Denver's ground delay program is live at 1 hour 18 minutes, Orlando's ground stop has fired, and a LaGuardia program is imminent for tonight

The 6 PM Wednesday update: the 3 PM issue's two forward-watches both fired, Denver's ground delay program went live at a 1 hour 18 minute average running to 11 PM ET and Orlando's ground stop went active through 6:30 PM ET, while the FAA's post-3:15 PM webinar advisory says a LaGuardia program is imminent and Newark is back in the plan for potential thunderstorm initiatives tonight, San Francisco's fog program was extended at airline request to 3 AM ET, Boston Logan holds at 1 hour 46 minutes through midnight, and a Las Vegas ground stop remains possible after 8 PM ET from staffing.

Denver's ground delay program went live

The 3 PM issue flagged Denver as the next risk at 6 PM ET. It fired. The FAA's Denver airport page, updated at 6:17 PM ET, shows a ground delay program in effect for weather and thunderstorms, with arriving flights delayed an average of 1 hour 18 minutes and airborne arrival delays between 1 hour 1 minute and 1 hour 15 minutes and increasing.

The FAA's current operations advisory (ADVZY 151, signed 5:46 PM ET) lists the Denver ground delay program running until 10:59 PM ET. The cause is dual: thunderstorms in the vicinity of the airport (listed as VCTS in the terminal constraints) plus a Denver Center staffing trigger. The advisory notes a high-altitude transcontinental route was issued to help Denver Center with its staffing shortage in Area 5, which runs from 7 PM to 10 PM ET.

This is a fresh program for today, separate from Tuesday's much larger Denver disruption. On Tuesday, CBS Colorado reported a ground delay from 3 PM to 9:59 PM averaging 103 minutes, and the Denver Post counted 925 delayed and 40 canceled flights by 7:25 PM. Today's Denver totals are far smaller so far, 713 delays and 5 cancellations per FlightAware's Denver page, but the program is live and the arrival delay is climbing.

No airline has posted a Denver-specific weather waiver yet. Delta's advisory page, checked at 6:18 PM ET, lists Atlanta, Mid-Atlantic, and New York weather waivers but nothing for Denver. Travelers connecting through Denver tonight should check flight status directly with their carrier, as the program runs nearly five more hours and arrival delays are increasing.

Orlando's ground stop fired, Tampa still possible

The 3 PM issue upgraded Orlando and Tampa from possible to probable ground stops as thunderstorms sat in the center of Jacksonville Center's airspace. Orlando's went active. The FAA advisory lists an Orlando ground stop running until 6:30 PM ET, with Tampa still listed as a possible ground stop through 8 PM ET.

Florida is carrying the day's heaviest convective activity. The advisory shows Florida-to-Northeast arrival routes active until 8 PM ET, Miami and Fort Lauderdale CDRs (canned departure routes) until 8 PM, and a Central Florida Hotline running until midnight ET. A Montreal (CYUL) ground delay program is also active until 8:59 PM ET, a downstream effect of the Florida-to-Northeast route constraints.

Orlando's on-time performance cratered in the evening window. Airport Overview shows MCO departures running at 71 percent on-time for the day but the 6 PM to 10 PM block dropping as low as 12 percent, an 88-point swing from the morning's 89 percent. The terminal forecast calls for thunderstorms and cumulonimbus clouds around 6 PM local time, exactly when the ground stop hit.

New York re-enters the plan for tonight

The biggest surprise in the 6 PM advisory is the Northeast coming back. After the two-day storm wall cleared at noon and JFK, Newark, LaGuardia, Philadelphia, and the DC airports all went on time, the FAA's post-3:15 PM webinar advisory now says a LaGuardia program will be implemented soon due to concerns about throughput and surface congestion, and Newark has been added to the plan for potential thunderstorm-related terminal initiatives.

