Alert archive / Iowa / Severe Thunderstorm Warnings in 2008

Severe Thunderstorm Warning 32, NWS Omaha, NE

May 6, 2008Page County, Iowa

NWS Omaha, NE issued this severe thunderstorm warning at May 6, 2008, 11:51 PM CDT for Page County, Iowa. It was in force for 24 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
May 6, 2008, 11:51 PM CDT (04:51 UTC)
Expired
May 7, 2008, 12:15 AM CDT
In force
24 min
Issued by
NWS Omaha, NE
Area
Storm-based polygon

County Page County, IA

The radar

The Omaha radar (KOAX), 121 km from the middle of the area, began a volume at 04:51 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 00:00Z, 4.9 hours before the alert went out and 121 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, Omaha, NE at 00:00Z on 2008-05-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 586 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, Omaha, NE at 00:00Z on 2008-05-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 32 square meters per square second.19395878Sfc1 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
586 J/kg
Mixed-layer CIN
-63 J/kg
Mixed-layer LCL
1633 m above ground
0-6 km bulk shear
33 kt
0-1 km storm-relative helicity
32 m²/s²
0-3 km storm-relative helicity
110 m²/s²
Significant tornado parameter
0.1
Supercell composite
1.4

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 May 6, 4:29 PM CDT, 7 hours 22 minutes earlier.

Area forecast discussion, May 6, 4:29 PM CDT, 7 hours 22 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
429 PM CDT TUE MAY 6 2008

.DISCUSSION...

LINE OF STRONG TSTMS SW THRU NE NEBRASKA INTO NW IA IS
INTERCEPTING BEST MOIST UNSTABLE INFLOW. EXPECT THIS TREND TO
CONTINUE AS LINE MOVES SE THIS EVE AND TNGT. HOWEVER IT IS
POSSIBLE THAT ANOTHER LINE WILL DEVELOP IN NW KS AND PROPOGATE NE
AS CAP WEAKENS FURTHER. 19Z OMA SOUNDING WAS WEAKLY CAPPED AT
800MB...WITH CAPE AROUND 1100. MOISTURE IS MODEST AND SO IS WIND
SHEAR. HAIL AND OUTFLOW DOMINATED TSTMS MOST LIKELY. FLOODING IS
NOT EXPECTED DUE TO PROGRESSION OF SYSTEM AND LACK OF DEEP MOISTURE.

TSTMS SHOULD SWEEP SOUTHEAST AND BE OUT OF OUR AREA OR NEARLY
SO BY MORNING. WED WILL BE A FAIR WEATHER DAY. COLD ADVECTION
BEHIND SYSTEM IS NOT VERY STRONG SO TEMPS SHOULD BE NEAR SEASONAL NORMS.

NEXT CHC FOR PRECIP COMES WITH A WEAKENING TROUGH MOVING ACROSS
FROM THE PACIFIC NW AND MOVING ACROSS CENTRAL/NRN PLAINS LATE THU
AND THU NGT. THERE MAY BE ENOUGH LEFTOVER MOISTURE FOR MODEST
THUNDERSTORMS WITH THIS SYSTEM.  WHAT APPEARS TO BE A STRONGER
TROUGH CROSSES THE REGION FRIDAY NGT TO SATURDAY NGT. KEPT POPS A
LITTLE HIGHER FOR THIS SYSTEM.

EXPECT THERE WILL BE A BREAK OF A COUPLE DAYS OR SO BETWEEN
SYSTEMS AS FLOW BEGINS TO BECOME MORE MERIDIONAL EARLY NEXT WEEK AFTER
FLATTENING FOR A LITTLE WHILE.  MODELS ARE HAVING SEVERE DIFFICULTY
HANDLING THE TIMING OF SYSTEMS BY THEN...SO FORECAST CONFIDENCE IS
RATHER LOW. HPC EVOLUTION OF FRONTS WAS AN ACCEPTABLE FIRST GUESS...
AND DID NOT DEVIATE GREATLY FROM THIS SOLUTION.

&&

.AVIATION...
FOR TAF SITES KOMA...KLNK AND KOFK FOR FORECAST VALID THRU 07/12Z.

EXPECT BROKEN LINE OF TSTMS FROM SW TO NE NEBRASKA TO ADVANCE SWD
THROUGH THE NIGHT WITH GREATEST INTENSITY THROUGH 03Z.  STRONGER
STORMS COULD PRODUCE HAIL...STRONG WINDS...AND HEAVY RAIN REDUCING
VSBYS. BEST CHC OF TSTMS AT OFK BEFORE 03Z.  OMA AND LNK HAVE BEST
CHC FROM ABOUT 01Z-08Z BARRING POSSIBLE DEVELOPMENT AHEAD OF MAIN LINE.
THERE MAY BE A FEW HRS OF MVFR STRATOCU FOLLOWING THE TSTMS...BUT
DRY AIR ADVECTION SHOULD THEN CLEAN OUT LOW CLDS.

&&

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

POLLACK/FOBERT
Hazardous weather outlook, May 6, 11:00 PM CDT, 51 minutes before
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In the hours before

Local storm report, May 6, 6:57 PM CDT, 4 hours 54 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
657 PM CDT TUE MAY 06 2008

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0650 PM     HAIL             10 WSW PETERSBURG       41.80N 98.26W
05/06/2008  E1.75 INCH       BOONE              NE   LAW ENFORCEMENT

&&

DEE
Local storm report, May 6, 7:03 PM CDT, 4 hours 48 minutes before
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Local storm report, May 6, 8:06 PM CDT, 3 hours 45 minutes before
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Local storm report, May 6, 8:56 PM CDT, 2 hours 55 minutes before
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Local storm report, May 6, 11:36 PM CDT, 15 minutes before
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Local storm report, May 6, 11:45 PM CDT, 6 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
May 6, 7:12 PM CDTSevere Thunderstorm WarningOAXBoone, Madison, Platte22 min
May 6, 7:49 PM CDTSevere Thunderstorm WarningOAXBurt, Cuming, Thurston26 min
May 6, 8:13 PM CDTSevere Thunderstorm WarningOAXBurt, Thurston21 min
May 6, 8:53 PM CDTSevere Thunderstorm WarningOAXBurt, Washington37 min
May 6, 10:38 PM CDTSevere Thunderstorm WarningOAXGage23 min
May 6, 11:12 PM CDTSevere Thunderstorm WarningOAXJohnson, Nemaha, Pawnee, Richardson48 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2008Every severe thunderstorm warning in 2008

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.