JFK, LaGuardia, Newark, Philadelphia, and DC are at PROBABLE for ground stops today as the severe-storm risk shifts from Chicago to the Mid-Atlantic

The morning after Chicago's 978-cancellation day: every overnight ground delay program has expired, the FAA's new operations plan drops O'Hare from the terminal list and puts eight Northeast airports at PROBABLE for ground stops or delay programs through 10 PM Eastern, the Storm Prediction Center posts a Slight Risk with an isolated tornado threat from Virginia into the Carolinas, a Flood Watch covers the New York tri-state through Wednesday, and American, Delta, United, and JetBlue all have fee waivers open for today.

What changed overnight

The five ground delay programs running when the last issue went out at 9 PM Eastern have all expired. O'Hare's GDP, extended to 2:59 AM, is over. Newark's GDP (11:29 PM), LaGuardia and Philadelphia's (11:59 PM), and JFK's (12:59 AM) are all done. Chicago's Department of Aviation counted 978 cancellations across O'Hare and Midway for July 27, and NBC Chicago reported O'Hare arrivals were still averaging nearly seven hours at the peak. That backlog will take airlines all day to unwind, but the airspace itself is clear this morning.

The FAA's current operations plan, ADVZY 033, is the first of the new day and it restructures the risk map. O'Hare and Midway, which dominated yesterday, are gone from the terminal plan. In their place, eight Northeast airports are listed at PROBABLE, the tier above POSSIBLE: JFK and LaGuardia, Philadelphia, Newark, and Morristown, and the DC metros of Reagan, Dulles, and BWI. Teterboro appears in the NAS Status forecast at POSSIBLE. The PROBABLE window runs from 6 AM Eastern through 10 PM. Boston is POSSIBLE after 2 PM, Orlando and Tampa after 11 AM, Miami and Fort Lauderdale after 2 PM, Charlotte and Denver after 4 PM, and San Francisco gets its routine low-ceiling GDP around 11 AM.

The advisory's narrative is direct: "Expected thunderstorms in the Northeast have ZBW, ZNY, ZDC terminal and enroute TMI's probable on the plan." A regional planning discussion is set for 6:30 AM Eastern to sharpen the timeline, with the next full planning webinar at 7:15 AM.

One thing that is different from yesterday: staffing is clean. ADVZY 033 lists no staffing triggers. Yesterday's New York GDPs were attributed to a ZNY staffing constraint compounding the thunderstorms, and the FAA told Bloomberg Law it was "slowing flights into JFK, LaGuardia, Newark Liberty and Philadelphia due to severe weather and staffing constraints at the New York Air Route Traffic Control Center." Today the constraint is weather alone, which means the ground programs will fire only if and when the storms do.

The severe-weather setup

The Storm Prediction Center's Day 1 Convective Outlook, issued at 1237 AM CDT, puts a Slight Risk (Level 2 of 5) across the southern Mid-Atlantic into the Carolinas. The summary names severe wind gusts and a tornado threat from the Mid-Atlantic southward into the Carolinas, with a few severe gusts and hail over the central High Plains as a secondary area.

The mechanism: an upper-level trough digging into the eastern US pushes a cold front into the central Appalachians. Ahead of it, dewpoints in the lower to mid 70s feed moderate instability by afternoon. SPC expects convection to first develop around midday in the higher terrain of northern Virginia and Pennsylvania, then expand southward through Virginia into North Carolina during the afternoon. The strongest instability is forecast from southeastern Virginia into central North Carolina, where MLCAPE could peak near 3000 J/kg with 40-to-50-knot deep-layer shear, supportive of supercells. The 0-3 km storm-relative helicity could reach 225 m2/s2 by mid-afternoon, which is what drives the isolated tornado threat, focused on the Delmarva and eastern North Carolina.

The tornado risk is 5 percent, which is higher than a typical summer convective day. A Facebook post from meteorologist Andrew Markowitz on Sunday evening framed it as a potential weak Nor'easter beginning Tuesday, with Mid-Atlantic storms carrying damaging winds, a few tornadoes, large hail, and heavy downpours, and the Northeast and New England looking at a widespread 2 to 4 inches of rain with a flash flood threat.

