Updraft: May 18, 2009 Archive

Frontal boundary overhead

Posted at 7:54 AM on May 18, 2009 by Paul Huttner

Weather is like real estate. Local local local.

A strong cold front will ease south today from Canada into Minnesota. This front marks the dividing line between cool springtime to the north and a warmer summery air mass to the south. Your weather depends on which side of the front you're on.

Much of Minnesota will be on the warm side of the front today. A howling south wind will pump in warmer air and push temperatures into the 80's south of the front. We could see our second 80 degree temperature this year in the Twin Cities today.

The front will sag south on Tuesday. The forecast models sometimes have a difficult time nailing down where these slow moving fronts will stall. The best bet this morning is that southward progress will stop just south of the Twin Cities. That would make the metro about 10 degrees cooler on Tuesday. Northern Minnesota will see 50's and 60's.

On Wednesday the front roars back north. It appears the warmest air mass of the season may gush in behind the front. I think we will see some 90's in southern Minnesota Wednesday, and we could make a run at our first 90 of the season in the Twin Cities Wednesday if everything goes just right.

There will be a chance of isolated but strong thunderstorms as the front passes overhead later today and again Tuesday night into Wednesday morning. The best hope for some much needed rainfall this week appears to be early Thursday morning.

We'll nail down the Memorial Day weekend forecast as the week goes on, but so far it looks pretty decent.

Enjoy the warm up, and watch up in the sky to see the front passing overhead this week!

PH

Lilac weather

Posted at 2:19 PM on May 18, 2009 by Paul Huttner

Lilacs in full bloom at the Huttner Weather Lab today.

Even lilacs have a story to tell.

Phenology is the science of watching plants and animals react to weather and climate.

Numerous studies have shown that everything from lilacs to robins are reacting to shorter winters and earlier springs. In the West, lilacs are blooming up to 2 weeks earlier than they did a few decades ago. This rapid springtime warm-up is also linked to evaporation of mountain snowpack before it has the chance to melt and runoff into rivers. This spring runoff is the lifeblood of western rivers like the Colorado, which supplies water to millions in the southwest. Anything that reduces winter snows and spring runoff poses problems for water supplies in places like Phoenix, Tucson, Vegas, San Diego and Los Angeles.

Local phenologist Jim Gilbert has charted lilac "peak bloom" at the Minnesota Landscape Arboretum for decades. According to Jim's Nature Notebook, this week is peak lilac bloom time. One look around and you can see why. The thing is that's about two weeks earlier than it was 40 years ago.

One thing that may be tougher to change is ice out dates in Minnesota. In some ways, ice out is more dependant on sun angle and wind than temperature. This year lakes were ice free as of about April 13th in the metro. That's about average. Even the stubborn ice in Minnesota's Arrowhead was gone by May 15th.

It's interesting to observe the changes over the past 40 years. Have you noticed changes in your back yard?

PH