Alert archive / New York / Mesoscale Discussions in 2018

Mesoscale Discussion 1492

September 21, 201818 counties in New York

The Storm Prediction Center issued this mesoscale discussion at Sep 21, 2018, 4:27 PM EDT for 18 counties in New York. It was in force for 63 min.

The area

The outline as issued.

The facts

Issued: Sep 21, 2018, 4:27 PM EDT (20:27 UTC)
Expired: Sep 21, 2018, 5:30 PM EDT
In force: 63 min
Issued by: the Storm Prediction Center
Chance of a watch: 80%

Counties Allegany County, NY, Cayuga 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, Seneca County, NY, St. Lawrence County, NY, Wayne County, NY, Wyoming County, NY, Yates County, NY

The radar

The Ft Drum radar (KTYX), 33 km from the middle of the area, began a volume at 20:30 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.

Severe Thunderstorm Watch 387Sep 21, 4:50 PM EDT

The nearest sounding before it

Buffalo Intl Airport, NY (KBUF), launched 12:00Z, 8.5 hours before the alert went out and 245 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: 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

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 21, 4:50 PM EDT	Severe Thunderstorm Watch	SPC	Allegany, Cattaraugus, Cayuga, Chautauqua, Erie, Franklin and 17 more	6 hr
Sep 21, 7:04 PM EDT	Mesoscale Discussion	SPC	Allegany, Cattaraugus, Cayuga, Chemung, Cortland, Genesee and 16 more	116 min

Nearby

Mesoscale Discussions in New York, 2018 Every mesoscale discussion 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.