Atmospheric River in the Pacific Northwest and Northern Rockies this Weekend

A Pacific storm and atmospheric river will impact the Pacific Northwest states and northern Rockies this weekend, bringing locally heavy low elevations rain and heavy high elevation snow in the mountains. By Sunday over the Interior Northwest, rain combined with snowmelt will increase the risk of flood hazards. Flood Watches are in effect. Read More >

Overview

A strong spring storm system moved across the Four State Region during the afternoon and evening of April 6, 2018. In a very warm and unstable atmosphere, a line of severe thunderstorms developed ahead of a cold front and moved southward across the region. These storms produced strong, damaging straight-line winds across much of the area. Ahead of the line to the south, numerous individual supercells developed. Many of these supercells produced large hail across the region, especially in Northeast Texas and Northwest Louisiana. Several reports of hail up to the size of golfballs were received. Some of these supercells also developed strong rotation.

One supercell in particular, near Coushatta, LA, was especially intense. This storm presented a very strong rotational couplet on radar and a very apparent Tornado Debris Signature in the dual-polarization data. Another brief tornado occurred between Natchez and Colfax, near the Melrose community in southern Natchitoches Parish.

Storm survey teams from the NWS-Shreveport were deployed to assess the damage from Friday's storms. The results of the surveys can be found below. The included map shows the tornado tracks and the reports of damaging winds and hail. This information is PRELIMINARY until published by NCEI in "Storm Data."

TOTAL TORNADO COUNT = 2

EF1 = 1

EF2 = 1

Tornado #1: Near Coushatta, LA

*CLICK TO VIEW ON MAP*
START POINT	8 miles W of Coushatta, De Soto Parish, LA
END POINT	2 miles ESE of Coushatta, Red River Parish, LA
RATING / PEAK WIND	EF2 / 125 mph
DATE	April 6, 2018
START TIME	7:31pm CDT
END TIME	8:02pm CDT
LENGTH/ WIDTH	10.26 miles/ 1800 yards
FATALITIES/ INJURIES	None
Summary: A tornado touched down along Highway 510 in eastern De Soto Parish near the Wemple community where it caused minor tree damage. It continued east across Bayou Pierre and produced significant tree damage with numerous uprooted and snapped trees along and near Highway 177. It also snapped a few utility poles and did significant damage to a large metal structure where it buckled the support beams as it crossed Highway 177. It continued east where it paralleled Highway 371 and snapped numerous trees. The tornado was at its strongest and widest as it crossed Highway 84 near the Armistead community. It destroyed a metal building and a few smaller metal outbuildings, a farm irrigation system, and snapped more utility poles. It caused more tree damage and snapped more utility poles along Riverfront Road before it crossed the Red River. It moved more east-southeast where it crossed Clark Street causing more significant tree damage and lifting a large metal framed carport and barn at a home here. The tornado continued moving east where it crossed Highway 480 before causing more widespread tree damage along Postell Springville, and Newton Roads. The tornado then turned slightly northeast before lifting near the intersection of Bruce Street and Highway 71 where it snapped and uprooted several trees.

Tornado #2: Near Melrose, LA

*CLICK TO VIEW ON MAP*
START POINT	6 miles SE of Natchez, Natchitoches Parish, LA
END POINT	6 miles SE of Natchez, Natchitoches Parish, LA
RATING / PEAK WIND	EF1 / 90-100 mph
DATE	April 6, 2018
START TIME	9:14pm CDT
END TIME	9:18pm CDT
LENGTH/ WIDTH	0.74 miles/ 50 yards
FATALITIES/ INJURIES	None
Summary: This tornado began along Louisiana Highway 484 very close to the Jerry Jones House, also called the Jones-Roque House, in the Isle Brevelle community near Melrose along the Cane River. Some minor roof damage with loss of shingles occurred to a home, and some of the metal roof of the Jerry Jones House was uplifted and removed. At the first home, a pickup truck parked in wet grass was pushed backwards 10 feet, and a SUV was flipped onto its roof. As this tornado traveled east-northeast, most of the damage was to pecan trees that were uprooted, snapped, and had large branches broken and twisted out of the tops of the trees. The tornado crossed the Cane River snapping and uprooting more trees. A wooden electrical pole was also snapped about halfway up its length. The tornado crossed Louisiana Highway 119 and moved into a pecan orchard breaking more large branches. The tornado moved into an adjacent open field and lifted. Local residents noted that a couple of the trees that sustained significant damage along the Cane River were in excess of 200 years old.

Click here to download the survey KMZ file.

This survey data is preliminary and subject to change as more information becomes available. Road accessibility and inconsistencies between mapping and GPS software may limit the accuracy of the tracks plotted on this map. Line widths are not representative of actual tornado widths. The information plotted on this map is intended for general reference use only.

For official post-storm information, use Storm Data from the National Centers for Environmental Information.

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Atmospheric River in the Pacific Northwest and Northern Rockies this Weekend

April 6, 2018: Severe Weather & Tornadoes