Seasonal Updates

    Chris Coleman, ERCOT Senior Meteorologist

    June 5, 2018 Update:

     11-15/5-9/3-6.  11 to 15 named storms (tropical storms and hurricane), 5 to 9 hurricanes, and 3 to 6 of those hurricanes being major (category three or stronger). While this range is still a reasonable forecast, it's more likely to be near the bottom of that range than the top. The early-June revision: 9-13/4-7/2-4.

    The Atlantic Ocean, between the Caribbean and Africa, is cooler-than-normal for early-June. This is the "Main Development Region" for tropical cyclones -- and this relatively cooler ocean water will act to hinder development. (Note: the Gulf of Mexico is currently more conducive for early-season development.) If the relative cooler region of the Atlantic hangs on until mid-summer, it's possible the number projections will be again adjusted downward.

    No changes to the temperature or precipitation outlooks for ERCOT this summer. It's starting out hotter-than-normal and that's likely to hold up for most of the summer season -- but not to 2011 levels. I'm not convinced the extreme temperature anomalies of May (2nd hottest May on record for the state) will hold all summer, but there's not much to change the above-normal temperature pattern. Again, strongest/hottest anomalies likely for West Texas.

    Summer 2018 Weather Outlook (published April 30)

    The temperature forecast for summer 2018 in Texas is hotter-than-normal for the ERCOT system. However, this is based on ERCOT as a whole. And generally when applying a 30-year normal. Based on a 10-year normal, the ERCOT system’s summer is expected to be close to normal. There may be some regional, less hot exceptions – including major populations.

    Both North and East/Southeast Texas show potential for temperatures ranging closer to normal. Of the large ERCOT cities, Austin and San Antonio are the most likely to experience a hotter-than-normal summer. Dallas is forecast with a slightly better chance than not of an above-normal summer for temperatures – but likely not extreme. Last year’s ten days of 100° or greater at DFW is more likely than not to be eclipsed (but not necessarily by a lot). Houston is in a similar category as Dallas. Less chance to see a strongly above-normal summer. Near-normal or a slight lean either side of normal is the most likely outcome.

    Summer 2018 Temperature Map

    The trough of low pressure impacting much of the eastern half of the U.S. with below-normal temperatures – especially the Ohio Valley – should hold this summer. There is also a ridge of high pressure over the western-half of the U.S., resulting in above-normal heat – especially for the Interior West. Texas will occasionally be impacted by both the trough to the east and ridge to the west. But, combining that with the drought supports more of the heat to build in from the West. However, there’s a least a slight chance the trough in the eastern U.S. could have more impact in ERCOT than currently forecast.

    This summer is very unlikely to approach the extremes of 2011 – the hottest summer on record for the state of Texas. Last summer (2017) was the 50th hottest summer on record (dating back to 1895). That’s toward the low end (coolest possible outcome) for the summer of 2018. There are some similarities to 2013, which was the 21st hottest summer on record. That’s probably about the top end (hottest) potential for this summer. Other similar years are 1996 (cooler than last summer) and 2006 (hotter than last summer, not as hot as 2013).

    Summer 2018 Precipitation Map

    The rainfall forecast for the majority of ERCOT is normal or below-normal precipitation. Best chance for below-normal rainfall matches the best chance for hotter-than-normal temperatures – South Texas and southern portions of West Texas. The Panhandle is showing signs of a wetter-than-normal summer, which would be quite welcome as the drought is most intense in this region of Texas (as of mid-spring). While drought may improve over portions of West Texas, (especially Panhandle), some deteriorating conditions are possible across South, Southwest, and into Central Texas. While I wouldn’t expect the widespread, intense drought of 2011 to develop, there’s likely to be some regionalized concerns developing and/or intensifying this summer in Texas.

    We remain under a weak influence of a La Niña. This should officially trend to neutral by late-spring, though I wouldn’t expect a quick swing to an El Niño. Neutral with some lingering La Niña influence should be expected into the summer season. This would support a relatively dry summer. It would also support another active hurricane season.

    The forecast for the 2018 hurricane season is:

    11-15/5-9/3-6

    11 to 15 total named storms in the Atlantic Basin (Atlantic, Caribbean, Gulf of Mexico). Five to nine of those being hurricanes. Three to six of those hurricanes forecast as major (category three or greater) hurricanes. This would again be an above-normal hurricane season. Too early to forecast if this will have any impact on Texas -- but it should be noted that it's far from unprecedented to have consecutive years with hurricane landfalls in Texas. This happened as recently as 2007 (Humberto) and 2008 (Ike).