The first two weeks of May brought repeated convective storm activity to the DMX HSA, with many strong to severe thunderstorms and significant, although not generally excessive rainfall. The primary cause of the active weather was the presence of an upper level low anchored over the western U.S. for much of this period. Shortwaves of variable strength were continually ejected from the upper low into a favorable, diffluent pattern aloft and strong jet dynamics combined with low-level moisture drawn northward from the Gulf of Mexico. The rains had a highly beneficial effect on the agricultural and water supply situation across the southern one-half of the HSA.  A storm system affected the region on May 3-4, producing heavy rains and severe weather across much of the HSA.  Rainfall for the 24 hours ending at 12Z on the 4th was heaviest over the southwest portions of Iowa as the system developed over Kansas and Nebraska. Some totals  included Chariton (CHRI4), 1.32"; Afton-KCCI (SAFI4), 0.84"; Guthrie Center (GTHI4), 0.80"; Humboldt (HBTI4), 0.70"; and Emmetsburg (EMTI4), 0.67". The heaviest rains fell on May 4, as showers and thunderstorms covered most of the HSA. Des Moines NWS (DMXI4) set a date rainfall record (ending midnight) of 2.73", breaking the 1886 record of 1.39". Mason City (WMTI4) also established a date record at 2.21", eclipsing the 1977 record of 1.82". The rains were particularly heavy in the mid-morning hours over central Iowa, prompting the issuance of a Flash Flood Warning for Polk, and parts of Dallas, Boone and Greene counties. There were several reports of water over roadways in the Des Moines metro area. By early afternoon a Flood Warning was issued for Walnut and Four Mile Creeks in the metro area. River Flood Statements were also issued for locations along the North Raccoon, Des Moines and South Skunk rivers. Later in the evening a Flood Warning was issued for the Raccoon River at SW 18th St. (Fleur Dr.) with a crest forecast near 15.5 feet (Flood Stage - 12 ft). Rainfall totals for the 24-hour ending at 12Z on the 5th were highest in the Des Moines, Raccoon and South Skunk basins and especially in the Des Moines metro area (see Fig. 1). Jefferson (JFFI4) had 3.58"; KCCI-TV (SKCI4), 3.28; Grimes Schoolnet (SGRI4), 3.20"; Jefferson-KCCI (SJEI4), 2.99"; and  Perry (PERI4), 2.73".  Initially, soil conditions were quite dry and a decent amount of the rainfall was absorbed.  Flooding was relatively minor and limited to crop lands for the most part.

Flood in MARSHALL, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in MONROE, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in PALO ALTO, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in POCAHONTAS, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in POLK, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 50K
Reported by: OFFICIAL NWS OBS.

Flood in POWESHIEK, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in SAC, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in STORY, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in WAPELLO, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in WARREN, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in WEBSTER, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in WINNEBAGO, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in WRIGHT, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in MADISON, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in MAHASKA, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in MARION, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in ADAIR, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in BOONE, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in CALHOUN, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in CARROLL, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in CLARKE, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in DALLAS, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in EMMET, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in GREENE, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in GUTHRIE, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in HAMILTON, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in HANCOCK, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in HUMBOLDT, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in JASPER, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in KOSSUTH, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.

Flood in LUCAS, IOWA
From 04-MAY-03 12:00:00 to 08-MAY-03 12:00:00 (CST)
Property damage: 5K
Reported by: OFFICIAL NWS OBS.