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Extension > Mark Seeley's WeatherTalk > July 2015

Friday, July 24, 2015

WeatherTalk will be back August 7

WeatherTalk will not be published Friday, July 24 or July 31. Mark Seeley will send the next WeatherTalk on Friday, August 7.

Friday, July 17, 2015

July's climate so far

July's climate so far:



Just over half way through the month July has brought cooler than normal temperatures to most parts of the state.  Only about 1 in 5 Minnesota climate observers have reported a high temperature of 90F or higher this month.  Many northern cities have reported overnight low temperatures in the upper 30s F.

Rainfall in July has been highly variable, but with some observers already reporting above normal totals for the month. In the northwestern portion of the state Newfolden (Marshall County) has already received 6.33 inches; in the north-central part of the state Aitkin reports 5.24 inches; in central Minnesota Milaca reports 5.13 inches and Mora reports 5.26 inches; in southern Minnesota Farmington reports 5.85 inches and Hastings 5.29 inches.

The outlook favors above normal rainfall during the 2nd half of July for much of the state, so perhaps most observers will see a sizable increase in monthly rainfall over the next two weeks.

New Seasonal Climate Outlook:


The NOAA-Climate Prediction Center released new seasonal outlooks this week on Thursday. For the period from August to October the outlook favors cooler than normal conditions for the mid-section of the country, with possibly southern counties in Minnesota seeing those conditions prevail as well. The outlook for rainfall over that period shows equal chances for above or below normal values to prevail in our area of the country.

Weekly Weather Potpourri:


Typhoon Nangka brought strong winds and heavy rains (up to 3 inches per hour) to parts of Japan on Thursday this week. The storm was blamed for two deaths and caused widespread delays in air and train travel.  In the Eastern Pacific Ocean, Hurricane Dolores was bringing large waves to parts of Baja California, but its heavy rains and winds were mostly remaining out to sea.

NOAA via its climate.gov web site provided an interesting analysis of the Western European Heat Wave that prevailed during late June and early June this year.  It was set up by an unusual weather pattern, and many new record high temperature values were set in Spain, Germany, France, and the United Kingdom. 

An eastern low pressure system parked off the coast was drawing cool, moist air from the south over Sydney Australia this week, where they experienced some unusually cold days with daytime high temperatures only in the mid-50s F, record-setting values for them.  Damaging winds and high surf were also affecting the coastal areas of eastern Australia.

This week in the International Journal of Climatology there is a review paper about the drivers of the Northern Hemisphere Polar Front Jet Stream written by scientists from the University of Sheffield in the United Kingdom.  Although there are no surprising conclusions reached, the paper provides a valuable review of all the natural ocean and atmospheric drivers that regulate the position and trajectory of the polar jet stream, along with anthropogenic climate change which has some influence as well.  Interestingly enough the solar cycle still plays an important role as a driver of polar jet stream behavior.

Another urbanization study from Geophysical Letter was reported in EOS this week.  This one documents reductions in the frequency of fog and low cloud cover along portions of the California coast as a result of urbanization along the coastal landscape.  The end result is a drier environment.

MPR Listener Question:


Last Sunday, July 12th was a miserable day here in Montevideo, MN.  I have never been so hot.  What was the maximum dew point and Heat Index that day?

Answer:


Indeed, it was a hot day.  Many observers reported dew points of 70F or higher and Heat Index values over 100F.  Dew points of 81F were reported from St James, Morris, New Ulm, Hutchinson, and Montevideo.  The maximum Heat Index of 111F was reported from Tracy and Montevideo, right where you live. 

Speaking of high dew points, during the month of June Twin Cities residents only experience one day with a dew point that high.  But so far in July we have already recorded dew points of 70F or higher on five days, and I suspect there will be more.

Greg Spoden, Minnesota DNR-State Climatologist has provided maps showing the extent of 70°F dew points in the state since late June. These are available on the Minnesota Climatology Working Group web site.

Twin Cities Almanac for July 17th:


The average MSP high temperature for this date is 83 degrees F (plus or minus 7 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 17th:

MSP weather records for this date include: highest daily maximum temperature of 99 degrees F in 1936; lowest daily maximum temperature of 65 degrees F in 2009: lowest daily minimum temperature is 52 degrees F in 1937 and 1976; highest daily minimum temperature of 79 F in 1936, 1942, and 2011; record precipitation of 3.71 inches 1997; and no snowfall has been recorded on this date.

Average dew point for July 17th is 62 degrees F, with a maximum of 81 degrees F in 2011 and a minimum of 38 degrees F in 1911.

All-time state records for July 17th:


The state record high temperature for this date is 110 degrees F at Worthington (Nobles County) in 1936. The state record low temperature for this date is 33 degrees F at Bigfork (Itasca County) in 1971.  State record precipitation for this date is 5.90 inches at Gull Lake (Cass County) in 1952; and there has not been any snowfall on this date.

Past Weather Features:



July 17, 1924 was certainly one of the coldest in Minnesota history.  Many northern communities reported morning low temperatures in the 30s F.  Some frosts were reported in local gardens. The observer at Babbitt reported a daytime high of only 62F, while Duluth only reached 64F.

By far the warmest July 17th in state history occurred during the famous Heat Wave of 1936.  The thermometers in 27 Minnesota communities reached the century mark or higher that day, which was the 12th day of a 14-day Heat Wave that killed over 900 Minnesota citizens.

Severe thunderstorms brought heavy rains and flash flooding over July 17-18, 1952.  Especially hard hit were areas of east-central Minnesota where Aitkin and Moose Lake received over 10 inches.  Portions of Highway 169 and Highway 61 were closed because of flooding and the Mississippi River rose above flood stage, a rare occurrence for mid-summer.  As a result of this storm and others, some observers reported their all-time wettest July including Aitkin with 15.52 inches, Brainerd with 10.49 inches, and Moose Lake with Moose Lake with 13.21 inches.

July 17, 1997 brought severe thunderstorms to the Twin Cities area.  MSP reported rainfall of 3.71 inches, with 3.50 inches at Richfield, and 4.00 inches at Hastings.  The resulting flash flooding closed portions of interstate 35W at Diamond Lake Road, Highway 100 at St Louis Park, and Highway 52 near Inver Grove Heights.

Outlook:


Quite sultry on Saturday with above normal temperatures and high dew points.  Chance for showers and thunderstorms.  Cooler on Sunday as temperatures fall back to near normal.  Continued near normal or slightly above normal temperatures into next week with chances for showers in the north, then more widespread chances for showers and thunderstorms on Wednesday and Thursday.  
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