Chris Coleman, ERCOT Meteorologist
Fall 2016 Weather Outlook
What’s Happening: We are no longer in an El Niño cycle but have instead trended toward a weak La Niña. Typically, La Niña commonly results in hotter and especially drier conditions for Texas. However, this La Niña is not strong, and that will continue to be the case through the fall season. As a result, other factors are very capable of overriding the expected La Niño characteristics. And those factors have resulted in lower maximum temperatures, higher humidity, and above-normal rainfall in recent summer weeks. A warm Pacific Ocean is the primary driver for this weather pattern.
Temperatures: The fall of 2015 was the seventh warmest on record for the state of Texas (dating back to 1895). It’s unlikely this coming fall will be as warm or warmer than the same season last year. The fall season (October 1 through November 30) is forecast to average near-normal temperatures across most of ERCOT.
October has some below-normal potential while November shows greater potential for above-normal temperatures. Neither month should be extreme. The two months combined result in the near-normal label for the season. Overall, there is a growing slight lean toward slightly below-normal for the season (a bit cooler than shown on the map, and a bit cooler than the preliminary fall forecast).
Regionally, Far West Texas and the Panhandle will have the most opportunity for a warmer-than-normal fall season. The rest of Texas will have periods of both above-normal and below-normal but neither extreme looks pronounced enough to dominate the season’s temperature pattern.
Precipitation: Last fall was the third consecutive wetter-than-normal autumn season for Texas. Indications suggest this trend will continue for a fourth consecutive fall. Near-normal to above-normal precipitation is forecast for the majority of the state. A portion of East Texas (including Houston) is forecast as drier-than-normal but there are increasing signs it may trend wetter.
October shows greater potential for significant precipitation than does November.
2015 and 2016 combined is on-track to be the wettest two consecutive years in Texas weather history.
Preliminary Winter 2016-17 Weather Outlook
There are early indications of another mild (warmer-than-normal) winter ahead. It will be difficult to match or exceed last winter’s lack of cold, however, but above-normal temperatures is the preliminary forecast for the December through February period in the ERCOT region. A scenario does exist that brings a significantly colder pattern to Texas. At this point, that’s far from likely to happen, but is worth monitoring over the next couple of months, prior to the release of the final winter forecast on November 1.
Early signs are pointing toward the late-summer through fall wetter-than-normal period to not carry through the winter season as well. Last winter measured very close to normal precipitation for Texas, on average. Good chance this coming winter will be drier than last. But with all of the recent precipitation in 2015 and 2016, this should not present any significant drought concerns heading into 2017.
Summer 2016 Weather Outlook (and Preliminary Fall Outlook):
Texas has experienced an abundance of weather extremes over the past year. El Niño drove many of the weather extremes, but there were other factors that resulted in highly unusual weather patterns with limited historical comparison. We are now transitioning away from El Niño’s influence. This has resulted in the summer of 2016 being a much more challenging forecast than typical.
The El Niño is going through a period of rapid weakening in the spring season. While its influence could carry over into the early-summer period, it will likely trend to neutral for much of the summer and potentially a La Niña before the summer is complete. While this El Niño was one of the strongest on record, I do not expect the anywhere near similar intensity associated with the possible La Niña development later this year. That’s a key point worth stressing. While you may hear from multiple sources that a La Niña is likely later in 2016, it’s not likely to be a strong La Niña. That means its impacts will be limited.
Below is the detailed forecast. There is a brief summary paragraph at the end of this write up.
Temperature Forecast: Texas has recorded a warmer-than-normal season each of the past four seasons (last summer through this spring). Trends are difficult to break – but they do end eventually.
My forecast, for ERCOT on average, is a near-normal summer for temperatures. Normal is based on a 10-to-15-year normal (applying a 30-year normal would result in a relatively hotter summer forecast). There may still be some hotter exceptions, but I do not believe it will be a widespread, extremely hot summer. Not top 20 type of heat (out of 121 historical summers). Last summer ranked as the 17th hottest summer on record. Interestingly though, most locations in ERCOT had their fewest number of 100 degree days since 2007. Unlikely the summer of 2016 ranks hotter than 17th hottest on record. Reasonable expectation would be somewhere between summer of 2015 (#17) and summer of 2014 (#48) -- and more similar to 2014 than 2015. Over a 10 to 15-year normal, this would be near-normal. 8 of the past 11 summers have ranked in the hottest one-third of all-time. Thus, emphasizing that a near-normal summer (even slightly below normal) based on a recent normal still has plenty of hot potential.
