After a quiet weather morning Minnesotans will be served up a sample of winterlike conditions with light freezing rain developing later today, particularly north of the Twin Cities.
Area outlined in purple is under a Freezing Rain Advisory, which extends north to cover the remainder of northern Minnesota for this evening. The tan shading highlights the big change in temperatures arriving on Friday night.Source:NWS Chanhassen, MN
Light rain is expected to develop later today and as the darkness sets in the precipitation will freeze on the surface. The critical factor is the low dew points this morning, which are not expected to climb much. As moisture falls evaporational cooling will occur. The ambient temperature will slip to 32 F or lower. Watch for slick spots this evening.
Strong thunderstorms, producing heavy rain and the threat for severe weather, continue to pound the lower Mississippi Valley this morning. Heavy rainfall will extend up to southern Illinois today.
Temperatures should top out in the middle to upper 30s in southern Minnesota today as clouds thicken.
Winter's main course arrives on Friday with a potential for several inches of snow in northwest Minnesota and eastern North Dakota. A Winter Storm Watch is posted for that area. Snow should fall heavily later on Friday and taper off on Saturday. Five to ten inches of snow could accumulate from Grand Forks to Roseau.
The center of the storm system is forecast to travel on a path that puts southeast Minnesota in the mild sector on Friday, with also limited precipitation amounts. Highs could top 40 in Rochester Friday afternoon.
Arctic air will sweep into the Great Lakes on Friday night and Saturday as icing on the wintry landscape. Blustery winds will add a sting to the air that we haven't experienced for some time. Bundle up on the weekend. Hoods or caps are recommended to cover the head and ears. Mittens are preferred over gloves to keep your fingers warm.
Seasonal temperatures remain in our weather picture through next week.
Once again the extreme southwest corner of Minnesota and Sioux Falls, S.D. were shorted on the rainfall in the past 24 hours. While Marshall picked up 1.68 inches of rain, Sioux Falls tallied less than a quarter inch (0.16).
Prior to strong storms firing up in southwest Minnesota on Wednesday afternoon, the mercury soared to 99 at Marshall and a record 102 degrees at Sioux Falls.
The heat index reached 100 dgrees in the Twin Cities in the afternoon hours. The maximum temperature in both Minneapolis and St. Paul was 92 degrees, with dew points in the lower 70s. It is interesting to note that with the dew point of only 55 at Sioux Falls, with a temperature of 101 at the time, their heat index was 100 degrees. it is indeed about the humidity when it comes to the feels-like temperature in the summer.
Temperatures will be more comfortable today but still summerlike. Look for afternoon readings only in the upper 70s in far northern Minnesota.
A stronger cool front is forecast to sweep through the upper Midwest on Friday night. This will bring a good chance for showers and thunderstorms to much of Minnesota later on Friday and Friday night.
On Saturday the passing cold front will usher in brisk northwest winds with a mixture of clouds and sun in the afternoon. You'll notice the change in the air mass.
Stand up and cheer if you embrace cooler temperatures -- on Sunday northwest winds will ease and plenty of sunshine should make for a comfortable afternoon.
Anyone feel like celebrating the heat and humidity that set a record in the Twin Cities on the 4th of July? The maximum temperature of 101 at the Twin Cities International Airport on Wednesday beat the old record of 100 set in 1949. Dew points in the 70s lifted heat index readings to near 110 degrees. We also set a record high minimum temperature of 81 degrees on the 4th. Surpassing the old record of 80 set in 1999.
A RECORD HIGH TEMPERATURE SET YESTERDAY IN ST CLOUD MINNESOTA...
THE HIGH TEMPERATURE WAS 97 DEGREES YESTERDAY IN ST CLOUD.
THIS BREAKS THE OLD RECORD OF 96 SET JULY 4 1988.
.A RECORD HIGH TEMPERATURE SET YESTERDAY IN EAU CLAIRE WISCONSIN...