Newark is listed as a possible ground stop or delay program through 8 PM ET. The advisory is explicit that no staffing triggers are in the works for Northeast facilities this time, unlike Tuesday and Tuesday night when a ZNY staffing shortage compounded the weather. This is weather-driven.

The scope is real but narrower than Tuesday's. Severe weather avoidance plan support is active for Boston and the New York metro, with escape routes being issued as needed. SWAP (severe weather avoidance plan) statements are running for Boston Center domestic and international traffic until 11 PM ET, New York Center until 11 PM ET, and the NY Metro Hotline until 11 PM ET. Several New York Center routes (L452, L454, L456, Y493, Y494) are closed due to thunderstorms with an update by 8 PM ET.

San Francisco's fog program extended to 3 AM, Boston holds

San Francisco's ground delay program was extended at the airlines' request. The 3 PM issue had it running to 6:59 PM ET. The 6 PM advisory now lists it through 2:59 AM ET, a roughly eight-hour extension. The FAA's SFO page, updated at 6:19 PM ET, shows the delay average holding at 41 minutes for low visibility, with airborne arrival delays at 15 minutes or less. The extension absorbs what the noon issue flagged as a probable second SFO program after 10 PM ET.

Boston Logan is the steadiest story of the day. The FAA's BOS page, updated at 6:17 PM ET, shows the ground delay program for low ceilings holding at a 1 hour 46 minute average, unchanged since noon, running through 11:59 PM ET. The runway 04 to 15R switch the noon issue warned could worsen things did not materialize as a problem. Airborne arrival delays are 15 minutes or less.

Las Vegas ground stop still possible tonight from staffing

The 3 PM issue flagged Las Vegas as a candidate for its own ground stop tonight. That watch holds. The advisory lists a Las Vegas ground stop or delay program as possible after 8 PM ET, driven by an L30 TRACON staffing trigger running from 8 PM to 3 AM ET. The advisory notes a ground stop may be needed around 11 PM ET for an arrival rate reduction tied to the staffing.

Two other staffing triggers are active: F11 TRACON from 7 PM to midnight ET, and Denver Center Area 5 from 7 PM to 10 PM ET (already feeding the Denver delay program above). Las Vegas is also flagged in the advisory's terminal constraints for wind, alongside Reagan National.

Cancellations today and the American residual

US cancellations climbed through Wednesday but stayed well below Tuesday's totals. FlightAware, checked at 6:18 PM ET, shows 502 cancellations within, into, or out of the United States today, up from 407 at the 6 AM count the morning issue reported, plus 5,058 US delays. Tuesday peaked above 2,000 US cancellations.

The American Airlines IT outage residual continues to fade into the background. The 3 PM issue noted American still led nationwide cancellations a day after its nationwide ground stop, with no root cause named. No new development on that front surfaced today: American has not named the failed system or vendor, and no DOT investigation has been announced. The outage, which hit at 6:29 PM ET Tuesday and lasted about 45 minutes, left 1,402 delays and 321 cancellations per FlightAware data cited by The Travel.

Waivers and rebooking

Delta has three weather waivers active, all on its advisory page as of 6:18 PM ET: Atlanta Summer Thunderstorms (posted 12:08 PM ET today), Mid-Atlantic Weather covering ABE, BOS, BWI, DCA, IAD, and PHL (posted July 28), and New York City Summer Weather covering EWR, HPN, JFK, and LGA (posted July 28). JetBlue's New York metro waiver covers July 27 through 29 with rebooking through August 1, making today the last covered travel day.

No airline has posted a Denver or Florida-specific waiver for today's new programs. The Department of Transportation's airline cancellation and delay dashboard tracks each carrier's rebooking and refund obligations. When a weather waiver is open, airlines typically allow rebooking in the same cabin between the same cities without a change fee, but only if the new flight falls within the waiver's travel and rebooking windows. With Denver's program running to 11 PM ET and the Northeast re-entering tonight, anyone flying through those hubs should check their airline's advisory page directly before assuming a waiver applies.