Special Story: A Cool Start to Spring

If you have the notion that this spring has been off to a cool start, you would be correct. Sure, we have had our share of 70s and 80s; highs have even crept up into the 90s in parts of southwest Oklahoma. But weekly cold blasts, causing temperatures to plummet anywhere from 20 to 30 degrees below normal, and slow recoveries from the cold blasts have left spring unseasonably cool so far. Let us examine some of the numbers below to see just how cold spring has been for Oklahoma City for March and April.

As we can see from the graphic to the right, both March and April have had mean temperatures below average. (We have included data from March on this graphic, as the “meteorological spring” begins on March 1.) April has been quite cold, however, and will go down in the record books as the 6th coldest April on record for Oklahoma City. You can see that, in addition to a mean temperature being 5.5 degrees below average, four records lows were either set or tied for the month of April. Let us now examine more closely the temperature trend for April in Oklahoma City.

Clearly, April had few days in which the temperature was around the same for more than two days in a row. Numerous temperature drops, reflective of the strong cold fronts, can be seen from the graph. The most notable drop in high temperatures occurred from April 9th to 10th, in which the high plummeted from 79 degrees on the 9th to 39 degrees on the 10th – a 40-degree change! The most notable drop in low temperatures occurred from April 8th to 9th, in which the low plummeted from 62 degrees on the 8th to 37 degrees on the 9th – a 25-degree change! This would be the most significant cold front of the month, but there were certainly others. Notice how four days out of the month had an actual high temperature that was lower than the average low temperature. That is chilly! And of course, let us not forget the two record lows which were tied – 29 degrees on the 11th and 35 degrees on the 25th – and two new record lows set – 33 degrees on the 19th and 31 degrees on the 24th.

As you may have seen in articles across the web already, what a difference one year makes when we consider spring temperatures! We go from March 2012, which went down in the record books as the hottest March on record for Oklahoma City with a mean temperature that was 8.6 degrees above average, to March 2013, with a mean temperature that was 2.7 degrees below average. We go from April 2012, with a mean temperature that was 4.3 degrees above average, to April 2013, the 6th coldest on record with a mean temperature that was 5.5 degrees below average. Also notice how much cooler the lowest recorded monthly temperatures have been this year compared to last. While 29 degrees was the lowest temperature recorded in March 2012, a very chilly 18 degrees was the lowest temperature recorded in March 2013. Moreover, that occurred on March 26, a week into spring! The difference in April’s lowest temperature for 2012 and 2013 is even more impressive. While 44 degrees was the lowest temperature recorded in April 2012, 29 degrees was the lowest temperature recorded in April 2013, occurring on the 11th of the month. As we saw from the April temperature trend graphic, that 29 degrees tied a record low for the date, which has been in place since 1940.

When May arrived, we wondered if a new month would finally bring warmer temperatures. Unfortunately, that thought did not last long as another powerful, arctic cold front plummeted temperatures into the 30s and 40s on the 2nd of the month. In Oklahoma, the high temperature went from 82 degrees on May 1st to 48 degrees on May 2nd. A new record low temperature of 37 degrees was set on the 2nd. Lows were slow to recover over the next couple of days, as near-record temperature of 34 and 37 degrees were recorded on May 3rd and 4th, respectively.

So, of course, this begs the question: WHY has spring been so cool thus far? This will probably lead you to a follow-up question: how long will the cool weather last? To answer the first question, we must turn to the jet stream. A persistent dip in the jet stream, referred to as a trough, has brought arctic air as far south as Texas and the Mexican border. More insight on the cool weather is provided in this Live Science article, with expert analysis being provided by Storm Prediction Center meteorologist Dr. Greg Carbin. This second Live Science article provides more analysis on the first question and also helps us answer the second. In short, the cool, winter weather looks to have given its final “goodbye” to the nation’s heartland. To support that statement, let us turn to this past week: our first full week in several weeks without a cold blast. A cold front did in fact move across the state but only knocked temperatures down to the 60s and 70s instead of the 30s and 40s.

Let us turn to the future and see if this warmer weather will last. Signs point to yes, as we see 70s, 80s, and even some 90s for highs with 50s and 60s for lows for the next seven days. Monday and Tuesday look to be the first days this year when we are actually able to talk about a “warm” blast, as highs across a great deal of the state soar into the mid-80s to low-90s. Cooler weather will follow, but by cooler this time, we mean the return of the upper-70s to low-80s. Based on this forecast, spring looks to have finally said “hello,” although summer does not seem to be too far away.

Sources: NWS, HOOT, Live Science