex County, NJ, Warren County, NJ, Columbia County, NY, Dutchess County, NY, Greene County, NY, Orange County, NY, Putnam County, NY, Rockland County, NY, Sullivan County, NY, Ulster County, NY, Berks County, PA, Bucks County, PA, Lehigh County, PA, Monroe County, PA, Montgomery County, PA, Northampton County, PA, Pike County, PA
The radar
The Philadelphia radar (KDIX), 134 km from the middle of the area, began a volume at 01:28 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, 1.4 hours before the alert went out and 173 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.
- Mixed-layer CAPE
- 619 J/kg
- Mixed-layer CIN
- -36 J/kg
- Mixed-layer LCL
- 807 m above ground
- 0-6 km bulk shear
- 33 kt
- 0-1 km storm-relative helicity
- 211 m²/s²
- 0-3 km storm-relative helicity
- 225 m²/s²
- Significant tornado parameter
- 0.5
- Supercell composite
- 3.4
The text
As transmitted.
313 ACUS11 KWNS 090125 SWOMCD SPC MCD 090125 MAZ000-CTZ000-NYZ000-NJZ000-PAZ000-090300- Mesoscale Discussion 1719 NWS Storm Prediction Center Norman OK 0825 PM CDT Wed Sep 08 2021 Areas affected...Eastern PA...Northern NJ...Southern NY...Northwestern CT...Western MA Concerning...Severe Thunderstorm Watch 491... Valid 090125Z - 090300Z The severe weather threat for Severe Thunderstorm Watch 491 continues. SUMMARY...Severe threat continues with storms this evening. DISCUSSION...Broken line of strong/severe convection continues to advance east at roughly 25kt. This activity is supported aloft by strengthening mid-level flow ahead of Great Lakes/OH Valley upper trough. Wind profiles continue to favor organized line segments/bow-type structures, the primary concern being with line segments oriented more north-south/perpendicular to the mean flow. One such feature has formed over south-central PA and is tracking east-northeast into western York County. If this storm maintains its current track/movement, it will approach southwestern portions of ww491 around 0330z. ..Darrow.. 09/09/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BOX...OKX...ALY...PHI...BGM...CTP... LAT...LON 40187644 42477414 42477258 40187492 40187644
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 9, 4:12 AM EDT | Mesoscale Discussion | SPC | 3 hr | |
| Sep 8, 10:42 PM EDT | Mesoscale Discussion | SPC | Essex, Hunterdon, Morris, Passaic, Somerset, Union and 1 more | 2 hr |
| Sep 8, 8:29 PM EDT | Severe Thunderstorm Watch | SPC | Adams, Lancaster, York | 4 hr |
Nearby
Mesoscale Discussions in New York, 2021Mesoscale Discussions in Pennsylvania, 2021Mesoscale Discussions in New Jersey, 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.