Paul Huttner has spoken before about the well-known effect of the forested region of northern Minnesota catching the warmth of the late winter and early spring sunshine.
Despite the two feet of snow on the ground, Crane Lake checked in with a temperature of 45 degrees F at 3 p.m. CDT. This relatively mild reading might suggest that someone go out and calibrate the thermometer.
Meanwhile, the bare, frozen soil of southern Minnesota, bathed in sunshine could only respond with temperatures in the upper 30s. It was 36 F in Jackson, MN at 3 p.m. CDT.
As of 7 a.m. CDT today Rochester reported a snow depth of 10 inches.
To our good fortune, the dominate chilly weather has kept down the threat for severe weather. There hasn't been a thunderstorm reported at the Twin Cities International Airport since Nov. 10, 2012.
On the national landscape, tornadoes have been few this year. The Storm Prediction Center has recorded two deaths from tornadoes in 2013. One in Texas and one in Georgia. The Georgia tornado was evaluated as an EF3.
You can track the national tornado statistics at the Storm Prediction Center's website.
No severe thunderstorms as expected across the CONUS through the remainder of March.
Differential heating is not just taking place in the forest. You can notice it in your own neighborhood by viewing the south-facing landscape.
There is still plenty of water in the remaining snowpack. Core samples are taken on Tuesday and reported to the NWS for monitoring the release of moisture in a rapid thaw.
I measured 2.3 inches of liquid remaining the average snowpack in my yard.
A mild rain storm, in concert with the thaw, creates a worst-case scenario for flooding.
The slow moderation will continue through the week. The sunshine and a bit of a wind help to evaporate some of the moisture from the melting snow.
Highs on Friday should be in the 40s over much of the state if we can hold on to some partial sunshine.
A mixture of rain and snow is forecast to develop on Friday night. The GFS model is consistent with dropping a half-inch of moisture in the Twin Cities Metro area on Saturday morning.
On Sunday afternoon temperatures will begin to slide. A very blustery day appears to be in store for Monday. The thermometer have a hard time reaching 40 F in the Twin Cities.
Craig Edwards(0 Comments)
The urban heat island is well observed in the climate records of metropolitan areas. If you reside in downtown Minneapolis/St. Paul you experienced a minimum temperature that was near or even above the thawing point of 32 degrees this morning. The International Airport recorded a low of 32 degrees, while Saint Anthony checked in with 34 degrees. All official temperatures are taken about five feet above ground level.
Meanwhile, it was a different story away from the urban region. Here is a sample of some other minimum temperatures recorded this morning: Chanhassen, Crystal, and Buffalo all at 27 degrees, Further away from downtown, it was a very nippy 23 degrees at Waseca, 25 at St. Cloud and one of the coldest readings of 21 degrees in Princeton. Temperatures in the middle twenties were observed in western Wisconsin as well, with a frosty 25 degrees in Eau Claire.
Obviously the the exact location of the thermometer has some bearing on the temperature, particularly when winds are calm and the sky is clear. But the reality is, we were all under the umbrella of the same air mass. When meterorologists predict lows from the middle 20s to the middle 30s, they are not hedging. They are bracketing the temperatures that can be different in a small radius.
Peter Synder of the University of Minnesota has embarked on additional research to capture the magnitude of the urban heat island in the Twin Cities. He is in particular need for observers within the Interstate 494/694 beltway. If you would be able to assist Peter and his work, he can be contacted at firstname.lastname@example.org. Here's the website for more information; http://www.islands.umn.edu/
I spoke with Greg Spoden at the Minnesota State Climate Office this afternoon and he related how some of his research has shown that with a slight north wind the urban heat island can expand to Farmington. Invaluable research here, especially when scientists are trying to resolve the human impact on global warming.
Greg also confirmed that the latest seasonal outlook for this winter, issued by NOAA yesterday, is using the new normals when defining regions that favor above or below normal temperatures.
Another nice day is in store for Saturday before the opportunity for moisture arrives on Saturday night. It felt quite comfortable in the sunshine this afternoon. We topped out at 60 degrees at the Twin Cities international Airport.
Often meteorologists refer to the prospect of showers as the "threat of rain". When you have been as dry as some locations in Minnesota, you call it an opportunity for rain.
Here's a look at how sparse rainfall has been since late July. As Greg noted, southern Minnesota is seeing moisture shortages that are extremely rare. Being in the zero percentile is not where you'd like to be if you're looking for soil moisture recharge for next year's growing season.
This afternoon's weather graphic from the National Weather Service in Chanhassen. Hopefully we can play out a win-win in the weather world, with precipitation falling overnight on Saturday.
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.
After measuring just shy of nine inches of fresh snow late Saturday afternoon, you can see how quickly the snow is melting away due in part to the mild soil temperatures. I purposely took this photo to show the micro-climate of the south facing exposure and the impact the spruce trees can have on collecting heat.
