For the first time in well over a month all forecast points in the HSA fell below flood stage on May 18th, as Estherville finally fell below flood stage. The respite was short-lived however, as heavy rains fell on the 20th- 21st  over mainly the western and northern half of the HSA.  Mean areal rainfall of 1 to as much as 3 inches was estimated over the central and northern portions of the Des Moines and Iowa river basins.  The Estherville ASOS station measured 2.95" in 24 hours; other significant reports from NWS cooperative stations included 2.52" at Jefferson, 2.37" at Harcourt,  2.10" at Rockwell City, 2.06" at Jewell and 1.97" at Iowa Falls.  These rains caused renewed rises to flood stage or higher on rivers in the Raccoon and Des Moines basin.  An extended period of unusually cool weather began on the 21st  and lasted through the duration of May, as a deep upper level trough became anchored over the eastern half of the U.S. A record low maximum temperature record was set on the 23rd at Des Moines, with a high temperature  of 53oF, which broke a 1976 record of 60oF. Scattered showers fell over most of the HSA during most of this period as the extremely cool temperatures aloft combined with strong May sun to create very unstable conditions. Most locations picked up some rainfall, but amounts were quite variable and generally less than a half-inch on any one day, with a few notable exceptions. These included 1.16" at Eldora (ELDI4) and 1.15" at Steamboat Rock (STBI4) for the 24 hours ending on the 25th. The very slow moving system continued to produce precipitation on the 25th, including some locally heavy showers especially over central Iowa.

Flood in DALLAS, IOWA
From 21-MAY-01 18:00:00 to 28-MAY-01 12:00:00 (CST)
Property damage: 30K
Reported by: OFFICIAL NWS OBS.

Flood in WINNEBAGO, IOWA
From 21-MAY-01 18:00:00 to 28-MAY-01 12:00:00 (CST)
Property damage: 30K
Reported by: OFFICIAL NWS OBS.

Flood in CARROLL, IOWA
From 21-MAY-01 18:00:00 to 28-MAY-01 12:00:00 (CST)
Property damage: 30K
Reported by: OFFICIAL NWS OBS.

Flood in HANCOCK, IOWA
From 21-MAY-01 18:00:00 to 28-MAY-01 12:00:00 (CST)
Property damage: 30K
Reported by: OFFICIAL NWS OBS.

Flood in KOSSUTH, IOWA
From 21-MAY-01 18:00:00 to 28-MAY-01 12:00:00 (CST)
Property damage: 30K
Reported by: OFFICIAL NWS OBS.

Flood in HAMILTON, IOWA
From 21-MAY-01 18:00:00 to 28-MAY-01 12:00:00 (CST)
Property damage: 30K
Reported by: OFFICIAL NWS OBS.

Flood in EMMET, IOWA
From 21-MAY-01 18:00:00 to 28-MAY-01 12:00:00 (CST)
Property damage: 30K
Reported by: OFFICIAL NWS OBS.

Flood in POCAHONTAS, IOWA
From 21-MAY-01 18:00:00 to 28-MAY-01 12:00:00 (CST)
Property damage: 30K
Reported by: OFFICIAL NWS OBS.

Flood in CALHOUN, IOWA
From 21-MAY-01 18:00:00 to 28-MAY-01 12:00:00 (CST)
Property damage: 30K
Reported by: OFFICIAL NWS OBS.

Flood in SAC, IOWA
From 21-MAY-01 18:00:00 to 28-MAY-01 12:00:00 (CST)
Property damage: 30K
Reported by: OFFICIAL NWS OBS.

Flood in HUMBOLDT, IOWA
From 21-MAY-01 18:00:00 to 28-MAY-01 12:00:00 (CST)
Property damage: 30K
Reported by: OFFICIAL NWS OBS.

Flood in WEBSTER, IOWA
From 21-MAY-01 18:00:00 to 28-MAY-01 12:00:00 (CST)
Property damage: 30K
Reported by: OFFICIAL NWS OBS.

Flood in GREENE, IOWA
From 21-MAY-01 18:00:00 to 28-MAY-01 12:00:00 (CST)
Property damage: 30K
Reported by: OFFICIAL NWS OBS.

Flood in PALO ALTO, IOWA
From 21-MAY-01 18:00:00 to 28-MAY-01 12:00:00 (CST)
Property damage: 30K
Reported by: OFFICIAL NWS OBS.