Alert archive / Utah / Flash Flood Warnings in 1998

Flash Flood Warning 39, NWS Salt Lake City, UT

August 21, 1998San Juan County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Aug 21, 1998, 8:39 PM MDT for San Juan County, Utah. It was in force for 66 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline the Iowa Environmental Mesonet reconstructed for it; the warning itself named whole counties.

The facts

Issued
Aug 21, 1998, 8:39 PM MDT (02:39 UTC)
Expired
Aug 21, 1998, 9:45 PM MDT
In force
66 min
Issued by
NWS Salt Lake City, UT
Area
Whole counties; the outline is the Mesonet’s reconstruction

County San Juan County, UT

The radar

The Grand Junction radar (KGJX), 181 km from the middle of the area, began a volume at 02:38 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

Salt Lake City I, UT (KSLC), launched 00:00Z, 2.7 hours before the alert went out and 346 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, Salt Lake City I, UT at 00:00Z on 1998-08-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 65 joules per kilogram.LCLEL10008507005003002001001 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, Salt Lake City I, UT at 00:00Z on 1998-08-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 3 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
65 J/kg
Mixed-layer CIN
-14 J/kg
Mixed-layer LCL
3375 m above ground
0-6 km bulk shear
37 kt
0-1 km storm-relative helicity
3 m²/s²
0-3 km storm-relative helicity
58 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 
TTAA00 KSLC 220248
FFWSLC
UTC037-220345-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
839 PM MDT FRI AUG 21 1998

THE NATIONAL WEATHER SERVICE IN SALT LAKE CITY HAS ISSUED A

   * FLASH FLOOD WARNING FOR...
     NORTH CENTRAL SAN JUAN COUNTY IN UTAH

   * UNTIL 945 PM MDT

   * AT 834 PM MDT WEATHER SERVICE DOPPLER RADAR INDICATED VERY HEAVY
     RAIN OVER EXTREME SOUTHEASTERN WAYNE COUNTY...NEAR THE       
CONFLUENCE OF THE GREEN AND COLORADO RIVERS...OR ABOUT 40 MILES      
NORTHWEST OF MONTICELLO.  THIS STORM IS MOVING TOWARD THE EAST 
SOUTHEAST AT ABOUT 15-20 MPH AND WILL BE CROSSING INTO THE NEEDLES 
REGION OF CANYONLANDS NATIONAL PARK BY 850 PM.  


EXCESSIVE RUNOFF FROM THIS STORM WILL CAUSE FLASH FLOODING OF CREEKS 
AND NORMALLY DRY WASHES.  HIKERS AND CAMPERS IN THE WARNING AREA 
SHOULD SEEK HIGHER GROUND IMMEDIATLEY.

LAT...LON 3804 11002 3791 10971 3835 10975

The office that day

Everything else NWS Salt Lake City, UT issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 21, 6:12 PM MDTFlash Flood WarningSLCEmery78 min
Aug 21, 9:48 PM MDTFlash Flood WarningSLCSan Juan57 min
Aug 22, 1:23 PM MDTSevere Thunderstorm WarningSLCDuchesne37 min
Aug 22, 1:30 PM MDTFlash Flood WarningSLCDuchesne60 min

Nearby

Flash Flood Warnings in Utah, 1998Every flash flood warning in 1998

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.