Some regions of Texas have greater potential for a hotter-than-normal summer than others. West Texas (the Panhandle, in particular) is forecast to have the best opportunity for a hotter-than-normal summer. It’s possible that may extend into portions of North Texas as well. Portions of East, Central, South, and all of the Coast show the greatest potential for below-normal temperatures. The average of the above-normal temperatures West and North and the below-normal temperatures East and South equate to a near-normal for the state. It’s unlikely either the above-normal temperature regions or the below-normal regions will deviate far from normal. To note, while regions of the state, such as the Rio Grande Valley, are not forecast to be above-normal, that does not mean the summer will be absent periods of hotter-than-normal weather.
Also to note, the late-summer (August-September) may hold greater potential for above-normal temperatures than the early-summer period.
There is certainly both hotter and milder scenarios possible for this upcoming summer season. Most seasons, one extreme or the other is easily ruled out. Not this summer. There are, however, more scenarios that suggest a milder weather pattern than hotter. Just not enough of a lean in the milder direction to fully convince me. That, and knowing recent seasons have been consistently both warmer-than-normal and mostly warmer-than-forecast.
100° Days: While also not as clear-cut as the general temperature forecast, there are indications of either a normal number or below-normal number of 100° days for the large ERCOT cities this summer. Dallas-Fort Worth, for example, averages 18 days of 100° or greater per year. Six of the seven preferred analogs (historical matches) recorded an average number of 100-degree days or fewer.
Precipitation Forecast: The above-normal temperatures should align well with the regions forecast to see below-normal rainfall this summer. That’s likely not what folks in West Texas wish to hear. The remainder of Texas shows either normal or above-normal rainfall potential. Overall, this will likely be a wetter summer than last year (with some drier exceptions West). The summer of 2015 ranked as the 27th driest (out of 121 summers) and 2nd driest of the past 15 years. Again, not likely any drier than that. But like the temperatures, can’t completely rule out a drier scenario than my final summer precipitation forecast; it may require an active tropical season in order to avoid that.
Drought: As of late-April, less than 3% of Texas is in a moderate or worse drought. An additional 11% of the state is abnormally dry (but no drought). The dry/drought regions are limited to the Panhandle and Far West Texas. From a hydrological perspective, it’s even better with no current significant hydrological concerns. That’s a good starting point heading into the summer season. Given the precipitation outlook, the greatest concerns moving forward the next several months will be in the same general region where the minor concerns are currently. West Texas. If the precipitation outlook holds true to form, there would be increasing agricultural-related drought concerns in West Texas. Fortunately, the wettest year on record (2015) for the state of Texas means it would take quite a while to turn around 180° to significant hydrological drought concerns. Any drought to develop through summer would be more of an agricultural drought. Very limited or no significant hydrological drought concerns developing over the next several months.
Hurricanes: While El Niño events tend to suppress hurricane development, La Niña events tend to do just the opposite – more activity than normal. While I believe the odds favor a La Niña before the end of the hurricane season (June 1 – November 30), it may not be much of a factor for the early part of the season. The transition makes for a difficult forecast. Currently, there is an abundance of wind shear across the entire Atlantic Basin. This is common for an El Niño (also common for the spring season) and significantly hinders hurricane development. The faster we see this wind shear diminish, the greater the opportunity for development of tropical systems. There is also currently an abundance of cooler-than-normal ocean temperatures over the northern half of the Atlantic. This also bears watching as it is not conducive to hurricane activity.
My updated forecast is 12/5/2. Twelve total named storms. Five of those, hurricanes. Two of those, major hurricanes (category three or greater) in the Atlantic Basic this season. While forecasting tracks is impossible from a long-range perspective, there are stronger indications for a more active Gulf of Mexico than both normal and as recorded in the past few years. This also means greater opportunity for a tropical storm or hurricane to make landfall in Texas. You can’t forecast tracks and landfalls until the tropical system exists, but you can see indications for greater opportunity for activity in the Gulf. At the same time, there’s greater potential for an overall quieter season (fewer numbers of cyclones) than an overall busier season. Near-normal or below-normal tropical activity for the Atlantic Basin as a whole with normal or above-normal activity in the Gulf of Mexico specifically.
Summer Weather Outlook Summary: Although there is potential for both a milder and hotter summer than forecast, it likely shouldn’t deviate much from a normal summer, based on a 10 or 15-year normal. There’s slightly greater potential for a mild summer than an extremely hot summer, however. Expect some significant lessening of the wet springtime pattern heading into summer. Though not likely to the extremes of 2015 (very wet spring to a very wet summer). There’s more dry potential than wet though an active hurricane season could alter that pattern. Long-term drought concerns will continue to be minimal.
Preliminary Fall Weather Outlook: At this time, we are forecasting normal weather for the autumn season (October-November). However, there are early indications of a warmer-than-normal fall pattern. Will need to see how the Pacific Ocean patterns take shape over the next few months before committing to this above-normal temperature forecast. But the potential is there to see a very warm pattern set up in September (late-summer) that continues through the fall season. Precipitation potential looks greatest over West Texas.