Updraft: April 30, 2012 Archive

Severe Weather Awareness, part two

Posted at 6:27 AM on April 30, 2012 by Craig Edwards (2 Comments)
Filed under: Climate, Severe weather

On Saturday afternoon I was monitoring the weather radar and the severe storm advancing toward St. Louis, Missouri. The Cardinals were playing the Brewers at Busch Stadium. An efficiently played ball game ended prior to the storm reaching the jammed ball park.

The strong storm revealed sufficient intensity to trigger a severe thunderstorm warning for the local area with hail reported greater than two and a half inches in diameter. The radar algorithm for the potential hail size was shown as greater than four inches on one vertical volume scan.

As the storm approached downtown St. Louis there were indications on Doppler radar of very strong winds and a tornado warning was eventually issued. Ultimately this became a killer storm with winds estimated near 70 mph. A hospitality tent was blown down and a serious weather calamity occurred. Here's a statement included in a story I spotted on the the internet. Deputy Fire Chief John Altmann cautioned that patrons need to understand a tent is not a safe place to be in bad weather."Tents are temporary structures."

Severe weather reports to SPC on Saturday, April 28th.

We are approaching peak severe weather season. At the same time we are moving into the warmer days of spring and outdoor activities, including graduation events and celebrations. Folks need to be aware of potential severe weather and have some plan in place for seeking sufficient shelter.

I remember attending a graduation party when I was 18 years old. The sirens were going off and I assisted in moving a dozen or so people into a crawl space. A brave few watched the sky.

The Storm Prediction Center is indicating a slight risk (35%) of severe weather in our neck of the woods on Tuesday.

Source: NOAA SPC

For more information on the background of the Storm Prediction Center's severe weather risk probabilities you can review at this link from SPC.

A trend toward milder, warmer temperatures begins today and lasts through most of the week.

Tuesday's mid afternoon temperatures.
Source: Twisterdata.com

A warm front, convergence zone, will be positioned over Minnesota on Wednesday. This will result in the continued potential for more showers and thunderstorms.

Looking ahead to May, here's the Climate Prediction Centers outlook issued earlier this month.

Source: NOAA Climate Prediction Center

This outlook could be refreshed, updated today.

As we close out April, 2012 we will find the statistics documenting another month of above normal temperatures. About two and half degrees above normal in the Twin Cities.

CE

(2 Comments)

Time to eat into the moisture deficit

Posted at 3:41 PM on April 30, 2012 by Craig Edwards
Filed under: Climate, Drought, Rainfall, Storms, Thunderstorms

Since late July Mother Nature has cheated Minnesota on moisture. We could hardly buy a snow storm this past winter. But perhaps we are on the brink of cutting into the deficit in southern Minnesota. Moisture hasn't been as scarce this month.

The precipitation totals from far northwest to south range from about an inch and a half to slightly more than three inches. A beneficial precipitation event occurred in Itasca and St. Louis Counties as a combination of snow and rain fell in mid April -- yet lake levels remain low.

Precipitation image for April 16th provide by NOAA

Some locations in central and southern Minnesota tallied more than a half of an inch of moisture in the past week. Here's a look at the moisture departure from early August to late April:

Source: Minnesota Climatological Working Group

Warmer temperatures are seen for the middle of the work week and those temps, along with increasing dew points, will create an environment favorable for thunderstorms. The first round of storms enters the weather scene on Tuesday and continues into Tuesday night.

There is a risk for strong thunderstorms, producing hail and gusty winds Tuesday afternoon and evening.

Source: NOAA Storm Prediction Center

There was enough cloud cover extending into the afternoon hours to hold the temperatures in the lower 60s in east central Minnesota.

As anticipated, NOAA released an update of the temperature outlook for the month of May today.

Source: NOAA Climate Prediction Center

A warm front may set up over central Minnesota on Wednesday. Warm fronts are known for spawning some good rainfall amounts, particularly overnight. We'll see.

--Craig Edwards