Alert archive / New Jersey / Mesoscale Discussions in 2012

Mesoscale Discussion 1972

September 18, 2012Kent County, Sussex County, Delaware; 17 counties in New Jersey; 5 counties in New York

The Storm Prediction Center issued this mesoscale discussion at Sep 18, 2012, 6:08 PM EDT for Kent County, Sussex County, Delaware; 17 counties in New Jersey; 5 counties in New York. It was in force for 67 min.

The area

The outline as issued.

The facts

Issued
Sep 18, 2012, 6:08 PM EDT (22:08 UTC)
Expired
Sep 18, 2012, 7:15 PM EDT
In force
67 min
Issued by
the Storm Prediction Center
All 24 counties

Kent County, DE, Sussex County, DE, Atlantic County, NJ, Bergen County, NJ, Burlington County, NJ, Camden County, NJ, Cape May County, NJ, Cumberland County, NJ, Essex County, NJ, Gloucester County, NJ, Hudson County, NJ, Mercer County, NJ, Middlesex County, NJ, Monmouth County, NJ, Morris County, NJ, Ocean County, NJ, Passaic County, NJ, Somerset County, NJ, Union County, NJ, Bronx County, NY, Kings County, NY, New York County, NY, Queens County, NY, Richmond County, NY

The radar

The Philadelphia radar (KDIX), 47 km from the middle of the area, began a volume at 22:11 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, 10.1 hours before the alert went out and 141 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 2012-09-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 114 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 2012-09-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 224 square meters per square second.19395878Sfc1 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
114 J/kg
Mixed-layer CIN
-4 J/kg
Mixed-layer LCL
721 m above ground
0-6 km bulk shear
45 kt
0-1 km storm-relative helicity
224 m²/s²
0-3 km storm-relative helicity
267 m²/s²
Significant tornado parameter
0.1
Supercell composite
0.6

Open this sounding in Storm Lab

The text

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

155 
ACUS11 KWNS 182208
SWOMCD
SPC MCD 182208 
NYZ000-NJZ000-PAZ000-DEZ000-MDZ000-182315-

MESOSCALE DISCUSSION 1972
NWS STORM PREDICTION CENTER NORMAN OK
0508 PM CDT TUE SEP 18 2012

AREAS AFFECTED...NJ...DE

CONCERNING...TORNADO WATCH 643...

VALID 182208Z - 182315Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 643 CONTINUES.

SUMMARY...WW 643 IS SCHEDULED TO EXPIRE AT 23Z. GIVEN THE PRESENCE
OF A DOWNSTREAM WW 646 IN WFO OKX/ALY AREAS...A LOCAL TEMPORAL
EXTENSION FOR WFO PHI IS RECOMMENDED.

DISCUSSION...LEADING EDGE OF LEAD CONVECTIVE LINE EXTENDED FROM
AROUND 25 SE MSV S/SWWD TO 20 E NHK. BASED ON CURRENT EXTRAPOLATION
THIS LINE DOES NOT APPEAR LIKELY TO CLEAR NJ/DE PRIOR TO 23Z WW
EXPIRATION. GIVEN 35-45 KT 0-1 KM SHEAR SAMPLED IN AREA VWP DATA AND
GENERALLY MIDDLE 70S SURFACE TEMPERATURES...SETUP WILL REMAIN
FAVORABLE FOR AREAS OF DAMAGING WINDS WITH STRONG WIND GUSTS /REF 38
KT AT KPHL AT 2154Z/ AND POTENTIALLY A BRIEF TORNADO OR TWO BEFORE
PUSHING OFF THE COAST.

..GRAMS.. 09/18/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...OKX...PHI...AKQ...

LAT...LON   41127447 41187422 41067386 40817364 40277382 38447474
            38497579 40877467 41127447

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 18, 11:14 AM EDTMesoscale DiscussionSPCNew Castle91 min
Sep 18, 11:19 AM EDTMesoscale DiscussionSPCKent, New Castle86 min
Sep 18, 12:10 PM EDTTornado WatchSPCKent, New Castle, Sussex9 hr
Sep 18, 1:56 PM EDTMesoscale DiscussionSPCKent, New Castle, Sussex64 min
Sep 18, 4:21 PM EDTMesoscale DiscussionSPCKent, New Castle, Sussex114 min
Sep 18, 6:15 PM EDTMesoscale DiscussionSPCKent, Sussex30 min
Sep 18, 12:57 PM EDTMesoscale DiscussionSPCAlbany, Broome, Chemung, Chenango, Columbia, Cortland and 11 more93 min
Sep 18, 1:21 PM EDTTornado WatchSPCBroome, Chenango, Cortland, Delaware, Madison, Oneida and 4 more5 hr
Sep 18, 2:10 PM EDTMesoscale DiscussionSPCClinton, Essex, Franklin, Fulton, Hamilton, Herkimer and 6 more95 min
Sep 18, 3:26 PM EDTMesoscale DiscussionSPCAlbany, Columbia, Dutchess, Essex, Franklin, Fulton and 11 more34 min
Sep 18, 3:38 PM EDTTornado WatchSPCAlbany, Columbia, Dutchess, Fulton, Greene, Hamilton and 13 more8 hr
Sep 18, 7:42 PM EDTMesoscale DiscussionSPCBronx, Kings, Nassau, Putnam, Queens, Suffolk and 1 more63 min

Nearby

Mesoscale Discussions in New Jersey, 2012Mesoscale Discussions in New York, 2012Mesoscale Discussions in Delaware, 2012Every mesoscale discussion in 2012

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.