Alert archive / Colorado / Severe Thunderstorm Warnings in 1999
Severe Thunderstorm Warning 142, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this severe thunderstorm warning at Sep 2, 1999, 7:30 PM MDT for Weld County, Colorado. It was in force for 45 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
- Sep 2, 1999, 7:30 PM MDT (01:30 UTC)
- Expired
- Sep 2, 1999, 8:15 PM MDT
- In force
- 45 min
- Issued by
- NWS Denver/Boulder, CO
- Area
- Whole counties; the outline is the Mesonet’s reconstruction
County Weld County, CO
The radar
The Cheyenne radar (KCYS), 75 km from the middle of the area, began a volume at 01:31 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 |
|---|---|---|---|
| Sep 2, 7:56 PM MDT | Hail 0.75 | New Raymer, CO |
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
Denver, CO (KDNR), launched 00:00Z, 1.5 hours before the alert went out and 125 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
- 761 J/kg
- Mixed-layer CIN
- -45 J/kg
- Mixed-layer LCL
- 1907 m above ground
- 0-6 km bulk shear
- 41 kt
- 0-1 km storm-relative helicity
- 99 m²/s²
- 0-3 km storm-relative helicity
- 293 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 3.2
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 Denver/Boulder, CO wrote its last area forecast discussion before this severe thunderstorm warning went out at Sep 2, 3:25 PM MDT, 4 hours 5 minutes earlier.
Area forecast discussion, Sep 2, 3:25 PM MDT, 4 hours 5 minutes before
AREA FORECAST DISCUSSION FOR NORTHEAST AND NORTH CENTRAL COLORADO NATIONAL WEATHER SERVICE DENVER COLORADO 325 PM MDT THU SEP 2 1999 LATEST SURFACE DATA SHOWS LOW NEAR LIMON WITH PLATTEVILLE PROFILER INDICATING EAST TO SOUTHWEST WINDS INCREASING ACROSS THE LOWER GATES. SHEAR PROFILE BECOMING FAVORABLE FOR SEVERE POTENTIAL. LATEST SATELLITE INDICATING WHAT SEEMS TO BE A SHORTWAVE MOVING ACROSS THE MOUNTAINS. CONVECTION ASSOCIATED WITH THIS WAVE ALREADY DEVELOPING OVER MOUNTAINS AND SHOULD HELP TO INITIATE STORMS ACROSS PLAINS. BEST CAPE VALUES ACROSS WELD...MORGAN AND WASHINGTON COUNTIES AND POINTS NORTHWARD...AND THIS LOOKS LIKE THE BEST AREA FOR SEVERE STORMS THIS EVENING. WEAK LIFT TO CONTINUE OVERNIGHT ACROSS CWA...AND SHOULD KEEP SOME SHOWERS GOING OVERNIGHT. FRIDAY POINTING TO ANOTHER INTERESTING DAY AS COLD UPPER TROUGH NEARS CWA AND HELPS TO DESTABILIZE ATMOSPHERE. IN ADDITION...LOW LEVEL SOUTHEAST WINDS...DECENT SHEAR AND UPPER SUPPORT AS NOTED BY MODEL DIV-Q FIELDS SEEM TO COME TOGETHER DURING AFTERNOON. WITH MODIFIED CAPE VALUES IN THE 1500 JOULES RANGE...POTENTIAL EXISTS FOR SOME STORMS TO BECOME SEVERE. AFTER UPPER LEVEL SUPPORT PASSES OVER CWA DURING AFTERNOON AND EVENING...MODELS INDICATE SUBSIDENCE OVER CWA OVERNIGHT FRIDAY INTO SATURDAY. WILL NOT CONTINUE PRECIPITATION OVERNIGHT. DECENT SURGE...WITH COOLER AIR TO DROP ACROSS CWA SATURDAY AM WITH SURFACE LOW PERSISTING OVER SOUTHEAST COLORADO AS TROUGH MOVES OVER AREA. NGM...AND TO SOME EXTENT THE AVN SHOW MODEL BIASES IN POSITION OF LOW. COULD BE TOO STABLE FOR SHOWERS OR STORMS TO DEVELOP DURING AFTERNOON...BUT FOR NOW...WILL KEEP SOME POPS GOING. IN LONGER TERM...MRF CONTINUE PROGRESSIVE MOVEMENT OF TROUGH WHILE BRINGING ANOTHER SURGE INTO NORTHEAST COLORADO SUNDAY. AGAIN MAY BE TOO STABLE FOR SHOWERS SUNDAY. BY MONDAY AND TUESDAY DRIER AND WARMER AIR MOVES IN BEHIND TROUGH WITH HIGH PRESSURE IN CONTROL. LESZCYNSKI .DEN...NONE.
In the hours before
Local storm report, Sep 2, 6:29 PM MDT, 1 hour 1 minute before
LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DENVER CO
629 PM MDT THU SEP 02 1999
...PRELIMINARY STORM REPORT FOR SEPTEMPBER 02 1999...
TIME(MDT) .....CITY LOCATION.....STATE ...EVENT/REMARKS...
....COUNTY LOCATION....
