Alert archive / New York / Mesoscale Discussions in 2021
Mesoscale Discussion 1871
The Storm Prediction Center issued this mesoscale discussion at Oct 16, 2021, 12:09 PM EDT for Berkshire County, Massachusetts; 12 counties in New York; 5 counties in Vermont. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Oct 16, 2021, 12:09 PM EDT (16:09 UTC)
- Expired
- Oct 16, 2021, 2:15 PM EDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch likely
- Chance of a watch
- 80%
Counties Berkshire County, MA, Albany County, NY, Clinton County, NY, Essex County, NY, Fulton County, NY, Hamilton County, NY, Montgomery County, NY, Rensselaer County, NY, Saratoga County, NY, Schenectady County, NY, Schoharie County, NY, Warren County, NY, Washington County, NY, Addison County, VT, Bennington County, VT, Chittenden County, VT, Grand Isle County, VT, Rutland County, VT
The radar
The Burlington radar (KCXX), 89 km from the middle of the area, began a volume at 16:11 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Albany, NY (KALY), launched 12:00Z, 4.2 hours before the alert went out and 134 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
- 50 J/kg
- Mixed-layer CIN
- -197 J/kg
- Mixed-layer LCL
- 735 m above ground
- 0-6 km bulk shear
- 49 kt
- 0-1 km storm-relative helicity
- 279 m²/s²
- 0-3 km storm-relative helicity
- 291 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.4
The text
As transmitted.
148
ACUS11 KWNS 161610
SWOMCD
SPC MCD 161609
VTZ000-MAZ000-NYZ000-161815-
Mesoscale Discussion 1871
NWS Storm Prediction Center Norman OK
1109 AM CDT Sat Oct 16 2021
Areas affected...Northeast NY...Western VT...Far Western MA
Concerning...Severe potential...Watch likely
Valid 161609Z - 161815Z
Probability of Watch Issuance...80 percent
SUMMARY...A narrow line of storms is expected to develop and move
east-northeastward this afternoon across northeast NY into western
VT and far western MA. Damaging wind gusts and a couple of brief
tornadoes are possible.
DISCUSSION...Showers and thunderstorms moving across northern NY
have shown a gradual strengthening trend over the past hour or so.
At the same time the downstream air mass across northeast NY and
adjacent western VT/far western MA continues to warm and
destabilize. Low-level southerly flow has also been strengthening
during this time (sampled well by the CXX VAD). Poor lapse rates
should keep buoyancy modest, but the strong forcing for ascent and
favorable vertical shear will still likely result in a narrow
convective line capable of damaging wind gusts and perhaps even a
tornado or two. The tornado threat appears to be relatively greater
across in the NY/VT border vicinity where temperatures have climbed
into the low/mid 70s amid mid 60s dewpoints. One or more watches
(including the potential for a tornado watch along the NY/VT border)
will likely be needed soon to address this developing severe threat.
..Mosier/Grams.. 10/16/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BOX...BTV...ALY...BGM...
LAT...LON 44247456 44857404 44987321 44277272 42177307 42517496
44247456SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 16, 12:35 PM EDT | Severe Thunderstorm Watch | SPC | Berkshire | 6 hr |
| Oct 16, 2:55 PM EDT | Mesoscale Discussion | SPC | Berkshire | 95 min |
| Oct 16, 5:39 PM EDT | Mesoscale Discussion | SPC | Essex, Franklin, Hampden, Hampshire, Middlesex, Norfolk and 2 more | 2 hr |
| Oct 16, 11:06 AM EDT | Mesoscale Discussion | SPC | Broome, Chenango, Cortland, Delaware, Madison, Otsego and 2 more | 114 min |
Nearby
Mesoscale Discussions in New York, 2021Mesoscale Discussions in Vermont, 2021Mesoscale Discussions in Massachusetts, 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.