Any chance of frost?

  This March has been incredibly warm. Our monthly temperature is more than 16 degrees above average, and this will go down as the warmest March in Twin Cities history! We topped out the upper 60s today, and we have reached 70 degrees or warmer on eight days this month. The previous March record for days of 70 degrees or warmer was five, set back in 1910. We have set eight new record highs this month, and have witnessed record warm low temperatures on ten days. On St. Patrick’s Day, we set a new record for our earliest 80 degree reading in any year. You can see a nice summary of our March 2012 records, courtesy of the Minnesota State Climatology Office, at  Mild March  .

  Despite our recent warm weather, some people are thinking about frost. Could plants, like these emerging daylilies, still be nipped by frost?

  The Minnesota State Climatology Office looked back at the ten warmest Marches in the “modern” Twin Cities climate history, which begins in 1872. They compiled this list of the final 32 degree or colder reading in each of those years:

Rank Year  Final Spring Frost Date
 1     1910    April 25
 2     1878    April 6
 3     1946    May 12
 4     2000    April 21
 5     2010    May 9
 6     1973    May 17
 7     1945    May 10
 8     1918    April 30
 9     1968    May 5
10    1987    April 23

  The list shows that a warm March doesn't necessarily mean that we won't see some frost in April or May. Our final 32 degree or colder reading happened as early as April 6, and as late as May 17, in the years with our warmest Marches. I should mention that light winds can allow frost to form at ground level when temperatures are above 32 degrees at instrument level, but historic frost data is not available. That is why the final occurrence of 32 degrees was used to estimate the dates of our last frost. Our next dip into the 30s could happen late Wednesday night/early Thursday morning in the Twin Cities. Check those forecasts Wednesday night if you have some tender plants to protect.

  I’ll leave you with a photo taken this afternoon at Lake Calhoun. Wind gusts of around 40 mph kicked up some whitecaps on the lake, and the water was splashing onto the walking path north of Tin Fish.  By the way, a sign at Tin Fish said that they expect to open after mid-April this year…another sign of our early warmup.

                           (You can left-click on the photo for a detailed view)

Lake Minnetonka ice

  We’re coming to the end of one of the most amazing stretches of weather in Minnesota history. Here in the Twin Cities, we’ve set new record highs on 8 of the past 10 days. We’ve also set records for warmest low temperature on 6 of the past 10 days, and today we will add another day to that tally. To top it off, we set a new record for earliest 80 degree reading in MSP when it hit 80 on St. Patrick’s Day! Details on records broken at MSP and other nearby locations can be found on the National Weather Service website Twin Cities NWS .

  The ice on area lakes melted quickly the past few days. Here is a photo of Lake Minnetonka, looking north from Excelsior Commons, taken on Friday:

                                (Left-click on the picture for a detailed view)

  Here’s how it looked today….nothing but open water:

  Media reports, including the StarTribune, state that the ice is now officially out on Lake Minnetonka. The water is still very cold, so swimming is weeks away, but a lot of people are enjoying this early dose of late-May weather. We're getting an early start to our golf season, and lawns have started to green up. I'm loving it! 

On thin ice

   It’s going to be hard to concentrate at work this week. Temperatures will soar and I’m expecting some record highs. We had our fourth warmest meteorological winter (December, January and February), and now this balmy stretch. A lot of people are loving it. I have some friends and relatives who are in Florida right now…maybe they should have stayed home to enjoy the warmth!

   Warm temperatures should lead to some gaping holes on area lakes later this week. When will ice-out be? That is a common question during warm spells in March. I spoke with Pat Sweeney, communications director of the Freshwater Society, which is headquartered in Excelsior, MN. He expects ice-out on Lake Minnetonka to occur this month. How is ice-out defined? From the Freshwater Society website, http://www.freshwater.org/ :  “The Freshwater Society declares ice out according to a formula Freshwater founder Dick Gray set: The ice is out when it is possible to travel by small boat from any one shore to another shore through any passage on the lake. The Hennepin County Sheriff’s Water Patrol uses another formula: When it is possible to go by boat from the patrol’s headquarters in Spring Park through the Narrows and around Big Island without having to significantly alter course because of ice. The patrol’s dates generally, but not always, coincide with the Freshwater dates.”
   Records of ice-out dates for Lake Minnetonka can be found at year-by-year and day-by-day. Ice-out has happened in March only seven times, based on records that go back to 1855. The earliest ice-out date for Lake Minnetonka was March 11, 1878. The second earliest was March 18, 2000-just twelve years ago. The median date of ice-out is April 14, meaning that half of the years have an earlier ice-out, and half of the years have a later ice-out.
   Early ice-outs are likely on a lot of lakes this year. The Minnesota State Climatology Office has an interactive web page with ice-out dates for many of our Minnesota lakes. You can find it at http://climate.umn.edu/lake_ice/ . Stay safe and enjoy the melt!  

The big melt

   We hit 60 degrees in the Twin Cities today. That wasn’t close to the record high of 69 degrees for this date, which was set twelve years ago, but it felt great. Morning satellite pictures showed mostly bare ground south of the Twin Cities, so today’s sunshine and southerly breezes led to soaring temperatures.

   Our modest Twin Cities snowcover shrank quite a bit today, and you could see water dripping from roofs and running along curbs. By afternoon, Lake Harriet had a layer of water sitting atop the ice:

                                       (left-click on image for a larger view) 

   Does this mean that winter is over? Most Minnesotans know that it’s too early to make that call. Our season snowfall sits at 22.1 inches in the Twin Cities, which is only about 50% of normal to date. On average, we see about nine inches of snow after March 6th. No big snows are in sight, but temperatures will be cooler the next few days. A return to the 50s is expected this weekend.

   You won’t be able to mow your lawn or plant your garden anytime soon...but if you really want to catch Spring fever, you could head out to the Como Park Conservatory. Once there, you can walk through the warm and humid Fern Room, then on to the Sunken Garden. I’ll finish with a picture of the Sunken Garden, taken last Sunday: