It might come as no surprise: This holiday shopping season is slated to be another record-breaking one online.

Digital spending during November and December is expected to reach $143.7 billion, up 14.1% from a year ago, according to a study by Adobe Analytics, which tracks transactions for 80 of the top 100 U.S. internet retailers including Walmart and Amazon.

Cyber Monday sales are expected to hit $9.4 billion, up nearly 19% from last year, Adobe said. Black Friday sales online are expected to be $7.5 billion, up 20.3%. Thanksgiving Day sales on the internet are forecast to surge 19.5%, to $4.4 billion, it said.

But the catch this season is retailers are going to have to fight harder for those dollars. There are six fewer days between Thanksgiving and Christmas this year — making for the shortest possible holiday season. Walmart has already started rolling out deals online, earlier than it ever has before, because of the shorter season. Target CEO Brian Cornell said earlier this month, "Every day is going to count."

The six lost days from the 2018 holiday season will leave nearly $1 billion in sales on the table, according to Adobe. For the first time, the research firm is calling for online sales to surpass $1 billion each day in November and December, because of the pinch for time.

"We fully expect [retailers] to be driving discounts and sales much earlier and much more consistently throughout the season," said Nate Smith, a product marketing manager for Adobe Analytics. "You are going to see that all through November."

Beyond deep discounts, companies will try to lure shoppers with expedited delivery options, curbside pickup, new loyalty program perks and events in stores. Chinese e-commerce giant Alibaba's 11.11 Global Shopping Festival on Nov. 11 could also spark U.S.-based retailers to offer deals that align with the shopping extravaganza.

Adobe Analytics also forecast the best days for shopping online, based on retailers' past price cutting.

Typically on Black Friday, for example, electronics are about 9% discounted, and you can save 6% on sporting goods. Toys are 32% cheaper on Dec. 1. Televisions are 19% off on Cyber Monday. And, if you can stomach the wait, electronics are typically about 27% less expensive on Dec. 27.

The National Retail Federation has forecast total holiday retail sales will grow by 3.8% to 4.2% this year, excluding automobiles, gasoline and restaurants. That equates to sales of between $727.9 billion and $730.7 billion. But the industry trade group also said "uncertainty over trade" could end up posing a drag on the season.