The U.S. Department of Agriculture will host its annual Agricultural Outlook Forum at the end of this week, where one of the most popular topics is the expectations for the upcoming U.S. corn and soybean crops.

Absent from the agenda, however, is a summer weather outlook specific to the United States.

Market bulls have been licking their chops over somewhat valid predictions that the U.S. corn and soybean crops may face weather hardships this summer. But they should not go all in on that notion just yet.

Central to these predictions of potential summer drought is the expected midyear flip from El Nino into La Nina, which has coincided with weather problems in the past (such as in 1988 and 2010). However, the transition by itself is simply not enough to place high risk on the U.S. summer.

Several atmospheric components factor in to summer weather outlooks, and they do not necessarily run in tandem with El Nino or La Nina patterns, nor are they always linked to one another. And not all of the individual components are pointing the same way at the moment.

It is too early to say with certainty what the summer weather will be like anywhere on the globe, but there is some indication right now that the scales are somewhat tipped in favor of warmth in the United States.

The blob has vanished

From mid-2013 through late last year, a large pool of warm surface water, affectionately coined "the blob," dominated the northeast Pacific Ocean near the Gulf of Alaska. But its reign has ended, and this could allow for a hotter U.S. summer. (tmsnrt.rs/1QwtBb3)

The blob owed its existence to a persistent ridge of high atmospheric pressure over that same region, and together the ridge and blob amplified the jet stream pattern over North America during their 2-1/2-year residency.

Under the “blob regime,” the jet stream was forced up and over the ridge near Alaska, tipping it on its axis and sending air plunging down toward the United States. When the jet stream – or dominant airflow – is oriented north-south in this manner, cold, Arctic air is pulled along for the ride. (tmsnrt.rs/1QwvWD3)

Thus it is no coincidence at all that the U.S. corn and soybean crops enjoyed generally cooler summers from 2013 to 2015. Now that the mechanism for this is largely gone, the summer could get quite warm if the jet stream falls into a mainly west-east pattern, which was often observed between 2010 and 2012 with harmful impacts to yields (tmsnrt.rs/1Tx7RB7).

It is vital to understand that the disappearance of the blob does not guarantee a hot U.S. summer, but it does greatly reduce the chances of a cool bias during the corn and soybean growing season, a key ingredient to higher yields, particularly for corn.

The oceans are warm

While sea surface temperatures in the northeastern Pacific have declined, they remain elevated along most of the coastal United States. If they are still warm into spring and summer, the mercury is likely to rise.

The expected retreat of El Nino this summer should ease the warm anomaly in the coastal Pacific. Sea surface temperatures in the Gulf of Mexico and the Atlantic Ocean are also quite high, but the continuation of this pattern is already in jeopardy.

The Gulf of Mexico is the central United States’ source for warm and moist air. The warmer the Gulf, the warmer the associated air mass. The same concept is true for the Atlantic Coast: a warmer Gulf Stream can result in higher temperatures for the Eastern United States.

These air masses will also be facing less opposition from Arctic air masses this summer due to the blob’s dissipation. This could allow for some particularly oppressive heat in grain and oilseed regions of the Central and Southern United States.

But sea surface temperatures have already dropped, and at a rapid pace over the past few weeks, especially in the Gulf. At this pace, the anomaly would surely be gone by summer, though more time is needed to tell whether this trend is temporary or if the waters are cooling for good (tmsnrt.rs/1KEGXWM).

WET SOIL - FOR NOW

With the exception of California, the United States is about as drought-free as it has been in recent memory. But current soil moisture may not give the best preview to summer conditions, as there is plenty of time for a drastic change, as history has shown.

The 2012 drought was one of the worst in U.S. history, but most of the corn and soybean belt were doing just fine the following February, save some dryness around southern Minnesota. Crop fields were torched across the country by July’s end, and ironically Minnesota farmers ended up with a record corn crop that year (tmsnrt.rs/1mSJ1ig).

Early dryness has even been featured in years when corn and soybean yields shattered records. This was the case in 2004, 2014 and 2015, when drought was much more widespread early on than it is today (tmsnrt.rs/1mSJd19).

But most of the major corn and soybean states are in a moisture surplus at the moment, which provides an extra layer of defense in case of pending drought. However, extremely wet soils can cause planting delays come the spring and can eventually lead to the development of disease.

The present dryness in North Dakota is worth keeping an eye on. The northern state produces just over half of the U.S. spring and durum wheat crops but has become increasingly important to corn and soybean production in recent years.

Northern states in particular, including North Dakota, rely heavily on the melting snow in springtime to replenish moisture reserves to reduce the chances of drought. For that reason, it is important to receive at least average snowfall during any given winter, and it is common for the snowpack to persist well into April in northern areas.

Winter-to-date snowfall in central and eastern North Dakota is running 20 percent below normal, though South Dakota and Minnesota are closer to average levels, so the deficit is relatively confined. However, the two-week forecast contains above-average temperatures and very little snow, adding further risk to the soils.

While a "wait-and-see" weather outlook might not be totally satisfying, it is likely the most sensible approach for now. Although additional clarity may not arrive until the spring, the odds of a summer drought are surely higher going into this year than they were in the past two years, so stay tuned.