July 2007 Saint Cloud Weather Summary

Not As Hot, But Much Drier July

7th Driest Growing Season So Far Since 1988

Saint Cloud Weather Summary for July 2007    

The dryness that has plagued parts of central, eastern, and south central Minnesota throughout the growing season continued in July 2007 with a vengeance. The July 2007 rainfall recorded at the Saint Cloud Regional Airport totalled 1.62 inches, less than half the normal amount of 3.34 inches. This made July 2007 the driest July since 1980 and the 15th driest out of 115 Julys in Saint Cloud records.

Even though we have had long dry periods during the past two summers, the growing season (April 1 - July 31) is off to its worst start since the last major drought in 1988. St. Cloud Airport has had only 7.48 inches of rainfall since April 1, nearly 5 1/2 inches behind the normal amount of 12.95 inches. This makes the 2007 growing season so far the 7th driest of the 115 years in St. Cloud records and the driest since the severe heat wave and drought of 1988. In fact, 1988 and 2007 are the only years that rank in the 7 driest since 1934. Nearly all of the 2007 deficit has occurred since the 2 1/2 inch rain event in early June. Between June 4 and July 31, the St. Cloud Regional Airport has only recorded 2.07 inches of rain, more than 5 inches below the normal amount of 7.11 inches. In comparison, the largest rainfall deficit we had last year was 6.47 inches between May 15 and August 22.

And, this water shortage is worse in areas surrounding St. Cloud because many areas surrounding St. Cloud got much less rainfall during the one major rain event of July 2007. On July 2-3, the St. Cloud Airport picked up 1.21 inches, but SCSU got only about 1/2 inch and areas to the south and west and well to the east got much less rain.

The effect of the dry conditions was intensified by the warm weather conditions over the last two weeks of July. The average temperature for July 2007 ended up being 72.3°F, 2.5°F above normal. Actually, July 2007 was running less than a degree warmer than normal through July 22, but central Minnesota was sideswiped at times by the intense heat that has dominated the western third of the country. Six of the 7 90°F+ highs in July were set during the last 9 days of the month, pushing the average temperature up. However, July 2007 did not even approach the intense heat of July 2005 and July 2006, the 8th warmest July in St. Cloud records. Just to compare, there were 9 straight days of 90°F+ highs ending July 2006, more than there were in all of July 2007. In fact, the only shot at an official heat wave (at least three consecutive days with a 90°F+ highs) would be ending the month, if St. Cloud hits 90°F today. The highest temperature so far in St. Cloud has been 94°F, set on July 7th and 25th. In contrast, July 31, 2006 had a high of 101°F, the only 100°F+ in the past 17 years.

So, the warm, but not extremely warm, but very dry July conditions has intensified the low water conditions of this growing season. Rainfall deficits, as the State Climatology Office Weekly Rainfall Map shows, are generally 5 to 7 1/2 inches from Little Falls eastward to the St. Croix and southeastward to the Twin Cities and also to the lower Minnesota River Valley to Mankato and across south central and southeastern Minnesota. Much of this area is ranked in the severe drought category on the latest National Drought Mitigation Center's Drought Monitor, which is a lower rating than we had at the end of the driest period last year. The dry conditions have dropped lake and stream levels to the lowest 10% of rankings in central Minnesota from the Crow Wing River through the Mississippi and St. Croix Rivers from Brainerd through the Twin Cities, as can be seen on the DNR Waters Streamflow Report. Another area of low streamflow has shown up this week in southeastern Minnesota.

While the dry period this year has been intense, especially since most of Minnesota didn't fully recover from the dry spell last year, it still doesn't approach the last major drought in Minnesota, during the 1986-1989 Great Plains drought. It was both hotter and drier (three straight years of less than 20 1/2 inches of rain) during that period. The most intense, but localized dry spell occurred in 1976 when only 14.93 inches fell.

In the short term, a small change in the flow pattern could give central Minnesota a better shot at rainfall over the next 5 days. Instead of the steering flow staying in Canada over the Plains, it will move along the northern US from today through the rest of the week. The immediate effect is that we will have more than one chance in the next week for significant rainfall. The first chance will be this afternoon as a cold front pushes through, but there will be a second shot at rainfall Saturday into Sunday. The long-range forecast shows other rainfall threats. While the long-range forecasts are usually poor at finding and timing these systems, it's the first time in more than a month that we will have multiple shots at rain.

Unfortunately, the tendency to produce thunderstorms this time of year will make it difficult for us to get a widespread heavy rain. And, we will need double the normal amount of August rain (3.93 inches) to really make a dent in the dry conditions.

    July 2007 Statistics