A typical Memorial Day weekend was in the works across the state. It was a Sunday, many people were running around, graduation parties were taking shape, people were outside enjoying the warm weather that encompassed the state that day. Meanwhile the atmosphere was about to unleash a monster that would be the first catastrophic tornado to hit the state in nearly 32 years. The Storm Prediction Center had been concerned about the possibility of severe weather for days.
In their statement they mentioned the following “THE COMBINATION OF THE MODERATE TO STRONG INSTABILITY AND MODERATELY STRONG DEEP LAYER SHEAR INDICATE THE POTENTIAL FOR SUPERCELLS AND/OR LARGER-SCALE BOWING STRUCTURES CAPABLE OF LARGE HAIL…DAMAGING WINDS AND A FEW TORNADOES”
By the morning of the event, the Storm Prediction Center had the state in a slight risk of severe weather with an enhanced risk for tornadoes, 
Here was their wording in that first outlook issued at 6z (1am Sunday Morning)
SWLY LOW LEVEL WINDS ARE EXPECTED TO PERSIST TODAY FROM THE CENTRAL
PLAINS INTO THE UPPER MS VALLEY/WRN GREAT LAKES REGION AS NRN PLAINS
UPPER TROUGH SHIFTS EWD. THIS WILL ALLOW MOISTURE TO CONTINUE TO
SURGE NEWD AS WARM FRONT LIFTS TOWARD THE UPPER GREAT LAKES.
SURFACE DEWPOINTS IN THE LOWER 60S SHOULD REACH PARTS OF NERN MN/WRN
UPPER MI…WITH UPPER 60S-AROUND 70 LIKELY INTO ERN IA/SWRN WI.
SURFACE HEATING IS EXPECTED TO COMMENCE LATER THIS MORNING IN THE
WAKE OF EARLY MORNING CONVECTION…AND AHEAD OF PRE-FRONTAL TROUGH.
THIS COMBINED WITH THE MOISTURE AND STEEP MID LEVEL LAPSE RATES WILL
SUPPORT A MODERATE-VERY UNSTABLE AIR MASS /MUCAPE RANGING FROM
2000-3500 J/KG/ FROM SERN MN/SWRN WI TO SERN NEB AND ERN KS.
RIGHT ENTRANCE REGION OF AN UPPER LEVEL JET WILL BE OVER THE UPPER
GREAT LAKES. THIS COMBINED WITH ASCENT ATTENDANT TO HEIGHT FALLS AS
NRN PLAINS LOW SHIFTS EWD AND SEVERAL MID LEVEL IMPULSES TRACK NEWD
WITHIN STRONG SWLY FLOW ALOFT WILL AID IN THE DEVELOPMENT OF TSTMS
THIS AFTERNOON FROM THE NRN MN SURFACE LOW SWWD ALONG THE TRAILING
PRE-FRONTAL TROUGH TO THE CENTRAL PLAINS. EFFECTIVE BULK SHEAR
AROUND 50 KT ACROSS THIS ENTIRE REGION SUGGESTS THREAT FOR TORNADIC
SUPERCELLS…SOME STRONG INTO THE UPPER MS VALLEY. THE STRONG
INSTABILITY AND STEEP LAPSE RATES WILL ENHANCE THE POTENTIAL FOR
HAIL…SOME VERY LARGE…AND DAMAGING WINDS.
The storms waited until mid-afternoon to fire. The Storm Prediction Center issued a PDS Tornado Watch at 3:30pm that afternoon. Here was the wording on that
URGENT – IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 363
NWS STORM PREDICTION CENTER NORMAN OK
330 PM CDT SUN MAY 25 2008
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
A LARGE PART OF IOWA
EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 330 PM UNTIL
1000 PM CDT.
…THIS IS A PARTICULARLY DANGEROUS SITUATION…
DESTRUCTIVE TORNADOES…LARGE HAIL TO 3 INCHES IN DIAMETER…
THUNDERSTORM WIND GUSTS TO 80 MPH…AND DANGEROUS LIGHTNING ARE
POSSIBLE IN THESE AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 75 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 60 MILES SOUTHWEST OF FORT
DODGE IOWA TO 50 MILES EAST SOUTHEAST OF CEDAR RAPIDS IOWA. FOR
A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU3).
REMEMBER…A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.
Thunderstorms fired across the central and north central portions of the state. The storm that went on to produce the Parkersburg-New Hartford tornado was first put under a Severe thunderstorm warning
BULLETIN – EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
417 PM CDT SUN MAY 25 2008
THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A
* SEVERE THUNDERSTORM WARNING FOR…
NORTHWESTERN GRUNDY COUNTY IN CENTRAL IOWA…
NORTHEASTERN HARDIN COUNTY IN CENTRAL IOWA…
BUTLER COUNTY IN NORTH CENTRAL IOWA…
SOUTHEASTERN FRANKLIN COUNTY IN NORTH CENTRAL IOWA…
* UNTIL 500 PM CDT.
* AT 414 PM CDT…NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL…AND
DESTRUCTIVE WINDS IN EXCESS OF 70 MPH. THIS STORM WAS LOCATED NEAR
IOWA FALLS…OR 43 MILES WEST OF WATERLOO…AND MOVING NORTHEAST AT
40 MPH.
* THE SEVERE THUNDERSTORM WILL BE NEAR…
ACKLEY BY 425 PM CDT…
APLINGTON BY 440 PM CDT…
PARKERSBURG BY 445 PM CDT…
ALLISON BY 450 PM CDT…
SHELL ROCK AND CLARKSVILLE BY 500 PM CDT…
Only 5 minutes later the warning was replaced by a Tornado warning for the same area.
BULLETIN – EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
422 PM CDT SUN MAY 25 2008
THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A
* TORNADO WARNING FOR…
NORTHWESTERN GRUNDY COUNTY IN CENTRAL IOWA…
NORTHEASTERN HARDIN COUNTY IN CENTRAL IOWA…
BUTLER COUNTY IN NORTH CENTRAL IOWA…
SOUTHEASTERN FRANKLIN COUNTY IN NORTH CENTRAL IOWA…
* UNTIL 445 PM CDT.
* AT 418 PM CDT…NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO NEAR IOWA
FALLS…OR 41 MILES WEST OF WATERLOO…MOVING NORTHEAST AT 39 MPH.
* THE TORNADO WILL BE NEAR…
ACKLEY BY 425 PM CDT…
APLINGTON BY 440 PM CDT…
THIS TORNADO WARNING REPLACES THE SEVERE THUNDERSTORM WARNING THAT
WAS IN EFFECT FOR THE SAME AREA. GO TO A BASEMENT OR SMALL INTERIOR
ROOM ON THE LOWEST FLOOR!
THIS IS A HAZARDOUS SITUATION. SEEK SHELTER IN A BASEMENT…OR IN AN
INTERIOR ROOM. STAY AWAY FROM WINDOWS. IF YOU ARE OUTSIDE OR IN A
CAR…SEEK SHELTER IN A REINFORCED BUILDING.
A TORNADO WATCH REMAINS IN EFFECT UNTIL 1000 PM CDT SUNDAY EVENING
FOR IOWA.
Continued in Part #2