United States Summer 2017 Forecast

Written by on May 2, 2017 in Spring 2017, United States of America with 0 Comments

This seasonal forecast for the upcoming June-August 2017 period is based on past, present and forecasted atmospheric, oceanic and ground conditions.

There are 3 main aspects I have looked at when compiling this forecast. 1) Past winter and current spring rainfall distribution. 2) sea surface temperature anomalies, particularly in the Pacific and Atlantic. 3) Current and forecasted ENSO (El Nino Southern Oscillation Index) state.

Winter rainfall distribution and anomaly is important but it becomes more important during the spring months as the amount of soil moisture content can determine level of atmospheric pressure and water vapour through soil-atmosphere feedback.

Key factors to the summer 2017 forecast

Drought area hits record low

Within the last week, the US drought area hit it’s lowest percentage since 2000 when records began thanks to excessive winter rain/snow and through the spring so far, heavy precipitation has turned the ground wetter over the wheat and cornfields of the Midwest. This could well deliver a cooler, wetter than normal summer for much of the Lower 48.

What an incredible turnaround for California.

Credit: Archlectic Design‏ @Archlectic

Record flooding in Missouri this past weekend.

Credit: Hunter Sweat

Check out the difference in drought between early September 2012 and late April 2017.

September 2012

Verses April 2017

Wet ground & record warm Gulf of Mexico = oppressive humidity, enhanced thunderstorm activity, flooding potential

While the US dramatically shrunk it’s drought, the Gulf of Mexico witnessed it’s warmest winter on record with an average skin temperature holding at a record 72 degrees and remains incredibly warm for the time of year.

Credit: Tropical Tidbits

The high soil moisture content combined with bountiful wheat crops and an abnormally warm Gulf of Mexico could push near record water vapour levels within the atmosphere east of the Rockies this summer. Humidity levels will likely hit uncomfortably oppressive levels many times this summer and we could see frequent thunderstorm activity as incoming solar rays hits the ground and draws moisture from soil to atmosphere through feedback.

The negative aspect to the big winter rains Out West is the bountiful growth in vegetation makes for great fuel for wildfires and the 2017 wildfire season could end up as one of the worst as a result.

The surrounding oceans

There are several factors which stand out regarding the SSTA’s (sea surface temperature). Firstly, for the first time in a few years, the North Pacific is cool. Factoring a cool North Pacific and neutral ENSO, I believe a cooler, wetter summer is on tap for Alaska.

While the interior US could overall see a cooler, wetter summer, the warm Gulf and Atlantic may make for a warm as well as humid summer across the South and up the East Coast.

CFSv2 June-August

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits


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