Updraft: August 2, 2012 Archive

Experiencing the new normal? Acclimating to the heat

Posted at 3:46 PM on August 2, 2012 by Craig Edwards
Filed under: Drought, Thunderstorms

It was long about March, on the heels of a relatively mild winter that the temperatures refused to settle below normal on a daily basis. Remember March of 2012, when we experienced the warmest March on record in the Twin Cities, more than 15 degrees above the new normal!

My colleagues at the Chanhassen National Weather Service Office posted a nice summary of the monthly average temperatures going back a year. If you were a skeptic about warming you might see some convincing evidence. Explore the warming summary here.

Are we getting acclimated to the heat of summer? After a high of 92 with a heat index of 100 degrees on Wednesday, perhaps temperatures in the upper 80s (five degrees above normal), with a dew point of around 60, don't feel so oppressive.

If you want to experience real summer misery, you still have time to visit Tulsa, where the maximum temperature on Wednesday was 112 degrees. Their average high temperature in July was over 100 degrees. Yikes. Their low temperature this morning was 86 degrees. This afternoon the mercury was approaching 110 in Tulsa.

The drought status was updated today. Not much good news in the central cornbelt. Rain that was badly needed last week was very spotty at best.

Here's a look at the Minnesota drought status. Marshall in southwest Minnesota picked up over 1.5 inches of rain yesterday. Not much to report around the very parched region of Sioux Falls.

For more details on the moisture surplus or deficency see this fine summary issued today by the State Climate Office.

After a quiet overnight, there will be a surge of warmer air headed our way on Friday. The high temperature could top out at 90 in the Twin Cities metro during the late afternoon. A strong weather system will be tracking towards the upper Midwest late Friday and is expected to ignite strong thunderstorms late in the day to our west.

See this strong jet stream forecast overhead by the GFS model for 7 p.m. CDT on Friday. The yellow shading entering southwest Minnesota indicates winds aloft at nearly 100 mph.

200mb wind speeds in knots from the GFS. Source NWS/College of Dupage

Couple these strong winds with low-level instability that will be centered in eastern South Dakota and southwest Minnesota, and you have the ingredients for potent storms Friday evening into Friday night.

Lifted index, a measure of instability and lift valid at 7 p.m. CDT. Pink shading indicating the most unstable air. Source:Twisterdata.com GFS model forecast

It's not surprising that the Storm Prediction Center is highlighting this region as having the greatest threat for severe storms Friday evening.

There are indications that this system might slow down crossing Minnesota and Wisconsin on Saturday. Showers could linger in eastern Minnesota on Saturday. Northwest winds may gust to 25 mph on Saturday, especially over northern Minnesota.

Sunday is looking mighty fine. One of the nicer days of summer, if you are into sunshine and comfortable temperatures.