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July Heat Continues

July Heat Continues:

The hot temperatures of July 4th weekend have persisted throughout the first 8 days of July. Most climate stations are reporting an average July temperature so far that ranges from 5 to 8 degrees F above normal. This is the warmest start to July since 2012 and among the ten warmest historically on a statewide basis. Generally, overnight minimum temperatures have been above normal to a greater degree than the daytime maximum temperatures. About 90 percent of all climate stations in the state have reported at least one day with 90°F or higher temperatures this month so far, including notoriously cooler places like International Falls, Gunflint Lake, and Ely. Many areas of the state have seen overnight minimum temperatures remain in the 70s F thanks to the very high dew points.

Most of the heat has not been record setting, but within the Minnesota statewide climate network there have been some reports of daily record temperature values. Seventeen climate stations have reported at least setting or tying one daily maximum temperature record so far this month, including 93°F at Tower (usually a cold spot in the state) on July 4th. There have been 19 high daily minimum temperature records set or tied so far this month as well.

With the frequency of dew points ranging from 70°F to 79°F around the state this week, the National Weather Service has had to issue several Heat Advisories, as well as an Excessive Heat Warning for some areas. On Wednesday, July 8th at least 20 communities reported an afternoon Heat Index Value ranging from 100°F to 105°F.

Rainfall has been less than normal in most places so far this month. But scattered heavy rains from thunderstorms have produced some record-setting values in places. Last week we talked about the record July 1st rainfalls in the far northwest at Crookston (2.54 inches) and at Karlstad (2.72 inches). This week record rainfalls were delivered to some central Minnesota locations, including:
2.25 inches at Pelican Rapids (July 8)
2.15 inches at Collegeville (July 8)
1.80 inches at Alexandria (July 8)
1.68 inches at Brainerd (July 8)

Then on July 9th the following record rainfalls were reported:
3.38 inches at Isle
2.33 inches at Floodwood
2.18 inches at Sandstone
2.12 inches at Wright

In addition, on July8th tornadoes were reported in Grant, Otter Tail, and Crow Wing Counties. Some damages to homes and farmsteads occurred near Dalton where storm chasers photographed a tornado that was on the ground for 8-9 miles. Unfortunately, a 30-year old man was killed near Dalton. You can read more about these storms at the MN State Climatology Office web site and at the NOAA-National Weather Service Grand Forks Office web site.

Weekly Weather Potpourri:

The NOAA-National Hurricane Center was issuing advisories on Tropical Storm Fay which expected to bring high winds and heavy rains to portions of Delaware, New Jersey, New York, and Connecticut Friday into early Saturday. Many areas may get 2-4 inches of rainfall.

NOAA this week produced a map to show when the climatological hottest day of the year occurs around the USA. There is quite a variation across June through August for most geographical locations. In Minnesota the hottest day of the year typically falls somewhere between July15 and July31. In the southwestern USA the hottest day of the year is usually in June, while in the southern states and some of the northwest it occurs in the first half of August.

The BBC reported that parts of southern Japan saw over a foot of rain earlier this week causing widespread flooding and some very serious damage to infrastructure, especially on Kyushu. The rains are expected to continue as well, with thousands of people already displaced from their homes.

MPR listener question:

Heard you talk about the high dew points (70°F or greater) in June and wondered if that trend has continued in July. How many hours of 70°F dew points have we had so far this month in the Twin Cities?

Answer:

Thanks to Senior Climatologist Kenny Blumenfeld of the MN State Climatology Office for staying on top of these data. His analysis shows 98 hours with a 70°F dew point so far this month. Last year July produced only 111 such hours for the whole month. In 1983 there were 305 hours. What might be more remarkable is that since June 27th we have measured a dew point of 60°F or higher every hour, the longest such streak in the Twin Cities since 1987, the year of the Super Storm 10 inch rain on July 23rd.

Twin Cities Almanac for July 10th:

The average MSP high temperature for this date is 84 degrees F (plus or minus 8 degrees F standard deviation), while the average low is 64 degrees F (plus or minus 6 degrees F standard deviation).

MSP Local Records for July 10th:

MSP records for this date include: highest daily maximum temperature of 106 degrees F in 1936; lowest daily maximum temperature of 69 degrees F in 1945; lowest daily minimum temperature of 49 degrees F in 1996; highest daily minimum temperature of 80 degrees F in 1936; record precipitation of 1.93 inches in 2002. No snowfall has been reported on this date.

Average dew point for July 10th is 59°F; the maximum dew point on this date is 77°F in 1999; and the minimum dew point on this date is 38°F in 1941.

All-time state records for July 10th:


The state record high temperature for this date is 112 degrees F at Wadena (Wadena County) in 1936. The state record low temperature for this date is 32 degrees F at Tower (St Louis County) in 1978. The state record precipitation for this date is 7.02 inches at Leech Lake (Cass County) in 1954. No snowfall has been reported on this date.

Past Weather Features:


By far the hottest July 10th in state history was in 1936, when every climate station in the state reported a daytime high of 90 degrees F or greater, except for Grand Marais (81°F). Over 60 climate stations reported a maximum temperature of 100°F or greater. The overnight low never fell below 82°F at Moorhead and Beardsley.


July 9-10, 1954 brought powerful thunderstorms to many parts of the state. These storms brought high winds and hail, but also very heavy rains, especially across northern counties. Portions of Cass County saw flooding brought on by 5-7 inch rains.


On July 10, 1996 campers in St Louis, Beltrami, Carlton, Pine, and Cass Counties woke up to morning temperatures in the 30s F. At Embarrass, MN the temperature started out at 34 degrees F bit warmed up to 73°F by late afternoon.

Outlook:

Near normal to even cooler than normal temperatures for Saturday with a chance for showers. Sunday and Monday will be dry with near normal temperatures and dew points. Later on Monday there will be increasing chances for showers lasting through Wednesday. Temperatures will not stray far from normal for this time of year most of next week.






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