Alert archive / Colorado / Tornado Warnings in 1999
Tornado Warning 61, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this tornado warning at Sep 1, 1999, 5:50 PM MDT for Logan County, Colorado. It was in force for 40 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
- Sep 1, 1999, 5:50 PM MDT (23:50 UTC)
- Expired
- Sep 1, 1999, 6:30 PM MDT
- In force
- 40 min
- Issued by
- NWS Denver/Boulder, CO
- Area
- Whole counties
County Logan County, CO
The radar
The Cheyenne radar (KCYS), 150 km from the middle of the area, began a volume at 23:53 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 watch it was issued in
The SPC watch in force over the same counties when this warning went out.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| Sep 1, 2:00 PM MDT | Severe Thunderstorm Watch | SPC | 6 hr |
The nearest sounding before it
Denver, CO (KDNR), launched 12:00Z, 11.8 hours before the alert went out and 96 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
- 52 J/kg
- Mixed-layer CIN
- -228 J/kg
- Mixed-layer LCL
- 1434 m above ground
- 0-6 km bulk shear
- 27 kt
- 0-1 km storm-relative helicity
- 60 m²/s²
- 0-3 km storm-relative helicity
- 91 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
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 tornado warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Denver/Boulder, CO wrote its last area forecast discussion before this tornado warning went out at Sep 1, 3:15 PM MDT, 2 hours 35 minutes earlier.
Area forecast discussion, Sep 1, 3:15 PM MDT, 2 hours 35 minutes before
AREA FORECAST DISCUSSION FOR NORTHEAST AND NORTH CENTRAL COLORADO NATIONAL WEATHER SERVICE DENVER COLORADO 315 PM MDT WED SEP 1 1999 NORTHEAST AREA UNDER GUN THIS EVENING AS CONDITIONS FAVORABLE FOR SOME SEVERE STORMS. LATEST PLATTEVILLE PROFILER INDICATING SHEAR BECOMING IMPRESSIVE AND CAPE VALUES INCREASING TO AROUND 1500 JOULES OVER MUCH OF THE PLAINS. LINE OF STORMS ASSOCIATED WITH SHORTWAVE MOVING OFF FOOTHILLS INTO THE FAVORABLE AIRMASS. SEVERE BOX ALREADY OUT FOR MUCH OF NORTHEAST COLORADO. LATEST RUC KEEPS SURFACE FRONT NORTH OF COLORADO THIS EVENING AS LOW LEVEL JET INCREASES SOUTHERLY FLOW. CONVECTION OVER MOUNTAINS TO INCREASE THIS EVENING AS SHORTWAVE OVER ARIZONA MOVES OVER AREA...AND SOME CONVECTION COULD LINGER WELL INTO THE NIGHT ESPECIALLY NORTHEAST CORNER. MODELS SIMILAR IN MOVING UPPER TROUGH CLOSER TO COLORADO NEXT 48 HOURS WHILE KEEPING MOISTURE PLUME OVER CWA. NEXT SHORTWAVE PROGGED OVER AREA THURSDAY AFTERNOON...WHICH WILL HELP TO INITIATE AFTERNOON CONVECTION. SURFACE FRONT DOESNT MAKE MUCH PROGRESS SOUTHWARD DURING PERIOD...BUT CONVECTION COULD AID IN MOVING THE FRONT INTO NORTHEAST COLORADO. MOST OF NORTHEAST COLORADO AGAIN IN SLIGHT RISK OF SEVERE VIA SPC THURSDAY AFTERNOON...AND SEEMS REASONABLE BASED ON FORECAST OF 1500 JOULES. SHEAR NOT AS IMPRESSIVE AS THIS EVENING... BUT DYNAMICS SHOULD HELP. AMS BECOMES MORE UNSTABLE FRIDAY AS 5H TEMPERATURES COOL IN RESPONSE TO THE APPROACHING TROUGH AND WILL INITIATE AFTERNOON CONVECTION. THICKNESS VALUES LOWER WITH TIME... SO TEMPERATURES TO COOL A FEW DEGREES EACH DAY. IN LONGER TERM...MRF SHOWS PROGRESSIVE MOVEMENT OF TROUGH OVER CWA OVER WEEKEND WITH RIDGE BUILDING OVER AREA MONDAY. BASED ON CURRENT DATA...THIS MAY NOT BE THAT FAR OFF. UPSLOPE AND LOW LEVEL MOISTURE PROGGED OVER THE AREA SATURDAY NIGHT AND SUNDAY. WILL CONTINUE THE CHANCE FOR SHOWERS AND STORMS THROUGH PERIOD...WITH SLIGHTLY WARMER CONDITIONS MONDAY. D-L .DEN...NONE.
In the hours before
Local storm report, Sep 1, 3:57 PM MDT, 1 hour 53 minutes before
LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DENVER CO
357 PM MDT WED SEP 01 1999
...PRELIMINARY STORM REPORT FOR SEPTEMBER 01 1999...
TIME(MDT) .....CITY LOCATION.....STATE ...EVENT/REMARKS...
....COUNTY LOCATION....
0251 PM 2 S MILTON CO 0.75 INCH HAIL
09/01/99 WELD
0321 PM 6 E LA SALLE CO 0.75 INCH HAIL
09/01/99 WELD
0313 PM 5 SE LA SALLE CO TORNADO
09/01/99 WELDLocal storm report, Sep 1, 3:57 PM MDT, 1 hour 53 minutes before
LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DENVER CO
357 PM MDT WED SEP 01 1999
...PRELIMINARY STORM REPORT FOR SEPTEMBER 01 1999...
TIME(MDT) .....CITY LOCATION.....STATE ...EVENT/REMARKS...
....COUNTY LOCATION....
0251 PM 2 S MILTON CO 0.75 INCH HAIL
09/01/99 WELD
0321 PM 6 E LA SALLE CO 0.75 INCH HAIL
09/01/99 WELD
0313 PM 5 SE LA SALLE CO TORNADO
09/01/99 WELDThe office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 1, 2:12 PM MDT | Severe Thunderstorm Warning | BOU | Adams, Weld | 33 min |
| Sep 1, 2:45 PM MDT | Severe Thunderstorm Warning | BOU | Weld | 30 min |
| Sep 1, 3:14 PM MDT | Tornado Warning | BOU | Weld | 31 min |
| Sep 1, 4:40 PM MDT | Tornado Warning | BOU | Weld | 30 min |
| Sep 1, 5:11 PM MDT | Severe Thunderstorm Warning | BOU | Logan, Weld | 49 min |
| Sep 1, 5:45 PM MDT | Severe Thunderstorm Warning | BOU | Larimer | 30 min |
Nearby
Tornado Warnings in Colorado, 1999Every tornado warning in 1999Tornadoes 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.