Alert archive / New York / Severe Thunderstorm Watches in 2021

Severe Thunderstorm Watch 529

October 16, 202121 counties in New York; 6 counties in Pennsylvania; 11 counties in Vermont

The Storm Prediction Center issued this severe thunderstorm watch at Oct 16, 2021, 12:35 PM EDT for 21 counties in New York; 6 counties in Pennsylvania; 11 counties in Vermont. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Oct 16, 2021, 12:35 PM EDT (16:35 UTC)
Expired
Oct 16, 2021, 7:00 PM EDT
In force
6 hr
Issued by
the Storm Prediction Center
Largest hail expected
1 in
Strongest gust expected
65 kt
All 38 counties

Albany County, NY, Clinton County, NY, Columbia County, NY, Delaware County, NY, Dutchess County, NY, Essex County, NY, Franklin County, NY, Fulton County, NY, Greene County, NY, Hamilton County, NY, Herkimer County, NY, Montgomery County, NY, Otsego County, NY, Rensselaer County, NY, Saratoga County, NY, Schenectady County, NY, Schoharie County, NY, Sullivan County, NY, Ulster County, NY, Warren County, NY, Washington County, NY, Lackawanna County, PA, Luzerne County, PA, Pike County, PA, Susquehanna County, PA, Wayne County, PA, Wyoming County, PA, Addison County, VT, Bennington County, VT, Chittenden County, VT, Franklin County, VT, Grand Isle County, VT, Lamoille County, VT, Orange County, VT, Rutland County, VT, Washington County, VT, Windham County, VT, Windsor County, VT

The radar

The Albany radar (KENX), 100 km from the middle of the area, began a volume at 16:40 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes
20%
One or more EF2 to EF5 tornadoes
10%
Ten or more severe wind reports
50%
One or more gusts of 65 knots or more
30%
Ten or more severe hail reports
5%
One or more hailstones of 2 inches or more
5%
Six or more combined severe hail and wind reports
60%

Warnings issued inside it

7 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Oct 16, 1:08 PM EDTSevere Thunderstorm WarningALYFulton, Hamilton, Herkimer52 min
Oct 16, 1:32 PM EDTSevere Thunderstorm WarningBTVClinton, Essex, Franklin43 min
Oct 16, 1:48 PM EDTSevere Thunderstorm WarningALYSaratoga, Warren42 min
Oct 16, 2:21 PM EDTSevere Thunderstorm WarningBTVClinton39 min
Oct 16, 2:40 PM EDTSevere Thunderstorm WarningBTVClinton, Essex65 min
Oct 16, 2:55 PM EDTSevere Thunderstorm WarningBTVChittenden, Franklin, Grand Isle, Lamoille, Orleans65 min
Oct 16, 3:41 PM EDTSevere Thunderstorm WarningALYGreene, Ulster64 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Albany, NY (KALY), launched 12:00Z, 4.6 hours before the alert went out and 87 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, Albany, NY at 12:00Z on 2021-10-16Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 50 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, Albany, NY at 12:00Z on 2021-10-16The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 279 square meters per square second.1939587897Sfc1 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
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

Open this sounding in Storm Lab

The text

As transmitted.

072 
WWUS20 KWNS 161631
SEL9  
SPC WW 161631
CTZ000-MAZ000-NYZ000-PAZ000-VTZ000-162300-

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 529
NWS Storm Prediction Center Norman OK
1235 PM EDT Sat Oct 16 2021

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Far western Connecticut
  Far western Massachusetts
  Eastern New York
  Northeast Pennsylvania
  Vermont

* Effective this Saturday afternoon and evening from 1235 PM
  until 700 PM EDT.

* Primary threats include...
  Scattered damaging winds and isolated significant gusts to 75
    mph possible
  A tornado or two possible

SUMMARY...A thin, low-topped convective line should intensify as it
spreads east across eastern New York into western New England, as
well as possibly across northeast Pennsylvania. A brief tornado
threat is anticipated across parts of the Champlain and Upper Hudson
Valleys.

The severe thunderstorm watch area is approximately along and 55
statute miles east and west of a line from 35 miles north northwest
of Burlington VT to 30 miles south southwest of Monticello NY. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU9).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

AVIATION...A few severe thunderstorms with hail surface and aloft to
1 inch. Extreme turbulence and surface wind gusts to 65 knots. A few
cumulonimbi with maximum tops to 350. Mean storm motion vector
24045.

...Grams

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Oct 16, 11:06 AM EDTMesoscale DiscussionSPCBroome, Chenango, Cortland, Delaware, Madison, Otsego and 2 more114 min
Oct 16, 12:09 PM EDTMesoscale DiscussionSPCAlbany, Clinton, Essex, Fulton, Hamilton, Montgomery and 6 more2 hr
Oct 16, 2:55 PM EDTMesoscale DiscussionSPCAlbany, Columbia, Delaware, Dutchess, Greene, Rensselaer and 7 more95 min
Oct 16, 5:39 PM EDTMesoscale DiscussionSPCNassau, Suffolk2 hr
Oct 16, 1:50 PM EDTMesoscale DiscussionSPCBerks, Bucks, Carbon, Chester, Delaware, Lancaster and 4 more115 min

Nearby

Severe Thunderstorm Watches in New York, 2021Severe Thunderstorm Watches in Vermont, 2021Severe Thunderstorm Watches in Pennsylvania, 2021Every severe thunderstorm watch 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.