THE HIGH TEMPERATURE WAS 98 DEGREES YESTERDAY IN EAU CLAIRE.
THIS BREAKS THE OLD RECORD OF 97 SET JULY 4 1999.
Bouts of thunderstorms moved through northern and central Minnesota yesterday and overnight. At daybreak this IR satellite image depicts the coldest cloud tops and the location of thunderstorms.
A weak frontal boundary has settled over central Minnesota this morning. This division in air masses is expected to remain nearly stationary today and this evening. Meanwhile a mid level trough (an inducer of thunderstorms) will approach the upper Midwest tonight. Chances for showers and thunderstorms are at least in the 50/50 range for the next 36 hours for much of central and southern Minnesota.
This afternoon temperatures will be several degrees lower than Wednesday's maximum temperatures. Readings of 100 degrees were recorded at St. Paul, Winona, Red Wing and Black River Falls, Wisconsin. It was a relatively comfortable 79 at Baudette on Wednesday afternoon. Thunderstorms prompted warnings of large hail and strong winds during the afternoon and nighttime hours.
Storm report from NOAA's Storm Prediction Center for Wednesday.
This computer image from the Rapid Update Cycle forecast model depicts the temperatures expected later this afternoon.
NOAA experts paint this graphic of rainfall potential ending at 7 a.m. CDT on Saturday. Some storms today and tonight may produce large hail.
Seasonal temperatures are seen statewide for Saturday and Sunday accompanied with lower dew points. In the meantime, southern Minnesota will experience two more days with readings in the lower to middle 90s.
Forecast temperatures for Sunday at 7 p.m. CDT
Source: NOAA GFS and Twisterdata.com
Have you noticed the earlire sunsets? Probably not! But the daylight is getting shorter.
Craig Edwards(2 Comments)
The thermometer climbed to a record 98 degrees at the Minneapolis-St. Paul International Airport this afternoon. This topped the old record of 96 degrees set in 1911. Heat Index values were over 100 degrees in many locations, as dew points were in the upper 60s to lower 70s. It was a sizzling 99 degrees in Red Wing at 4 p.m.
Based on the extended period of heat and humidity forecast for the next 48 hours the National Weather Service has elevated the heat advisory to an excessive heat warning for Hennepin and Ramsey counties.
Maximum temperatures for Tuesday are shown in this National Weather Service forecast.
A severe thunderstorm watch is in effect until 7 p.m. for parts of northern Minnesota. This watch may be extended east and south this evening.
Storm Prediction Center's outlook for damaging wind potential for the rest of today and tonight:
Source: NOAA Storm Prediction Center
A weak wind shift line sags into central Minnesota late tonight and has the potential to drag thunderstorms as far south as the Twin Cities. Don't expect much relief as the winds briefly turn to the northeast.
Your 4th of July will indeed be hotter than a firecracker. Marching bands in midday parades will be beating the drum for cold refreshments.
Dreaming of a cool down? Perhaps this weekend as temperatures slip below the 90 degree mark for daytime highs.
A continuation of above normal temperatures is expected through mid July.
Six- to ten-day outlook from NOAA
Be cautious and act responsibly if heading to the lake for the next couple of days.
Mother Nature is turning up the heat this week. It is a good time to be positioned closed to cool water. Slow down. We will experience dangerous heat index levels through Thursday, particularly over southern Minnesota and adjacent areas.
One of the computer models is showing a chance that the thermometer could reach 100 degrees in the shade in the Twin Cities this afternoon. A heat advisory has been posted for all but far northeast Minnesota for today. Hot and humid conditions will push the Heat Index Value close to 105 for several hours. The record high for the Twin Cities for today is 96 degrees, set in 1911.
The heat index does not take into consideration exposure to direct sunshine. Temperatures in the direct sunshine can be as much as 15 degrees hotter.
Mid afternoon temperature forecast from the NAM:
The UV index will be high. If you must be in the sunshine be sure to apply appropriate skin protection.
