TIM MCGILL

Gene Blevins, Reuters, May 21, 2013

I've tried to sort through the myriad of resources with information regarding the Moore tornado and selected a few that stand out.

• KFOR-TV has an interactive map that compares the tracks of tornadoes that hit Moore in 1999, 2003 and Monday
• Timeline of the events leading up to and including the touchdown in Newcastle-Moore from the Norman office of the NWS
• Excellent overview of the tornado from Dr. Jeff Master's Wunderblog that includes chaser video
• Does climate change play a role in tornadoes?
• Power of the tornado compared to an atomic bomb
• Aerial view of the devastation
• How bad is an EF-5 tornado?
• Before and after pictures from Moore

The most important link is how to help victims of the tornado.

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(Star-Telegram/Paul Moseley)

Our unusually cool spring (April was 23rd coolest on record for contiguous US) has produced an unusually low number of tornadoes this severe weather season thus far.  The cool start to this year combined with last year's drought has helped set a record for lack of tornadoes.  From May 2012 through April 2013 there have been just 197 EF-1 or stronger tornadoes, the fewest for any twelve-month period since 1954.  There were seven deaths during that same 12-month period ending with April this year.  Only one other 12 month period had fewer deaths.  There were 5 tornado deaths during the 12-month period from September 1899 to August 1900.

Severe weather season may be kicking back into high gear soon though.  The killer EF-4 Texas tornado that left 6 dead in Granbury was one of 16 tornadoes to touch down during the outbreak.  There have been 251 preliminary reports of tornadoes with 9 deaths so far this year.  Last year through May there were 617 tornadoes with 542 deaths.  The Storm Prediction Center has outlooked a broad swath of the plains for a slight risk of severe weather tomorrow (see image below). 2" diameter hail, supercells and tornadoes are all possible tomorrow there.

The risk area then shifts eastward Sunday and Monday (see bottom image below).  Much of  western Illinois is included in the slight risk area outlooked for Sunday into Monday morning.

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What a difference a year makes!   2012 was the hottest year on record for the contiguous United States.  Record highs outpaced record lows by a ratio of 14 to 1 in 2012.  So far this year, record lows have outpaced record highs by 1.3 to 1.  We have also more than doubled the amount of record snowfall reports year to date this year compared to last year.    There have been 5687 reports of record snowfall so far this year compared to 2574 through this point last year.  Those are the numbers at a national level.

We have seen the same remarkable reversal after breaking down some numbers locally.

58% of days this year have been below average.  So far this year the number of days with below average temperatures has outpaced days at or above average by about 1.4 to 1.  77% of days to date last year were at or above average and the number of days at or above average outpaced the number of days below average by a ratio of 3.3 to 1.

What a difference a lake makes!

While most of us will be milder than average through Thursday, a wind off the lake the next few days will keep it considerably cooler lakeside.

There was more than a 25° spread between the coolest spots lakeside yesterday and the warmest spots inland.  Here are some of the warmest and coolest highs Sunday recorded on our WeatherBug network:

• 74° DeKalb
• 75° Morris
• 76° Kankakee
• 77° Streator

Lakeside locations:

• 51° Wilmette
• 54° Highland Park
• 56° Winnetka
• 57° Kenosha

We will see a similar spread the next few days with 70s away from the lake and 50s lakeside.

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After our early preview of summer with back to back 80s on Tuesday and Wednesday, we saw a dramatic drop in temperatures yesterday and today we will fail to climb above the 50s for highs.  It could always be worse....

Record snow fell across several states yesterday to our west and northwest.  Record breaking snow piled up from Missouri to the Northwoods of Wisconsin.   If confirmed, the 15.4" reported in Dodge Center, MN could break the all-time daily snowfall record for the state of Minnesota for the month of May.  Here are some of the more impressive numbers:

• 18.0" Hayward, WI
• 17.5" Goodhue, MN
• 16.0" Ellsworth, WI
• 15.0" Oak Center, MN
• 14.0" Rochester, MN
• 11.0" Forest City, IA

There are signs that spring will bounce back soon.  The NAO or North Atlantic Oscillation index has been a fairly reliable forecast indicator in the past.  Postive values usually means above average temperatures.  The latest European Model NAO index forecast (see image below) has it trending positive again this weekend and through most of next week.  In fact, most of next week we should see highs in the 70s.  No 80s, but above average most of the week. Hang in there, the average high by the end of May is 75°.

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Between yesterday and todays's 80°+ highs we will see the first back to back 80s in about 7 months.  O'Hare's 85° high Tuesday was the warmest we have seen in 230 days going back to the middle of last September.  It felt just like July with temperatures 20° above average or what we typically see in the middle of summer.

The big question is how long will this last?

The answer is not very long, unfortunately.

A slow moving storm system will spin up clouds and showers (with a few rumbles of thunder) starting tomorrow and right on through the weekend.  Winds off the lake will keep us cooler through early next week.  The longer range forecast from the Climate Prediction Center outlooks most of the eastern part of the country for cooler than average temps (see image below).

It could always be worse.  Snow will fall later today and into tomorrow from the Twin Cities in Minnesota through the northwoods of Wisconsin where up to a foot of spring snow could pile up.  Record snowfall is possible in Minneapolis where the all-time record for a single storm's snowfall during the month of May is 3".  The GFS model spits out just under 4" for Minneapolis between now and noon Friday but most other models are indicating a bit more than that (see image below).

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Adding insult to injury, most areas saw another quarter of an inch of rain to three quarters of an inch fall  yesterday and overnight.    Topping the list was Flossmoor with 1.10" of rain.

Here are some other notable rainfall amounts form our WeatherBug network:

• .91" Chicago (Nathanael Greene Elementary School)
• .82" Hoffman Estates
• .81" Streator
• .79" Justice
• .79" Schaumburg

The additional rain may prolong flooding on area rivers and streams and slow the rate at which the water recedes.  Still, this recent rain is much lighter in comparison with the record rainfall that occurred last week.  That rain has resulted in record flooding.  Here are some of the record crests seen recently according to the United States Geological Survey:

•         River                    Location                             April 2013 Crest          Previous Record
•      Des Plaines        Des Plaines                                 10.92'                            10.88'
•      Fox                     McHenry, Tailwater                       7.49'                              7.20'
•      Illinois                 Morris                                          24.91'                            24.84'

Check out the NOAA's Advanced Hydrologic Prediction Service (image below) for more detail information regarding area rivers.   Chicago's National Weather Service office also has an excellent review of our recent flooding.

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Wednesday and Thursday's spring soaking brings our April rainfall to just under 8" at 7.83" at O'Hare.  It is the third wettest April to date on record.  Here are some of the impressive two day totals reported on our WeatherBug network:

• 6.33" Wilmette
• 5.86" Hillside
• 5.66" Winfield
• 5.65" Downers Grove
• 5.53" Lombard
• 5.30" Morton Grove

Only spotty light showers or sprinkles in the short term forecast for today and then a mainly dry weekend.  Our RPM model shows only about a tenth of an inch of rain from now until early Sunday morning.

The longer range forecast offers hope for a drier pattern emerging towards the end of the month and into early May.  The 8 to 14 day forecast from the Climate Prediction Center has us outlooked for drier (and cooler) than average conditions for the period.

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