Alert archive / Colorado / Severe Thunderstorm Warnings in 1999

Severe Thunderstorm Warning 124, NWS Denver/Boulder, CO

August 28, 1999Adams County, Colorado

NWS Denver/Boulder, CO issued this severe thunderstorm warning at Aug 28, 1999, 3:44 PM MDT for Adams County, Colorado. It was in force for 31 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
Aug 28, 1999, 3:44 PM MDT (21:44 UTC)
Expired
Aug 28, 1999, 4:15 PM MDT
In force
31 min
Issued by
NWS Denver/Boulder, CO
Area
Whole counties; the outline is the Mesonet’s reconstruction

County Adams County, CO

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Aug 28, 2:15 PM MDTSevere Thunderstorm WatchSPC5 hr

The nearest sounding before it

Denver, CO (KDNR), launched 12:00Z, 9.7 hours before the alert went out and 95 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, Denver, CO at 12:00Z on 1999-08-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1 joules per kilogram.LCLLFCEL10008507005003002001001 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, Denver, CO at 12:00Z on 1999-08-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 62 square meters per square second.1939Sfc1 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
1 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1080 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
62 m²/s²
0-3 km storm-relative helicity
83 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

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 Aug 28, 2:30 PM MDT, 1 hour 14 minutes earlier.

Area forecast discussion, Aug 28, 2:30 PM MDT, 1 hour 14 minutes before
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In the hours before

Special weather statement, Aug 28, 11:00 AM MDT, 4 hours 44 minutes before
COZ030-032>050-290600-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER CO
1100 AM MDT SAT AUG 28 1999

THIS OUTLOOK PERTAINS TO THE FOLLOWING COLORADO COUNTIES

ADAMS     ARAPAHOE     BOULDER   CLEAR CREEK   DENVER       DOUGLAS
ELBERT    GILPIN       GRAND     JACKSON       JEFFERSON    LARIMER
LINCOLN   LOGAN        MORGAN    PARK          PHILLIPS     SEDGWICK
SUMMIT    WASHINGTON   WELD

SYNOPSIS...A BAND OF MONSOONAL MOISTURE FROM MEXICO WILL CONTINUE TO
STREAM NORTHWARD ON SOUTH TO SOUTHWESTERLY FLOW ALOFT OVER NORTHEAST
AND NORTH CENTRAL COLORADO THROUGH THE AFTERNOON AND EVENING HOURS.
RESIDUAL MOISTURE AT LOW LEVELS FROM YESTERDAYS HEAVY RAINS HAS
INCREASED OVER THE PLAINS.  AN UPPER LEVEL DISTURBANCE WILL AID IN
DESTABILIZING THIS VERY MOIST AIR MASS OVER THE AREA.  WITH FREEZING
LEVELS SLIGHTLY LOWER AND STRONGER WINDS ALOFT PROVIDING MORE SHEAR
THAN YESTERDAY THE THREAT OF SEVERE THUNDERSTORMS PRODUCING LARGE HAIL
AND DAMAGING WINDS WILL INCREASE.  IN ADDITION...WITH THE AMOUNT OF
MOISTURE IN THE AIR MASS AT 170 PERCENT OF NORMAL FOR THIS TIME OF
YEAR...THE THREAT OF HEAVY THUNDERSTORM RAINFALL WILL CONTINUE TO BE
HIGH EVEN THOUGH THE STORMS WILL BE MOVING AT A FASTER RATE OF SPEED.
THE THREAT OF THE HEAVY RAIN PRODUCING FLOODING WILL BE INCREASED DUE
TO ALREADY SATURATED SOILS.  THE THREAT OF DEADLY CLOUD TO GROUND
LIGHTNING FROM THESE STORMS WILL CONTINUE TO BE PRESENT.

BY MIDDAY SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM OVER THE
MOUNTAINS AND EASTERN FOOTHILLS AND MOVE TO THE NORTHEAST OVER THE
FRONT RANGE URBAN CORRIDOR AND THE NORTHEASTERN PLAINS DURING THE
AFTERNOON AND EVENING.  A FEW OF THESE STORMS OVER THE URBAN CORRIDOR
AND ON THE PLAINS MAY BE SEVERE...PRODUCING LARGE HAIL AND DAMAGING
WINDS.  THE STRONGEST THUNDERSTORMS WILL BE CAPABLE OF PRODUCING UP
TO 3 INCHES OF RAIN IN AN HOUR.  THIS HEAVY AMOUNT OF RAIN WILL CAUSE
LOCAL FLOODING OF STREETS...HIGHWAYS AND UNDERPASSES...NORMALLY DRY
GULCHES...SMALL CREEKS AND STREAMS AND LOW LYING OR FLOOD PRONE
AREAS.  THE HEAVY RAIN MAY ALSO TRIGGER MUD AND ROCK SLIDES IN
CANYONS AND STEEP TERRAIN.

