Walmart Moves Freight Ahead Of The Storm. For Marketplace, It Moves The Promise.

Days before a storm reaches a store, Walmart’s supply chain technology team has already run it. Predictive artificial intelligence and machine learning models weigh historical weather patterns against real-time data to project how the network will respond, and planners use the output to reposition inventory, adjust transit times, and reroute shipments to unaffected locations before conditions deteriorate. Indira Uppuluri, Walmart’s senior vice president of supply chain technology, described the approach in an interview with Supply Chain Dive published July 29. What that machinery does to the companies shipping into Walmart divides sharply by segment, and neither segment has the full picture in writing.

The forecast is one input among many. Uppuluri said Walmart brings a range of signals together to model what a weather event would mean for its stores and customers, with transportation capacity and associate availability weighed alongside the storm track. Walmart is more specific elsewhere about where those signals originate. In a June 24 post on its corporate site, Tracy Dufault, senior vice president of strategic initiatives for disaster relief, said the company combines its own historical data with weather data, information it receives from FEMA and other state agencies, and third-party insights to understand “where risks are emerging and what communities are likely to need.”

That work runs through Walmart’s Global Security Operations Center, which the company describes as the home of its Emergency Operations Center and as using predictive modeling to generate automated forecasting across the United States. Tom Bedard, Walmart’s senior manager of emergency operations, said in the same post that the team watches storm prediction forecasts and begins communications once a threat crosses a defined threshold.

The Digital Twin Reassigns Which Distribution Center Serves A Store

The mechanism underneath the supply chain side is digital twin technology. A June 24 post on Walmart’s Global Tech blog describes transportation teams working with virtual replicas of the logistics network to simulate how goods move under stress, and it names three outputs the modeling produces: an evaluation of capacity needs, proactive operational adjustments, and the alignment of stores with alternative distribution centers.

That third output has the most direct bearing on supplier operations. Walmart’s post does not describe the trigger conditions, but the capability it names is the reassignment of a store to a different servicing facility. Uppuluri told Supply Chain Dive that rerouting inventory to unaffected distribution centers is one common tactic Walmart uses to keep products flowing during a weather event.

Walmart Is Modeling The Demand Spike Before It Happens

Weather changes what shoppers buy, and Walmart is forecasting that shift rather than absorbing it. Uppuluri gave Supply Chain Dive a plain example: heavy rainstorms drive umbrella purchases, and that expectation shapes where Walmart directs inventory ahead of the event.

The forecasting capability predates the current weather work. In an October 2025 interview with Supply Chain Dive, Uppuluri described a demand model built entirely inside Walmart that predicts across multiple future horizons, drawing on past demand patterns, planned events, and global and local trends. She described the inventory consequence in the same conversation, saying that when an unexpected demand surge starts to deplete inventory faster than projected, AI forecasting tools can “adjust replenishment schedules and flow of goods through the supply chain.”

Suppliers planning around a weather week should assume the replenishment signal can move ahead of the event rather than after it, and that the move can originate in a forecast rather than in a stockout.

For Some Categories, Walmart Does Not Wait For The Forecast

A portion of the assortment sits outside the prediction cycle entirely. Walmart states in its June 24 corporate post that the majority of emergency supplies needed to prepare and respond are the same regardless of what form the disaster takes, and it names them: batteries, bottled water, flashlights and generators. The same post says Walmart stocks and reserves known emergency inventory in nearby distribution centers, and that early forecasting can push that reserved inventory out to stores and clubs ahead of an event.

The planning posture for suppliers in those categories is different as a result. Walmart is carrying reserved stock against storms that have not formed, so the baseline it works from already anticipates a season rather than an event. Suppliers in those categories should be careful about reading every weather-week movement as a fresh demand signal.

Route Changes Happen Before The Road Closes

Storms are not the only exposure. Uppuluri told Supply Chain Dive that wildfires create obstacles in areas including California and Colorado, where highway closures can eliminate lanes, and that Walmart adjusts driver routes ahead of time where it can. When a fire develops on short notice, she said, Walmart’s transportation center sends alerts to affected drivers on what actions to take.

In Canada, the same problem produced a tool built outside the engineering organization. Jeff McIntosh, director of transportation for Walmart Canada, used AI coding tools to build what Walmart describes as a storm rerouting agent, according to a July 24 Global Tech post. The agent cross-references 10-day forecasts against real-time highway and ferry closures, carrier data and other operational signals. McIntosh told Walmart’s blog that the idea came from a mid-March ice storm in Montreal, where his teams had two to three days of notice and still spent “12, 14 hours working furiously” rerouting trucks, adjusting dispatch schedules and rescheduling store deliveries. Walmart is explicit in the same post that the agent is one tool among several, listed alongside the command center described above, official weather warnings, simulation tools and predictive insights.

Walmart Reroutes Online Orders Without Saying Whose Inventory Moves

Online orders run through a separate system. Walmart’s Global Tech post describes an intelligent fulfillment engine that weighs inventory availability, delivery speed and network capacity to choose a fulfillment path, and that recalculates those paths during weather events to hold service levels. CIO Dive reported on July 13 that Uppuluri’s team owns that engine. Neither source says which inventory it reaches.

For 1P, The Movement Is Physical And Arrives Without Notice

Everything described so far operates on inventory Walmart already owns. The repositioning, the store-to-DC reassignment, the reserved emergency stock and the transit-time adjustments all happen downstream of delivery. The supplier experiences the effect through order patterns and receiving windows rather than through any notification the reporting describes. None of Walmart’s public materials address how weather-driven changes interact with OTIF measurement, which is the first question a 1P supply chain team will ask.

For Marketplace, The Buffer Depends On The Seller’s Own Record

For Marketplace sellers who fulfill their own orders, Walmart’s mechanism operates on the delivery promise rather than on the freight. Walmart’s Marketplace Learn shipping and fulfillment policy, updated July 2, states that Walmart may extend delivery promise times because of weather-related delays affecting seller or carrier operations. The same page notes that promise times may not need extending at all if a seller consistently meets the On-time Delivery Rate standard, which Walmart sets at 90% or higher.

The control a seller holds over this runs in one direction. Walmart’s Delivery Promise Optimization setting lets sellers opt out of having their promise times shortened. The policy states that there is no opt-out from having them extended.

Walmart is describing a buffer that arrives based on a seller’s own track record rather than on the severity of the weather. Walmart’s seller performance standards list weather delays as non-seller-accountable for On-time Delivery Rate, so a storm should not itself erode the score that determines the buffer. Sellers should read On-time Delivery Rate as a weather-season variable and not only as a performance metric. Walmart separately caps Additional Days Off at 30 per fulfillment center per calendar year and says excessive use is closely monitored. The policy does not carve weather closures out of that allowance.

WFS sellers sit outside both descriptions. The Marketplace shipping policy governs seller-fulfilled orders, and the fulfillment engine material never specifies its inventory scope.

The more consequential part of Uppuluri’s account may be what the simulations produce when no storm is coming. Walmart is running the same models to understand how its resources are being used across the network and where optimization is available, and the exercise keeps returning an answer that has nothing to do with weather. “As we run through these simulations, sometimes we realize maybe we can run our network slightly differently,” Uppuluri said. “Maybe we can configure it differently.” A configuration change decided in a simulation would reach suppliers the same way the weather reroutes do, through changed order patterns and not through notice.

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