Why do you think the migration was held back
in the Plains States between September 7-13, 1998?
Using the migration data and weather maps below, find the locations where large numbers of monarchs were observed. Then carefully inspect the weather on the days before these sightings occurred. Click on face of map to enlarge.

(Maps by Purdue University Weather Processor.)

September 5	September 6	September 7
September 8	September 9	September 10
September 11	September 12	September 13

Note about dates on maps: All maps show weather on the evening of date shown. The time and date stamped on each map is based on "universal time", the time in Greenwich, England. Because it is 5-6 hours earlier in eastern North America than in England the stamp appears to be on the next day.

Monarch Migration Data
Reported Sept. 8- Sept. 14, 1998

Date	Town	St/Prov	Lat (N)	Long (W)
09/14/98	Victoria	MN	44.90	-93.75
09/13/98	Mukwonago	WI	42.88	-88.34
09/13/98	Henryville	IN	38.54	-85.79
09/13/98	St. Louis	MO	38.75	-90.30
09/12/98	St. Louis	MO	38.75	-90.30
09/12/98	Sharon	MA	42.11	-71.18
09/12/98	Wayzata	MN	44.96	-93.54
09/11/98	Iowa City	IA	41.69	-91.45
09/11/98	Rochester	IN	41.07	-86.26
09/11/98	Council Bluffs	IA	41.03	-95.58
09/11/98	Mound City	MO	40.15	-95.19
09/11/98	North Bend	NE	41.51	-96.78
09/11/98	Merrimack	NH	42.86	-71.52
09/11/98	Mystic	CT	41.36	-71.98
09/10/98	Northfield	MN	44.48	-93.16
09/10/98	Hershey	PA	40.26	-76.64
09/10/98	Rye	NH	43.01	-70.77
09/10/98	Cape May	NJ	38.94	-74.96
09/09/98	Brighton	ON	44.03	-77.73
09/09/98	Northfield	MN	44.48	-93.16
09/09/98	Lisbon	OH	40.74	-80.76
09/09/98	Brighton	ON	44.03	-77.73
09/08/98	Racine	WI	42.69	-87.81
09/08/98	Reston	VA	38.96	-77.34
09/07/98	Toronto	ON	44.00	-78.00
09/07/98	San Angelo	TX	31.57	-100.52
09/07/98	Dorchester	ON	42.98	-81.07
09/07/98	Mount Carroll	IL	42.12	-89.98
09/07/98	Cedar Rapids	IA	41.97	-91.66
09/07/98	Lincoln	NE	40.81	-96.71
09/07/98	Lincoln	NE	40.81	-96.71

Copyright 1998 Journey North. All Rights Reserved.