Alert archive / New York / Mesoscale Discussions in 2015

Mesoscale Discussion 1503

July 21, 20154 counties in New Jersey; 7 counties in New York; Philadelphia County, Pennsylvania

The Storm Prediction Center issued this mesoscale discussion at Jul 21, 2015, 7:00 PM EDT for 4 counties in New Jersey; 7 counties in New York; Philadelphia County, Pennsylvania. It was in force for 90 min.

The area

The outline as issued.

The facts

Issued: Jul 21, 2015, 7:00 PM EDT (23:00 UTC)
Expired: Jul 21, 2015, 8:30 PM EDT
In force: 90 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

Counties Hudson County, NJ, Mercer County, NJ, Middlesex County, NJ, Monmouth County, NJ, Bronx County, NY, Kings County, NY, Nassau County, NY, New York County, NY, Queens County, NY, Richmond County, NY, Suffolk County, NY, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 84 km from the middle of the area, began a volume at 23:03 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 nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 11.0 hours before the alert went out and 95 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: 298 J/kg
Mixed-layer CIN: -53 J/kg
Mixed-layer LCL: 1331 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 19 m²/s²
0-3 km storm-relative helicity: 87 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 21, 12:53 PM EDT	Mesoscale Discussion	SPC	Albany, Broome, Delaware, Fulton, Greene, Montgomery and 8 more	67 min

Nearby

Mesoscale Discussions in New York, 2015 Mesoscale Discussions in Connecticut, 2015 Mesoscale Discussions in New Jersey, 2015 Every mesoscale discussion in 2015

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.