Alert archive / Iowa / Tornado Warnings in 2001

Tornado Warning 69, NWS Omaha, NE

July 17, 2001Pottawattamie County, Iowa

NWS Omaha, NE issued this tornado warning at Jul 17, 2001, 11:15 PM CDT for Pottawattamie County, Iowa. It was in force for 30 min. 1 report came from inside the area while it was in force.

The area

The outline the Iowa Environmental Mesonet reconstructed for it; the warning itself named whole counties, with what was reported inside it.

The facts

Issued: Jul 17, 2001, 11:15 PM CDT (04:15 UTC)
Expired: Jul 17, 2001, 11:45 PM CDT
In force: 30 min
Issued by: NWS Omaha, NE
Area: Whole counties; the outline is the Mesonet’s reconstruction

County Pottawattamie County, IA

The radar

The Omaha radar (KOAX), 47 km from the middle of the area, began a volume at 04:18 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
Jul 17, 11:35 PM CDT	Thunderstorm Wind 60 E	Carter Lake, IA	Large tree limbs were broken by thunderstorm wind gusts which were around 70 mph. A gust of 70 mph was measured at Eppley Airfield which is just a mile or so east of Carter Lake.

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 watch it was issued in

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

Issued	Product	Office	Lasted
Jul 17, 10:00 PM CDT	Severe Thunderstorm Watch	SPC	5 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 4.3 hours before the alert went out and 47 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: 3248 J/kg
Mixed-layer CIN: -91 J/kg
Mixed-layer LCL: 1677 m above ground
0-6 km bulk shear: 49 kt
0-1 km storm-relative helicity: -30 m²/s²
0-3 km storm-relative helicity: 154 m²/s²
Significant tornado parameter: 0.9
Supercell composite: 40.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
WFUS53 KOAX 180416
TOROMA

IAC155-180445-

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE OMAHA NE
1115 PM CDT TUE JUL 17 2001

THE NATIONAL WEATHER SERVICE IN OMAHA HAS ISSUED A

* TORNADO WARNING FOR...
  WESTERN POTTAWATTAMIE COUNTY IN SOUTHWEST IOWA

* UNTIL 1145 PM CDT

* AT 1113 PM CDT...RADAR INDICATED A THUNDERSTORM WITH VERY STRONG
  ROTATION AND A DEVELOPING TORNADO 7 MILES WEST OF COUNCIL BLUFFS...
  OR ABOUT OVER OMAHA...MOVING SOUTHEAST AT 25 MPH.

* SOME LOCATIONS AFFECTED...
  CRESCENT
  COUNCIL BLUFFS
  MCCLELLAND

THIS IS A DANGEROUS SITUATION!  IN ADDITION TO THE TORNADO 
THREAT...LARGE HAIL TO GOLFBALL SIZE WILL OCCUR WITH THIS STORM.

TAKE COVER NOW IN A BASEMENT OR IN AN INTERIOR ROOM ON THE LOWEST
LEVEL OF A STRONG BUILDING. CARS AND MOBILE HOMES SHOULD BE
ABANDONED. GO TO A SAFE PLACE NOW.

LAT...LON 4143 9593 4119 9591 4117 9566 4135 9562

MEAD

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 17, 10:36 PM CDT	Severe Thunderstorm Warning	OAX	Pottawattamie	39 min
Jul 17, 11:16 PM CDT	Severe Thunderstorm Warning	OAX	Montgomery	44 min
Jul 17, 11:44 PM CDT	Severe Thunderstorm Warning	OAX	Pottawattamie	31 min
Jul 17, 11:57 PM CDT	Severe Thunderstorm Warning	OAX	Montgomery, Page	33 min
Jul 18, 12:00 AM CDT	Severe Thunderstorm Warning	OAX	Mills	45 min
Jul 18, 12:13 AM CDT	Severe Thunderstorm Warning	OAX	Montgomery	47 min
Jul 18, 12:45 AM CDT	Severe Thunderstorm Warning	OAX	Page	30 min
Jul 18, 12:59 AM CDT	Tornado Warning	OAX	Page	31 min
Jul 18, 1:02 AM CDT	Severe Thunderstorm Warning	OAX	Montgomery	18 min

Nearby

Tornado Warnings in Iowa, 2001 Every tornado warning in 2001 Tornadoes in 2001

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.