A Look Back At Spring, A Look Ahead To Summer

In yesterday’s blog, I mentioned the fact that the month of May has been cooler and drier than normal.  Now that we are into June and summer, thought a brief look back at this past Spring would be appropriate.  By the way, from a climatological perspective, Spring is the calendar months of Mar-May and Summer Jun-Aug, regardless of the dates on the calendar.  So, with that in mind, this past Spring was both drier and warmer than normal.  Although May turned out to be 1.4 degrees cooler than normal, March was 5.2 degrees warmer than normal and April was 2.7 degrees warmer than normal which more than made up for the relatively cool May. 

With respect to precipitation, as shown yesterday there was considerable variation from one location to the next with regard to total rainfall.  As previously mentioned, the month of May was 2.00” drier than normal, but April balanced that out with a total that was 2.10” wetter than normal.  March though was 0.43” below normal making the Spring on balance drier than normal.  Again, those numbers are from the airport in Tulsa, your location could have received much more or much less as shown yesterday.

Our current pattern continues to support widespread showers/storms moving slowly and therefore the potential for locally heavy rains that will be just that, very localized.  Some locations could pick up a quick couple of inches in a downpour while nearby locations receive little or none at all.  Notice the 5 day QPF map which continues to show the heavier rainfall totals over that time period further south with a noticeable N/S gradient across OK.  Am using the 5 day QPF because we should finally get a break after that with a more stable pattern returning over the weekend and going into next week.

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The overall weather pattern is rather unusual for this time of year with a disturbance aloft cutting off in Texas and only slowly moving and gradually weakening.  This pattern will also help a weak surface front drift further south in succeeding days, eventually bringing drier, more stable air into our area.  Notice the wind pattern aloft as shown at 1 PM today, 1 PM Friday, and Saturday night which shows the evolution of this anomalous pattern.  All three of these are at the 500 mb level or at an elevation of about 18,000’. 

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The first map shows the current SW flow aloft over the state which will contain embedded weak disturbances and therefore the chances of showers/storms at just about any time for tonight into Thursday, although the afternoon hours should be the most likely time. 

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The second map shows how that system has completely closed off by mid day Friday, and the last one shows it weakening and drifting further away from us.  That will allow for a stronger northerly flow aloft to penetrate over the state which in turn will push the surface frontal boundary further southward and bring drier, more stable air into OK.

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As you can see on our forecast page, the bottom line of these changes will be to keep a good chance of rain through Friday although the better chances will be shifting southward and then ending on Saturday with only a slight chance of a few showers.  After that, the sun will be more persistent and with drier air in place we will see mild nights but progressively warmer days going into next week.  By later in the week, our surface winds will also return to a southerly component helping to heat things up as we go further into June.

By the way, the outlook for the month of June is for temperatures to average below normal, largely due to the relatively cooler start that we are now having.  Precipitation falls into the EC category meaning there are equal chances of wetter, drier, or near normal rainfall for the month.

So, stay tuned and check back for updates.

Dick Faurot