Snow Across the Great Lakes, Central Appalachians, and Northeast; Unsettled Weather in the West

Light to moderate snow will continue into Saturday over the Great Lakes, Central Appalachians, and Northeast. This weekend into next week, a series of atmospheric rivers will bring gusty winds, periods of heavy rain, and mountain snow to northern California and the Pacific Northwest. Colder temperatures are in store for the weekend from the Great Lakes to East Coast. Read More >

Overview

A multi-day severe weather event unfolded across a large portion of the United States near the end of April 2014. Severe weather occurred from the Central Plains, into the Southeast, and eventually affected the Mid-Atlantic States. Several rounds of severe thunderstorms developed across the Four State Region beginning late on April 27, 2014, before storms finally moved east of the area during the evening of April 28, 2014.

The first thunderstorm developed during the late afternoon of April 27 across North Texas. This storm moved northeast and eventually produced quarter-size hail during the early evening hours in McCurtain County in Southeast Oklahoma. Additional thunderstorms developed later in the night and moved east-northeast across East Texas and into Western Louisiana and Southern Arkansas. One of these storms produced hail ranging in size from golf balls (1.75" in diameter), to tennis balls (2.50" in diameter), to softballs (4.50" in diameter). The report of softball-sized hail near Atlanta, TX, in Cass County, was confirmed via a picture sent to local media. Very large hail from this storm was reported along its track from Alba, TX, in Wood County to Atlanta.

Another one of these overnight thunderstorms strengthened as it moved into Extreme Northwest Louisiana during the early morning hours of April 28. Damage from a damage from a suspected tornado was reported west of Plain Dealing, LA, in Bossier Parish. Once the sun came up, a survey team from the National Weather Service office in Shreveport investigated the damage. The team determined that a tornado began in Caddo Parish, in the town of Hosston, LA, and ended near where the damage was reported west of Plain Dealing. This tornado was rated EF2 based on damage to a house west of Plain Dealing.

Additional damage was reported farther south in Panola and Rusk Counties in East Texas. A second survey team was deployed to investigate these reports. The team determined that the damage was caused by straight-line winds.

TOTAL TORNADO COUNT = 1

EF2 = 1

Tornado Table

Graphics

Photos

Damage Map

TOR. #	START POINT	END POINT	RATING	PEAK WIND	START TIME	END TIME	LENGTH/ WIDTH	FATALITIES/ INJURIES	REMARKS
#1	Hosston, Caddo Parish, LA	5 miles W of Plain Dealing, Bossier Parish, LA	EF2	115 mph	3:09am CDT	3:15am CDT	5 miles/ 550 yards	None	This tornado began near Hosston, LA, and produced EF-0 and EF-1 damage uprooting and snapping trees as it travelled ENE. One home in Hosston sustained minor damage. The tornado crossed the Red River and into Bossier Parish and produced EF-2 damage when a home was lifted and shifted off its foundation by 2 feet. This tornado finally dissipated about 5 miles west of Plain Dealing, LA, just north of the intersection of Millers Bluff Road and State Highway 537.

Why did thunderstorms not develop until the late evening and overnight hours? The top left image below is the upper-air observation from Shreveport at 00z on April 28 (7pm CDT on April 27). The red line indicates the temperature as the weather balloon went from the surface (bottom of the reading) to higher in the atmosphere. Usually, the temperature decreases with height (temperature scale increases from right to left along the bottom of the image). Notice the point where the temperature line goes sharply to the right just below 700mb. This is a called an "inversion" because the temperature profile is inverted; the temperature stays the same or slightly increases. When forecasting thunderstorms, meteorologists typically cally this a "capping inversion" or a "cap" because this warm, stable layer of air caps the atmosphere, prevents air from rising and keeps thunderstorms from developing. Earlier soundings taken at 12z and 18z indicated a very strong cap that stayed in place for much of the day.

The 500mb upper-air analysis from 00z on April 28 (top right image) showed a strong upper trough was moving from northeast Colorado and into the Central Plains. At the same time, a strong upper level jet streak was moving across the Southern Plains. The combination of these features provided enhanced lifting that finally overcame the cap during the evening hours and led to thunderstorm development along a dryline that was located across Southeast Oklahoma and East Texas. The bottom left image shows the dryline and other surface features at 00z on April 28.