Alert archive / Utah / Severe Thunderstorm Warnings in 1999
Severe Thunderstorm Warning 41, NWS Salt Lake City, UT
NWS Salt Lake City, UT issued this severe thunderstorm warning at Aug 21, 1999, 5:45 PM MDT for Garfield County, Kane County, San Juan County, Utah. It was in force for 60 min. No storm report in the archive falls inside the area while it was in force.
The area
The counties it named.
The facts
- Issued
- Aug 21, 1999, 5:45 PM MDT (23:45 UTC)
- Expired
- Aug 21, 1999, 6:45 PM MDT
- In force
- 60 min
- Issued by
- NWS Salt Lake City, UT
- Area
- Whole counties; the outline is the Mesonet’s reconstruction
Counties Garfield County, UT, Kane County, UT, San Juan County, UT
The radar
The Cedar City radar (KICX), 160 km from the middle of the area, began a volume at 23:45 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
Flgstf/Belemont, AZ (KFGZ), launched 12:00Z, 11.8 hours before the alert went out and 271 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
- 95 J/kg
- Mixed-layer CIN
- -75 J/kg
- Mixed-layer LCL
- 1282 m above ground
- 0-6 km bulk shear
- 20 kt
- 0-1 km storm-relative helicity
- 63 m²/s²
- 0-3 km storm-relative helicity
- 109 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.
What forecasters said that day
The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Salt Lake City, UT wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 21, 3:25 PM MDT, 2 hours 20 minutes earlier.
Area forecast discussion, Aug 21, 3:25 PM MDT, 2 hours 20 minutes before
UTAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SALT LAKE CITY UTAH 325 PM MDT SAT AUG 21 1999 SYNOPSIS...SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE OVER UTAH THIS EVENING AND AGAIN SUNDAY. THE AIRMASS WILL SLOWLY WARM AND DRY INTO EARLY NEXT WEEK. DISCUSSION...BIG PICTURE THE NEXT FEW DAYS HAS THE MEAN RIDGE STRENGTHENING OVER THE WESTERN CONUS. SUB-TROPICAL MOISTURE WILL CONTINUE TO AFFECT THE CENTRAL AND EASTERN PORTIONS OF THE STATE. THUNDERSTORMS POPPING OVER THE MOUNTAIN RANGES CENTRAL AND EASTERN UTAH. STORMS IN SW UTAH HAVE BEEN INTERESTING...AND HAVE ISSUED A COUPLE OF SVRS. CURRENTLY HAVE AN FFW OUT FOR THE UPPER REACHES OF THE PARIA RIVER BETWEEN BRYCE CANYON NP AND KODACHROME BASIN SP. STORMS HAVE BEEN SMALL IN AREAL COVERAGE BUT WEAK PERSISTENT ROTATION OBSERVED ALONG THE SOUTHERN FLANKS OF STORMS MOVING TO THE SOUTH...OR TO THE RIGHT OF THE STEERING WINDS. WILL ADD SOUTHWEST UTAH COUNTIES TO THE FFA AND REMOVE PORTIONS OF THE SOUTHWEST MOUNTAINS. MODELS ADVERTISE NEW UPPER LOW DEVELOPING NEAR KSFO WHILE THE RIDGE REBUILDS OVER THE EASTERN GREAT BASIN. SLOW DRYING FOR WESTERN UTAH WHILE EASTERN REMAINS UNDER DEEP SUB-TROPICAL MOISTURE INTO MID-WEEK. SLC 2221 CDC 4322 GIBSON .SLC...FLASH FLOOD WATCH SOUTHWEST AND SOUTH CENTRAL UTAH UNTIL 900 PM.
The office that day
Everything else NWS Salt Lake City, UT issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 21, 12:32 PM MDT | Severe Thunderstorm Warning | SLC | Kane | 63 min |
| Aug 21, 2:17 PM MDT | Severe Thunderstorm Warning | SLC | Kane | 48 min |
| Aug 21, 2:51 PM MDT | Flash Flood Warning | SLC | Kane | 84 min |
| Aug 21, 3:35 PM MDT | Flash Flood Warning | SLC | Washington | 85 min |
Nearby
Severe Thunderstorm Warnings in Utah, 1999Every severe thunderstorm warning in 1999
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.