An El Niño watch was issued in the latest outlook from NOAA, indicating an increasing chance for El Niño conditions to develop later this year.

NOAA indicates that ENSO-neutral conditions (neither La Niña or El Niño) will likely last through this summer, with the chance of an El Niño increasing to 50 percent during the fall and 65 percent during winter 2018-19.

(MORE: Warm Water Creeps Eastward in the Pacific )

ENSO-neutral conditions have been in place this spring, meaning sea-surface temperatures across the central and eastern equatorial Pacific have been close to average, and as mentioned, are expected to remain in place into this summer.

As a reminder, the criteria for El Niño conditions are that the average sea-surface temperatures in a region of the central and eastern equatorial Pacific known as Niño 3.4 need to be at least 0.5 degrees Celsius warmer than average in the preceding month and the anomaly has persisted or is expected to persist for three consecutive months. In addition, the atmosphere over the tropical Pacific also needs to exhibit certain characteristics.

Over the past four weeks equatorial water temperatures were near average across most of the Pacific Ocean, with the exception of the western Pacific, which has continued to have above-average water temperatures.

Water temperatures in the far eastern equatorial Pacific remain slightly cooler-than-average, but as shown in the map below, the change from early May to early June has been an increase in temperature.

Recently there has been a build-up of heat within the tropical Pacific Ocean , NOAA noted in its outlook. This would support a gradual development of El Niño conditions.

In addition, positive subsurface temperature anomalies have strengthened and expanded across the equatorial Pacific over the past two months, the NOAA report notes.

The majority of computer models indicate that El Niño conditions become most likely during the upcoming fall and winter.

What Does This Mean For U.S. Weather?

If El Niño conditions were to develop, there are implications to the weather in the U.S.

First, if an El Niño pattern were to emerge this fall during the Atlantic hurricane season the number of tropical cyclones that develop could be suppressed.

(MORE: 2018 Atlantic Hurricane Season Outlook )

When El Niño is in place during hurricane season, stronger-than-average upper-level winds develop over portions of the Atlantic Ocean. As a result, possible tropical cyclones are torn apart.

However, there are other factors that contribute to the number of named storms that develop, so a developing El Niño does not mean there will be fewer storms.

If El Niño conditions are present during the winter, the jet stream pattern over the U.S. shifts and can result in a wetter-than-average winter across the southern tier of the U.S., including portions of California.

During an El Niño winter temperatures are also typically cooler-than-average from the southern Plains into the Southeast and warmer-than-average from eastern Alaska into western and central Canada and into the Pacific Northwest, northern Plains and Midwest.

The strength of the El Niño plays an important role in impacts across the U.S., including in the tropical Atlantic. At this point, it is too early to know when an El Niño pattern may develop and how strong it might be.