Atmospheric River Bringing Heavy Rain to Southern California and Heavy Snow to the Sierra Nevadas

A strong atmospheric river will continue heavy rain over southern California through Friday. The heaviest rainfall is ongoing today in the Los Angeles Basin. Flash and urban flooding is possible. A prolonged heavy snowfall has begun over the Sierra Nevada Mountains and will continue through Friday. Travel will become increasingly difficult over the passes due to snow and strong winds. Read More >

Overview

The NWS conducted a Storm Damage Survey early Thursday June 21, 2012 on storms which impacted southeastern Nelson and southern Grand Forks Counties on the preceding Wednesday evening, 20 June 2012. The survey confirmed that a persistent but non-damaging funnel had occurred over east-central Alder Township, in Nelson County, south of Petersburg. The survey also confirmed weak tornado damage from two distinct tornadoes which occurred along a line between Kempton (northeast of Northwood) and Thompson, in Grand Forks County. No significant structural damages were observed.

Tornado
Storm Reports

Tornadoes:

Tornado - 4 E Kempton, ND
GRAND FORKS COUNTY

Date	June 20, 2012
Time (Local)	6:49 PM
EF Rating	F0
Est. Peak Winds	70 mph
Path Length	1 mile
Max Width	20 yards
Injuries/Deaths	0/0
Summary: This long, thin and rope-like tornado lasted for just a couple of minutes and tracked eastward for about one mile, nearly to the Avon and Pleasant View township line. Numerous large branches were knocked down in a farmstead shelter belt and a couple of large tree limbs were snapped off in a field shelterbelt. Maximum width estimated to 20 yards and peak winds estimated to 70 mph.

Tornado - 7 ENE Northwood
GRAND FORKS COUNTY

Date	June 20, 2012
Time (Local)	7:02 PM
EF Rating	F1
Est. Peak Winds	90 mph
Path Length	2 miles
Max Width	30 yards
Injuries/Deaths	0/0
Summary: This rope like tornado lasted for over 4 minutes and tracked due east for nearly two miles in the far northwest corner of Union township. Several tree tops were snapped in field shelter belts and at least one tree was uprooted near a farmstead shelterbelt. Maximum width estimated to around 30 yards and peak winds estimated to 90 mph.

The Enhanced Fujita (EF) Scale classifies tornadoes into the following categories:

EF0 Weak 65-85 mph	EF1 Moderate 86-110 mph	EF2 Significant 111-135 mph	EF3 Severe 136-165 mph	EF4 Extreme 166-200 mph	EF5 Catastrophic 200+ mph

Storm Reports

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
338 PM CDT THU JUN 21 2012

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0350 PM     HAIL             MAZA                    48.39N 99.20W
06/20/2012  E0.75 INCH       TOWNER             ND   PUBLIC

0549 PM     HAIL             MICHIGAN                48.03N 98.12W
06/20/2012  E0.75 INCH       NELSON             ND   CO-OP OBSERVER

0611 PM     FUNNEL CLOUD     8 SSE PETERSBURG        47.90N 97.93W
06/20/2012                   NELSON             ND   PUBLIC

            AFTER STORMS WENT THROUGH A THIN FUNNEL CLOUD APPEARED ON
            THE BACK EDGE OF THE CLOUD. IT APPEARED TO BE JUST SOUTH
            OF PETERSBURG BUT WAS MORE DISTANT AND MORE CLOSELY
            VIEWED OVER EAST CENTRAL ALDER TOWNSHIP. FROM A DISTANCE
            THE FUNNEL APPEARED TO BE NEAR THE GROUND BUT AS VIEWED
            FROM NEARBY THE FUNNEL REMAINED SEVERAL HUNDRED FEET
            ABOVE THE TREE TOPS.

0630 PM     HAIL             5 NE NASH               48.52N 97.44W
06/20/2012  E0.50 INCH       WALSH              ND   TRAINED SPOTTER

            SO MUCH HAIL FELL GROUND WAS COVERED.

0630 PM     TSTM WND DMG     5 NE NASH               48.52N 97.44W
06/20/2012                   WALSH              ND   TRAINED SPOTTER

            APPROXIMATELY THE TOP 30 FEET OF 100 FOOT COTTONWOOD TREE
            TWISTED OF AS GUST FRONT PUSHED THROUGH FARMSTEAD. NO
            OTHER DAMAGE REPORTED.

0649 PM     TORNADO          4 E KEMPTON             47.82N 97.53W
06/20/2012  F0               GRAND FORKS        ND   PUBLIC

            THIS LONG... THIN AND ROPE LIKE TORNADO LAST FOR JUST A
            COUPLE OF MINUTES AND TRACKED EASTWARD FOR ABOUT ONE
            MILE... NEARLY TO THE AVON AND PLEASANT VIEW TOWNSHIP
            LINE. NUMEROUS LARGE BRANCHES WERE KNOCKED DOWN IN A
            FARMSTEAD SHELTER BELT AND A COUPLE OF LARGE TREE LIMBS
            WERE SNAPPED OFF IN A FIELD SHELTERBELT. MAXIMUM WIDTH
            ESTIMATED TO 20 YARDS AND PEAK WINDS ESTIMATED TO 70 MPH.


0702 PM     TORNADO          7 ENE NORTHWOOD         47.77N 97.43W
06/20/2012  F1               GRAND FORKS        ND   NWS STORM SURVEY

            THIS ROPE LIKE TORNADO LASTED FOR OVER 4 MINUTES AND
            TRACKED DUE EAST FOR NEARLY TWO MILE IN THE FAR NORTHWEST
            CORNER OF UNION TOWNSHIP. SEVERAL TREE TOPS WERE SNAPPED
            IN FIELD SHELTER BELTS AND AT LEAST ONE TREE WAS UPROOTED
            NEAR A FARMSTEAD SHELTERBELT. MAXIMUM WIDTH ESTIMATED TO
            AROUND 30 YARDS AND PEAK WINDS ESTIMATED TO 90 MPH.

0725 PM     HAIL             2 N THOMPSON            47.80N 97.11W
06/20/2012  E0.75 INCH       GRAND FORKS        ND   TRAINED SPOTTER

            ABOUT FOUR MINUTES OF PEA TO PENNY SIZED HAIL ALONG WITH
            VERY STRONG WINDS.

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Atmospheric River Bringing Heavy Rain to Southern California and Heavy Snow to the Sierra Nevadas

June 20, 2012 - 2 weak tornadoes in Grand Forks county