Alert archive / New York / Severe Thunderstorm Watches in 2018
Severe Thunderstorm Watch 387
The Storm Prediction Center issued this severe thunderstorm watch at Sep 21, 2018, 4:50 PM EDT for 23 counties in New York; 6 counties in Pennsylvania. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 21, 2018, 4:50 PM EDT (20:50 UTC)
- Expired
- Sep 21, 2018, 10:34 PM EDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 0.5 in
- Strongest gust expected
- 60 kt
All 29 counties
Allegany County, NY, Cattaraugus County, NY, Cayuga County, NY, Chautauqua County, NY, Erie County, NY, Franklin County, NY, Genesee County, NY, Jefferson County, NY, Lewis County, NY, Livingston County, NY, Monroe County, NY, Niagara County, NY, Onondaga County, NY, Ontario County, NY, Orleans County, NY, Oswego County, NY, Schuyler County, NY, Seneca County, NY, St. Lawrence County, NY, Steuben County, NY, Wayne County, NY, Wyoming County, NY, Yates County, NY, Cameron County, PA, Clearfield County, PA, Elk County, PA, McKean County, PA, Potter County, PA, Warren County, PA
The radar
The Ft Drum radar (KTYX), 65 km from the middle of the area, began a volume at 20:53 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
- 5%
- Ten or more severe wind reports
- 60%
- One or more gusts of 65 knots or more
- 20%
- 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
- 70%
Warnings issued inside it
18 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 21, 5:15 PM EDT | Severe Thunderstorm Warning | BUF | Cattaraugus, Chautauqua, Erie | 45 min |
| Sep 21, 5:22 PM EDT | Severe Thunderstorm Warning | BUF | Cattaraugus, Chautauqua | 38 min |
| Sep 21, 5:27 PM EDT | Severe Thunderstorm Warning | BUF | Erie, Genesee, Niagara, Orleans | 48 min |
| Sep 21, 5:29 PM EDT | Severe Thunderstorm Warning | CTP | Warren | 2 hr |
| Sep 21, 5:54 PM EDT | Severe Thunderstorm Warning | BUF | Allegany, Cattaraugus, Chautauqua, Erie, Wyoming | 66 min |
| Sep 21, 6:30 PM EDT | Severe Thunderstorm Warning | CTP | Clearfield, Elk, McKean, Warren | 60 min |
| Sep 21, 6:31 PM EDT | Severe Thunderstorm Warning | BUF | Genesee, Livingston, Monroe, Ontario, Wayne, Wyoming | 59 min |
| Sep 21, 6:48 PM EDT | Tornado Warning | BUF | Allegany, Cattaraugus | 42 min |
| Sep 21, 6:51 PM EDT | Severe Thunderstorm Warning | BUF | Allegany | 54 min |
| Sep 21, 7:04 PM EDT | Severe Thunderstorm Warning | BGM | Cayuga, Seneca, Steuben, Yates | 41 min |
| Sep 21, 7:07 PM EDT | Tornado Warning | BUF | Ontario | 23 min |
| Sep 21, 7:19 PM EDT | Severe Thunderstorm Warning | BGM | Steuben | 41 min |
| Sep 21, 7:37 PM EDT | Severe Thunderstorm Warning | CTP | Cameron, Elk, McKean, Potter | 83 min |
| Sep 21, 7:40 PM EDT | Severe Thunderstorm Warning | BGM | Cayuga, Chemung, Cortland, Onondaga, Schuyler, Seneca and 3 more | 35 min |
| Sep 21, 7:54 PM EDT | Severe Thunderstorm Warning | BGM | Chemung, Steuben | 51 min |
| Sep 21, 8:10 PM EDT | Severe Thunderstorm Warning | BGM | Chemung, Cortland, Schuyler, Seneca, Steuben, Tioga and 1 more | 35 min |
| Sep 21, 8:58 PM EDT | Severe Thunderstorm Warning | CTP | Lycoming, Potter, Tioga | 47 min |
| Sep 21, 9:09 PM EDT | Flash Flood Warning | BGM | Steuben | 3 hr |
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, 8.8 hours before the alert went out and 196 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
- 445 J/kg
- Mixed-layer CIN
- -72 J/kg
- Mixed-layer LCL
- 1045 m above ground
- 0-6 km bulk shear
- 41 kt
- 0-1 km storm-relative helicity
- 334 m²/s²
- 0-3 km storm-relative helicity
- 332 m²/s²
- Significant tornado parameter
- 0.5
- Supercell composite
- 4.9
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 21, 4:27 PM EDT | Mesoscale Discussion | SPC | Allegany, Cayuga, Franklin, Genesee, Jefferson, Lewis and 12 more | 63 min |
| Sep 21, 7:04 PM EDT | Mesoscale Discussion | SPC | Allegany, Cattaraugus, Cayuga, Chemung, Cortland, Genesee and 16 more | 116 min |
| Sep 21, 3:37 PM EDT | Mesoscale Discussion | SPC | Crawford, Erie, Lawrence, Mercer, Venango | 83 min |
| Sep 21, 4:32 PM EDT | Severe Thunderstorm Watch | SPC | Allegheny, Armstrong, Beaver, Butler, Clarion, Crawford and 9 more | 4 hr |
Nearby
Severe Thunderstorm Watches in New York, 2018Severe Thunderstorm Watches in Pennsylvania, 2018Every severe thunderstorm watch in 2018
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.