On the afternoon of July 26th, a significant severe weather event impacted portions of the Binghamton, NY forecast area. By the late morning/early afternoon, a warm front had lifted north through the region placing much of the Binghamton forecast area in a moderately unstable airmass (Fig. 1).

Fig. 1: 2:00 PM HPC surface analysis.

Aloft, multiple approaching upper-level shortwave troughs approached the region from the central Great Lakes during the early afternoon hours which provided the initial forcing for thunderstorm development (Fig 2). Also at mid-levels, water vapor imagery showed a punch of mid-level dry air (reddish appearance in Fig. 2) which helped create mid-level convective instability along with a favorable setup for strong damaging winds. The presence of dry air aloft is a key indicator meteorologists look for when determining severe weather potential. Dry mid- level air can rapidly descend in a storm creating strong damaging winds along the surface.

Fig. 2: 1:40 PM water vapor image.

Thunderstorms developed over southwestern New York and northwestern Pennsylvania by early afternoon. As these storms continued east, they matured into a multicell line as they approached western Stueben County. Before moving into the Binghamton forecast area, multiple severe weather reports were recorded upstream across western New York. Knowing the history of the storms off to the west, the first of multiple severe weather warnings as issued at 2:25 PM for Steuben County. As the storms raced east at 50-55 mph through southern Steuben County, the system matured into a well-defined bow echo (Fig. 3) by the time it was entering western Chemung County. As the storm was entering western Chemung County, a well-defined “inflow notch” was detected by radar with broad rotation noted around this feature. Within the core of the bow, the Binghamton, NY WSR-88D Doppler radar estimating winds to be anywhere from 50-70 mph (Fig. 4). Embedded within the leading edge of the bow, Doppler radar detected a low-level rotational couplet (Fig. 5) heading towards the Elmira area. As this rotational couplet moved towards Elmira, an EF-1 tornado touched down in West Elmira. The tornado then continued east into Elmira where it affected the downtown district before finally lifting just east of the city.

Fig. 3: Base reflectivity at 3:51 PM just prior to the storm reaching the Elmira area.

Fig. 4: Base velocity at 3:51 PM just prior to the storm reaching the Elmira area.

Fig. 5: Storm relative motion valid at 3:46 PM.

After moving through Elmira, the storm system quickly moved east through the Twin Tiers, where numerous damage reports such as trees and wires down were received. As the system moved into the Binghamton area a tornado warning was issued for eastern Tioga and much of Broome Counties at 4:24 PM. The strongest winds plowed into southwest Broome County where numerous damage reports were received from Owego east through Apalachin, Vestal, the Town of Binghamton, and Conklin (Fig 6).

Fig. 6: Base velocity imagery valid at 4:36 PM. As the system moved through central Susquehanna County, a brief EF-1 tornado occurred just south of Montrose along the Bridgewater/Dimock Township line (Fig. 7) at approximately 4:45 PM.

Fig. 7: Storm relative motion valid at 4:45 PM. Out ahead of the main line, a supercell thunderstorm developed over Columbia County, PA and moved into western Luzerne County around 5:05 PM (Fig. 8).

Fig. 8: Supercell thunderstorm moving into southwestern Luzerne County at 5:06 PM.

As this storm entered the county, Doppler radar indicated strong mid-level rotation. Downburst winds associated with this storm produced straight line wind damage in the Township of Sugarloaf. The storm continued to move east where it produced additional straight line wind damage along East Foothills Drive in the Town of Hazel. As the storm entered western Foster Township, a brief tornado occurred just southwest of Freeland at 5:44 PM (Fig. 9).

Fig. 9: Storm relative motion valid at 5:45 PM.

Beyond this, the bow echo and associated strong winds raced east through the remainder of the Binghamton forecast area with additional damage was reported. In total, 5 tornadoes occurred within the Binghamton forecast region. Below is an image of the storm reports for the duration of the event. Notice the high number of wind damage reports which is a direct result of the strong winds associated with the eastward moving bow echo structure.