Monday, October 25, 2010

Fall Freeze-Free Excess Extended;
Minneapolis at 19 Days Beyond Average First Frost, Record Low Pressure Possible

Following a low temperature of 36° on Friday, Minneapolis has extended its string of days without frost to 19 days past the average date of the first 32° temperature. Lows on Saturday, Sunday, and this morning were 52°, 53°, and 52°, respectively. Following the passage of a strong storm, temperatures will drop by midweek, with lows of 34° predicted for Wednesday and Thursday. The expected low of 31° on Friday would make this the 9th latest first freeze, tied with 1963.

The 0.01" of rainfall on Saturday ended the 27-day dry spell, the 8th longest in Minneapolis records.

The National Weather Service (NWS) notes that the approaching storm is similar to the one on Nov. 10, 1998, which brought the record lowest pressure reading for the state of Minnesota, 962.8 mb. The forecast map from this morning's GFS model shows a low pressure area centered over Minnesota early Tuesday afternoon with a minimum pressure of less than 960 mb. The NWS forecast discussion points out that this would be 5 to 6 standard deviations below the average. The winds associated with this storm are expected to be 30-40 mph with gusts to near 60 mph.

Images (click to enlarge): Forecast low temperatures for central Minnesota on Friday, October 29, 2010, from National Weather Service; GFS model 30-hour forecast for 1 PM CDT, October 26, 2010, from NCEP/NWS/NOAA

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