THE SKY IS THE LIMIT...
It was another banner day around the region with highs cracking the 40s in most areas. even touching 50 in spots south of HWY 34. This welcome change began slowly but has really blossomed the past few days. In the Cedar Rapids meteogram below, you can see that after a high of 6 below the 14th, highs have increased every day for 9 consecutive days reaching today's peak of 42.
The warming trend ended a 12 day stretch from February 6-17th where highs remained below 15 degrees. That 12 day string is the 4th longest for that benchmark. The 3 streaks that are longer all occurred at least 85 years ago. 1936, as we've mentioned numerous times, was really nasty with 19 consecutive days of highs below 15!
So why the big change? It's all in the position of the jet stream my friends. Back on February 7 when we were headed into the teeth of the cold, the 500mb jet looked like this. The source region for our air was the Arctic with an extension of the Polar Vortex situated over the NC United States.
Now the stratospheric warming that drove the bitter cold has reversed and the Arctic Oscillation which was strongly negative has flipped to positive. This is the current 500mb pattern which has turned upper level winds zonal (west to east) over the Midwest. That cuts the tie to the worst of the cold and brings more of a Pacific influence to out air masses.
A very important teleconnection had been a major driver during the month long siege of cold. It's known as the A0 (Arctic Oscillation). Here you can witness how deeply negative the AO was back on February 7th when it was nearly off the scale. When you see it in a negative phase, especially one as deep as this, you know the door to cold is wide open. That was a big tip-off as to what was ahead of us.
Now the AO has evolved to this which has a healthy positive phase indicated all the way out to March 10th on the EURO ensemble. That should highly restrict our chances of another surge if severe cold through that period.
Additionally, once you get to March 10th you can see that average highs range from 41 in Dubuque to 46 in the Quad Cities and 48 in Burlington. If a similar situation developed as we saw a month ago, the air mass would not be nearly as vicious thanks to the longer days, stronger sun, and mostly likely far less snow cover. There is light at the end of the tunnel.
Taking this a step further, assuming the AO remains positive, the next couple of weeks should be tolerable and many of those days should be near to above normal. Here is the 15 day temperature departures on the GFS broken down into 5 day increments. These would be even warmer were it not for the existing snow cover.
So with that good news. and not much else to talk about the rest of the week, I'll sign off. The sky is the limit! Until next time, roll weather...TS
ONLY 58 COPIES LEFT:
A SECOND PRINTING OF MY NEW BOOK IS AVAILABLE...
The second printing of my new book Derecho, Iowa's Inland Hurricane has just arrived and can be purchased below. However they are going fast and if you are interested in having the most authoritative account of this extreme event you need to act now. Don't miss this opportunity to own the weather story of a generation. You can order yours at derechobook.com See the book endorsements below
*This book has been quite the talk with the Iowa State Library promoting it. I have never seen the State Library promote any books like this unless it was an award winner of particular interest to libraries. Hopefully your sales are through the roof!
Jolene Kronschnabel-Director of Hawkins Memorial Library, La Porte City, Iowa
*I ordered one of your Derecho books about the storm in Cedar Rapids, IA back in December. I love it! I had also bought one that the Cedar Rapids Gazette sold. Your book by far is so much better, you have a lot more pictures and it just tells more of the story. Thank you for putting a wonderful keepsake together! Do you have any left? If so can you tell me how to get at least one more.
Thank you so much! Penny Brecke
*911, IOWA'S INLAND HURRICANE-Great stuff! I couldn't put the book down and read it in one night!
*Hi Terry and Carolyn!
Thank you for my book, the kind dedication and wonderful job on the book warmed my heart!! Loved all the info-great job Terry! Carolyn the stories brought tears to my eyes. I have to admit it was difficult to read at first-reliving that day, but joy also with the way you wrote them in such good faith! We are living in town as our house is still gutted. Work is slow but progressing. The damage was far greater than we thought, but it will be glorious again one day! Love and prayer.
*I received my book yesterday (just in time for Christmas). Thank you for all the hard work it took to put it together and trying so hard to get this book out. My husband will love it. Enjoyed your Christmas Video.
*Got the book today and am reading it now! Very well done. Thanks.