Alert archive / Nebraska / Severe Thunderstorm Warnings in 2004

Severe Thunderstorm Warning 308, NWS Omaha, NE

July 15, 2004Knox County, Nebraska

NWS Omaha, NE issued this severe thunderstorm warning at Jul 15, 2004, 11:05 AM CDT for Knox County, Nebraska. 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: Jul 15, 2004, 11:05 AM CDT (16:05 UTC)
Expired: Jul 15, 2004, 11:45 AM CDT
In force: 40 min
Issued by: NWS Omaha, NE
Area: Counties, with a storm outline in the text

County Knox County, NE

The radar

The Sioux Falls radar (KFSD), 142 km from the middle of the area, began a volume at 16:08 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

Omaha, NE (KOAX), launched 12:00Z, 4.1 hours before the alert went out and 193 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: 13 J/kg
Mixed-layer CIN: -468 J/kg
Mixed-layer LCL: 1009 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: 48 m²/s²
0-3 km storm-relative helicity: 127 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

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 Omaha, NE wrote its last area forecast discussion before this severe thunderstorm warning went out at Jul 15, 2:55 AM CDT, 8 hours 10 minutes earlier.

Area forecast discussion, Jul 15, 2:55 AM CDT, 8 hours 10 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
255 AM CDT THU JUL 15 2004

.DISCUSSION...
FOG THIS MORNING AND RAIN CHANCES TODAY INTO TONIGHT ARE THE MAIN
CONCERNS THIS FORECAST.

07Z SURFACE ANALYSIS INDICATES SMALL TEMPERATURE/DEWPOINT SPREADS
WITH PATCHY FOG DEVELOPING ALONG THE MISSOURI RIVER.  THINK THAT
SOME SPOTS COULD SEE LOW VISIBILITIES THIS MORNING...HOWEVER
CONVECTIVE DEBRIS CLOUDS FROM SOUTH DAKOTA CONTINUE TO MOVE QUICKLY
SOUTH...AND AM HOPEFUL THAT THEY WILL HELP KEEP THINGS FROM REACHING
DENSE FOG ADVISORY CRITERIA WITH WIDESPREAD VISIBILITIES LESS THAN
1/4 MILE.

NEXT ISSUE SURROUNDS CONVECTIVE CHANCES TODAY.  MAY NEED TO HAVE A
SMALL POP THIS MORNING OVER MAINLY NORTHEAST NEBRASKA DUE TO
SOUTHWARD MOVING CONVECTION OVER SOUTH DAKOTA.  OTHERWISE...AGREE
WITH SPC DAY 1 OUTLOOK THAT THIS AFTERNOON AND ESPECIALLY THIS
EVENING COULD BE ACTIVE WITH SEVERE WEATHER.  MOISTURE CONVERGENCE
INCREASES ALONG A FRONT AS INSTABILITY RISES.  SURFACE BASED CAPES
FROM THE ETA ARE FORECAST TO RISE TO 3000-4000 J/KG BY 00Z. DEEP
LAYER (0-6KM) SHEAR VALUES OF NEAR 40 KTS SHOULD ALSO SUPPORT
SUPERCELLS. RELATIVELY HIGH PRECIPITABLE WATER VALUES OF NEAR 2
INCHES IN SOUTHEAST NEBRASKA THIS EVENING ALSO SUGGESTS SOME HEAVY
RAIN POTENTIAL.  THE BOUNDARY THEN PUSHES SOUTH TONIGHT AND BY 15Z
FRIDAY IS FORECAST TO BE SOUTH OF THE CWA INTO NORTHERN KANSAS.

RAIN CHANCES FROM FRIDAY AFTERNOON INTO THE REMAINDER OF THE WEEKEND
LOOK RATHER SMALL AND HAVE TRENDED TO A DRIER LOOK TO THE FORECAST.
UPSLOPE FLOW MAY DEVELOP STORMS ACROSS WESTERN NEBRASKA FRIDAY
NIGHT...HOWEVER THE ETA ONLY BRINGS THIS INTO CENTRAL NEBRASKA
BEFORE HAVING IT DISSIPATE.  THIS DOESNT SEEM UNREASONABLE WITH
SURFACE HIGH PRESSURE IN PLACE AND LESS DEEP MOISTURE TO WORK WITH.
MAY KEEP A SMALL CHANCE IN THE WESTERN AREAS FRIDAY NIGHT CLOSER TO
THE BETTER 850 MB MOISTURE...BUT DRY IT OUT IN THE EAST.  ANOTHER
POTENTIAL TROUBLE SPOT ON SATURDAY NIGHT COULD BE AN INCREASE IN
MID-LEVEL MOISTURE WITH THE ETA BRINGING ACROSS 700MB MOISTURE
ADVECTION.  WILL NOT JUMP ON THIS YET AND TRY TO GO MAINLY DRY
SATURDAY INTO SUNDAY.  NEXT BEST CHANCE FOR RAIN LOOKS TO COME ALONG
A SURFACE TROF MONDAY NIGHT INTO TUESDAY AND THE CURRENT FORECAST
COVERS THIS WELL ALREADY.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.

&&

KING

Hazardous weather outlook, Jul 15, 5:26 AM CDT, 5 hours 39 minutes before

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The office that day

Everything else NWS Omaha, NE issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 15, 11:46 AM CDT	Severe Thunderstorm Warning	OAX	Knox, Pierce	59 min
Jul 15, 12:36 PM CDT	Severe Thunderstorm Warning	OAX	Madison	54 min
Jul 15, 6:08 PM CDT	Tornado Warning	OAX	Knox	52 min
Jul 15, 6:33 PM CDT	Tornado Warning	OAX	Antelope	27 min

Nearby

Severe Thunderstorm Warnings in Nebraska, 2004 Every severe thunderstorm warning in 2004

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.