As Austin starts the fall season in earnest with part one of the Austin City Limits Music Festival this weekend, the American-Statesman chatted online about the weather with Lower Colorado River Authority meteorologist Bob Rose. Below are excerpts:
The eyes of the world are upon us for Austin City Limits festival this weekend and next. Will people need ponchos?
I think the weather for ACL is going to be outstanding this weekend with highs in the 80s and low humidity. Next weekend’s ACL looks a little more uncertain, with possibly a chance for rain.
So sunglasses during the day and sweaters at night?
I wouldn’t go as far as sweaters, but maybe a light jacket. We might see lows in the upper 50s Saturday and Sunday mornings. I do want to remind everyone to use sunscreen. It will be sunny both days.
And the outlook for fall?
As you may know, a strong El Niño is in place, and forecasters believe we will begin to see the wet influence from El Niño beginning in the latter half of October. November and December look to be pretty wet with frequent rains. Rainfall should trend above normal. Temperatures should be trending cooler, and possibly even below normal in November and December.
So what is going on with the El Niño and this stubborn high pressure?
We’ve only see about three El Niños of this magnitude over the past 100 years. The El Niño did help maintain the high-pressure ridge over Texas during September, but as we move further into fall, that influence will wane and we should begin to see the more typical wet and cloudy response from El Niño. However, this one may not be as excessively wet as some of the previous ones we’ve seen.
I wasn’t aware until this year of the self-sustaining dome effect high pressure creates. Can you explain how that happens?
In regards to the self-sustaining high pressure area, it has to do with the ground drying out. Once the high-pressure system develops, it limits rainfall, and the hot summer sun bakes the ground. This allows the ground to heat up, which reinforces the high pressure ridge.
So you are not worried about this being an increasing trend?
I’m not worried about this being an increasing trend. Having the ridge of high pressure over Texas during the summer months is normal. How long it lingers and how intense it gets is what is troubling. 2011 was the worst. But the ridge has been showing up in our summer weather for a long, long time.
Everybody wants to know when we can expect our first “cold snap.” When might that happen, and is El Niño a wild card in that as well?
On the first cold snap question. I think it will be sometime around the third or fourth week of October. I don’t see anything on the near-term horizon that is real cold. But I do think it is coming later this month. … Every year will be different but we often tend to get our first good cold fronts in early to mid-October.
Bob, we have you on record as saying there would be no more than 10 days this summer with triple-digits, and we had twice as many.
Ouch! I thought you might have forgotten about that forecast for 10 100-degree days. Yes, I was wrong. I, along with many other forecasters, thought the wet pattern in June would have lingered longer and prevented the excessive heat. As it turned out, the rain shut off in June and we started see the 100s in late July. At least it wasn’t as bad as 2011 with 90 100-degree days. But yes, it turned out to be much too optimistic of a forecast.
You have so much technology at your disposal. Do you have any use for the weather apps we laypeople use?
Believe it or not, I have some of those weather apps on my phone as well. … The ones that have radar and can provide warnings and watches I find the best. They are valuable, especially when you are away from your computer.
LCRA has a few tools folks might find helpful. Our hydromet mobile Web page has temperature and rainfall from over 200 weather stations from around the area. You can overlay radar on top of the information and get historical data as well. You can also find my weather blog on lcra.org.
Lake Travis has recovered to the point to where it’s more than three-fourths full — how optimistic are you about the Highland Lakes staying at their historically normal levels?
With the forecast for a wet winter, I think the levels of both Lake Travis and Lake Buchanan will stay about where they are right now. If it does turn really wet, the lake levels should rise over the next few months. But there’s no guarantee.
I will mention one more thing about the winter. El Niño winters often bring our area a somewhat better chance for snow. Do you want me to go out on a limb and predict the number of snow/ice days we’ll have?
Darn! Can I get away with saying a few? Somewhere in the range of three to five.