Localized Downburst Winds Near Roscoe April 24th, 2012

The combination of decaying showers and thunderstorms, along with a very dry air mass above the surface, allowed higher wind speeds aloft to descend in a highly localized manner near Roscoe, in Keith County - on Tuesday evening at around
725 PM MDT (625 PM MDT).

Dry microbursts, produced by high based thunderstorms that generate little surface rainfall, occur in environments characterized by a thermodynamic profile exhibiting an inverted-V thermal and moisture profile, as viewed on a Skew-T log-P thermodynamic diagram. Some radar animations, and examples of the inverted-V profiles will be provided below. Damage photographs taken near Roscoe are also located below.

Damage near Roscoe

Damage near Roscoe

Damage near Roscoe

Click here for a GR2Analyst radar loop

Radar Loop from the evening of April 24th, 2012
Radar Loop above, from the evening of April 24th, 2012

Click here for brief animation of atmospheric soundings from North Platte, Nebraska
(provided courtesy of the University of Wyoming)


Atmospheric sounding from North Platte valid 7 PM CDT April 24th
Atmospheric sounding above, from North Platte
valid 7 PM CDT April 24th, 2012

.TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON  
   
.DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE.
 
 
..REMARKS..  
 
0725 PM TSTM WND GST 2 S ROSCOE 41.11N 101.60W  
04/24/2012 E80.00 MPH KEITH NE EMERGENCY MNGR  
 
*** 1 INJ *** SEMI-TRAILER BLOWN OFF INTERSTATE 80 MILE  
MARKER 134. WIND SPEED IS ESTIMATED.  
 
0725 PM TSTM WND GST ROSCOE 41.13N 101.60W  
04/24/2012 E80.00 MPH KEITH NE EMERGENCY MNGR  
 
TWO CAR GARAGE COMPLETELY DEMOLISHED AND A 12 INCH  
DIAMETER PINE TREE IN THE YARD SNAPPED IN HALF 8 FEET  
ABOVE THE GROUND.  
 
0725 PM TSTM WND GST ROSCOE 41.13N 101.60W  
04/24/2012 E80.00 MPH KEITH NE EMERGENCY MNGR  
 
TWO POWER POLES WERE BENT OVER AT A 45 DEGREE ANGLES DUE  
TO STRAIGHT LINE WINDS.  
 
0728 PM TSTM WND GST 4 E ROSCOE 41.13N 101.52W  
04/24/2012 E80.00 MPH KEITH NE EMERGENCY MNGR  
 
*** 1 INJ *** CAR BLOWN OFF INTERSTATE 80 AT MILE MARKER  
137 DUE TO STRAIGHT LINE WINDS.  
Preliminary local storm reports above

Page composition
by
Steve Carmel


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