Alert archive / Colorado / Severe Thunderstorm Warnings in 1990

Severe Thunderstorm Warning 34, NWS Denver/Boulder, CO

July 11, 1990Adams County, Boulder County, Jefferson County, Colorado

NWS Denver/Boulder, CO issued this severe thunderstorm warning at Jul 11, 1990, 1:42 PM MDT for Adams County, Boulder County, Jefferson County, Colorado. It was in force for 48 min. 5 reports 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: Jul 11, 1990, 1:42 PM MDT (19:42 UTC)
Expired: Jul 11, 1990, 2:30 PM MDT
In force: 48 min
Issued by: NWS Denver/Boulder, CO
Area: Whole counties

Counties Adams County, CO, Boulder County, CO, Jefferson County, CO

The radar

The WSR-88D network and its archive begin in 1991, so there is no radar volume for this alert.

What was reported inside it

Time	Report	Where
Jul 11, 2:05 PM MDT	Hail 1	Boulder, CO
Jul 11, 2:05 PM MDT	Hail 1.5	Jefferson, CO
Jul 11, 2:10 PM MDT	Hail 2.75	Jefferson, CO
Jul 11, 2:17 PM MDT	Hail 1	Adams, CO
Jul 11, 2:30 PM MDT	Hail 1.75	Jefferson, 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. Storm Data before 1996 records only tornadoes, thunderstorm wind and hail.

The nearest sounding before it

Fort Carson/Butt, CO (KFCS), launched 12:00Z, 7.7 hours before the alert went out and 132 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1472 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: -4 m²/s²
0-3 km storm-relative helicity: 5 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 KDEN 111945
SVRDEN
COC059-013-001-112030-

BULLETIN...IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DENVER CO
142 PM MDT WED JUL 11 1990

THE NATIONAL WEATHER SERVICE HAS ISSUED A SEVERE THUNDERSTORM
WARNING EFFECTIVE UNTIL 230 PM  MDT FOR PEOPLE IN THE
FOLLOWING COUNTIES OF NORTHEAST COLORADO:

     NORTHERN JEFFERSON
     SOUTHERN BOULDER
     FAR WESTERN ADAMS 

INCLUDING THE FOLLOWING TOWNS/CITIES:

     BOULDER..ELDORADO SPGS..JAMESTOWN..LAFAYETTE..LOUISVILLE..
     NIWOT..SUPERIOR...BROOMFIELD...NORTHGLENN

THE STORM WAS LOCATED VERY NEAR NIWOT..WHICH IS 27 MILES
NORTHWEST OF DENVER.  NATIONAL WEATHER SERVICE DOPPLER RADAR 
SHOWED A MOVEMENT TO THE SOUTH AT 20 MPH.  

RESIDENTS IN THE PATH OF THIS STORM SHOULD TAKE COVER.  
LOCALLY HEAVY RAIN...LARGE DAMAGING HAIL...FREQUENT DANGEROUS 
LIGHTING WILL ACCOMPANY THIS STORM.  

INTENSE LIGHTNING IS LIKELY WITH THIS STORM.  IF OUTDOORS..
STAY AWAY FROM HIGH OBJECTS.  MOVE INDOORS IF POSSIBLE.  WHEN
INDOORS..STAY AWAY FROM WINDOWS AND DOORS AND AVOID USING
TELEPHONES AND ELECTRICAL EQUIPMENT.

TO REPORT SEVERE WEATHER HAVE THE NEAREST LAW ENFORCEMENT
AGENCY RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE OFFICE
IN DENVER..OR CALL YOUR REPORT TO THE NATIONAL WEATHER SERVICE
AT 361-0663.  DO NOT CALL THIS NUMBER FOR INFORMATION.

RTG

LAT..LON  3984 10508 3983 10536 4012 10539 4012 10507

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.

In the hours before

Special weather statement, Jul 11, 12:48 PM MDT, 54 minutes before

COZ011-014-111930-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
1245 PM MDT WED JUL 11 1990

...THUNDERSTORMS ARE BEGINNING TO DEVELOP ALONG THE FOOTHILLS...

AT 1241 PM NATIONAL WEATHER SERVICE DOPPLER RADAR SHOWED
THUNDERSTORMS BEGINNING TO FIRE OVER THE NORTHERN FOOTHILLS AND
PALMER DIVIDE.  THE STRONGEST STORM WAS LOCATED 7 MILES EAST OF
ESTES PARK...AND MOVING SOUTHEAST AT 20 MPH.

STORMS WILL CONTINUE TO DEVELOP ALONG THE FOOTHILLS EARLY
THIS AFTERNOON...AND MOVE OUT INTO THE PLAINS BY MID
AFTERNOON.  STORMS SHOULD CONTINUE MOVING SOUTHEAST AT 15 TO 25 MPH.
LOCALLY HEAVY RAIN...HAIL...AND FREQUENT LIGHTNING WILL BE POSSIBLE
WITH STORMS THIS AFTERNOON.

RTG

The office that day

Everything else NWS Denver/Boulder, CO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 11, 1:00 PM MDT	Severe Thunderstorm Warning	BOU	Boulder, Larimer	40 min
Jul 11, 2:15 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Denver, Jefferson	90 min
Jul 11, 2:30 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Denver, Jefferson	15 min
Jul 11, 3:10 PM MDT	Severe Thunderstorm Warning	BOU	Douglas	30 min

Nearby

Severe Thunderstorm Warnings in Colorado, 1990 Every severe thunderstorm warning in 1990

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.