Chris Coleman, ERCOT Meteorologist
2016-17 Winter Weather Outlook
Update on December 23, 2016:
Even with a moderately-strong cold front earlier December – and a strong cold front that moved through on the 17th-18th – December is unlikely to end up below-normal. Based on a 30-year normal, the state will likely average slightly-to-moderately above-normal. Based on a 10-year normal, the state will likely average near-normal to slightly-above.
The first week to ten days of January may offer some colder weather. But I cannot yet fully commit to that. However, it could be challenging to hold onto this very mild pattern we are entering in late-December for more than 7-10 days.
When I put together the winter outlook, it was based on a set of six historical winters. The average of the six was near-normal to slightly above-normal temperatures for Texas this winter. Interestingly, the average of the six historical winters resulted in a mild December. The primary historical winter is 2005-06. That winter was much colder. As it turns out, we are generally in-between those two extremes. But, as mentioned, this winter will not and has not been minus colder-than-normal periods (even much colder-than-normal). That's likely to continue to be the case going forward into January and February. Best opportunities for below-normal temperatures will be in the Panhandle and occasionally North Texas. The colder outbreaks will impact South Texas much less.
I do see signs this winter is straying away from what would be applying January and February of 2006 (which were quite mild). As a result, I'm continuing to look over other potential historical matches. At this point, I see no reason to deviate much from my original winter forecast. General theme again being: Near-normal to slightly above-normal for the three months, on average. Including strongly cold periods -- but not enough strongly cold periods to dominate the majority of the winter (as we saw in Jan-Mar of 2014, for example).
If I see reason to update again, I will do so.
NOTE ADDED 11/4/16: This winter has greater potential to be warmer than forecast rather than colder. Still can't completely discount a relatively cold winter, but it's the least likely scenario. HOWEVER, this does not mean this winter will be void of any cold/very cold periods (read below for more insight).
The winter of 2015-16 was the 8th warmest on record for the state of Texas (121 historical winters). It will be very difficult to match or top that this coming winter, although a very warm autumn could continue into winter’s start. There are still indicators in place that would result in another mild winter. But it’s increasingly possible this winter won’t be minus some periods of significant cold.
The forecast is for temperatures to average near-normal to above-normal across the ERCOT region over the three-month winter period. Highest potential for a warmer-than-normal winter will be over West Texas. Below-normal potential is greatest over East Texas and along the Gulf Coast, but it will likely be interrupted with warm periods, resulting in a winter that is near-normal to possibly a bit cooler-than-normal.
And to emphasize, mild winters can have periods of extreme cold. We have not seen a colder day since February 2, 2011. Yet, that winter was the 68th coldest on record. Many records fell during an extremely cold December of 1989 (no month has been colder since). But that winter was only the 76th coldest on record. Yes, normal to mild winters sometimes have periods of record-breaking cold.
This winter again has mild potential. But the greatest potential is in the early-winter period. January and February are both likely to have colder-than-normal periods (polar vortex) affecting large swaths of the U.S. However, I see the highest potential for those polar outbreaks to impact the eastern third of the country. For Texas, that means we could occasionally get clipped by a cold outbreak, but the heart of the cold would shift east and the colder periods would be short-lived and less frequent.
If you recall the winters of 2013-14 and 2014-15, the first of those two winters was much colder. The polar outbreaks plunged directly through the Plains states and impacted Texas on a regular basis. This resulted in the 30th coldest winter in Texas weather history. The following winter did have a couple of strongly cold periods, but the heart of the cold air was shunted east. The winter of 2015-16 was the 69th coldest on record.
That’s what we are likely looking at for this coming winter. Something between last winter (ranked 8th warmest or 114th coldest) and the winter of 2014-15, which was 69th coldest. I expect it to be colder than last winter. I doubt it will be considered a bitterly cold winter. But there very well could be a couple of periods that are quite cold. And those periods are more likely to occur in January or February than in December. And there’s a realistic chance the entire state of Texas experiences another warmer-than-normal winter.
Probability of being one of the 40 warmest winters on record: 35%
Probability of being one of the 40 coldest winters on record: 15%
Probability of being one of the 42 winters in-between the two extremes (near-normal): 50%
2016 has been a wetter-than-normal year. However, the fall season has trended much drier. And the forecast for this coming winter is mostly drier-than-normal with some potential for normal or slightly above-normal precipitation in both the Panhandle and Gulf Coast/South Texas regions. But in general, this would result in our second consecutive drier-than-normal season.
Drought is not currently a significant issue in Texas. However, there are portions of the state with increasing concerns, including both Northeast Texas and the Rio Grande Valley. Drought concerns have potential to increase with a winter precipitation forecast that is mostly below-normal. Texas has minimal immediate hydrological concerns, as the reservoirs are mostly full. But if we do make it through the winter season with the rainfall deficit increasing, that would put added emphasis on needed rain next spring and summer.
We are in a weak La Niña phase currently. This will likely fade before next spring. However, dry conditions do commonly coincide with a La Niña, so there is support for this relatively dry period continuing for the next couple or few months. I do not see indicators of this continuing throughout 2017.