JULY/AUGUST 2016 WEATHER UPDATE
The month of May 2016 brought some periods of cooler than normal weather to the contiguous U.S. and for the month as
whole temperatures for the lower 48 states as whole were closer to normal tha
than during most of the previous several months
th
extending back into the latter part of 2015. Spring of 2016, comprised
co
of March, April and May, still ranked as the 6 warmest
th
since 1895 for the lower 48 states as whole,
wh
as well as the 18 wettest. The summer of 2016,, June, July and August, had a
warm start with a return of above normal temperatures in a large part of the contiguous U.S. in June. June rainfall was highly
variable over the central and eastern part of the nation. Below are maps from the High Plains Climate Center showing
temperature departures from normal and
a percent of normal precipitation for most of June 2016.
Sea
ea surface temperatures in the key Nino3.4 region of the Tropical Pacific continued to cool during this past spring, dropping
into the neutral range during May signaling an end of the latest El Nino. During June the trend in these temperatures became
more variable
le in the neutral range close to zero instead of showing a continued, steady cooling. The latest weekly value is -0.4
degrees C. These temperatures
peratures are measured near the equator. Over the past several weeks there have remained areas in the
Pacific Ocean farther north and farther south of the equatorial regions in which sea surface temperatures have remained
warmer than normal
Sea Surface Temperature Anomalies For NINO 3.4 Region In Degrees C.
Further cooling toward weak La Nina conditions is expected during the remainder of summer, but this trend is occurring slower
than it appeared a month or two ago. There is some variance among computer models in these trends. The majority show
weak La Nina or negative neutral conditions into later this year, with very few showing strong La Nina developing. A few
models show an slight upward trend in sea surface temperatures later in the year.
The El Nino of 2015-16 was among strongest since 1950, in the range of the 1997-98 and 1982-83 events and slightly exceeding
the 1972-73 event. The 1973 event weakened quickly and La Nina conditions developed during the late spring into early
summer, with moderate La Nina developing during the summer. The 1983 event weakened more slowly with weak El Nino
conditions lasting into early summer and cooler than normal sea surface temperatures developing later and not nearing La Nina
conditions until fall. In 1998 El Nino weakened during the spring with weak La Nina conditions developing during the summer.
Trends of this year appeared to be closest to the trends of 1998, however a more consistent downward trend in sea surface
temperatures is needed this summer to continue following the trends of 1998. Spring wetness was a trend in 1973, 1983 and
1998, but spring temperatures and June temperatures were not as warm overall as in 2016. This was especially true of 1983.
Past weather conditions do not make any of these years a real good analog year. Some of the other years in which weaker El
Nino conditions, but at least moderate to strong in intensity, transitioned to negative neutral and weak La Nina during
summer included 2010, 2007, and 1995. Trends in these years all have some differences to this year. Some have a few past
weather similarities, but none is a solid match. I used these three years and 1998 as starting point to look at composites of
July and August weather, plus adding in some other years for comparison that would be farther down the list of analogs for
now. The August outlooks are based on these composites, plus a continuation of earlier forecasts for this summer in general.
The July outlook is more based on a continuation of earlier forecasts for this summer, along with current trends in our daily
products and current climate models.
Some thoughts on crop related weather heading into June:
•
Above normal June temperatures and highly variable rainfall left some parts of the Midwest in need of rain in late
June. Weather pattern into first few days of July will likely bring some southwestern areas of Midwest some
beneficial rain. For July as whole above normal temperatures are forecast in the Midwest, and at least some short
periods of temperatures hot enough to stress summer crops will likely occur. At this time, I don’t expect lengthy
periods of unusually hot weather in most areas. Variable rainfall will likely result in some areas where rainfall will
not meet crop demands and more significant amounts will be needed.
•
Trend for above normal temperatures and variable rainfall in the Delta and Southeast will likely stress summer
crops at times and lead to areas being in need of more significant rain during July.
•
Late June and early July rainfall slows winter wheat harvest in Central Plains, and completion of harvest at times in
Southern Plains, but lengthy delays not seen in most areas.
June 28, 2016
Dan Hicks/Meteorologist
Freese-Notis Weather
515-282-9310
weather@weather.net IM: weathertrader89 Twitter: @freesenotis