The National Weather Service has a Flood Watch in effect for the New York tri-state area from Tuesday morning into Wednesday, with forecast rainfall of 2 to 5 inches and locally higher amounts, and rates at times exceeding 1 inch per hour. That covers key commuting hours and raises the risk of urban and small-stream flooding just as weekday travel demand peaks.

What this means for airports: the SPC Slight Risk covers the southern Mid-Atlantic into the Carolinas, with the DC metros at its northern edge and convection initiating in northern Virginia and Pennsylvania around midday. AccuWeather expects the broader I-95 thunderstorm impact to extend from Washington through Philadelphia and New York to Boston. The FAA's PROBABLE tier for the eight Northeast airports lines up with that broader outlook. The first storms are expected around midday, which puts the earliest realistic window for a ground stop or delay program in the early afternoon, similar to yesterday when the New York GDPs went live around 3 PM.

All four major airlines have waivers open for today

This is the first day since the July 18 to 22 siege that American, Delta, United, and JetBlue all have active fee waivers covering July 28 travel. Johnny Jet compiled the terms on Sunday evening, and the carrier pages confirm them.

American Airlines (current as of July 27): covers BWI, CLT, JFK, LGA, EWR, PHL, IAD, DCA, and HPN for travel on July 28. Tickets must be purchased by July 26. Rebook travel between July 27 and 30. Changes must be booked by July 28. Basic Economy is included.

Delta Air Lines: covers EWR, HPN, JFK, and LGA for travel July 27 to 28. Rebook through July 31 without a fare difference if you stay in the same cabin.

United Airlines: covers BWI, JFK, LGA, EWR, PHL, IAD, and DCA for travel on July 28. Move your trip to July 27 to 30 on eligible flights without change fees or fare differences.

JetBlue: covers ISP, JFK, LGA, EWR, and HPN for travel July 27 through 29. Rebook through August 1 or request a refund if your flight is canceled.

The airport lists are not identical. American is the broadest, adding Charlotte and White Plains that United omits. JetBlue is the only one covering Long Island MacArthur. If your itinerary touches any of these airports today, open your carrier's waiver page directly before rebooking, because the same-city-pair rule usually still binds and phone lines will be under pressure once storms fire.

Tracking: Chicago recovery, what to watch today

O'Hare's 24-hour statistics on flychicago.com show 145 delayed and 19 canceled in the rolling window, down sharply from yesterday's peak. Midway is recovering too. The 978 Chicago cancellations from yesterday will ripple through the network all day as airlines reposition aircraft and crews, but the airspace is open.

What to watch today:

The 6:30 AM Eastern regional planning discussion (1030Z) and the 7:15 AM webinar (1115Z) will sharpen the timeline. If the FAA upgrades any NE airport from PROBABLE to EXPECTED, or adds a staffing trigger, that raises confidence. The first real test is around midday, when SPC expects convection to initiate in northern Virginia and Pennsylvania. If storms develop on schedule, the first ground stop or delay program at a NE hub would likely follow in the early afternoon. If the morning stays clear and the cold front slows, the window could push later, as it did on several days earlier this month when the 2 PM wall fizzled entirely.

The FAA NAS Status page and the advisory page are the primary sources for when programs go live. FlightAware tracks cancellation counts as they build. The FAA's daily air traffic report for July 27 already named today's airports in its forecast (Atlanta, Chicago, Denver, Detroit, Florida, New York, and Washington), and the July 28 update should post this morning.

Honest caveat: nothing is active right now. The FAA's terminal active list is empty. This is a forecast, and convective forecasts have fizzled on many days this month. What makes today different from those fizzles is the PROBABLE tier for eight airports, the SPC Slight Risk with a tornado threat over the Mid-Atlantic, and the fact that all four airlines have already committed waivers. The airlines and the SPC both see this as a real event. Whether it becomes a ground stop depends on whether the storms verify.