SPOTTER ACTIVATION MAY BE REQUIRED THIS AFTERNOON.

GARD...WFO BOULDER
Special weather statement, Aug 28, 11:00 AM MDT, 4 hours 44 minutes before
COZ030-032>050-290600-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER CO
1100 AM MDT SAT AUG 28 1999

THIS OUTLOOK PERTAINS TO THE FOLLOWING COLORADO COUNTIES

ADAMS     ARAPAHOE     BOULDER   CLEAR CREEK   DENVER       DOUGLAS
ELBERT    GILPIN       GRAND     JACKSON       JEFFERSON    LARIMER
LINCOLN   LOGAN        MORGAN    PARK          PHILLIPS     SEDGWICK
SUMMIT    WASHINGTON   WELD

SYNOPSIS...A BAND OF MONSOONAL MOISTURE FROM MEXICO WILL CONTINUE TO
STREAM NORTHWARD ON SOUTH TO SOUTHWESTERLY FLOW ALOFT OVER NORTHEAST
AND NORTH CENTRAL COLORADO THROUGH THE AFTERNOON AND EVENING HOURS.
RESIDUAL MOISTURE AT LOW LEVELS FROM YESTERDAYS HEAVY RAINS HAS
INCREASED OVER THE PLAINS.  AN UPPER LEVEL DISTURBANCE WILL AID IN
DESTABILIZING THIS VERY MOIST AIR MASS OVER THE AREA.  WITH FREEZING
LEVELS SLIGHTLY LOWER AND STRONGER WINDS ALOFT PROVIDING MORE SHEAR
THAN YESTERDAY THE THREAT OF SEVERE THUNDERSTORMS PRODUCING LARGE HAIL
AND DAMAGING WINDS WILL INCREASE.  IN ADDITION...WITH THE AMOUNT OF
MOISTURE IN THE AIR MASS AT 170 PERCENT OF NORMAL FOR THIS TIME OF
YEAR...THE THREAT OF HEAVY THUNDERSTORM RAINFALL WILL CONTINUE TO BE
HIGH EVEN THOUGH THE STORMS WILL BE MOVING AT A FASTER RATE OF SPEED.
THE THREAT OF THE HEAVY RAIN PRODUCING FLOODING WILL BE INCREASED DUE
TO ALREADY SATURATED SOILS.  THE THREAT OF DEADLY CLOUD TO GROUND
LIGHTNING FROM THESE STORMS WILL CONTINUE TO BE PRESENT.

BY MIDDAY SCATTERED SHOWERS AND THUNDERSTORMS WILL FORM OVER THE
MOUNTAINS AND EASTERN FOOTHILLS AND MOVE TO THE NORTHEAST OVER THE
FRONT RANGE URBAN CORRIDOR AND THE NORTHEASTERN PLAINS DURING THE
AFTERNOON AND EVENING.  A FEW OF THESE STORMS OVER THE URBAN CORRIDOR
AND ON THE PLAINS MAY BE SEVERE...PRODUCING LARGE HAIL AND DAMAGING
WINDS.  THE STRONGEST THUNDERSTORMS WILL BE CAPABLE OF PRODUCING UP
TO 3 INCHES OF RAIN IN AN HOUR.  THIS HEAVY AMOUNT OF RAIN WILL CAUSE
LOCAL FLOODING OF STREETS...HIGHWAYS AND UNDERPASSES...NORMALLY DRY
GULCHES...SMALL CREEKS AND STREAMS AND LOW LYING OR FLOOD PRONE
AREAS.  THE HEAVY RAIN MAY ALSO TRIGGER MUD AND ROCK SLIDES IN
CANYONS AND STEEP TERRAIN.

SPOTTER ACTIVATION MAY BE REQUIRED THIS AFTERNOON.

GARD...WFO BOULDER

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 28, 1:34 PM MDTSevere Thunderstorm WarningBOUDouglas26 min
Aug 28, 1:57 PM MDTSevere Thunderstorm WarningBOUArapahoe, Douglas, Elbert33 min
Aug 28, 2:17 PM MDTTornado WarningBOUAdams, Arapahoe28 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; the sounding from the Mesonet's radiosonde archive.