Alert archive / New York / Severe Thunderstorm Watches in 2021
Severe Thunderstorm Watch 395
The Storm Prediction Center issued this severe thunderstorm watch at Jul 27, 2021, 11:12 AM EDT for 29 counties in New York; Bradford County, Susquehanna County, Pennsylvania. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 27, 2021, 11:12 AM EDT (15:12 UTC)
- Expired
- Jul 27, 2021, 5:58 PM EDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 60 kt
All 31 counties
Allegany County, NY, Broome County, NY, Cattaraugus County, NY, Cayuga County, NY, Chautauqua County, NY, Chemung County, NY, Chenango County, NY, Cortland County, NY, Delaware County, NY, Erie County, NY, Genesee County, NY, Livingston County, NY, Madison County, NY, Monroe County, NY, Niagara County, NY, Oneida County, NY, Onondaga County, NY, Ontario County, NY, Orleans County, NY, Oswego County, NY, Otsego County, NY, Schuyler County, NY, Seneca County, NY, Steuben County, NY, Tioga County, NY, Tompkins County, NY, Wayne County, NY, Wyoming County, NY, Yates County, NY, Bradford County, PA, Susquehanna County, PA
The radar
The Buffalo radar (KBUF), 96 km from the middle of the area, began a volume at 15:12 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
- 5%
- One or more EF2 to EF5 tornadoes
- 2%
- Ten or more severe wind reports
- 50%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 20%
- One or more hailstones of 2 inches or more
- 5%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
6 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 27, 2:23 PM EDT | Severe Thunderstorm Warning | BGM | Chemung, Schuyler, Steuben, Tioga, Tompkins | 52 min |
| Jul 27, 2:29 PM EDT | Severe Thunderstorm Warning | BGM | Chenango, Cortland, Madison, Oneida, Onondaga, Otsego | 61 min |
| Jul 27, 2:56 PM EDT | Severe Thunderstorm Warning | BGM | Broome, Chenango, Tioga | 64 min |
| Jul 27, 3:51 PM EDT | Severe Thunderstorm Warning | BGM | Broome, Delaware | 39 min |
| Jul 27, 4:03 PM EDT | Severe Thunderstorm Warning | BGM | Bradford | 27 min |
| Jul 27, 4:22 PM EDT | Severe Thunderstorm Warning | BGM | Delaware, Sullivan | 53 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
Buffalo Intl Airport, NY (KBUF), launched 12:00Z, 3.2 hours before the alert went out and 93 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
- 15 J/kg
- Mixed-layer CIN
- -173 J/kg
- Mixed-layer LCL
- 1473 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km storm-relative helicity
- 95 m²/s²
- 0-3 km storm-relative helicity
- 75 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
089 WWUS20 KWNS 271509 SEL5 SPC WW 271509 NYZ000-PAZ000-LEZ000-LOZ000-272200- URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 395 NWS Storm Prediction Center Norman OK 1110 AM EDT Tue Jul 27 2021 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Western and Central New York Northeast Pennsylvania Lake Erie Lake Ontario * Effective this Tuesday morning and evening from 1110 AM until 600 PM EDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...A fast-moving line of thunderstorms over Ontario will track eastward into western New York and intensify through the early afternoon. Damaging winds will be possible along the leading edge of these storms. The severe thunderstorm watch area is approximately along and 65 statute miles north and south of a line from 25 miles west of Buffalo NY to 40 miles south southeast of Utica NY. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU5). 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 1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 28040. ...Hart
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 27, 10:33 AM EDT | Mesoscale Discussion | SPC | Allegany, Cattaraugus, Cayuga, Erie, Genesee, Livingston and 9 more | 117 min |
| Jul 27, 2:01 PM EDT | Mesoscale Discussion | SPC | Albany, Allegany, Broome, Cattaraugus, Cayuga, Chemung and 29 more | 89 min |
| Jul 27, 2:47 PM EDT | Severe Thunderstorm Watch | SPC | Albany, Columbia, Dutchess, Fulton, Greene, Hamilton and 10 more | 6 hr |
| Jul 27, 4:36 PM EDT | Mesoscale Discussion | SPC | Albany, Bronx, Columbia, Delaware, Dutchess, Greene and 12 more | 84 min |
| Jul 27, 6:09 PM EDT | Mesoscale Discussion | SPC | Albany, Bronx, Broome, Columbia, Delaware, Dutchess and 10 more | 96 min |
Nearby
Severe Thunderstorm Watches in New York, 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.