Alert archive / New York / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 29, NWS Burlington, VT

July 20, 2021Franklin County, St. Lawrence County, New York

NWS Burlington, VT issued this severe thunderstorm warning at Jul 20, 2021, 4:44 PM EDT for Franklin County, St. Lawrence County, New York. It was in force for 61 min. 14 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Jul 20, 2021, 4:44 PM EDT (20:44 UTC)
Expired: Jul 20, 2021, 5:45 PM EDT
In force: 61 min
Issued by: NWS Burlington, VT
Area: Storm-based polygon
Hail: 1.0 in
Wind: 70.0 mph

Counties Franklin County, NY, St. Lawrence County, NY

The radar

The Burlington radar (KCXX), 117 km from the middle of the area, began a volume at 20:45 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 was reported inside it

Time	Report	Where	Remark
Jul 20, 4:48 PM EDT	TSTM WND DMG	Canton, NY	LARGE TREE DOWN.
Jul 20, 5:00 PM EDT	TSTM WND DMG	1 Wsw South Colton, NY	ONE LARGE TREE AND NUMEROUS SMALL TREES DOWN.
Jul 20, 5:05 PM EDT	TSTM WND DMG	Norwood, NY	NUMEROUS TREES AND POWERLINES DOWN.
Jul 20, 5:05 PM EDT	TSTM WND DMG	Potsdam, NY	NUMEROUS TREES DOWN AND PEA-SIZED HAIL.
Jul 20, 5:06 PM EDT	TSTM WND DMG	Brasher Falls, NY	TREE DOWN ON WIRE.
Jul 20, 5:10 PM EDT	FUNNEL CLOUD	Helena, NY	TIME ESTIMATED BY RADAR.
Jul 20, 5:21 PM EDT	TSTM WND DMG	Bombay, NY	TREES DOWN.
Jul 20, 5:22 PM EDT	HAIL 1	2 Sw St. Regis, NY	QUARTER-SIZED HAIL.
Jul 20, 5:29 PM EDT	TSTM WND DMG	Fort Covington, NY	VERY OLD TREE DOWN.
Jul 20, 5:30 PM EDT	TSTM WND DMG	Westville Center, NY	TREES DOWN.
Jul 20, 5:32 PM EDT	TSTM WND DMG	Westville Center, NY	TREES DOWN.
Jul 20, 5:37 PM EDT	TSTM WND DMG	Constable, NY	TREES DOWN.
Jul 20, 5:38 PM EDT	TSTM WND DMG	10 S Malone, NY	LARGE TREE SNAPPED IN HALF.
Jul 20, 5:48 PM EDT	TSTM WND DMG	Chateaugay, NY	TREES DOWN.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Jul 20, 3:05 PM EDT	Severe Thunderstorm Watch	SPC	8 hr

The nearest sounding before it

Albany, NY (KALY), launched 12:00Z, 8.7 hours before the alert went out and 221 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: 85 J/kg
Mixed-layer CIN: -145 J/kg
Mixed-layer LCL: 793 m above ground
0-6 km bulk shear: 19 kt
0-1 km storm-relative helicity: 45 m²/s²
0-3 km storm-relative helicity: 95 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.3

Open this sounding in Storm Lab

The text

As transmitted.

712 
WUUS51 KBTV 202044
SVRBTV
NYC033-089-202145-
/O.NEW.KBTV.SV.W.0029.210720T2044Z-210720T2145Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Burlington VT
444 PM EDT Tue Jul 20 2021

The National Weather Service in Burlington has issued a

* Severe Thunderstorm Warning for...
  Franklin County in northern New York...
  St. Lawrence County in northern New York...

* Until 545 PM EDT.

* At 442 PM EDT, a line of severe thunderstorms was located from 
  near St. Regis, New York to 18 miles southwest of Nelson Corner, 
  New York moving east at 40 mph.

  HAZARD...70 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Expect considerable tree damage. Wind damage is also 
           likely to mobile homes, roofs, and outbuildings. Minor 
           hail damage to vehicles is possible. 

* Locations impacted include...
  Potsdam, Gouverneur, Canton, Massena, Norfolk, Oswegatchie, Moira,
  De Kalb, Bangor, Fowler, Parishville, Fort Covington, Colton,
  Bombay, Bryants Mill, Massena International Airport - Richards
  Field, Helena, Burke, Cranberry Lake and Brushton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4499 7402 4465 7396 4407 7484 4405 7507
      4436 7577 4499 7476
TIME...MOT...LOC 2042Z 300DEG 30KT 4503 7459 4418 7594 

HAIL...1.00IN
WIND...70MPH
 
$$

Evenson/LaRocca

1 follow-up statement

344 
WWUS51 KBTV 202121
SVSBTV

Severe Weather Statement
National Weather Service Burlington VT
521 PM EDT Tue Jul 20 2021

NYC033-089-202145-
/O.CON.KBTV.SV.W.0029.000000T0000Z-210720T2145Z/
Franklin NY-St. Lawrence NY-
521 PM EDT Tue Jul 20 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 545 PM EDT
FOR FRANKLIN AND ST. LAWRENCE COUNTIES...

At 519 PM EDT, a line of severe thunderstorms over northern New York 
was located along a line extending from North Burke to near Balmat, 
moving east at 45 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Law enforcement and public reported numerous trees down in 
         Ogdensburg and Lisbon in Saint Lawrence County New York.

IMPACT...Expect wind damage to trees and powerlines. Minor hail 
         damage to vehicles is possible. 

Locations impacted include...
Potsdam, Gouverneur, Canton, Massena, Norfolk, Oswegatchie, Moira,
Bangor, Fowler, Parishville, Fort Covington, Colton, Bombay, Bryants
Mill, Degrasse, Helena, Burke, Carry Falls Reservoir, Cranberry Lake
and Brushton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4499 7402 4465 7396 4407 7484 4405 7507
      4427 7556 4453 7521 4475 7507 4484 7499
      4499 7476
TIME...MOT...LOC 2119Z 268DEG 43KT 4499 7415 4420 7537 

HAIL...1.00IN
WIND...60MPH
 
$$

Evenson/LaRocca

The office that day

Everything else NWS Burlington, VT issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 20, 3:53 PM EDT	Severe Thunderstorm Warning	BTV	Franklin, St. Lawrence	52 min
Jul 20, 5:35 PM EDT	Severe Thunderstorm Warning	BTV	Essex	55 min
Jul 20, 5:50 PM EDT	Severe Thunderstorm Warning	BTV	Clinton, Essex, Franklin	40 min
Jul 20, 6:31 PM EDT	Severe Thunderstorm Warning	BTV	Clinton, Essex	59 min
Jul 20, 7:32 PM EDT	Severe Thunderstorm Warning	BTV	Essex	58 min

Nearby

Severe Thunderstorm Warnings in New York, 2021 Every severe thunderstorm warning 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.