Alert archive / New Jersey / Tornado Watches in 2009
Tornado Watch 739
The Storm Prediction Center issued this tornado watch at Sep 11, 2009, 4:12 AM EDT for Kent County, New Castle County, Sussex County, Delaware; 10 counties in New Jersey. It was in force for 8 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 11, 2009, 4:12 AM EDT (08:12 UTC)
- Expired
- Sep 11, 2009, 11:57 AM EDT
- In force
- 8 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 0.5 in
- Strongest gust expected
- 60 kt
Counties Kent County, DE, New Castle County, DE, Sussex County, DE, Atlantic County, NJ, Burlington County, NJ, Camden County, NJ, Cape May County, NJ, Cumberland County, NJ, Gloucester County, NJ, Middlesex County, NJ, Monmouth County, NJ, Ocean County, NJ, Salem County, NJ
The radar
The Philadelphia radar (KDIX), 38 km from the middle of the area, began a volume at 08:13 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
- 40%
- One or more EF2 to EF5 tornadoes
- 10%
- Ten or more severe wind reports
- 20%
- One or more gusts of 65 knots or more
- 5%
- 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
- 20%
Warnings issued inside it
6 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 11, 4:55 AM EDT | Severe Thunderstorm Warning | PHI | Cape May, Cumberland | 65 min |
| Sep 11, 5:36 AM EDT | Severe Thunderstorm Warning | PHI | Atlantic, Cape May, Cumberland | 69 min |
| Sep 11, 5:52 AM EDT | Severe Thunderstorm Warning | PHI | Atlantic, Cape May, Cumberland | 53 min |
| Sep 11, 6:49 AM EDT | Severe Thunderstorm Warning | PHI | Atlantic, Cape May, Cumberland | 86 min |
| Sep 11, 6:59 AM EDT | Flash Flood Warning | PHI | Cape May | 3 hr |
| Sep 11, 8:46 AM EDT | Severe Thunderstorm Warning | PHI | Monmouth | 39 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 00:00Z, 8.2 hours before the alert went out and 203 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 919 m above ground
- 0-6 km bulk shear
- 30 kt
- 0-1 km storm-relative helicity
- 146 m²/s²
- 0-3 km storm-relative helicity
- 196 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
248
WWUS20 KWNS 110813
SEL9
SPC WW 110813
DEZ000-NJZ000-CWZ000-111600-
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 739
NWS STORM PREDICTION CENTER NORMAN OK
405 AM EDT FRI SEP 11 2009
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
DELAWARE
SOUTHERN AND CENTRAL NEW JERSEY
COASTAL WATERS
EFFECTIVE THIS FRIDAY MORNING FROM 405 AM UNTIL NOON EDT.
TORNADOES...HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 30 STATUTE
MILES EAST AND WEST OF A LINE FROM 25 MILES NORTH NORTHEAST OF
LAKEHURST NEW JERSEY TO 35 MILES SOUTH SOUTHEAST OF DOVER
DELAWARE. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).
REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.
DISCUSSION...SFC LOW NOW APPROX. 75 NM E OF OCEAN CITY MD EXPECTED
TO CONTINUE SLOWLY N OR POSSIBLY NNW THROUGH LATER THIS MORNING.
BELT OF MODERATE TO STG ESE 925-700 MB FLOW WILL ADVECT A TONGUE OF
INCREASINGLY WARM/MOIST AIR WNWWD INTO DELAWARE BAY AND SRN/CNTRL
NJ. COUPLED WITH STRONGLY VEERING LOW LVL WIND PROFILES AND
CONVERGENT LOW LVL FLOW...SETUP MAY YIELD SMALL CLUSTERS OF STORMS
WITH LOW LVL ROTATION/ISOLD TORNADOES.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
400. MEAN STORM MOTION VECTOR 12035.
...CORFIDISPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 11, 2:46 AM EDT | Mesoscale Discussion | SPC | Atlantic, Burlington, Camden, Cape May, Cumberland, Monmouth and 1 more | 2 hr |
| Sep 11, 7:39 AM EDT | Mesoscale Discussion | SPC | Atlantic, Burlington, Camden, Cape May, Cumberland, Monmouth and 1 more | 2 hr |
Nearby
Tornado Watches in New Jersey, 2009Tornado Watches in Delaware, 2009Every tornado watch in 2009
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.