Friday, May 24, 2019

High Winds in Northern Utah

Easterly flow caused high winds to northern Utah on 23 May 2019 and with it, many power outages (KSL story).

This picture is from my grandpa's backyard in North Logan. Winds knocked down many trees and fences in the neighborhood...


At 0700 UTC (1:00 AM local time), winds gusts exceeded 60 MPH in Brigham City.

Maximum wind gusts exceeding 40 MPH for the previous 24 hours at 1800 UTC (12:00 PM local time) are shown below...

The HRRR forecasts compared with HRRR 3-yr climatology shows this was an exceptional wind event for this time of year and location. Below shows that the wind speeds in northern Utah exceeded the 95th percentile wind speed by over 10 m/s.
Area Forecast Discussion 
  National Weather Service Salt Lake City UT 
  413 AM MDT Thu May 23 2019 
   
  .SYNOPSIS... 
  The unsettled weather pattern with a trough over the western  
  United States will continue through Friday. There will be  
  somewhat of a hiatus Saturday into Sunday as the trough redevelops 
  a little farther west allowing a drier southwest flow aloft to 
  prevail. This new trough will move across Utah early next week. 
   
  && 
   
  .SHORT TERM (Through 00Z Monday)...Strong easterly winds have been 
  blowing overnight across the northern Wasatch Front and Cache 
  Valley. These winds are expected to remain strong through at least 
  early morning as the 700mb winds remain above 35 kts from about  
  Brigham City northward as well as across the Cache Valley. Farther 
  south the winds have not been as strong as the 700mb winds near  
  the Ogden area were forecast to only be 30 kts earlier this  
  evening and are forecast to be down to under 20 kts by mid  
  morning. May be able to drop the High Wind Warning highlight  
  sooner than later, especially for Davis and Weber counties. The  
  strength of these easterly winds downsloping along the northern  
  Wasatch Front and Cache Valley has prevented showers from  
  occurring overnight, but as these winds relax and the instability  
  of the cold pocket aloft moves in from the south later this  
  morning through this afternoon showers will become widespread.

Area Forecast Discussion 
  National Weather Service Salt Lake City UT 
  1033 AM MDT Thu May 23 2019 
   
  .SYNOPSIS... 
  The upper level low pressure over northwest Utah will maintain  
  unsettled weather across much of the region through early Friday. 
  The low pressure will exit the area and bring a break in  
  widespread precipitation Friday night through the weekend. The  
  next storm system will move across Utah early next week. 
   
  && 
   
  .DISCUSSION...The upper trough centered over the Great Basin is 
  showing multiple circulation centers this morning. These 
  circulations will consolidate into one center over northwest Utah 
  this afternoon, then lift northeast toward the northern Plains   
  later tonight through Friday. A residual upper trough will remain 
  behind the exiting upper low, with this feature merging with the 
  next upper low moving into the Pacific Northwest early in the 
  weekend.  
   
  The canyon/downslope high wind event for areas north of SLC is  
  winding down late this morning. Decreasing easterly near 700 mb  
  winds and the retreat of the tight northeast surface gradient back 
  into western/central Wyoming signals the end of the strongest  
  winds, though gusty easterly winds will continue through around  
  mid-afternoon. Will keep the current High Wind Warning going  
  through the scheduled expiration at 19Z.

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