Severe thunderstorms are possible in northern Minnesota today. Stay alert for developing storms and the risk for gusty winds and hail from the lake country north.
We do not see a break in the hot temperatures until a weak cool front settles south of the Great Lakes on Friday. Temperatures may be close to normal on the weekend. Highs will likely still be in the 80s.
Take it easy today. Complete necessary outdoor chores early in the day if possible.
Soon we may be longing for a scene like this!
Yesterday's maximum temperature topped out at only 35 degrees at International Falls, which was four degrees below the average high of 39. The high on Saturday at the Falls was 58 degrees. In the Twin Cities the afternoon temperature failed to reach 60 for the first time since we settled for 52 degrees on March 12th. It was a good run well above normal temperatures.
Clouds are expected to prevail today. The maximum temperature in the Twin Cities may struggle to reach 50 degrees with periods of showers and thundershowers. Showers and thunder spread from central to northern Minnesota this evening. Many places are still short of precipitation for the month of March.
Here's a look at the potential precipitation totals for the next couple of days.
Due to the low dew points expected to hold over northeast Minnesota today and tonight, some of the precipitation is likely to occur as freezing rain. A Freezing Rain Advisory has been posted for a sliver of the Arrowhead Region for tonight. Freezing rain will coat tree limbs and pwer lines during the cover of darkness.
Details can be found by clicking on this statement from the National Weather Service in Duluth.
Strong winds are on tap as a low pressure system winds up over the upper Midwest later today. The National Weather Service has issued a Wind Advisory for portions of western Minnesota, where gusts could top 35 mph. Brisk winds are expected across much of the state on Tuesday as well.
The NAM depicts a strong surge of warm air as the low tracks towards International Falls at midday on Tuesday. This pressure pattern illustrates the potential for wind gusts to 40 mph in southern Minnesota.
It appears the trend continues to be our friend as we head into April. NOAA's Climate Prediction Center posted their April temperature outlook earlier this month. They sometimes refresh this outlook on the last day of the month.
Precipitation outlook from NOAA for April.
The normal maximum/minimum for the Twin Cities on April 1st are 50/31 degrees.
I spent a couple hours outdoors this morning and it sure felt warm in the August sunshine. With only a slight cooling breeze it was a blessing to have dew points some twenty degrees lower than Tuesday. The dew point at the Twin Cities International Airport was 74 degrees yesterday and a more comfortable 55 degrees this afternoon.
While the mercury has climbed to ninety degrees or better at MSP this summer season on fourteen days, we are looking at a period out a couple weeks were it may be more to our delight with regard to heat. The average temperature for July in St. Cloud was about 4.5 degrees warmer than normal. The Twin Cities average temp was 5.6 degrees above normal for July 2011.
We have turned the corner for "normal" maximum temperatures in the heart of summer and are slowly creeping down into the lower 80s. By the time we reach August 13th the average high in the Twin Cities is down from 84 to 81 degrees. The 8-14 day outlook from the Climate Prediction Center depicts odds favoring at or somewhat below normal temperatures for the upper Midwest.
In case you think we had it bad here, and we did with the high dew points, the average maximum temperature for July in Dallas, TX was over 101 degrees. More than 70 percent of Texas is in an exceptional drought. They could use a decaying tropical storm to move inland and dump generous rainfall. That doesn't appear likely soon.
Keeping an eye on Tropical Storm Emily and the computer generated track is the challenge for hurricane forecasters in NOAA's Hurricane Forecast Center.
Here's the link to follow the tropical storm's the reminder of the season. NOAA's Hurricane Center website.
The latest update on the storm named Emily predicts a path that takes it over Haiti with winds of 50 mph and rainfall of over five inches. From the Hurricane Center's most recent statement this afternoon....Tropical Storm EMILY Public Advisory:
RAINFALL...EMILY IS EXPECTED TO PRODUCE TOTAL RAIN ACCUMULATIONS
OF 6 TO 10 INCHES IN PUERTO RICO WITH ISOLATED AMOUNTS OF 12 INCHES.
