Multiple days of heavy rainfall soaked the Northeast this week, dropping over six inches of rainfall. The NWS Weather Prediction Center (WPC) Extended Forecast Discussion issued at 0744 UTC 22 July 2026 began to message “Ample subsequent northern stream system energies set to dig into the upper trough position over the East should support organized enhanced to heavy convective rainfall”, about a week before the heavy rainfall. By Day 5, a Marginal Risk Excessive Rainfall Outlook (ERO) was issued for the 24-hour period ending at 1200 UTC 29 July, which was upgraded to a Slight Risk by Day 3, and Moderate Risk by Day 2.
Figure 1: NWS WPC Day 5 ERO (left) and Day 2 ERO (right)
One-minute GOES-East Mesosector imagery during the afternoon of 28 July 2026 showed the expanding canopy of storms across much of the Mid Atlantic. LightningCast output, overlaid on the Day Cloud Phase Distinction (DCPD) RGB, had probabilities providing lead time before the GLM observed lightning as convection initiated across Maryland and Virginia, while also capturing the growing complex of storms across Central and Southern New Jersey.
Figure 2: GOES-East Mesosector LightningCast output, overlaid on the DCPD RGB imagery, from 1749-1947 UTC 28 July 2026. This animation was exported from AWIPS, and display files can be shared upon request.
The potent upper-level trough spawned a surface low pressure system, with its swirl quite evident in the morning visible satellite imagery on 29 July 2026. WPC analyzed a 998 hPa low at 1200 UTC. GOES-East Mid-Level Water Vapor (WV) imagery, overlaid with the RAP 500 hPa Geopotential Heights showed the cutoff low as moisture continued to pivot into New England.
Figure 3: GOES-East CONUS Visible Band 02 imagery from 1146-1656 UTC 29 July 2026. This animation was exported from AWIPS, and display files can be shared upon request.
The WPC MetWatch Desk issued a Mesoscale Precipitation Discussion (MPD) at 1440 UTC 29 July discussing the ‘Stacked low-to-mid level low’ that was ‘supplying very moist flow (1.5-1.8″ PWs) from the Atlantic just to the east of this circulation’, elevating the threat for flash flooding over the next six hours. The Advected Layered Precipitable Water (ALPW) Product showed the sufficient transport of moisture at all levels of the atmosphere, though it slowly weakened with time as the cutoff low meandered into 30 July 2026.
The evolution of the dynamic system that fired off severe storms and caused flash flooding can be seen in the GOES Mid-Level WV imagery from 1710 UTC 28 July to 1640 UTC 29 July 2026.
Figure 8: GOES-East Mid-Level Water Vapor imagery from 1710 UTC 28 July to 1640 UTC 29 July 2026. This animation was exported from AWIPS, and display files can be shared upon request.
New York’s Capital District received the most rainfall as the system’s ‘comma head’ pivoted overhead, with totals exceeding half of a foot around Albany, up to 9″.
