Alert archive / Iowa / Severe Thunderstorm Warnings in 1999

Severe Thunderstorm Warning 94, NWS La Crosse, WI

August 9, 1999Floyd County, Iowa

NWS La Crosse, WI issued this severe thunderstorm warning at Aug 9, 1999, 9:58 PM CDT for Floyd County, Iowa. It was in force for 32 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: Aug 9, 1999, 9:58 PM CDT (02:58 UTC)
Expired: Aug 9, 1999, 10:30 PM CDT
In force: 32 min
Issued by: NWS La Crosse, WI
Area: Whole counties

County Floyd County, IA

The radar

The La Crosse radar (KARX), 154 km from the middle of the area, began a volume at 02:59 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
Aug 9, 10:20 PM CDT	Thunderstorm Wind 55	Charles City, IA

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
Aug 9, 6:30 PM CDT	Tornado Watch	SPC	6 hr

The nearest sounding before it

Minneapolis, MN (KMPX), launched 00:00Z, 3.0 hours before the alert went out and 209 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: 1808 J/kg
Mixed-layer CIN: -66 J/kg
Mixed-layer LCL: 733 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: 291 m²/s²
0-3 km storm-relative helicity: 301 m²/s²
Significant tornado parameter: 2.4
Supercell composite: 13.0

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 La Crosse, WI wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 9, 3:31 PM CDT, 6 hours 27 minutes earlier.

Area forecast discussion, Aug 9, 3:31 PM CDT, 6 hours 27 minutes before

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LA CROSSE WI
208 PM CDT MON AUG 9 1999

SEVERE WEATHER POTENTIAL THIS EVENING IS MAIN FORECAST CONCERN.

EARLIER MCS AND ON-GOING CONVECTION IS HOLDING WARMEST AND MOST
UNSTABLE AIR WELL SOUTH AND WEST OF FORECAST AREA...EVEN AS LOW
LEVEL FLOW HAS BEEN INCREASING DRAMATICALLY TODAY. WARM FRONT APPEARS
TO STRETCH FROM EAST CENTRAL IOWA INTO SOUTHWEST MINNESOTA AS OF 18Z.
ALTHOUGH FOCUS HAS BEEN ON SOUTHWEST MINNESOTA FOR DEVELOPMENT...
STRONG LOW LEVEL CONVERGENCE ON NOSE OF 40+ MPH 850 MB JET CONTINUES
TO INITIATE CONVECTION ACROSS SOUTHEAST MINNESOTA. THIS AREA WAS LONG
EARLIER OUTFLOW...IS ELEVATED...AND HAS GENERATED UP TO 2 INCH
DIAMETER HAIL.

STILL UNCERTAIN OF EXACTLY WHERE FUTURE DEVELOPMENT WILL OCCUR...BUT
GIVEN SUCH STRONG SHEAR VALUES...WILL KEEP MENTION OF SEVERE STORMS
GOING IN 1ST PERIOD. SHORT TERM MODELS IN AGREEMENT BRINGING SHORT
WAVE TROUGH CURRENTLY OVER NORTHWEST NORTH DAKOTA QUICKLY INTO
REGION THIS EVENING...BUT WILL USE NGM/AVN SOLUTION KEEPING BRUNT OF
DYNAMICS FURTHER NORTH. BETTER INSTABILITY WILL ADVECT IN THIS
EVENING GIVEN STRONG LOW LEVEL FLOW...WHICH COULD PUSH SEVERE THREAT
FURTHER NORTH.

IN LATER PERIODS...NORTHWEST FLOW CONTINUES AND DRY WEATHER RETURNS
TUESDAY INTO WEDNESDAY. NORTHWEST FLOW ALWAYS TRICKY BUT NO IMPULSES
ARE SEEN UPSTREAM AT THIS POINT AND WILL KEEP TREND OF PLEASANT
WEATHER GOING.

UPDATED...WILL REMOVE SEVERE WEATHER WORDING FROM FAR NORTH AND
EAST ZONES BASED ON REALIGNMENT OF STORM PREDICTION CENTER OUTLOOK.
ALTHOUGH CONFIDENCE IS LOWER NOW...WILL GO AHEAD AND LEAVE SEVERE
RISK IN ELSEWHERE BUT APPEARS WARM FRONT WILL HAVE TOUGH TIME MAKINnG
NORTHWARD PROGRESS THIS EVENING. ELEVATED CONVECTION MAY STILL CAUSE
PROBLEMS. COORD W/GRB

.LSE...NONE.

SHEA

In the hours before

Local storm report, Aug 9, 4:04 PM CDT, 5 hours 54 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
404 PM CDT MON AUG 9 1999

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0127 PM    ROCHESTER                 MN   .88 INCH HAIL
08/09/99   OLMSTED

0132 PM    ROCHESTER                 MN   1 INCH HAIL
08/09/99   OLMSTED

0133 PM    ROCHESTER                 MN   1.25 INCH HAIL
08/09/99   OLMSTED

0134 PM    RUSHFORD                  MN   .75 INCH HAIL
08/09/99   FILLMORE

0148 PM    1 E CHESTER               MN   2 INCH HAIL
08/09/99   OLMSTED

BREESER/SHEA

Local storm report, Aug 9, 4:46 PM CDT, 5 hours 12 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
446 PM CDT MON AUG 9 1999

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0250 PM    2 S HOUSTON               MN   .75 INCH HAIL
08/09/99   HOUSTON                        REPORTED BY MAIL CARRIER.

SHEA

Special weather statement, Aug 9, 7:05 PM CDT, 2 hours 53 minutes before

MNZ079-086>088-094-095-100040-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE LA CROSSE WI
705 PM CDT MON AUG 9 1999

...A TORNADO WATCH IS IN EFFECT FOR SOUTHEAST MINNESOTA...

THUNDERSTORMS CONTINUE TO DEVELOP ACROSS SECTIONS OF SOUTHERN
MINNESOTA...AND THERE HAVE BEEN REPORTS OF TORNADOES.

IF YOU LIVE IN SOUTHEAST MINNESOTA...BE PREPARED FOR SEVERE
WEATHER THIS EVENING.  KNOW WHAT TO DO IF A TORNADO WARNING
IS ISSUED FOR YOUR COUNTY OR COMMUNITY.

SHEA

Special weather statement, Aug 9, 9:35 PM CDT, 23 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

The office that day

Everything else NWS La Crosse, WI issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 9, 7:41 PM CDT	Tornado Warning	ARX	Wabasha	64 min
Aug 9, 8:00 PM CDT	Tornado Warning	ARX	Dodge	60 min

Nearby

Severe Thunderstorm Warnings in Iowa, 1999 Every 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.