0510 PM 1 N LONGMONT CO 0.75 INCH HAIL
09/02/99 BOULDER
0515 PM 6 E PLATTEVILLE CO 1.00 INCH HAIL
09/02/99 WELD
0618 PM LA SALLE CO 0.75 INCH HAIL
09/02/99 WELD
0620 PM 6 E LA SALLE CO 0.75 INCH HAIL
09/02/99 WELDLocal storm report, Sep 2, 6:29 PM MDT, 1 hour 1 minute before
LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DENVER CO
629 PM MDT THU SEP 02 1999
...PRELIMINARY STORM REPORT FOR SEPTEMPBER 02 1999...
TIME(MDT) .....CITY LOCATION.....STATE ...EVENT/REMARKS...
....COUNTY LOCATION....
0510 PM 1 N LONGMONT CO 0.75 INCH HAIL
09/02/99 BOULDER
0515 PM 6 E PLATTEVILLE CO 1.00 INCH HAIL
09/02/99 WELD
0618 PM LA SALLE CO 0.75 INCH HAIL
09/02/99 WELD
0620 PM 6 E LA SALLE CO 0.75 INCH HAIL
09/02/99 WELDLocal storm report, Sep 2, 7:05 PM MDT, 25 minutes before
LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DENVER CO
705 PM MDT THU SEP 02 1999
...PRELIMINARY STORM REPORT FOR SEPTEMBER 02 1999...
TIME(MDT) .....CITY LOCATION.....STATE ...EVENT/REMARKS...
....COUNTY LOCATION....
0625 PM KERSEY CO 0.75 INCH HAIL
09/02/99 WELD
0655 PM 23 NW FT MORGAN CO 1.50 INCH HAIL
09/02/99 MORGANLocal storm report, Sep 2, 7:05 PM MDT, 25 minutes before
LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DENVER CO
705 PM MDT THU SEP 02 1999
...PRELIMINARY STORM REPORT FOR SEPTEMBER 02 1999...
TIME(MDT) .....CITY LOCATION.....STATE ...EVENT/REMARKS...
....COUNTY LOCATION....
0625 PM KERSEY CO 0.75 INCH HAIL
09/02/99 WELD
0655 PM 23 NW FORT MORGAN CO 1.50 INCH HAIL
09/02/99 MORGANLocal storm report, Sep 2, 7:05 PM MDT, 25 minutes before
LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DENVER CO
705 PM MDT THU SEP 02 1999
...PRELIMINARY STORM REPORT FOR SEPTEMBER 02 1999...
TIME(MDT) .....CITY LOCATION.....STATE ...EVENT/REMARKS...
....COUNTY LOCATION....
0625 PM KERSEY CO 0.75 INCH HAIL
09/02/99 WELD
0655 PM 23 NW FT MORGAN CO 1.50 INCH HAIL
09/02/99 MORGANLocal storm report, Sep 2, 7:05 PM MDT, 25 minutes before
LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DENVER CO
705 PM MDT THU SEP 02 1999
...PRELIMINARY STORM REPORT FOR SEPTEMBER 02 1999...
TIME(MDT) .....CITY LOCATION.....STATE ...EVENT/REMARKS...
....COUNTY LOCATION....
0625 PM KERSEY CO 0.75 INCH HAIL
09/02/99 WELD
0655 PM 23 NW FORT MORGAN CO 1.50 INCH HAIL
09/02/99 MORGANThe office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 2, 6:13 PM MDT | Severe Thunderstorm Warning | BOU | Morgan, Weld | 47 min |
| Sep 2, 6:15 PM MDT | Severe Thunderstorm Warning | BOU | Weld | 35 min |
| Sep 2, 6:52 PM MDT | Tornado Warning | BOU | Morgan, Weld | 38 min |
| Sep 2, 7:46 PM MDT | Tornado Warning | BOU | Weld | 44 min |
| Sep 2, 8:02 PM MDT | Severe Thunderstorm Warning | BOU | Morgan, Weld | 43 min |
| Sep 2, 8:22 PM MDT | Tornado Warning | BOU | Morgan | 38 min |
| Sep 2, 8:31 PM MDT | Severe Thunderstorm Warning | BOU | Logan, Weld | 44 min |
| Sep 3, 3:47 PM MDT | Severe Thunderstorm Warning | BOU | Adams, Arapahoe, Denver | 43 min |
| Sep 3, 3:47 PM MDT | Severe Thunderstorm Warning | BOU | Weld | 43 min |
| Sep 3, 4:29 PM MDT | Severe Thunderstorm Warning | BOU | Adams, Denver, Weld | 41 min |
| Sep 3, 5:02 PM MDT | Severe Thunderstorm Warning | BOU | Adams, Denver, Jefferson | 43 min |
| Sep 3, 5:02 PM MDT | Severe Thunderstorm Warning | BOU | Boulder | 43 min |
| Sep 3, 5:13 PM MDT | Severe Thunderstorm Warning | BOU | Morgan, Weld | 32 min |
| Sep 3, 5:25 PM MDT | Severe Thunderstorm Warning | BOU | Weld | 35 min |
| Sep 3, 5:45 PM MDT | Severe Thunderstorm Warning | BOU | Adams, Denver | 45 min |
| Sep 3, 5:45 PM MDT | Severe Thunderstorm Warning | BOU | Weld | 45 min |
| Sep 3, 5:51 PM MDT | Severe Thunderstorm Warning | BOU | Morgan | 39 min |
Nearby
Severe Thunderstorm Warnings in Colorado, 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.