RAINFALL ACCUMULATIONS OF 6 TO 12 INCHES WITH ISOLATED AMOUNTS OF 20
INCHES ARE POSSIBLE OVER THE DOMINICAN REPUBLIC AND HAITI. THESE
RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES.
Track projection as of early this afternoon for Emily.
Always subject to change, but the forecast strength remains below hurricane force of 75 mph winds until early next week.
Enjoy the seasonal temperatures the next couple of days. Overnight temperatures may allow you to shut down the A/C and bring in some outside air.
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
CENTRAL AND SOUTHERN MINNESOTA
EFFECTIVE THIS TUESDAY MORNING AND AFTERNOON UNTIL 100 PM CDT.
HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 55
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 45 MILES NORTHEAST
OF EAU CLAIRE WISCONSIN TO 10 MILES SOUTH OF ORTONVILLE
Heavy rain fell across portions of northeast Minnesota and northwest Wisconsin overnight. Three and a third inches of rain was reported at Askov in Pine County, MN and near Floodwood in St. Louis County, MN. The automated gauge at the Duluth Airport captured two and a half inches of rain.
Severe thunderstorms are possible in the southern portion of Minnesota and west central Wisconsin this morning as a cool front slips through the region. Less humid conditions are on tap for Wednesday.
Here's the complete report of the record dew point for this summer as published Monday afternoon by the Minnesota State Climate Office:
The Exceptionally Muggy Summer of 2011
The National Weather Service is forecasting a break in the high dew point temperatures over the next few days after the muggy day today. So far this summer as of 3pm August 1, there have been 274 hours of dew point temperatures of 70 degrees or higher recorded at the Twin Cities International Airport. The record is 512 hours in 2002. What really stands out are the counts of extremely muggy dew point temperatures. So far this summer as of 3pm August 1, there have been 98 hours of dew point temperatures of 75 degrees or higher. This breaks the old record of 78 hours that was set back on 2001.
Twin Cities International Airport
Greatest Number of hours with dew point
temperature of 70 degrees F
Rank Year Hours
1. 2002 512
2. 1983 392
3. 1995 387
4. 2001 357
5. 1955 345
1981-2010 average = 182
so far in 2011 274
(through 3pm August 1)
Twin Cities International Airport
Greatest Number of hours with dew point
temperature of 75 degrees F
Rank Year Hours
1. 2011 98 (as of 3pm August 1)
2. 2001 78
3. 1999 64
4. 1987 60
5. 1995 56
1981-2010 average = 18
This visible satellite image shows a couple of important aspects about this afternoon's weather. First, the clouds that remained over eastern Minnesota and western Wisconsin which kept temperatures from climbing into the lower 90s. Second, the clearing in western Minnesota that has allowed sunshine and high dew points to produce heat index values about 100; including 106 at 3PM in Canby.
In the previous blog you'll note the Storm Prediction Center's rather high probability of tornado potential in western Minnesota. There is a boundary from the differential heating due to the cloud-free area and the persistent cloud cover. This is displayed nicely in the graphic of the dew points, temperatures and pressure field as generated from 3PM surface observations.
Temperature contours are in red, dew point highlighted by colored background and pressure field in black. Basic meteorology suggests the inflow of winds from the south and southeast, along with the advancing low pressure, high dew points and afternoon heating will result in thunderstorm development in eastern South Dakota and western Minnesota.
We'll watch how this unfolds in the later afternoon and early evening hours.
Meanwhile, Pete Boulay of the State Climate Office shared this tid-bit after probing the dew points recorded this summer at the Twin Cities International Airport. So far this summer as of 3pm August 1, there have been 98 hours of dew point temperatures of 75 degrees or higher. This breaks the old record of 78 hours that was set back on 2001.
Some branches were blown down along with power lines as the storms swept through east central Minnesota between 1230PM and 230PM this afternoon. Here's a link to the storm reports out of the Chanhassen NWS Office.