This is what occurs in the Northland of Minnesota in February when we see temperaures warm nicely in the forested areas on sunny days.
The snow had a water content of an inch. Ponds and creeks are showing the response to the weekend precipitation.
Posted at 4:30 PM on August 26, 2010
by Craig Edwards
Filed under: Microclimates
Have fun navigating to a location to find out how cool it got overnight. I was curious about the impact of the urban heat island effect when I observed the International Airport had a low of 56 and St. Paul Homan Field had a minimum of 54. Chaska had a low of 49 degrees.
Clearly the sunshine from Wednesday was absorbed and held in the downtown streets and buildings.
The coldest reading I could find this morning was 36 at Grand Marais and Cook. It was 46 degrees as close as Lake Elmo.
Winds pick up for your Friday afternoon and a repeat is in store for Saturday.
Posted at 3:30 PM on June 24, 2010
by Craig Edwards
Filed under: Microclimates
Why am I showing you all these visible satellite images? Because they are a key tool for meteorologist in the summertime convective season. They give clues on convergence boundaries and areas of differential heating that may spawn thunder clouds.
This visible picture distinguishes a couple of features. One, the differential heating as a result of the land heating while the larger body of water of the Upper and Lower Red Lake warms less than the land mass. Thus there are minimal or no cumulus clouds shown over the lake water.
The second feature that caught me eye is what appears to be a plume of smoke running from northwest to southeast over southern Canada. This too has resulted in differential heating with cumulus clouds flanking the smoke plume to the north and south.
If you animate the imagery it will display the movement of the features in the layered wind field. Animate the visible picture. Check out the convection that has blossomed in northern Minnesota that has resulted in severe weather potential.
While this tool is invaluable for short term, twelve hour forecasting, we must rely on computer models to dissect the layers of the atmosphere and project the anticipation of clouds and precipitation days out.
Boundaries from the previous convection (thunderstorms) establish new areas for differential heating and convergence zones. It is more than a challenge to get a handle on where these boundaries may end up sixty hours from now.
It can be like spring or summer in Target Field at the same moment, depending on where your seats are.
At a recent Twins/Yankees game I took the time to visit several different sections and "take the temperature" of the seats and the fans. What I found are temperatures that vary widely in different sections of Target Field at the same time.
While it is not a surprise to find changing temperatures in Target Field, the magnitude of the difference in the apparent or "feels like" temperature was remarkable. It was like the difference between a cool spring day and a warm summer afternoon depending on the section number on your ticket.
Thursday May 27th
Location: Left field seats section 313.
-Air temperature: 80 degrees.
-Apparent temperature: Near 90 degrees.
I enter Target Field through Killebrew Gate 3 in center field. Under the crowded but shady concourse with the breeze it feels very close to the ambient air temperature of 80 degrees. But as I emerge into the direct sunshine in the left and center field bleachers, it's instant July.
The seats are very warm to the touch. The fans are dressed for summer. My low tech thermometer and weather spidey senses tell me the apparent or "feels like" temperature in the sun soaked center field seats is close to 90 degrees. Center field faces directly west into the now sinking but still potent evening sun, and you can feel every degree.
Location: 3rd base line near section 11, row 1 .
-Air temperature: 77 degrees.
-Apparent temperature: 74 degrees.
As Nick Blackburn throws the game's first pich to Derek Jeter, I am in the press pit next to the Yankee dugout at field level just below the first row of section 11.
The shade of the stadium's high canopy has covered the area along the 3rd base line now for some time, and the temperature is noticeably more comfortable than it was in the outfield just minutes earlier.
There is now a slight breeze to subtract just a few more degrees from the apparent temperature. I would estimate the feels like temp here is a cozy 74 degrees as the game starts.
Location: 1st base side concourse at the top of section 109 .
-Air temperature: 74 degrees.
-Apparent temperature: 68 degrees.
I make my way to the concourse along the first base line behind section 109. This area has been in shade pretty much all day. It now feels considerably cooler here. The breeze blowing through the openings in the concourse is cool to the senses. I notice many fans here wearing sweatshirts, even as T-shirt clad fans in center field soak up the last rays of evening sun across the stadium.
On this relatively warm summer like evening at Target Field, I observed differences in apparent temperature in different sections of the ball park of as much as 22 degrees over a period of about an hour. On this day it was relatively warm, but it would be good to know where you're sitting on a sunny day as you decide how to dress for the game.
I talked with Kevin Smith, Twins media guru about the stark contrast in temperatures around Target Field. His observations seem to indicate that the biggest differences occur on sunny, relatively cool and breezy spring days with temperatures in the 60s. He has seen fleece in the upper deck sections along the 1st base line and shorts and T-Shirts in the sun down the 3rd base line during cool sunny day games.
Bottom line: Know your seat, sun angles and the expected weather before you head out to Target Field this summer.
Here are a few more images from the Twins Yankees most recent game.