Severe Thunderstorms and Heavy Rainfall in the Ohio Valley and Great Lakes; Winter Weather in the Northern Tier

A slow moving front extending from the Great Lakes region into the Plains will bring snow, wintry mix, and ice accumulation north of the front from the Upper Midwest into New England, and severe weather and heavy rain south of the front. Scattered severe thunderstorms with damaging gusts, severe hail, and heavy rain are expected across parts of the Great Lakes/Midwest through tonight. Read More >

Overview

On July 15, 2012, a short-wave moving through a ridge brought a surge of moisture and anomalously high precipitable water to Pennsylvania. This influx of moisture caused a surge of CAPE values over the region and led to the formation of two bow echoes, one developing over central PA and moving eastward, the other forming in southern PA and primarily impacting Harrisburg. With the exception of two tornadoes in Bradford County, PA and St Mary’s County, MD, the event was dominated by low-end wind damage and reports of fallen trees.


Surface Map 7/15/20	WPC National Forecast Chart	500-mb Analysis 7/15/20

24-H QPF 7/15/20 0Z - 7/16/20 0Z	WPC Analysis/Radar Composite 18Z	SPC Storm Reports for 07/15/12

KCCX radar at 2103 UTC 7/15/12. Upper left shows 0.5 degree reflectivity, upper right shows 0.50 degree velocity, lower right shows storm relative velocity and lower left shows the terrain. Arrow shows origin of bow and its approximate path.