An inverted trough of low pressure at the surface moved through the state during the early morning of the 20th into the day on the 20th. At the same time, a strong low pressure deepened in the upper atmosphere over and just northeast of the state.  The combination drew down Arctic air into the central U.S. A tight pressure gradient developed between the developing low to the east and Arctic high pressure to the northwest.  Winds increased on the 20th, and continued through most of the day on the 21st.  Sustained wind speeds were in the 25 to 35 MPH range, with gusts of 40 to 50 MPH.  Very little snow fell with the inverted trough, generally an inch or two, however antecedent snow cover was quite high with 7 to 12 inches common.  The winds caused whiteout conditions for an extended period of time as the snow that was loose blew in open areas.  Much of the deeper snow had crusted over, so blizzard conditions were somewhat sporadic and not as widespread as would normally be expected.  The first and second order reporting stations did not meet blizzard criteria outside of occasionally, however law enforcement officials reported visibility frequently reduced to between 10 and 100 feet in open areas.  Travel was therefore not recommended across all of the northern part of Iowa north of U.S. Highway 30.  Roads drifted shut quickly and snowplows were taken off of several roads during the height of the storm.  In addition to the wind, temperatures fell below zero, resulting in dangerous wind chill indices in the -30 to -40 F. range.

Blizzard in SAC, IOWA
From 20-DEC-08 12:00:00 to 21-DEC-08 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Blizzard in CALHOUN, IOWA
From 20-DEC-08 12:00:00 to 21-DEC-08 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Blizzard in HUMBOLDT, IOWA
From 20-DEC-08 12:00:00 to 21-DEC-08 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Blizzard in WRIGHT, IOWA
From 20-DEC-08 12:00:00 to 21-DEC-08 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Blizzard in WORTH, IOWA
From 20-DEC-08 14:00:00 to 21-DEC-08 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Blizzard in HANCOCK, IOWA
From 20-DEC-08 12:00:00 to 21-DEC-08 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Blizzard in CERRO GORDO, IOWA
From 20-DEC-08 14:00:00 to 21-DEC-08 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Blizzard in POCAHONTAS, IOWA
From 20-DEC-08 12:00:00 to 21-DEC-08 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Blizzard in WEBSTER, IOWA
From 20-DEC-08 12:00:00 to 21-DEC-08 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Blizzard in HAMILTON, IOWA
From 20-DEC-08 12:00:00 to 21-DEC-08 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Blizzard in FRANKLIN, IOWA
From 20-DEC-08 14:00:00 to 21-DEC-08 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Blizzard in KOSSUTH, IOWA
From 20-DEC-08 12:00:00 to 21-DEC-08 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Blizzard in WINNEBAGO, IOWA
From 20-DEC-08 12:00:00 to 21-DEC-08 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Blizzard in EMMET, IOWA
From 20-DEC-08 12:00:00 to 21-DEC-08 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Blizzard in PALO ALTO, IOWA
From 20-DEC-08 12:00:00 to 21-DEC-08 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Blizzard in BUTLER, IOWA
From 20-DEC-08 14:00:00 to 21-DEC-08 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Blizzard in BREMER, IOWA
From 20-DEC-08 14:00:00 to 21-DEC-08 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Blizzard in HARDIN, IOWA
From 20-DEC-08 14:00:00 to 21-DEC-08 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Blizzard in GRUNDY, IOWA
From 20-DEC-08 14:00:00 to 21-DEC-08 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Blizzard in BLACK HAWK, IOWA
From 20-DEC-08 14:00:00 to 21-DEC-08 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement