We all know and talk about April 27, 2011, and deservedly so. But, the whole month of April that year was just non-stop severe weather across the Eastern half of the country.

This is a synopsis of the overall pattern that was present during the timeframe, and what was expected and ultimately became of it:
NOAA - National Centers for Environmental Information

quote:
National Overview:

The weather pattern over the contiguous United States during April 2011 consisted of a westerly flow with strong low pressure waves or troughs embedded in the flow. Some of the troughs formed deep low pressure systems with slow moving cold fronts which generated heavy rain and severe weather, especially in the Midwest to Southeast. According to preliminary reports, April had 875 reports of tornadoes which caused over 350 deaths. The National Weather Service expected the confirmed tornado count to exceed 600, which is a record for any month. There were over 2000 preliminary reports of hail damage and more than 3200 wind damage reports, with most of the damage occurring from the southern and central Plains to the Atlantic coast. Tornadoes were observed on two-thirds of the days of the month, with the biggest tornado outbreaks reported on the 14th-16th and 25th-27th.

quote:
The storm track repeatedly tapped Gulf of Mexico moisture in a southerly surface airflow that generated storm systems week after week over the Midwest. The resulting well-above-normal rainfall culminated in widespread record flooding in the Ohio Valley by the end of the month. Some areas received up to 20 inches of rain during the month, which is nearly half their normal annual precipitation. Six states (Illinois, Indiana, Kentucky, Ohio, Pennsylvania, and West Virginia) had the wettest April on record.

The first widespread severe weather event of the month was the April 4-5 Tornado Outbreak/Derecho. Tornado, wind, and damage reports stretched from East Texas, much of Louisiana, the Deep South states, and all the way to Maryland.

@JosephPattonWx

From a NWS report on April 6, 2011:
NSSL News

quote:
A truly remarkable number of wind events did occur in this recent event. In fact, while the number of wind reports across a 24 hour period remain preliminary and will need to be further reviewed by NWS meteorologists in the affected areas, it is likely that in the final analysis, the wind reports numbers alone will far exceed any other severe weather outbreak in the official records of the NWS.

NOAA.gov Final Report

quote:
As previously mentioned, the April 4-5, 2011 derecho was responsible for a record number (1096) of non-duplicate damaging wind reports in a 24-hour period. Yet, as shown in Figure 5, only six officially observed wind gusts meeting the National Weather Service definition of "severe" (greater than or equal to 50 kts (58 mph)) were recorded, and only one "significant" (65 knots (75 mph) or greater) gust was observed --- despite the relatively high density of observing sites in the path of the storm. This illustrates one of the difficulties involved in using wind reports alone to place a given derecho in historical perspective, or to assess its meteorological significance. Because of the many trees and man-made structures present over the southern and eastern United States relative to some parts of the country (e.g., the Rockies and northern Plains), and because of the sizable population density in those regions, the southern and eastern states are especially vulnerable to the hazards posed by derechos. But does this mean that derechos necessarily are more common there?

Weather.gov - NWS storm surveys for Arkansas and Lousiana from April 4, 2011

Same for Georgia

Wikipedia with a complete list of all 46 tornadoes and a decent breakdown of the event

My hope is to use this thread to talk about other severe weather events in the month of April 2011 as those anniversaries come, including April 27, 2011.

This post was edited on 4/5/21 at 1:38 pm