Ducky today, hints of a warm bias this summer?

The meteorological time warp we call spring this year continues to deliver unusual weather for late March.

Those puddles on your morning commute this morning could have easily been snow drifts considering the calendar. Instead, a good early season soaking rain on already thawed ground and rapidly greening lawns.

So far, rainfall totals are coming in pretty close to what the National Oceanic and Atmospheric Administration's 4 km NAM model depicts below. Many locations will come up with around half and inch with some locally heavier totals approaching an inch in southern Minnesota.

The main wave of rain this morning sails quickly east today. Scattered spotty showers linger through tonight, as colder breezes blow in behind departing low pressure. Enough cold air works in behind the system to trigger a few snow flakes at times, but accumulation is not in the weather cards for most of us.

The Twin Cities National Weather Service office does a nice job of wrapping the storm as colder air filters in.

Severe season gets closer

This system was tame across Minnesota. But it's a good reminder that severe weather is not far away this time of year. Do you have your NOAA weather radio tuned up?

Here's what happened on March 29, 1998.

Cool snap

Temperatures run below seasonal average for the next few days. The average high in the metro hits 50 degrees by this weekend.

Hints of a warmer than average spring and early summer?

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There may be some early signs of a warmer than average spring and summer this year. That wouldn't be a huge shock, considering we've just logged the warmest 12 months on record in the Twin Cities.

Here's NOAA's CFS v2 climate forecast system for the next three months through June. The bias suggest temperatures 1 to 2+C (2 to 4 degrees F) warmer than average across Minnesota and the Upper Midwest this spring.

Hot summer?

This falls more in the line of semi-educated seasonal weather forecast speculation. Buyer beware.

I took a quick look at seven cases since 1964 when at least moderate El Nino events (+1.0C) were followed the next year by La Nina events. This is hardly rock solid, but it may offer some clues to next summer.

•  5 of 7 or 71 percent of (El Nino-La Nina) summers (Jun-Aug) were warmer than average in the Twin Cities.

• The average of those 7 summers was +1.5F vs. average at MSP.

• The average number of 90-degree days in those 7 summers was 20 days.

• That’s almost twice the 30-year average for 90-degree days in the metro which is now 11 days. (1981-2010 data)

•  5 of the 7 years (71 percent) were also drier than average, with summer rainfall -2.42” vs. average overall. But there was high variability here with two wet summers also.

• 1988 is one of the summers in the data set. 1988 was one of the hottest and driest summers on record.

• 1988 set the record of 44 days at or above 90 degrees at MSP.

• 2010 is also in the data set. We set a record of 113 tornadoes in Minnesota that year.

So the bottom line is there appears to be a bias toward warmer than average temperatures and a higher than average number of 90+ degree days after El Nino in summers that transition to La Nina. Keep in mind it’s a very small sample size and probably not statistically valid.

My hunch? I do think there a bias toward a warmer than average summer, with a higher than average number of 90-degree days this summer.

NOAA’s official seasonal outlook for June, July and August also favors a warmer than average summer over Minnesota.

Time to get the AC unit tuned up early this year?

Pacific Ocean temps key to predicting U.S. heat waves?

The more "teleconnections" we can find, the better seasonal forecasting will get. Here's one study in Nature Geoscience that says Pacific Ocean water temps may be the key to increasing forecast lead time on summer heat waves.

Climate Central elaborates.

The researchers then looked to see if those days of extreme heat tended to correspond with any particular patterns of sea surface temperatures in the North Pacific. One pattern “just popped up super clearly,” McKinnon, a postdoctoral researcher at the National Center for Atmospheric Research in Boulder, Colo., said. In an area spanning the breadth of the ocean basin and roughly the same latitudes as the U.S., they found cooler-than-normal waters to the north butted up against warmer-than-normal waters to the south.

And not only did the pattern show up at the same time as the extreme heat in the eastern U.S., the team could trace it back in time to before the heat wave hit and use it to predict the likelihood of the extreme hot weather.

The researchers found the ocean pattern could be used to predict increased odds for extreme heat in the broad region up to 50 days out, with the skill of the predictions increasing closer to the event as the ocean pattern evolved.

The team used the pattern to do a “hindcast” of the punishing summer of 2012, and were able to predict increased odds of extreme heat for the end of June as early as mid-May.

The pattern could also be used to predict extreme heat for some individual stations, the team found, mostly in a region in the middle of the country. The clearer connection there is likely due to the fact that the domes of hot air associated with heat waves tend to be centered on that area, McKinnon said.