Heavy rain also was reported with over two inches at Hutchison and an inch and a half at Target Field near downtown Minneapolis from late morning to mid afternoon.
Stay abreast of potentially dangerous weather conditions developing as we go into the evening hours.
While we are calling this sweltering, oppressive atmosphere a Heat Wave, it equally worthy of being called a High Dew Point Warning. Yesterday afternoon and evening dew points, a very good indicator of the moisture in the atmosphere, were in the lower 80s over a large swath of southern Minnesota. It is very rare to observe sustained high dew points over a broad area this far north.
Dew point measurement can me impacted by the microclimate of the sensors location. We see dew points at their highest in southern Minnesota from mid July through about mid August. A number of us in the weather business believe that these seasonally high dew points are the results of the evapo-transpiration of the maturing corn corps across Iowa and southern Minnesota. Moisture is released back into the low levels of the atmosphere and we feel its affects.
A slight drop in dew points is seen for today. We may well see a few degrees of additional heat on the thermometer. That translates to Heat Index values of 105 to 115, in the shade, during the middle of the day. This is excessively sweltering when you add into the equation direct sunlight. Stay out of the sun today if you can. Unless you are standing in the lake.
Dogs and cats instinctly slow down in this weather. If your dog needs to have a walk, make it a quick trip early in the morning or in the evening. Provide plenty of water for pet during this sultry period.
Follow the advice from health officials with regard to your well being. Apply the number one rule; slow down. Dress in light colors with a brimmed hat.
Heat spell breaks a bit towards the end of the week. Just so you know; the climate records document the next seven to ten days as the warmest period during the calendar year.
The sensible temperature is about fifteen degrees warmer in the direct sunshine.
Think cool thoughts today.
When you listen to a weather observation it sounds so simple. There are a number of automated meteorological observation units that take nearly continous weather observations. The official NWS automated observations are recorded and transmitted by ASOS-Automated Surface Observation System.
The FAA has augmented these observations with their own units known as AWOS-Automated Weather Observation Systems. Here is a link to the automated observation sites. In addition, the Minnesota Department of Transporation has some weather observing sites.
When I began my career with the NWS at Mitchell Field in Milwaukee I was a weather observer. Fortunately we had automated sensors already in the early 1970s. We were required to observe the cloud cover, along with the horizontal visibility on an hourly basis. This visual observation along with the temperature, dew point, wind and pressure was transmitted by teletype.
On a regular basis we would ensure the automated temperature and dew point sensor was reading accurately. Once a week the weather observer would stand in a shaded grassy area and swing a sling psychrometer that would measure the dry bulb and the web bulb temperatures. We would then calculate the dew point; ultimately deriving the relative humidity.
Here's a photo of how they still determine relative humidity when on a forest fire incident.
If you want to read more about the meteorological measurements you can check your knowledge at this NWS website.
I was partial correct when I said you would notice an increase in dew points today. The Twin Cities International Airport had a dew point of 51 degrees at this time on Wednesday. The dew point rose to 65 degrees when light rain fell at 6AM, but has since fallen back to 56 degrees. The dew point is in the lower 60s at Rochester this afternoon.
Check out the change in cloud cover from early this morning (see previous blog) to this afternoon on the visible satellite image.
Thunderstorms were firing up in portions of the Minnesota River Valley in west central Minnesota.
Latest computer model information still supports the best chance for thundershowers in central Minnesota on Saturday afternoon and evening.(2 Comments)
Italy's Mt. Etna is Europe's most active volcano and erupts frequently, but it doesn't get much better than this for video. Check out the dazzling images as Mt. Etna erupts again in Sicily.
The story from UPI:
"CATANIA, Italy, May 12 (UPI) -- Mount Etna on the Italian island of Sicily sent smoke, volcanic shards and ash thousands of feet into the air Thursday.
The airport in Catania, Sicily's second-largest city, was closed for a while, the Italian news agency ANSA reported. It partially reopened later Thursday.
Ash fell on the city and surrounding farmland. The eruption, which was not a major one, began late Wednesday.
Organizers said the eruption will not affect Sunday's stage of the Giro d'Italia, when competitors will be bicycling on Etna's slopes, The Daily Telegraph reported. Rocks fell on some of the roads that are part of the course.
"Sunday's stage is not at risk. The stretch in question is only the last 4 miles on Etna," director Angelo Zomegnan said. "But on-site teams are already working to clear the road. We are calm."
Lightning vs. plane in London:
I buried this near the end of this mornings post, but it's probably worth another look.
Check out this amazing video of lightning hitting a plane last month at London's Heathrow Airport.
Fishing opener weather history all over the map:
The Minnesota Climatology Working Group has a great recap of historical weather conditions for the Minnesota fishing opener. As you might guess, the weather can be all over the place in mid-May.
2011 Minnesota Fishing Opener Weather
Minnesota's Fishing Opener weather is typified by partly cloudy to cloudy skies, morning temperatures in the low 40's, and afternoon temperatures climbing to near 70. Three out of four years are free of measurable precipitation. A trace of snow has been reported in northern Minnesota on at least five of the last 63 fishing openers. On at least four occasions, some lakes were still frozen for the opener. Generally there is enough wind to be felt on the face, maybe enough to 'fly' a flag. Weather on Minnesota fishing opener dates is highly variable. 63 years of fishing opener weather data are summarized here to offer a glimpse of what is 'typical' and what is 'extreme'.
Opening day temperatures have started as low as 24 degrees at International Falls (1996,2004), with freezing temperatures possible even in Minneapolis (31 degrees in 1979). On the warm side, St. Cloud saw 92 degrees in 1987, Minneapolis reported 91 in 1987, and International Falls reached 88 in 1977. The average early morning temperature varies from the high 30's in the northeast to the high 40's along the southern border. The average afternoon temperature generally ranges from the mid 60's along the northern border, to the low 70's in the extreme south. Along the shore of Lake Superior, highs are held in the mid 50's.
Three quarters of past opening days have been free of measurable precipitation. Two thirds of the fishing openers have been free of any precipitation, measurable or not. On those days with measurable rain, the amounts averaged close to a half-inch in the south and a quarter inch in the north. No amounts over one inch were recorded at International Falls, while Minneapolis experienced 1.15 in 1962 and 1.64 in 1965. St. Cloud saw 1.03 inches in 2008. Snowfall has generally has been limited to traces. Traces of snow were officially recorded in 1963, 1993, and 2009 at International Falls, and in 1968 at St. Cloud. A tenth (.1) of an inch fell at International Falls in 2000.
Statewide, less than one year in five offers totally clear skies. The average amount of cloudiness lies near that fuzzy boundary between 'partly cloudy' and 'cloudy', but over half of the dates were classified as cloudy.
Average daily wind speeds generally range between 8 and 15 miles per hour. This range can is described as 'wind felt on face ...' to '... wind extends light flag'. The predominant wind direction is split fairly evenly between blowing from the northwest, south, and east.
Fog has been reported on the fishing opener, occurring about one year in ten in the south, about one year in six in the north. By early to mid May, Minnesota is entering its thunderstorm season. The possibility of thunderstorms is greatest in the south (about one in seven), less in the north (about one in eleven). The weather should be monitored carefully if the skies appear threatening.
For May 14, 2011 at St. Cloud, the sun will rise at 5:47 a.m.; sunset will come at 8:39 p.m. For International Falls, sunrise/sunset is 5:34 a.m. and 8:46 p.m. respectively. For Minneapolis, sunrise will be 5:46 a.m. and sunset at 8:34 p.m. Add one minute for each 10 miles west of a given location (at the same latitude) to get a rough estimate of sunrise and sunset times. Sunrise/sunset information can be obtained for any community using a Web site offered by the US Naval Observatory.
Fishing opener 2010 began with very calm winds and plenty of sunshine over northern Minnesota with more clouds than sun over the central and south. Winds were calm in the morning, picking up a bit in the afternoon.
And finally, yes there have been years with ice covered lakes for the opener. On opening day in 1950, lakes were still frozen as far south as Detroit Lakes and Osakis. Four other years with frozen lakes, primarily in the north, were 1966, 1979, 1996, 2008 and 2009. Just a couple lakes in the far northeastern tip of Minnesota still had ice on them for the '09 opener.
This season, the ice left the lakes a bit later than historical averages over the south and parts of central Minnesota with near average over the north. The 2011 Governor's Fishing Opener is on Pokegama Lake. The average date of ice out for Pokegama Lake is is April 24. The ice left Pokegama Lake on April 27.
More information about fishing in Minnesota can be found at the Department of Natural Resources.
A history of past fishing openers back to 1948 can be found at the Minnesota Historical Society .
Dew point records smashed Tuesday:
UM Climate Guru and my MPR colleague Mark Seeley has some great info on how Tuesday's July like air mass featured tropical humidity levels that smashed dew point record for May 10th.
Topic: High Dewpoint Records for May
"Tuesday, May 10th was quite a day in Minnesota. During the afternoon strong southeast winds brought in very warm, moist air across southern counties. Many observers reported near-record setting or record setting temperatures in the 90s F, spiking between 4:00 and 6:00 pm. Some of the record-setters included:
Waseca 92 F (tied record for May 10th in 1987) Wells, St James, and Fairmont 93 F Amboy and Winnebago 96 F
The readings at Amboy and Winnebago were just shy of the all-time state record for May 10th of 97 degrees F at Beardsley in 1928.
Even more impressive than these high temperatures was the rise in dewpoints. Many observers reported record high dewpoints by late afternoon, including MSP International Airport which reached a July-like 70 degrees F. Windom, Fairmont, St James, and Faribault also reported dewpoints of 70 degrees F. Even higher dewpoints occurred at Hutchinson (73 F), Albert Lea (74 F) and Waseca (78 F). These numbers are incredible amounts of water vapor for the first half of May. In some cases they pushed the Heat Index Value (combination effect of temperature and dewpoint) to 100 degrees F or higher. It is believed that the Waseca dewpoint of 78 degrees F is the highest ever measured in the month of May. In the MSP historical records dewpoints of 70 degrees F or higher have only been reached in 1912, 1916, and 1962.
The dramatic rise in temperature and dewpoint helped fuel severe weather across the state. There were over 40 reports of large hail during the evening of May 10th including 2.0 inch diameter hail stones at Chanhassen, Eden Prairie, Forest Lake, and Brainerd. Golden Valley, St Louis Park, and Fort Ripley reported 2.5 inch diameter hail, and Albertville reported 2.75 inch diameter hail."
As always, you can hear Mark's commentary exclusively on MPR's Morning Edition with Cathy Wurzer at abour 6:45 Friday morning.
Posted at 9:09 PM on December 29, 2010
by Craig Edwards
Filed under: dew point
Milder air has pentetrated Minnesota this evening. Not only have temperatures climbed into the middle thirties over the southern half of the state, but dew points have increased as well. This will result in the potential for dense fog.
As a trough of low pressure sets up over far western Minnesota overnight and Thursday a large portion of the state will stay on the mild side of this system. A light rain is likely for southeast Minnesota.
Accumulating snowfall is still in the forecast for far northwest Minnesota into Thursday afternoon. A band of mixed rain and snow is possible from about Granite Falls to Hibbing.
The second system on Friday remains a work in progress. A band of heavy snow is likely to set up in west central Minnesota and expand east and northeast during the afternoon and evening.
An icy blast of arctic air is in the offing to begin the New Year.
Update 4:45pm: (Original post 8:29am)
Check out the 4pm dew point reading of 68 degrees at St. James Tuesday.
Notice how the 68 degree dew point reading is a good 10 degrees higher than many of the surrounding surface sites. It looks like the corn is doing a good job of evaporating soil moisture into the lower atmosphere in corn country today!
Anyone who's driven through southern Minnesota knows corn is king in the summer landscape. Now we know it's making our summers a bit more humid too.
According to Pete Boulay at the Minnesota State Climatology Office, Minnesota's corn crops may be boosting dew points by as much as 1 to 5 degrees on summer days in and near cornfields.
Pete confirmed the readings last week by taking measurements with a little thing called a "pshychro-dyne" instrument which measures temperatures used to calculate the dew point. August 12th was a hot steamy day (high was 92 at MSP) with relatively light winds in the morning. So Pete headed out into the dense corn stand at the UM St. Paul Campus and began to take readings.
Here's what he found: (These are excerpts from Pete's email)
There's been discussion about certain AWOS sites in Minnesota and their proximity to row crops, especially St. James. The dew point temperatures at sites like St. James are consistently higher than other locations during the high dew point season of July and August. Could the close proximity of actively transpiring crops be the explanation?
I wasn't quite hot enough on Thursday, so I did a little dew point experiment on August 12 using a "pshychro-dyne" instrument. I measured the wet and dry bulb temperature at the St. Paul Campus Weather Station and the small, but dense corn plot in front of the station. It was a sunny day with very few clouds. Winds were light before noon, but became fairly breezy from the south by afternoon. Readings were measured at 5ft above the ground and were conducted in either shade or in the instrument shelter.
Here's a photo of the instrument used.
First value (T) is dry bulb, the second value (Tw) is wet bulb, the third value (Td) is dew point temperature. Dew point temperature was calculated at http://www.csgnetwork.com/dewptrelhumcalc.html All are in degrees F.
August 12, 2010
11:18am field by parking lot 1/3rd mile south of station T85 Tw75 Td71
11:30am middle of corn next to station to south T87 Tw79 Td76 (light wind)
11:33am in instrument shelter T88 Tw76 Td71 (light wind)
4:40pm in instrument shelter T89 Tw78 Td74 (moderate south wind)
4:43pm in corn south of station T89 Tw79 Td75 (moderate south wind)
Campus station HMP35C reading
11:00am T86 Td76
Noon T89 Td76
4pm T90 Td78
5pm T90 Td79
The dew point temperature was higher in the corn by 1-5 degrees F, wind may play a role.
It feels very hot and muggy in the middle of a corn field in August.
State Climatology Office
DNR - Division of Ecological and Water Resources
The salient point here is that Pete found dew points between 1 and 5 degrees F higher in the corn on a hot summer day, than in nearby areas. Now, this is by no means a comprehensive scientific study, it's just one really qualified climate expert taking readings in a corn field. But I'll take Pete Boulay and his "psychro dyne" readings any day.
A little inside baseball here. Several of us in the local meteorological community have wondered if automated weather stations like St. James read higher dew points because they are located very near cornfields. Corn is an efficient evaporator of soil moisture, and releases that moisture into the surrounding air.
My take away from Pete's little experiment is that corn does play a role by increasing summer dewpoints in densely planted areas. The effect is real, and millions of acres in the Midwest are planted with corn. This is not instrument failure, but rather success in picking up on the air mass modification by some row crops.
The next question is; are the higher moisture levels significant enough to cause additional low level moisture to fuel thunderstorms and enhance rainfall? In science, we call this process a "feedback loop."
There are still many unanswered questions about corn and humidity. But on one day in August in the sweaty summer of 2010, a guy with a "psychro dyne" in a corn filed in St. Paul confirmed what many meteorologists have long observed. The corn is making things more humid in Minnesota....at least in the middle of the corn field.
Also unanswered is whether or not Pete saw Shoeless Joe Jackson dissapear into the corn at the UM St. Paul Campus. (Sorry, I couldn't resist.)