Alert archive / New York / Severe Thunderstorm Watches in 2017

Severe Thunderstorm Watch 412

July 13, 20174 states

The Storm Prediction Center issued this severe thunderstorm watch at Jul 13, 2017, 1:57 PM EDT for 4 states. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued
Jul 13, 2017, 1:57 PM EDT (17:57 UTC)
Expired
Jul 13, 2017, 6:36 PM EDT
In force
5 hr
Issued by
the Storm Prediction Center
Largest hail expected
1 in
Strongest gust expected
60 kt
All 32 counties

Capitol Planning Region, CT, Greater Bridgeport Planning Region, CT, Lower Connecticut River Valley Planning Region, CT, Naugatuck Valley Planning Region, CT, Northeastern Connecticut Planning Region, CT, Northwest Hills Planning Region, CT, Southeastern Connecticut Planning Region, CT, Berkshire County, MA, Hampden County, MA, Hampshire County, MA, Bergen County, NJ, Essex County, NJ, Hudson County, NJ, Morris County, NJ, Passaic County, NJ, Sussex County, NJ, Union County, NJ, Bronx County, NY, Columbia County, NY, Dutchess County, NY, Greene County, NY, Kings County, NY, Nassau County, NY, New York County, NY, Orange County, NY, Putnam County, NY, Queens County, NY, Richmond County, NY, Rockland County, NY, Suffolk County, NY, Ulster County, NY, Westchester County, NY

The radar

The Brookhaven radar (KOKX), 81 km from the middle of the area, began a volume at 18:00 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
30%
One or more gusts of 65 knots or more
10%
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
60%

Warnings issued inside it

11 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Jul 13, 2:12 PM EDTSevere Thunderstorm WarningOKXSoutheastern Connecticut Planning Region48 min
Jul 13, 2:13 PM EDTSevere Thunderstorm WarningOKXOrange, Putnam, Rockland, Westchester39 min
Jul 13, 2:24 PM EDTSevere Thunderstorm WarningALYNorthwest Hills Planning Region66 min
Jul 13, 2:27 PM EDTSevere Thunderstorm WarningOKXGreater Bridgeport Planning Region63 min
Jul 13, 2:38 PM EDTSevere Thunderstorm WarningOKXSoutheastern Connecticut Planning Region52 min
Jul 13, 3:08 PM EDTSevere Thunderstorm WarningALYNorthwest Hills Planning Region22 min
Jul 13, 3:17 PM EDTSevere Thunderstorm WarningALYDutchess, Ulster58 min
Jul 13, 3:19 PM EDTSevere Thunderstorm WarningOKXGreater Bridgeport Planning Region, Naugatuck Valley Planning Region41 min
Jul 13, 3:58 PM EDTSevere Thunderstorm WarningALYNorthwest Hills Planning Region62 min
Jul 13, 4:36 PM EDTSevere Thunderstorm WarningOKXLower Connecticut River Valley Planning Region, Naugatuck Valley Planning Region54 min
Jul 13, 4:50 PM EDTSevere Thunderstorm WarningPHIHunterdon, Mercer, Middlesex, Monmouth, Morris, Somerset55 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

Brookhaven, NY (KOKX), launched 12:00Z, 6.0 hours before the alert went out and 81 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-pSkew-T log-p diagram, Brookhaven, NY at 12:00Z on 2017-07-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 572 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Brookhaven, NY at 12:00Z on 2017-07-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 103 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
572 J/kg
Mixed-layer CIN
-82 J/kg
Mixed-layer LCL
1449 m above ground
0-6 km bulk shear
30 kt
0-1 km storm-relative helicity
103 m²/s²
0-3 km storm-relative helicity
140 m²/s²
Significant tornado parameter
0.1
Supercell composite
2.3

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 13, 11:09 AM EDTMesoscale DiscussionSPC2 hr
Jul 13, 4:43 PM EDTMesoscale DiscussionSPC62 min
Jul 13, 2:33 PM EDTMesoscale DiscussionSPCBurlington, Camden, Gloucester, Hunterdon, Mercer, Middlesex and 3 more57 min
Jul 13, 2:57 PM EDTSevere Thunderstorm WatchSPCBurlington, Camden, Gloucester, Hunterdon, Mercer, Middlesex and 4 more6 hr
Jul 13, 6:23 PM EDTMesoscale DiscussionSPCBurlington, Camden, Gloucester, Ocean97 min

Nearby

Severe Thunderstorm Watches in New York, 2017Severe Thunderstorm Watches in Connecticut, 2017Severe Thunderstorm Watches in New Jersey, 2017Every severe thunderstorm watch in 2017

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.