Alert archive / Utah / Severe Thunderstorm Warnings in 1999
Severe Thunderstorm Warning 28, NWS Salt Lake City, UT
NWS Salt Lake City, UT issued this severe thunderstorm warning at Aug 11, 1999, 12:48 PM MDT for Davis County, Weber County, Utah. It was in force for 57 min. 1 report came from inside the area while it was in force.
The area
The counties it named, with what was reported inside it.
The facts
- Issued
- Aug 11, 1999, 12:48 PM MDT (18:48 UTC)
- Expired
- Aug 11, 1999, 1:45 PM MDT
- In force
- 57 min
- Issued by
- NWS Salt Lake City, UT
- Area
- Whole counties; the outline is the Mesonet’s reconstruction
Counties Davis County, UT, Weber County, UT
The radar
The Salt Lake City radar (KMTX), 39 km from the middle of the area, began a volume at 18:51 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 was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| Aug 11, 1:15 PM MDT | Hail 1.5 | Bountiful, UT | After producing the Salt Lake tornado, that same cell dropped 1 1/2 inch hail in Bountiful. |
NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.
The nearest sounding before it
Salt Lake City I, UT (KSLC), launched 12:00Z, 6.8 hours before the alert went out and 40 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
- 57 J/kg
- Mixed-layer CIN
- -58 J/kg
- Mixed-layer LCL
- 1441 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 24 m²/s²
- 0-3 km storm-relative helicity
- 31 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 11, 9:00 AM MDT, 3 hours 48 minutes earlier.
Area forecast discussion, Aug 11, 9:00 AM MDT, 3 hours 48 minutes before
UTAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SALT LAKE CITY UTAH 900 AM MDT WED AUG 11 1999 SYNOPSIS...AN UPPER LEVEL LOW PRESSURE SYSTEM OVER NEVADA WILL MOVE EAST NORTHEAST ACROSS UTAH TODAY. DRIER WESTERLY FLOW ALOFT WILL MOVE INTO THE STATE TONIGHT AND THURSDAY. DISCUSSION...VORT LOBE HAS MOVED NORTHEAST OUT OF UTAH IN THE LAST HOUR AND RAIN HAS ENDED IN NORTHERN ZONES. UPPER LEVEL TROUGH AND COLD POCKET WILL CROSS AREA AROUND MID DAY WHICH COULD DESTABILIZE AIRMASS AGAIN. HAVE UPDATED ALL NORTHERN ZONES TO JUST A CHANCE OF SHOWERS WITH UPPER LEVEL COLD POCKET. NO OTHER CHANGES AT THIS TIME. SLC 311 CDC 211 DUNN .SLC...NONE.
The office that day
Everything else NWS Salt Lake City, UT issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 11, 12:48 PM MDT | Severe Thunderstorm Warning | SLC | Salt Lake | 57 min |
| Aug 11, 1:46 PM MDT | Severe Thunderstorm Warning | SLC | Morgan, Summit | 59 min |
| Aug 11, 2:19 PM MDT | Severe Thunderstorm Warning | SLC | Davis, Morgan, Weber | 56 min |
| Aug 11, 2:19 PM MDT | Severe Thunderstorm Warning | SLC | Salt Lake | 56 min |
| Aug 11, 3:09 PM MDT | Severe Thunderstorm Warning | SLC | Davis, Morgan, Weber | 51 min |
| Aug 11, 3:10 PM MDT | Severe Thunderstorm Warning | SLC | Box Elder | 60 min |
| Aug 11, 3:42 PM MDT | Tornado Warning | SLC | Box Elder | 33 min |
| Aug 11, 4:04 PM MDT | Tornado Warning | SLC | Box Elder, Cache | 26 min |
| Aug 11, 4:04 PM MDT | Tornado Warning | SLC | Franklin | 26 min |
| Aug 11, 1:46 PM MDT | Severe Thunderstorm Warning | SLC | Uinta | 59 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; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.