Estimated Ice Out Dates - 1997
(State Climatology Office - DNR - Waters, April 1, 1997)
Winter 96-97 started cold but unlike spring 1996, temperatures this year are tending to be warmer in late March and early April. The date of the end of snow cover this year appears to be slightly early in some parts of the southern third of the state. However, in the northern 2/3 of the state deep overwinter snow conditions are still a foot or more greater than what would ordinarily be expected at the end of March. Once again this year, with a late March pattern of snow depths over much of the state which looks more like the pattern typical of the end of February, the last date of snow cover is expected to be later than normal.
The first week of April is expected to average a many degrees above normal, thus melting of snow and/or ice should progress rapidly in the early part of the month. However, some coolness may occur later and the 30-day outlook indicates near-normal temperatures for April overall. Given the recent moderate temperatures and the warm temperatures expected over the next week or so and given a near normal end to snow cover in the south, lakes there are expected to lose their ice up to a half week early to near their normal dates. In the north, the lateness of the end to snow cover will probably be most pronounced in the west and be more near normal in the east. In the northern 2/3 of the state, lake ice-out dates should range from about one week late in the west to only slightly late dates in the east.
The accompanying map of 'Normal' Ice Out Dates gives the AVERAGE date of when deeper and larger lakes experience ice out. In virtually all years ice-out occurs within about 2 weeks of the dates on that map. The amount of days 'early' or 'late' discussed above can be used with this map.
Of course any short term but significantly hot or cold spells not accounted for in this discussion may alter the estimated dates; hot and windy days can advance ice-out dramatically. Also significant local variations may occur due to a given lake's circumstances. Finally, smaller or shallow lakes and ponds can be expected to lose their ice as much as 5 to 7 days earlier than the mapped dates.
mcwg@soils.umn.edu
URL:
http://climate.umn.edu/doc/journal/iceout97.htm
Last modified: April 2, 1997
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