Heavy Snow and Disruptive Ice in the Upper Midwest; Severe Thunderstorms in the Southern Plains

A late season winter storm will produce a combination of heavy snow and disruptive ice starting this evening in the Northern Plains and moving into the Upper Midwest and Great Lakes by tonight continuing through Thursday. Severe thunderstorms will likely produce severe wind gusts, large hail, a few tornadoes, and heavy rainfall across the southern and central Plains today. 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.