Alert archive / Utah / Severe Thunderstorm Watches in 2002

Severe Thunderstorm Watch 683

September 16, 200212 counties in Utah

The Storm Prediction Center issued this severe thunderstorm watch at Sep 16, 2002, 2:45 PM MDT for 12 counties in Utah. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Sep 16, 2002, 2:45 PM MDT (20:45 UTC)
Expired: Sep 16, 2002, 8:00 PM MDT
In force: 5 hr
Issued by: the Storm Prediction Center

Counties Beaver County, UT, Carbon County, UT, Daggett County, UT, Duchesne County, UT, Emery County, UT, Piute County, UT, Sanpete County, UT, Sevier County, UT, Summit County, UT, Utah County, UT, Wasatch County, UT, Wayne County, UT

The radar

The Cedar City radar (KICX), 197 km from the middle of the area, began a volume at 20:46 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.

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Sep 16, 5:15 PM MDT	Flash Flood Warning	SLC	Utah	3 hr
Sep 16, 5:18 PM MDT	Flash Flood Warning	SLC	Utah	3 hr

The nearest sounding before it

Salt Lake City I, UT (KSLC), launched 12:00Z, 8.8 hours before the alert went out and 182 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2960 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 102 m²/s²
0-3 km storm-relative helicity: 120 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

000 
WWUS20 KWNS 162047
SEL3  
SPC WW 162045
UTZ000-170200-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 683
STORM PREDICTION CENTER NORMAN OK
245 PM MDT MON SEP 16 2002

THE STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

   NORTHEASTERN AND CENTRAL UTAH                               

EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 245 PM UNTIL 800
PM MDT.

HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 70 STATUTE MILES
EAST AND WEST OF A LINE FROM 50 MILES SOUTHEAST OF MILFORD UTAH TO
55 MILES NORTHWEST OF VERNAL UTAH.

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR 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.  SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE
TORNADOES.

OTHER WATCH INFORMATION...THIS SEVERE THUNDERSTORM WATCH REPLACES
SEVERE THUNDERSTORM WATCH NUMBER 682.  WATCH NUMBER 682 WILL NOT BE
IN EFFECT AFTER 245 PM MDT.

DISCUSSION...THUNDERSTORMS WILL CONTINUE TO DEVELOP SLOWLY EWD
ALONG SURFACE COLD FRONT AND AHEAD OF UPPER LOW OVER EXTREME EAST
CENTRAL NV. AIR MASS IS MARGINALLY UNSTABLE...BUT STRONG MID LEVEL
WINDS ARE PROVIDING SUFFICIENT SHEAR FOR ORGANIZED STORMS...AND DRY
BOUNDARY LAYER AIR MASS IS FAVORABLE FOR A FEW SEVERE WIND GUSTS. 

AVIATION...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 21040.

...IMY

405,1085 375,1110 375,1133 405,1113

NNNN

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 16, 8:20 AM MDT	Severe Thunderstorm Watch	SPC	Beaver, Box Elder, Cache, Davis, Garfield, Iron and 13 more	7 hr

Nearby

Severe Thunderstorm Watches in Utah, 2002 Every severe thunderstorm watch in 2002

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.